Bevis, M. G., E. Kendrick, R. Smalley, I. W. D. Dalziel, D. J. Caccamise, I. Sasgen, M. Helsen, F. W. Taylor, H. Zhou, A. Brown, D. Raleigh, M. Willis, T. J. Wilson, and S. Konfal, Geodetic measurements of vertical crustal velocity in West Antarctica and implications for ice mass balance, Geochem., Geophys., Geosyst., 10, Q10005, 2009, 10 citations, doi:10.1029/2009GC002642, #2135 
We present preliminary geodetic estimates for vertical bedrock velocity at twelve survey GPS stations in the West Antarctic GPS Network, an additional survey station in the northern Antarctic Peninsula, and eleven continuous GPS stations distributed across the continent. The spatial pattern of these velocities is not consistent with any postglacial rebound (PGR) model known to us. Four leading PGR models appear to be overpredicting uplift rates in the Transantarctic Mountains and West Antarctica and underpredicting them in the peninsula north of 65°. This discrepancy cannot be explained in terms of an elastic response to modern ice loss (except, perhaps, in part of the peninsula). Therefore, our initial geodetic results suggest that most GRACE ice mass rate estimates, which are critically dependent on a PGR correction, are systematically biased and are overpredicting ice loss for the continent as a whole.
Burr, G. S., J. W. Beck, C. Thierry, G. Cabioch, F. W. Taylor, and D. J. Donahue, Modern and Pleistocene reservoir ages inferred from South Pacific corals, Radiocarbon, 51, 319-335, 2009, 3 citations, #2072
Frohlich, C., M. J. Hornbach, F. W. Taylor, C.-C. Shen, A. Moala, A. E. Morton, and J. Kruger, Huge erratic boulders in Tonga deposited by a prehistoric tsunami, Geology, 37, 131-134, 2009, 19 citations, doi:10.1130/G25277A.1, #2000
Along some coastlines there are erratic boulders apparently emplaced by tsunamis or cyclonic storms; evaluating their origin and time of emplacement places constraints on the frequency, severity, and location of coastal hazards. Seven such large coral limestone boulders are present near Fahefa village on Tongatapu Island, southwest Pacific, apparently emplaced by a prehistoric tsunami. These boulders are 10–20 m above sea level and above any possible source, and all are 100–400 m from the present shoreline. Coral 230Th ages indicate that the limestone formed during the last interglacial sea-level highstand, ca. 120–130 ka. The largest boulder is ~20 times more massive than any reported boulders emplaced by historically documented storms and may be the largest known tsunami or storm erratic worldwide situated above its source. We performed computer simulations to assess whether tsunamis produced by earthquakes, undersea landslides, or volcanoes could emplace the boulders. The simulations indicate that either volcanic flank collapse along the Tofua arc ~30–40 km to the southwest or undersea landslides on the submarine slopes of Tongatapu could be responsible. Either could explain why these boulders are not widespread on Tongatapu, and instead occur in a localized group along the western coast. This study demonstrates that small (<1 km3) submarine slope failures sometimes generate locally large tsunamis. The Fahefa boulders are in a well-studied and well-populated area, yet were unknown to the scientific community until recently; this suggests that systematic searches elsewhere for erratic boulders and other tsunami deposits might provide new information for assessing the size and extent of prehistoric tsunamis.
Shen, C.-C., K.-S. Li, K. Sieh, D. Natawidjaja, H. Cheng, X. Wang, R. L. Edwards, D. D. Lam, Y.-T. Hsieh, T.-Y. Fan, A. J. Meltzner, F. W. Taylor, T. M. Quinn, H.-W. Chiang, and K. H. Kilbourne, Variation of initial 230Th/232Th and limits of high precision U-Th dating of shallow-water corals, Geochimica et Cosmochimica Acta, 72, 4201-4223, 2008, 26 citations, doi:10.1016/j.gca.2008.06.011, #1944
One hundred eighty UâTh data, including 23 isochrons on 24 pristine modern and Holocene corals and 33 seawater samples, were analyzed using sector-field mass spectrometry to understand the variability of initial 230Th/232Th (230Th/232Th0). This dataset allows us to further assess the accuracy and precision of coral 230Th dating method. By applying quality control, including careful sampling and subsampling protocols and the use of contamination-free storage and workbench spaces, the resulting low procedural blanks give an equivalent uncertainty in age of only ±0.2â0.3 yr for 1â2 g of coral sample. Using site-specific 230Th/232Th0 values or isochron techniques, our study demonstrates that corals with an age less than 100 yrs can be 230Th-dated with precisions of ±1 yr. Six living subtidal coral samples were collected from two continental shelf sites, Nanwan off southern Taiwan in the western Pacific and Son Tra off central Vietnam in the South China Sea; one coral core was drilled from an open-ocean site, Santo Island, Vanuatu, in the western tropical Pacific; and modern and fossil intertidal coral slabs, 17 in total, were cut from six sites around the islands of Simeulue, Lago, North Pagai and South Pagai of Sumatra in the eastern Indian Ocean. The results indicate that the main source of thorium is the dissolved phase of seawater, with variation of 230Th/232Th0 depending on local hydrology. With intense input of terrestrial material, low 230Th/232Th0 atomic ratios of 4.9 à 10−6 and 3.2 à 10−6 with a 10% variation are observed in Nanwan and Son Tra, respectively. At the Santo site, we find a value of 5.6 à 10−6 at 4 horizons and one high value of 24 à 10−6 in a sample from AD 1974.6 ± 0.5, likely due to the upwelling of cold water during a La Niña event between AD 1973 and 1976. The natural dynamics of 230Th/232Th0 recorded in the intertidal corals at sites in the Sumatran islands are complicated so that this value varies significantly from 3.0 to 9.4 à 10−6. Three of the 141 modern coral 230Th ages differ from their true ages by −23 to +4, indicating the presence of detrital material with anomalous 230Th/232Th values. Duplicate measurement of coeval subsamples is therefore recommended to verify the age accuracy. This improved high precision coral 230Th dating method raises the prospects of refining the age models for band-counted and tracer-tuned chronologies and of advancing coral paleoclimate research.
Taylor, F. W., M. G. Bevis, I. W. D. Dalziel, R. Smalley, C. Frohlich, E. Kendrick, J. Foster, D. A. Phillips, and K. Gudipati, Kinematics and segmentation of the South Shetland Islands-Bransfield basin system, northern Antarctic Peninsula, Geochem., Geophys., Geosyst., 9, Q04035, 2008, 4 citations, doi:10.1029/2007GC001873, #1938
New GPS measurements demonstrate tectonic segmentation of the South Shetland Islands platform, regarded as a microplate separating the Antarctic Peninsula from the oceanic portion of the Antarctic plate. King George, Greenwich, and Livingston islands on the central and largest segment are separating from the Antarctic Peninsula at 7-9 mm/a, moving NNW, roughly perpendicular to the continental margin. Smith and Low islands on the small southwestern segment are moving in the same direction, but at 2.2-3.0 mm/a. The Elephant Island subgroup in the northeast moves at 7 mm/a relative to the Peninsula, like the central group, but toward the WNW. This implies that it is presently coupled to the Scotia plate on the northern side of the South Scotia Ridge transform boundary; thus the uplift of these northeasternmost islands may be caused by Scotia-Antarctic plate convergence rather than by subduction of thickened oceanic crust.
Taylor, F. W., R. W. Briggs, C. Frohlich, A. Brown, M. J. Hornbach, A. K. Papabatu, A. J. Meltzner, and D. Billy, Rupture across arc segment and plate boundaries in the 1 April 2007 Solomons earthquake, Nature Geoscience, 1, 253-257, 2008, 15 citations, doi:10.1038/ngeo159, #1939
The largest earthquakes are generated in subduction zones, and the earthquake rupture typically extends for hundreds of kilometres along a single subducting plate. These ruptures often begin or end at structural boundaries on the overriding plate that are associated with the subduction of prominent bathymetric features of the downgoing plate1, 2. Here, we determine uplift and subsidence along shorelines for the 1 April 2007 moment magnitude MW 8.1 earthquake in the western Solomon Islands, using coral microatolls which provide precise measurements of vertical motions in locations where instrumental data are unavailable. We demonstrate that the 2007 earthquake ruptured across the subducting Simbo ridge transform and thus broke through a triple junction where the Australian and Woodlark plates subduct beneath the overriding Pacific plate. Previously, no known major megathrust rupture has involved two subducting plates. We conclude that this event illustrates the uncertainties of predicting the segmentation of subduction zone rupture on the basis of structural discontinuities.
Delong, K. L., T. M. Quinn, and F. W. Taylor, Reconstructing 20th century sea surface temperature variability in the southwest Pacific: A replication study using multiple coral Sr/Ca records from New Caledonia, Paleoceanography, 22, PA4212, 2007, 11 citations, doi:10.1029/2007PA001444, #1875
Coral-based climate reconstructions typically have not used multiple cores from a region to capture and replicate a climate signal largely because of concerns of coral conservation, analytical expense, and time constraints. Coral Sr/Ca reproducibility through the twentieth century was investigated using three intracolony and three intercolony coral records from the reefs offshore of Amédée Island, New Caledonia. Different sampling resolutions were examined in coral Sr/Ca (fortnightly and monthly) and δ 18O (fortnightly, monthly, and seasonally) as well as similar scale subsampling of the daily in situ sea surface temperature (SST) record. The mean coral Sr/Ca, δ 18O, and SST values do not change as a function of sampling resolution. The coral Sr/Ca signal is highly reproducible; the average absolute offset between coeval monthly Sr/Ca determinations between any two coral time series is 0.035 ± 0.026 mmol/mol (1σ) (∼0.65°C), which is less than twice the analytical precision of the coral Sr/Ca measurements. The stack average of the monthly coral Sr/Ca variations and monthly anomalies are significantly correlated with monthly in situ SST (1967â1992; r = −0.96 and −0.64, respectively; p < 0.05; and n = 302) and 1° grid monthly SST data product (1900â1999; r = −0.95 and −0.56, respectively; p < 0.05; and n = 1198). The coral Sr/CaâSST reconstruction exhibits interannual and decadal- timescale fluctuations that exceed those observed in the gridded SST record, which may reflect true differences between SST at a shallow reef site and those averaged over a 1° grid box or inadequacies in the methodology used to create the gridded SST product when few observations are available. A warming trend of ∼0.6°C is observed in the twentieth century coral Sr/CaâSST record.
Holland, C. L., R. B. Scott, S.-I. An, and F. W. Taylor, Propagating decadal sea surface temperature signal identified in modern proxy records of the tropical Pacific, Climate Dynamics, 28, 163-179, 2007, 4 citations, doi:10.1007/s00382-006-0174-0, #1830
Analysis of 86 years of multiple modern coral δ18O records in the tropical Pacific reveals a basin-scale decadal pattern of variability. Although coral δ18O records the effects of both temperature and seawater δ18O variability due to salinity effects, in practice, most of the records used here agree well with observations of sea surface temperature on longer timescales. These coral proxy records reveal strong variability near a 12-year period. Their relative phasing suggests a signal propagating from the southwestern subtropical Pacific to other regions. The results are consistent with recent studies based on instrumental data and with coupled climate model studies, in which advection of thermal anomalies leads to El Niño/Southern Oscillation-like variability on decadal timescales. Additionally, there is evidence for a significant shift in many of the time series, along with a decrease in the decadal variability, occurring in the early 1940s. Finally, the proxy records indicate the presence of strong teleconnections between the eastern tropical Pacific and high latitude climate.
Kilbourne, K. H., T. M. Quinn, T. P. Guilderson, R. S. Webb, and F. W. Taylor, Decadal- to interannual-scale source water variations in the Caribbean sea recorded by Puerto Rican coral radiocarbon, Climate Dynamics, 29, 51-62, 2007, 8 citations, doi:10.1007/s00382-007-0224-2, #1914
Water that forms the Florida Current, and eventually the Gulf Stream, coalesces in the Caribbean from both subtropical and equatorial sources. The equatorial sources are made up of, in part, South Atlantic water moving northward and compensating for southward flow at depth related to meridional overturning circulation. Subtropical surface water contains relatively high amounts of radiocarbon (14C), whereas equatorial waters are influenced by the upwelling of low 14C water and have relatively low concentrations of 14C. We use a 250 year record of Δ14C in a coral from southwestern Puerto Rico along with previously published coral Δ14C records as tracers of subtropical and equatorial water mixing in the northern Caribbean. Data generated in this study and from other studies indicate that the influence of either of the two water masses can change considerably on interannual to interdecadal time scales. Variability due to ocean dynamics in this region is large relative to variability caused by atmospheric 14C changes, thus masking the Suess effect at this site. A mixing model produced using coral Δ14C illustrates the time varying proportion of equatorial versus subtropical waters in the northern Caribbean between 1963 and 1983. The results of the model are consistent with linkages between multidecadal thermal variability in the North Atlantic and meridional overturning circulation. Ekman transport changes related to tradewind variability are proposed as a possible mechanism to explain the observed switches between relatively low and high Δ14C values in the coral radiocarbon records.
Smalley, R., I. W. D. Dalziel, M. G. Bevis, E. Kendrick, D. S. Stamps, E. C. King, F. W. Taylor, E. Lauria, A. Zakrajsek, and H. Parra, Scotia arc kinematics from GPS geodesy, Geophys. Res. Lett., 34, L21308, 2007, 6 citations, doi:10.1029/2007GL031699, #1892
GPS crustal velocity data from the Scotia and South Sandwich plates, transform azimuths, spreading data, and an updated earthquake slip vector catalog provide the first Scotia and South Sandwich plate Euler vector estimates not dependent on closure as the GPS data tie them to the global plate circuit. Neither the GPS data, which sample limited portions of the plates, nor the geologic data, which are not tied to the global spreading circuit, are sufficient individually to define the Euler vectors. As Scotia plate GPS measurements do not sample the stable plate interior, plate boundary deformation field modeling is necessary for Euler vector estimation. Our South America-Antarctic and Scotia-South Sandwich Euler pole estimates agree with previous estimates from either GPS or geologic data. Our South America-Scotia Euler vector, however, is significantly different and near the South America-Antarctic Euler vector producing an approximately coaxial motion of Scotia between South America and Antarctica.
Gallup, C. D., D. M. Olson, R. L. Edwards, L. M. Gruhn, A. Winter, and F. W. Taylor, Sr/Ca-sea surface temperature calibration in the branching Caribbean coral Acropora palmata, Geophys. Res. Lett., 33, L03606, 2006, 2 citations, doi:10.1029/2005GL024935, #1846
We measured Sr/Ca ratios by thermal ionization mass spectrometry in radial and axial growth of modern Caribbean Acropora palmata corals. Comparison of our results with sea surface temperature (SST) allows radial and axial Sr/Ca-SST calibrations of Sr/Ca (mmol/mol) = 11.30 − 0.07072 Ãâ SST (ðC) and Sr/Ca (mmol/mol) = 11.32 ââ¬â 0.06281 x SST (ðC), respectively. Application of the calibrations to fossil Acropora palmata from the last glacial maximum in Barbados (Guilderson et al., 1994) imply ∼7ðC cooler conditions than the present, much larger than the 1ââ¬â1.5ð cooling suggested by modern analog technique foraminifera-based estimates (Trend-Staid and Prell, 2002). If the foraminifera-based estimates are correct, then the excess cooling suggested by the Barbados corals could be explained by a 5% shift in the marine Sr/Ca ratio or an addition of ∼20% abiotic secondary aragonite.
Quinn, T. M., and F. W. Taylor, SST artifacts in coral proxy records produced by early marine diagenesis in a modern coral from Rabaul, Papua New Guinea, Geophys. Res. Lett., 33, L04601, 2006, 15 citations, doi:10.1029/2005GL024972, #1813
We investigated the effects of early marine diagenesis on the skeletal geochemistry of a Porites coral collected live offshore of Rabaul, Papua New Guinea. The lowermost 14 cm of the ∼1.9 m coral core contains physical evidence of alteration, which is clearly visible in X-radiograph, SEM and petrography images. Abrupt and significant increases in coral δ18O and Sr/Ca, and decreases in coral Mg/Ca occur at the transition from unaltered to altered skeleton, all of which imply significant SST cooling, if the altered nature of the coral skeleton went unrecognized. Screening for the effects of early marine diagenesis should become a standard procedure in coral-climate studies.
Quinn, T. M., F. W. Taylor, and T. J. Crowley, Coral-based climate variability in the Western Pacific Warm Pool since 1867, J. Geophys. Res., 111, C11006, 2006, 8 citations, doi:10.1029/2005JC003243, #1907
We have generated monthly resolved, stable isotope (δ 18O and δ 13C) and Sr/Ca time series from a massive Porites coral from Rabaul (4°S, 152°E): a site located in the warmest sector of the Western Pacific Warm Pool (WPWP). The coral δ 18O and Sr/Ca time series are well correlated to each other and positive excursions in both records coincide with times of ENSO warm phase events. These time series contain abundant interannual variability that exhibits the well-recognized pattern of low amplitude ENSO variation between ∼1920â1960 and high amplitude ENSO variation between 1880â1920 and 1960â1997. The ENSO-filtered coral δ 18O and Sr/Ca time series are well matched to each other (r = 0.73) and to similarly filtered coral δ 18O records from Papua New Guinea (r > 0.56). There is no long-term trend in the coral δ 18O record, but there is a long-term trend of increasing coral Sr/Ca from 1867 to 1997. This trend in coral Sr/Ca suggests a cooling of ∼0.7°C, which is rather unlikely and implies that factors other than SST may be influencing the coral Sr/Ca record. The trend in coral Sr/Ca is not an analytical artifact, nor a product of time varying riverine input, nor a product of skeletal diagenesis, nor the results of kinetic effects, but may reflect surface-water variability in Sr/Ca. Despite the presence of a nonclimatic trend in coral Sr/Ca, the Rabaul coral records contain abundant interannual- to multidecadal-scale variability, much of which is coherent with other proxy records from the WPWP and with instrumental records of ENSO variability.
Caccamise, D. J., M. A. Merrifield, M. G. Bevis, J. Foster, Y. L. Firing, M. S. Schenewerk, F. W. Taylor, and D. A. Thomas, Sea level rise at Honolulu and Hilo, Hawaii: GPS estimates of differential land motion, Geophys. Res. Lett., 32, L03607, 2005, 12 citations, doi:10.1029/2004GL021380, #1799
Since 1946, sea level at Hilo on the Big Island of Hawaii has risen an average of 1.8 ± 0.4 mm/yr faster than at Honolulu on the island of Oahu. This difference has been attributed to subsidence of the Big Island. However, GPS measurements indicate that Hilo is sinking relative to Honolulu at a rate of −0.4 ± 0.5 mm/yr, which is too small to account for the difference in sea level trends. In the past 30 years, there has been a statistically significant reduction in the relative sea level trend. While it is possible that the rates of land motion have changed over this time period, the available hydrographic data suggest that interdecadal variations in upper ocean temperature account for much of the differential sea level signal between the two stations, including the recent trend change. These results highlight the challenges involved in estimating secular sea level trends in the presence of significant low frequency variability.
Taylor, F. W., P. Mann, M. G. Bevis, R. L. Edwards, H. Cheng, K. B. Cutler, S. C. Gray, G. S. Burr, J. W. Beck, D. A. Phillips, G. Cabioch, and J. Recy, Rapid forearc uplift and subsidence caused by impinging bathymetric features: Examples from the New Hebrides and Solomon arcs, Tectonics, 24, TC6005, 2005, 16 citations, doi:10.1029/2004TC001650, #1800
Isotopically dated corals from the central New Hebrides and New Georgia Island Group, Solomon Islands, indicate that both forearcs underwent rapid late Quaternary subsidence that was abruptly replaced by hundreds of meters of uplift at rates up to ∼8 mm/yr, while total plate convergence was only a few kilometers. Two mechanisms that might account for these rapid reversals in vertical motion include (1) a âdisplacementâ mechanism in which the forearc is displaced upward by the volume of an object passing beneath on the subducting plate (as the object moves deeper and vacates the base of the forearc, the forearc subsides to near its original position) and (2) a âcrustal shorteningâ mechanism in which the forearc thickens and uplifts because of horizontal shortening when a large object impinges on the forearc and abruptly increases interplate coupling on the shallow end of the main thrust zone. Rapid subsidence follows when the impinging object is broken or otherwise decoupled, shallow interplate coupling becomes weak, and the uplifted forearc extends and subsides. The displacement mechanism surely plays a role on timescales over which plates converge tens of kilometers, but it fails to explain the geographic pattern, short time frame, and abruptness of the change from subsidence to uplift that we observe. The crustal shortening mechanism is preferred because it allows the observed abrupt uplift when an object impinges on a forearc and causes locking of a shallow segment of the interplate thrust zone.
Burr, G. S., C. Galang, F. W. Taylor, C. D. Gallup, R. L. Edwards, K. B. Cutler, and B. Quirk, Radiocarbon results from a 13-kyr BP Coral from the Huon Peninsula, Papua New Guinea, Radiocarbon, 46, 1211-1224, 2004, 8 citations, #1753
Cutler, K. B., S. C. Gray, G. S. Burr, R. L. Edwards, F. W. Taylor, G. Cabioch, J. W. Beck, H. Cheng, and J. C. Moore, Radiocarbon calibration and comparison to 50 kyr BP with paired 14C and 230TH dating of corals from Vanuatu and Papua New Guinea, Radiocarbon, 46, 1127-1160, 2004, 29 citations, #1731
Hughen, K. A., M. G. L. Baillie, E. Bard, J. W. Beck, C. J. H. Bertrand, P. G Blackwell, C. E. Buck, G. S. Burr, K. B. Cutler, P. E. Damon, R. L. Edwards, R. G. Fairbanks, M. Friederich, T. P. Guilderson, B. Kromer, G. McCormac, S. Manning, C. B. Ramsey, P. J. Reimer, R. W. Reimer, S. Remmele, J. R. Southon, M. Stuiver, S. Talamo, F. W. Taylor, J. Van Der Plicht, and C. E. Weyhenmeyer, Marine04 radiocarbon age calibration, 0-26 cal kyr BP, Radiocarbon, 46, 1059-1086, 2004, 585 citations, #1798
Kilbourne, K. H., T. M. Quinn, and F. W. Taylor, A fossil coral perspective on western tropical climate ~350 ka, Paleoceanography, 19, PA1019, 2004, 10 citations, doi:10.1029/2003PA000944, #1730
The nature of tropical climate variability ∼350 ka is addressed using δ18O and Sr/Ca records from a modern and a fossil coral from Vanuatu (southwestern tropical Pacific Ocean). Modern El Niño events at Vanuatu produce positive coral δ18O and Sr/Ca anomalies; similar anomalies observed in the fossil coral records suggest that El Niño was operative 350 kyr ago. Seasonal variations in coral Sr/Ca, a sea surface temperature (SST) proxy, have the same amplitude in both corals, whereas seasonal δ18O variations are smaller in the fossil coral than in the modern coral. This is consistent with displacement of the South Pacific Convergence Zone toward the southwest during the boreal summer ∼350 ka. Mathematical modeling results preclude warmer SST and higher SSS at Vanuatu during this time, but permit the surface ocean to be ∼2°C cooler and 0â2 psu fresher than today. Assessing the potential of variations in late Quaternary seawater Sr/Ca remains the largest obstacle to accurately reconstructing tropical SST using pristine fossil corals.
Kilbourne, K. H., T. M. Quinn, F. W. Taylor, T. Delcroix, and Y. Gouriou, El Niño-Southern Oscillation-related salinity variations recorded in the skeletal geochemistry of a Porites coral from Espiritu Santo, Vanuatu, Paleoceanography, 19, PA4002, 2004, 17 citations, doi:10.1029/2004PA001033, #1754
Coral skeletal geochemistry offers the potential to reconstruct the sea surface salinity (SSS) history of the tropical oceans on seasonal to interannual and perhaps centennial timescales because of the strong link between variation in SSS and seawater δ18O in tropical regions. We explore this potential using a monthly resolved, 65-year record of skeletal δ18O and Sr/Ca variations in a Porites coral from Espiritu Santo, Vanuatu. We demonstrate that El NiñoâSouthern Oscillationârelated climate variability strongly influences coral δ18O at Santo through local salinity changes associated with the position of the South Pacific Convergence Zone and the movement of its associated salinity front. Such a demonstration provides the âground truthâ data that can be used to place paleoclimate variability estimated using existing fossil coral records from this region into a modern conceptual framework. We also evaluate different methods of combining coral δ18O and Sr/Ca to reconstruct SSS and conclude that the coral δ18O anomaly time series provides the best fit to recent in situ SSS data at Santo.
Reimer, P. J., M. G. L. Baillie, E. Bard, A. Bayliss, J. W. Beck, C. J. H. Bertrand, P. G. Blackwell, C. E. Buck, G. S. Burr, K. B. Cutler, P. E. Damon, R. L. Edwards, R. G. Fairbanks, M. Friederich, T. P. Guilderson, A. G. Hogg, K. A. Hughen, B. Kromer, G. McCormac, S. Manning, C. B. Ramsey, R. W. Reimer, S. Remmele, J. R. Southon, M. Stuiver, S. Talamo, F. W. Taylor, J. Van Der Plicht, and C. E. Weyhenmeyer, IntCal04 terrestrial radiocarbon age calibration, 0-26 cal kyr BP, Radiocarbon, 46, 1029-1058, 2004, 1986 citations, #1801
Schmidt, A., G. S. Burr, F. W. Taylor, J. K. OMalley, and J. W. Beck, A semiannual radiocarbon record of a modern coral from the Solomon Islands, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 223, 420-427, 2004, 7 citations, doi:10.1016/j.nimb.2004.04.080, #1675
Radiocarbon records from modern corals have long been recognized for their usefulness as a geochemical tracer of surface ocean waters and oceanic upwelling. Pacific corals are especially interesting because of their potential relevance to El Niño â Southern Oscillation (ENSO) events. At present, the Pacific Ocean is undersampled with respect to radiocarbon time series. This study establishes a 14C time series for a coral from the Solomon Islands, located near the center of the Western Pacific Warm Pool (WPWP). We present radiocarbon results from a Porites colony which grew in Marau Sound, on the east coast of Guadalcanal. A semiannual record of 14C was constructed from measurements of alternating bands which grew continuously from 1944 to 1994. The record reflects the uptake of atmospheric bomb-produced 14C since the late 1950s with superimposed subannual radiocarbon variations, presumably related to changes in ocean circulation. Although the coral radiocarbon is influenced by ENSO events, the record is not closely correlated with the Southern Oscillation Index (SOI) for the same period.
Stephans, C. L., T. M. Quinn, F. W. Taylor, and T. Correge, Assessing the reproducibility of coral-based climate records, Geophys. Res. Lett., 31, L18210, 2004, 18 citations, doi:10.1029/2004GL020343, #1755
Multi-channel seismic reflection data acquired in the Pacific Ocean off the Muroto peninsula of Shikoku Island, Japan reveal the two-dimensional distribution of fine structures in the Kuroshio Current. Eighty-one seismic sections, each extending 80 km perpendicular to the current and separated by 100 m, were acquired from 20 June to 15 August 1999 (57 days). The seismic data clearly show that fine structures extend over 40 km perpendicular to the current in almost all of the profiles. A simulation study using acoustic model from CTD data demonstrates that fine structure of temperature and salinity identified in CTD data acquired from the Kuroshio Current off the Ashizuri peninsula yield a synthetic seismic profile with characteristics similar to the Muroto transect profiles.
Cabioch, G., K. Banks-Cutler, J. W. Beck, G. S. Burr, T. Correge, R. L. Edwards, and F. W. Taylor, Continuous reef growth during the last 23 kyr BP in a tectonically active zone (Vanuatu, southwest Pacific), Quaternary Sci. Rev., 22, 1771-1786, 2003, 19 citations, doi:10.1016/S0277-3791(03)00170-7, #1674
At Urélapa island, Vanuatu, sea-level rise and a tectonic uplift of 3 mm yr−1 have controlled water depth and the colonization and reef development on a substrate from 23 until 6 cal kyr BP. Analysis of coralgal assemblages offers insights on the mode of reef growth and on water depth over the reef for the studied period. Those assemblages, precisely dated by the 230Th/234U method, give valuable information on the rate and timing of sea-level rise since the Last Glacial Maximum. The Urélapa reef sequences are characterized by upwards replacement of reef frameworks which indicates changes in wave energy through time. The sudden acceleration of sea-level rise associated with meltwater pulse-1B at around 11.3 cal kyr BP is marked by a change in reef growth strategy, from a keep-up mode to a catch-up mode. We examine the delay in timing of the occurrence of suitable substrates, the role of paleoceanographic factors and the influence of possible jumps in sea level.
Calmant, S., B. Pelletier, P. Lebellegard, M. G. Bevis, F. W. Taylor, and D. A. Phillips, New insights on the tectonics along the New Hebrides subduction zone based on GPS results, J. Geophys. Res., 108, 2319, 2003, 24 citations, doi:10.1029/2001JB000644, #1676
At the New Hebrides (NH) subduction zone, ridges born by the subducting Australia plate enter the trench and collide with the overriding margin. Results from GPS surveys conducted on both sides of the trench and new bathymetry maps of the NH archipelago bring new light on the complex tectonics of this area. Convergence vectors present large variations that are not explained by Australia/Pacific (A/P) poles and that define four segments. Vectors remain mostly perpendicular to the trench and parallel to the earthquake slip vectors. Slow convergence (i.e., 30â40 mm/yr) is found at the central segment facing the D'Entrecasteaux Ridge. The southern segment moves faster than A/P motion predicts (89 to 124 mm/yr). Relatively to a western North Fiji basin (WNFB) reference, the northern and southern segments rotate in opposite directions, consistently with the extension observed in the troughs east of both segments. Both rotations combine in Central Vanuatu into an eastward translation that âbulldozesâ the central segment into the WNFB at ∼55 mm/yr. That model suggests that the motion of the central segment, forced by the subduction/collision of the D'Entrecasteaux ridge, influences the motion of the adjoining segments. The New Caledonia archipelago is motionless with respect to the rest of the Australia plate despite the incipient interaction between the Loyalty ridge and the NH margin. Southeast of the interaction area, convergence is partitioned into a ∼50 mm/yr trench-normal component accommodated at the trench and a ∼90 mm/yr trench-parallel component, close to the A/P convergence, and presumably accommodated by a transform boundary at the rear of the NH arc.
Cutler, K. B., R. L. Edwards, F. W. Taylor, H. Cheng, J. Adkins, C. D. Gallup, P. M. Cutler, G. S. Burr, and A. L. Bloom, Rapid sea-level fall and deep-ocean temperature change since the last interglacial period, Earth Planet. Sci. Lett., 206, 253-271, 2003, 149 citations, doi:10.1016/S0012-821X(02)01107-X, #1673
We have dated Huon Peninsula, Papua New Guinea and Barbados corals that formed at times since the Last Interglacial Period, applying both 230Th and 231Pa dating techniques as a test of age accuracy. We show that Marine Isotope Stage (MIS) 5e ended prior to 113.1±0.7 kyr, when sea level was −19 m. During MIS 5b sea level was −57 m at 92.6±0.5 kyr, having dropped about 40 m in approximately 10 kyr during the MIS 5câ5b transition. Sea level then rose more than 40 m during the MIS 5bâ5a transition, also in about 10 kyr. MIS 5a lasted until at least 76.2±0.4 kyr, at a level of −24 m at that time. Combined with earlier data that places MIS 4 sea level at −81 m at 70.8 kyr, our late MIS 5a data indicate that sea level fell almost 60 m in less than 6 kyr (10.6 m/kyr) during the MIS 5â4 transition. The magnitude of the drop is half that of the glacialâinterglacial amplitude and approximately equivalent to the volume of the present-day Antarctic Ice Sheet. During this interval the minimum average rate of net continental ice accumulation was 18 cm/yr, likely facilitated by efficient moisture transport from lower latitudes. At three specific times (60.6±0.3, 50.8±0.3, and 36.8+0.2 kyr) during MIS 3, sea level was between −85 and −74 m. Sea level then dropped to −107 m at 23.7±0.1 kyr early in MIS 2, before dropping further to Last Glacial Maximum (LGM) values and then rising to present values during the last deglaciation. Times of rapid sea-level drop correspond to times of high winter insolation at low northern latitudes and high winter latitudinal gradients in northern hemisphere insolation, supporting the idea that these factors may have resulted in high water-vapor pressure in moisture sources and efficient moisture transport to high-latitude glaciers, thereby contributing to glacial buildup. We combined our sea-level results with deep-sea δ18O records as a means of estimating the temperature and ice-volume components in the marine δ18O record. This analysis confirms large deep-ocean temperature shifts following MIS 5e and during Termination I. Deep-ocean temperatures changed by much smaller amounts between MIS 5c and 2. Maximum temperature shift in the deep Pacific is about 2°, whereas the shift at a site in the Atlantic is 4°. Under glacial conditions temperatures at both sites are near the freezing point. The shift in the Atlantic is likely caused by a combination of changing proportions of northern and southern source waters as well as changing temperature at the sites where these deep waters form.
Smalley, R., E. Kendrick, M. G. Bevis, I. W. D. Dalziel, F. W. Taylor, E. Lauria, R. Barriga, G. Casassa, E. Olivero, and E. Piana, Geodetic determination of relative plate motion and crustal deformation across the Scotia-South America plate boundary in eastern Tierra del Fuego, Geochem., Geophys., Geosyst., 4, 1070, 2003, 10 citations, doi:10.1029/2002GC000446, #1650
Global Positioning System (GPS) measurements provide the first direct measurement of plate motion and crustal deformation across the Scotia-South America transform plate boundary in Tierra del Fuego. This plate boundary accommodates a part of the overall motion between South America and Antarctica. The subaerial section of the plate boundary in Tierra del Fuego, about 160 km in length, is modeled as a two dimensional, strike-slip plate boundary with east-west strike. Along the Magallanes-Fagnano fault system, the principal fault of this portion of the plate boundary, relative plate motion is left-lateral strike-slip on a vertical fault at 6.6 ± 1.3 mm/year based on an assumed locking depth of 15 km. The site velocities on the Scotia Plate side are faster than the relative velocity by an additional 1â2 mm/yr, suggesting there may be a wider region of diffuse left-lateral deformation in southern Patagonia. The north-south components of the velocities, however, do not support the existence of active, large-scale transpression or transtension between the South America and Scotia plates along this section of the plate boundary.
Gallup, C. D., H. Cheng, F. W. Taylor, and R. L. Edwards, Direct determination of the timing of sea level change during Termination II, Science, 295, 310-313, 2002, 116 citations, doi:10.1126/science.1065494, #1619
An outcrop within the last interglacial terrace on Barbados contains corals that grew during the penultimate deglaciation, or Termination II. We used combined 230Th and 231Pa dating to determine that they grew 135.8 ± 0.8 thousand years ago, indicating that sea level was 18 ± 3 meters below present sea level at the time. This suggests that sea level had risen to within 20% of its peak last-interglacial value by 136 thousand years ago, in conflict with Milankovitch theory predictions. Orbital forcing may have played a role in the deglaciation, as may have isostatic adjustments due to large ice sheets. Other corals in the same outcrop grew during oxygen isotope (18O) substage 6e, indicating that sea level was 38 ± 5 meters below present sea level, about 168.0 thousand years ago. When compared to the 18O signal in the benthic V19-30/V19-28 record at that time, the coral data extend to the previous glacial cycle the conclusion that deep-water temperatures were colder during glacial periods.
Buddmeier, R. W., and F. W. Taylor, Sclerochronology, in Quaternary Geochronology: Methods and Applications, edited by J. M. Sowers, J. S. Notter, and W. R. Lettis, Amer. Geophys. Un. Reference Shelf, 4, 2.43-2.66, 2000, #1169
Zachariasen, J., K. Sieh, F. W. Taylor, and W. S. Hantoro, Modern vertical deformation above the Sumatran subduction zone: Paleogeodetic insights from coral microatolls, Bull. Seismol. Soc. Amer., 90, 897-913, 2000, 34 citations, doi:10.1785/0119980016, #1414
Coral microatolls from the coast and outer-arc islands of Western Sumatra retain a stratigraphic and morphologic record of relative sea-level change, which is due in large part to vertical tectonic deformation above the Sumatran subduction zone. Low water levels, whose fluctuations produce measurable changes in coral morphology, limit the upward growth of the microatolls. Annual rings, derived from seasonal variations in coral density, serve as an internal chronometer of coral growth. The microatolls act as natural long-term tide gauges, recording sea-level variations on time scales of decades. Field observations and stratigraphic analysis of seven microatolls, five from the outer-arc islands and two from the mainland coast, indicate that the Mentawai Islands have been submerging at rates of 4â10 mm/yr over the last four or five decades, while the mainland has remained relatively stable. The presence of fossil microatolls up to several thousand years old in the intertidal zone indicates that little permanent vertical deformation has occurred over that time. Thus, most of the strain accumulated in the past few decades represents interseismic deformation that is recovered during earthquakes. Elastic dislocation models using these submergence data suggest that elastic strain is being accumulated in the interseismic period and that the subduction zone in this region is fully coupled.
Cabioch, G., F. W. Taylor, T. Correge, J. Recy, R. L. Edwards, G. S. Burr, F. L. Cornec, and K. Banks, Occurrence and significance of microbialites in the uplifted Tasmaloum reef (SW Espiritu Santo, SW Pacific), Sedimentary Geol., 126, 305-316, 1999, 6 citations, doi:10.1016/S0037-0738(99)00046-9, #1472
In the SW Pacific Ocean, subduction of the d'Entrecasteaux ridge system has caused rapid uplift of the central New Hebrides Island Arc. The maximum uplift rate of 6 mm yr−1 occurs along the southwest coast of Espiritu Santo Island, near Tasmaloum. The Tasmaloum uplifted reef sequence internal structure, which is strongly linked to its tectonic context, was investigated through a series of drill-holes to depths up to 42 m. Although a stable tropical coast would undergo approximately 120 m of post-glacial sea-level rise, the net relative sea-level rise on such a rapidly uplifting coast is only about 20 m. Colonization of the Tasmaloum fringing reef occurred by 24 ka, upon a pre-reef substrate composed of a thick bioclastic sand formation accumulated during the last glacial period. During the post-glacial sea-level rise, the vertical succession of reef assemblages reflects environmental and bathymetric variations controlled by the interplay of rapid, but variable rates of sea-level rise and more or less constant uplift of 5â6 mm yr−1. Microbialite crusts, composed of high-magnesian calcite laminae, occur in the Tasmaloum reef from 20 to 6 ka and are particularly abundant from 16 to 10 ka. The development of microbialite crusts is related to nutrient enrichment of interstitial waters through mixing with meteoric groundwater. After 6 ka, when sea level ceased rising in the region and continuing uplift caused rapid emergence of the reef, microbialites disappear within the subtidal assemblages. Several explanations can be put forward for their disappearance. In particular, nutrient input changes are a likely cause. A new hydrologic and oceanographic regime was established when sea level ceased rising. This change was accompanied by warming of tropical waters.
Zachariasen, J., K. Sieh, F. W. Taylor, R. L. Edwards, and W. S. Hantoro, Submergence and uplift associated with the giant 1833 Sumatran subduction earthquake: Evidence from coral microatolls, J. Geophys. Res., 104, 895-919, 1999, 85 citations, #1471
The giant Sumatran subduction earthquake of 1833 appears as a large emergence event in fossil coral microatolls on the reefs of Sumatra's outer-arc ridge. Stratigraphic analysis of these and living microatolls nearby allow us to estimate that 1833 emergence increased trenchward from about 1 to 2 m. This pattern and magnitude of uplift are consistent with about 13 m of slip on the subduction interface and suggest a magnitude (Mw ) of 8.8â9.2 for the earthquake. The fossil microatolls also record rapid submergence in the decades prior to the earthquake, with rates increasing trenchward from 5 to 11 mm/yr. Living microatolls show similar rates and a similar pattern. The fossil microatolls also record at least two less extensive emergence events in the decades prior to 1833. These observations show that coral microatolls can be useful paleoseismic and paleogeodetic instruments in convergent tectonic environments.
Burr, G. S., J. W. Beck, F. W. Taylor, J. Recy, R. L. Edwards, G. Cabioch, T. Correge, D. J. Donahue, and J. M. OMalley, A high-resolution radiocarbon calibration between 11,700 and 12,400 calendar years BP derived from 230Th ages of corals from Espiritu Santo Island, Vanuatu, Radiocarbon, 40, 1093-1105, 1998, 49 citations, #1286
Cabioch, G., F. W. Taylor, and J. Recy, Environmental and tectonic influences on growth and internal structure of a fringing reef at Tasmaloum (SW Espiritu Santo, New Hebrides Island Arc, SW Pacific), Spec. Publ. Int. Assoc. Sedimentology, 25, 261-277, 1998, #1238
Mann, P., F. W. Taylor, M. B. Lagoe, A. Quarles, and G. S. Burr, Accelerating Late Quaternary uplift of the New Georgia Island group (Solomon Island arc) in response to subduction of the recently active Woodlark spreading center and Coleman seamount, Tectonophysics, 295, 259-306, 1998, 34 citations, doi:10.1016/S0040-1951(98)00129-2, #1284
The New Georgia Island Group of the Solomon Islands is one of four places where an active or recently active spreading ridge has subducted beneath an island arc. We have used coral reef terraces, paleobathymetry of Neogene sedimentary rocks, and existing marine geophysical data to constrain patterns of regional Quaternary deformation related to subduction of the recently active Woodlark spreading center and its overlying Coleman seamount. These combined data indicate the following vertical tectonic history for the central part of the New Georgia Island Group: (1) subsidence of the forearc region (Tetepare and Rendova Islands) to water depths of 1500 m and deposition of marine turbidites until after 270 ka; (2) late Quaternary uplift of the forearc to sea level and erosion of an unconformity; (3) subsidence of the forearc to 500 m BSL and deposition of bathyal sediments; and (4) uplift of the forearc above sea level with Holocene uplift rates up to at least 7.5 mm/yr on Tetepare and 5 mm/yr on Rendova. In the northeastern part of the New Georgia Island Group, our combined data indicate a slightly different tectonic history characterized by lower-amplitude vertical motions and a more recent change from subsidence to uplift. Barrier reefs formed around New Georgia and Vangunu Islands as they subsided >300 m. By 50â100 ka, subsidence was replaced by uplift that accelerated to Holocene rates of 1 mm/yr on the volcanic arc compared with rates up to 7.5 mm/yr in the forearc area of Tetepare and Rendova.
Uplift mechanisms, such as thermal effects due to subduction of spreading ridges, tectonic erosion, or underplating of deeply subducted bathymetric features, are not likely to function on the 270-ka period that these uplift events have occurred in the New Georgia Island Group. A more likely uplift mechanism for the post-270-ka accelerating uplift of the forearc and volcanic arc of the New Georgia Island Group is progressive impingement of the Coleman seamount or other topographically prominent features on the subducting plate. Regional effects we relate to this ongoing subduction-related process include: (1) late Quaternary (post-270 ka), accelerating uplift of the RendovaâTetepare forearc area in response to initial impingement of the Coleman seamount followed by exponentially increasing collisional contact between the forearc and seamount; (2) later Quaternary propagation of uplift arcward to include the volcanic arc as the area of collisional contact between the forearc and seamount increased; and (3) large-wavelength folding that has produced regional variations in late Holocene uplift rates observed in both forearc (southern Rendova, Tetepare) and volcanic arc (New Georgia Island) areas. We propose that the dominant tectonic effect of Coleman seamount impingement is horizontal shortening of the forearc and arc crust that is produced by strong coupling between the subducting seamount and the unsedimented crystalline forearc of the New Georgia Island Group. The horizontal forces due to mechanical resistance to subducting rugged ridge and seamount topography may have terminated spreading of the Woodlark spreading center entering the trench (Ghizo ridge) and converted it to a presently active strike-slip fault zone.
Mann, P., C. S. Prentice, G. S. Burr, L. R. Pena, and F. W. Taylor, Tectonic geomorphology and paleoseismology of the Septentrrional fault system, Dominican Republic, in Active Strike-Slip and Collisional Tectonics of the Northern Caribbean Plate Bounday Zone, edited by J. F. Dolan and P. Mann, Boulder, CO, Geol. Soc. Amer. Spec. Paper, 326, 63-123, 1998, #1384
Quinn, T. M., T. J. Crowley, F. W. Taylor, C. Henin, P. Joannot, and Y. Joan, A multicentury stable isotope record from a New Caledonia coral: Interannual and decadal sea surface temperature variability in the southwest Pacific since 1657 A. D., Paleoceanography, 13, 412-426, 1998, 98 citations, #1332
A 335 year stable isotope record from a New Caledonia coral (22°S, 166°E) helps fill a large gap in historical climate reconstructions. Although the long-term coral δ18O-based sea surface temperature (SST) trend is one of warming, there are notable decadal fluctuations, especially in the early 18th and early 19th centuries. Mean annual SSTs between 1658 and 1900 are estimated to be ∼0.3°C lower than the 20th century average, with interdecadal excursions of 0.5°-0.8°C. Time series analyses of the coral isotope record reveals significant concentrations of variance in the El Niño band; an inderdecadal spectral peak is present, but its robustness requires additional statistical evaluation. A secular but irregular decrease in coral δ13C values begins in the mid-1800s and may reflect the anthropogenic perturbation of the carbon reservoir. These and other results indicate that the New Caledonia coral isotope record is a valuable source of information on southwest Pacific climate history.
Beck, J. W., J. Recy, F. W. Taylor, R. L. Edwards, and G. Cabioch, Abrupt changes in Early Holocene tropical sea surface temperature derived from coral records, Nature, 385, 705-707, 1997, 158 citations, doi:10.1038/385705a0, #1278
Calmant, S., B. Pelletier, R. Pillet, M. Regnier, P. Lebellegard, D. Maillard, F. W. Taylor, M. G. Bevis, and J. Recy, Interseismic and coseismic motions in GPS series related to the Ms 7.3 July 13, 1994, Malekula earthquake, central New Hebrides subduction zone, Geophys. Res. Lett., 24, 3077-3080, 1997, 12 citations, #1331
On July 13, 1994, an earthquake M s =7.3 occurred at Malekula, in the New Hebrides archipelago. The GPS data collected across the New Hebrides trench between 1990 and 1996 were processed in order to separate the interseismic and coseismic motions from the drifts related to the convergence with the Australian plate. The GPS‐derived coseismic displacements at the GPS site in Malekula are 49 ± 15 mm southward, 230 ± 30 mm westward and 170 ± 37 mm downward, when the CMT‐derived displacements are 50 mm southward, 210 mm westward and 150 mm downward. Taking into account the interseismic strain accumulation (25 mm/yr at the source established from historical seismicity, 7.5 mm/yr at the GPS site), the strain‐free convergence rate at Malekula is 49 ± 3 mm/yr. Other GPS‐derived convergence rates are 95 ± 1 mm/yr at Efate and 37 ± 2 mm/yr at Santo. These rates imply a regional right‐lateral motion between the Efate and the Santo‐Malekula segments. In contrast, the focal mechanism of the earthquake mostly indicates a left‐lateral motion. Therefore, we hypothesize that the earthquake is related to variations in the interplate coupling along the converging boundary of the Santo‐Malekula segment.
Crowley, T. J., T. M. Quinn, F. W. Taylor, C. Henin, and P. Joannot, Evidence for a volcanic cooling signal in a 335-year coral record from New Caledonia, Paleoceanography, 12, 633-639, 1997, 31 citations, #1333
Although volcanic cooling events have been detected in tree ring records, their occurrence in marine records has received much less attention. Herein we report results from a 335-year oxygen isotope record (1657-1992) from a New Caledonia coral indicating that as many as 16 interannual-scale cooling events occur within 1 year of a volcanic eruption as determined by ice core records. There are also pentadal/decadal-scale cooling events beginning in 1675, 1813, and 1903 that immediately postdate volcanic eruptions. However, the interannual correspondences are complicated by the fact that some of the cooling events also coincide with El Niños, which cause cooling in this part of the western South Pacific. If our conclusions are substantiated by further work, occurrence of distinct volcanic cooling signals may enable refinement of coral chronologies by use of the "event stratigraphic" approach, with the most promising correlation horizons being associated with the following eruptions: 1808 (Unknown), 1813-1821 (several eruptions), 1835 (Coseguina), 1883 (Krakatau), and possibly 1963 (Agung).
Quinn, T. M., F. W. Taylor, T. J. Crowley, and S. M. Link, Evaluation of sampling resolution in coral stable isotope records: A case study using records from New Caledonia and Tarawa, Paleoceanography, 11, 529-542, 1996, 65 citations, #1236
We have generated a 40-year-long, monthly stable isotope record from a Porites lutea coral collected offshore of Amedee, New Caledonia (22°S, 167°E) to investigate the relation between sampling resolution in coral isotope studies and retrieval of sea-surface environmental information. We interpret the high correlation between our oxygen isotope record and a twenty-year long sea-surface temperature record at the monthly timescale (r=0.88) to indicate that our coral isotope record is an accurate monitor of environmental conditions offshore of Amedee. The character of the signal and the percent variance explained in the record at the annual band, at the quasi-biennial oscillation band ((QBO) 2.0-2.4 years), and at the El Nino-Southern Oscillation band ((ENSO) 3-8 years) changes little in response to a reduction in sampling density from monthly to bimonthly to quarterly. Similar results have been obtained in a reanalysis of a coral isotope record from Tarawa, Kiribati. Our results indicate that a significant amount of the information obtained from high-density sampling can also be retrieved from lower-density sampling. In particular, bimonthly sampling yields virtually no drop-off in variance explained, and quarterly sampling is satisfactory for resolving interannual and decadal-scale trends in time series. The proposed sampling approach may enable a more rapid filling in of numerous spatial holes in coral sampling sites needed for reconstruction of long-term decadal-scale variations in climate.
Quinn, T. M., T. J. Crowley, and F. W. Taylor, New stable isotope results from a 173-year coral record from Espiritu Santo, Vanuatu, Geophys. Res. Lett., 23, 3413-3416, 1996, 26 citations, #1237
Long coral records provide valuable information on pentadal‐decadal scale climate variability. Previously we have reported on a preliminary analysis of a 173‐year record (1806â1978) from the island of Espiritu Santo (Republic of Vanuatu). Although this record contained information in the pentadal‐decadal band, low sampling resolution raised questions about the validity of the results. Herein we report new data from the Santo record, in which the sampling resolution has been doubled and the validation database expanded. Variations in coral δ18O at Santo record the combined effects of variations in SST and rainfall‐induced salinity changes. The most prominent spectral peaks in the time series are at the annual cycle and 14â15 and 7.4 years. The robust occurrence of the 14â15 year peak provides additional support to the importance of this oscillation as a cause of decadal‐scale climate variability. Overall, our new results provide greater credibility to the conclusions raised in the earlier study and indicate that the Santo record can more confidently be incorporated into the still‐small network of multicentury coral records of climate change.
Bevis, M. G., F. W. Taylor, B. E. Schutz, J. Recy, B. L. Isacks, S. Helu, R. Singh, E. Kendrick, J. Stowell, B. L. Taylor, and S. Calmant, Geodetic observations of very rapid convergence and back-arc extension at the Tonga arc, Nature, 374, 249-251, 1995, 176 citations, doi:10.1038/374249a0, #1080
THE Earth's most active zone of mantle seismicity arises from the subduction of the Pacific plate at the Tonga trench1. It is not known why this slab generates so many more earthquakes than other subducting slabs worldwide. Above the subduction zone the active Tofua (Tonga) volcanic arc is separated by the V-shaped Lau basin from a remnant arc, the Lau ridge, located at the eastern edge of the Australian plate2. The irregular and discontinuous magnetic lineations within the basin have proven difficult to interpret3,4, and so the regional kinematic framework has been obscure. We report geodetic measurements of crustal motion within the Tonga-Lau system, which reveal the fastest crustal motions yet observed. The Lau basin is opening at a rate which increases northwards to a maximum of 160 mm yr-1 No straining is observed within the northern Tonga ridge, suggesting that it comprises part of a rigid microplate. Convergence rates across the Tonga trench increase northwards to a maximum of 240 mm yr-1. The extraordinary seismic activity of the subducting slab is probably related to this unusually rapid subduction.
Calmant, S., P. Lebellegard, F. W. Taylor, M. G. Bevis, D. Maillard, J. Recy, and J. Bonneau, Geodetic measurements of convergence across the New Hebrides subduction zone, Geophys. Res. Lett., 22, 2573-2576, 1995, 15 citations, #1268
Between 1990 and 1994, geodetic measurements (GPS observations) have been conducted across the New Hebrides subduction zone where the Australia plate subducts under the New Hebrides Arc. This paper establishes convergence rate variations along the trench. In the South, at Tanna, the relative motion is oriented N244 ±4 and has a uniform rate of 11.7±0.8 cm/yr. The rate at Efaté is 10.3±0.9 cm/yr, oriented N242 ±4. Both azimuths very well compare with slip vectors of the last major earthquakes. In the North, the rate at Santo is only 3.6 ±1.2 cm/yr, oriented N253 ± 26. The difference in the convergence rates between Santo on the one hand and Efaté and Tanna in the other hand points to a right lateral shear zone between Santo and Efaté. At Santo where the plate coupling is very high, the very low convergence rate might be related to the absence of recent strong earthquakes. No significant variations are detected for the baselines within the Australia plate.
Chen, J. K., F. W. Taylor, R. L. Edwards, H. Cheng, and G. S. Burr, Recent emerged reef terraces of the Yenkahe resurgent block, Tanna, Vanuatu: Implications for volcanic, landslide and tsunami hazards, J. Geology, 103, 577-590, 1995, 17 citations, doi:10.1086/629777, #1161
Emerged reef terraces record the extraordinarily rapid Holocene uplift rate of the fault-bounded Yenkahe resurgent block (YRB), located within a partially submerged Quaternary caldera on Tanna Island, Vanuatu, southwest Pacific. The presently active volcano, Yasur, is located at the western end of the YRB. Episodic uplift of the YRB is probably associated with the movement of magma below the Yenkahe area. A historically recorded uplift at Port Resolution Bay in a.d. 1878 raised the shoreline ~ 15 m. This a.d. 1878 event was accompanied by a local earthquake and a tsunami that reached ~ 12 m elevation. Coral samples from terraces at mean altitudes of 155 m and 15 m above present sea level yield [tex-math]$^{230}Th/^{234}U$[/tex-math] dates of a.d. [tex-math]$1002 \pm 10$[/tex-math] and a.d. [tex-math]$1868 \pm 4$[/tex-math], respectively. These ages imply a mean uplift of 156 mm/yr for the YRB since a.d. 1002 until a.d. 1992. This volcanically related uplift occurs within the context of regional uplift of the southern New Hebrides arc. The late Holocene uplift rate, ~ 1 mm/yr, was determined from emerged terraces on the north and west coasts of Tanna. There have been several large volcanic eruptions in the geological history of Tanna; continued emplacement of magma at shallow levels below the YRB poses a possible volcanic hazard to the population there. Numerous faults in the weakly consolidated YRB strata and relief created by rapid uplift increase the probability of hazards from landslides and tsunamis.
Mann, P., F. W. Taylor, R. L. Edwards, and T.-L. Ku, Actively evolving microplate formation by oblique collision and sideways motion along strike-slip faults: An example from the northeastern Caribbean plate margin, Tectonophysics, 246, 1-69, 1995, 73 citations, doi:10.1016/0040-1951(94)00268-E , #1061
The pattern of folding, faulting, and late Quaternary coral-reef uplift rates in western and central Hispaniola (Haiti and Dominican Republic) suggest that the elongate Gonave microplate, a 190,000-km2 area of the northeastern Caribbean plate, is in the process of shearing off the Caribbean plate and accreting to the North American plate. Late Cenozoic transpression between the southeastern Bahama Platform and the Caribbean plate in Hispaniola has inhibited the eastward motion of the northeastern corner of the plate. Transpression is manifested in western and central Hispaniola by the formation of regional scale folds that correspond to present-day, anticlinal topographic mountain chains continuous with offshore anticlinal ridges. Areas of most rapid Quaternary uplift determined from onland coral reefs 125 ka and younger, coincide with the axial traces of these folds. Offshore data suggest recent folding and faulting of the seafloor. Onshore reef data do not conclusively require late Quaternary folding, but demonstrate that tectonic uplift rates of the axial areas of the anticlines decrease from the Northwest Peninsula of Haiti (0.37 mm/yr) to to the central part of the coast of western Haiti (0.19 mm/yr) to the south-central part of western Haiti (0 mm/yr).
Formation of the 1200-km-long Enriquillo-Plantain Garden-Walton fault zone as a âbypassâ strike-slip fault has isolated the southern edge of the Gonave microplate and is allowing continued, unimpeded eastward motion of a smaller Caribbean plate past the zone of late Neogene convergence and Quaternary uplift of coral reefs in Hispaniola. Offshore seismic reflection data from the Jamaica Passage, the marine strait separating Jamaica and Haiti, show that the Enriquillo-Plantain Garden fault zone forms a narrow but deep, active fault-bounded trough beneath the passage. The active fault is continuous with active faults mapped onshore in western Haiti and eastern Jamaica; the bathymetric deep is present because the Jamaica Passage fault segment represents a 50-km-wide, transtensional left-step of the fault trace between Haiti and Jamaica.
Onshore satellite imagery and field observations suggest that the Enriquillo-Plantain Garden fault forms a continuous trace extending from central Hispaniola east of Lake Enriquillo, Dominican Republic, to the westernmost end of the southern peninsula of Haiti. The regional lineament corresponds to a recent fault scarp in Quaternary alluvium of the Clonard pull-apart basin in the central part of the southern peninsula of Haiti and suggests that at least this part of the lineament has undergone recent slip. Calmus (1983) has suggested a total offset of 30â50 km of the Enriquillo-Plantain Garden fault zone in the southern peninsula of Haiti using the apparent offset of lithologic units. Seismic reflection data from Lake Enriquillo document recent deformation of Quaternary lake sediments where the lineament crosses the lake. Leveling of the crest of a late Holocene coral reef and associated algal tufa around Lake Enriquillo demonstrate late Holocene vertical movement and tilting in a 1500-m-wide zone parallel to the fault trend. Lateral offset is difficult to show in the Enriquillo Valley area because of rapid recent sedimentation into the valley.
The pattern of inactive strike-slip faults and fold belts of Cenozoic age in Cuba and the Yucatan basin suggest that two elongate microplates were sheared off the proto-Caribbean plate and accreted to the North American plate by a similar process in Paleocene and Eocene times. Age of terminal deformation in western, central and eastern Cuba is consistent with southeastward younging and migration of arc collision. The similarity of the size and sequence of events in Cuba suggests that the process of oblique collision and sideways motion of the plate along a new strike-slip fault towards a free face may be an important process of microplate formation and interplate transfer in other areas.
Min, G. R., R. L. Edwards, F. W. Taylor, J. Recy, C. D. Gallup, and J. W. Beck, Annual cycles of U/Ca in coral skeletons and U/Ca thermometry, Geochimica et Cosmochimica Acta, 59, 2025-2042, 1995, 107 citations, doi:10.1016/0016-7037(95)00124-7, #1173
We have discovered annual variations in the 238U/40Ca ratio of Porites coral skeletons. Measurements were made using thermal ionization mass spectrometric techniques, yielding precisions of ±2. (2σ) for 238U/40Ca and ±lâ° (2σ) for 88Sr/40Ca. Coralline aragonite subsamples weighed 2 mg, enabling submillimeter sampling resolution corresponding to monthly temporal resolution. The annual nature of the cycles was confirmed by comparison with annual banding observable in X-radiographs. For two modern and one fossil sample, the amplitude of the U/Ca variation ranges from 6 to 23%, well outside of analytical error. As annual U/Ca cycles appear to be a general feature of primary coralline aragonite, the preservation of such features will be important in identifying unaltered coral for U-series dating studies. U/Ca variations mimic and are in phase with annual variations in 88Sr/40Ca. For a given fractional shift in Sr/Ca, the fractional shift in U/Ca is about 6 times larger. For the two modern corals, 238U/40Ca is strongly anticorrelated with measured temperature, suggesting that 238U/40Ca has potential as a paleothermometer. If temperature is the only significant control on coralline 238U/40Ca, we reach the following conclusions from analyses of fossil samples: a Vanuatu sample, which grew halfway through the last deglaciation, gives U/Ca temperatures 4 to 5°C below modern values. U/Ca thermometry applied to published data for Barbados corals indicates that (1) temperature generally correlates with sea level, (2) glacial temperatures (stages 2 and 4) were 4 to 6°C lower than interglacial temperatures (stages 7a, 5e, and 1), and (3) temperatures rose from glacial to interglacial values early in the last deglaciation. Thermometry applied to Papua New Guinea corals indicates that (1) temperatures were 5 to 6°C lower than interglacial temperatures from 13 to 10 Ky , then rose to present values 9 Ky , (2) the temperature depression between 13 and 10 Ky is consistent with low temperatures observed in Vanuatu during the same time interval, and (3) the Papua New Guinea deglacial temperature history differs from that of Barbados. The results generally support estimates of tropical temperatures obtained from Sr/Ca thermometry and snow line elevation data, but disagree with those based on foram transfer functions. A thermodynamic model suggests that coralline 238U/40Ca may also be sensitive to marine carbonate ion concentration, raising the possibility that some of the observed glacial-interglacial 238U/40Ca variation may result from glacial-interglacial carbonate ion changes. However, the key experiments that might establish a coralline 238U/40Ca-carbonate ion relationship have yet to be performed.
Taylor, F. W., M. G. Bevis, B. E. Schutz, J. Recy, S. Calmant, D. Charley, M. Regnier, B. Perin, M. Jackson, and C. Reichenfeld, Geodetic measurements of convergence at the New Hebrides island arc indicate arc fragmentation caused by an impinging aseismic ridge, Geology, 23, 1011-1014, 1995, 50 citations, doi:10.1130/0091-7613(1995)023<1011:GMOCAT>2.3.CO;2, #1172
Global positioning system (GPS) measurements in 1990 and 1992 from two sites on the southern New Hebrides island arc give convergence rates with the Australian plate of 103 ± 5 mm/yr and 118 ± 10 mm/yr. In contrast, GPS measurements in the central New Hebrides indicate anomalously low convergence rates of ≈42 mm/yr. On geologic time scales, the mean central New Hebrides convergence rate has been 85â132 mm/yr. Elastic fault models with a locked interplate thrust zone indicate that maximum possible rates of horizontal elastic strain are insufficient to account for the anomalously slow convergence. Therefore, we propose that the central New Hebrides segment is moving eastward relative to adjacent arc segments at a rate of ≈36â83 mm/yr. This displacement is accommodated by crustal shortening at the eastern margin of the arc and strike-slip faults crosscutting the arc. Resistance to subduction of the aseismic D'Entrecasteaux Ridge system is the likely cause for horizontal forces sufficient to shove a large segment eastward and fragment the arc. This process demonstrates that subducting bathymetric features can impose fundamental structural modifications on an arc that may represent the initial stages of arc polarity reversal.
Quinn, T. M., F. W. Taylor, and A. N. Halliday, Strontium-isotopic dating of neritic carbonates at Bougainville Guyot (site 831), New Hebrides island arc, Proc. Ocean Drill. Prog., Sci. Results, 134, 89-95, 1994, #980
Taylor, F. W., T. M. Quinn, C. D. Gallup, and R. L. Edwards, Quaternary plate convergence rates at the New Hebrides island arc from the chronostratigraphy of Bougainville Guyot (site 831), Proc. Ocean Drill. Prog., Sci. Results, 134, 47-57, 1994, #982
Edwards, R. L., J. W. Beck, G. S. Burr, D. J. Donahue, J. M. A. Chappell, A. L. Bloom, E. R. M. Druffel, and F. W. Taylor, A large drop in atmospheric 14C/12C and reduced melting in the younger Dryas, documented with 230Th ages of corals, Science, 260, 962-968, 1993, 300 citations, doi:10.1126/science.260.5110.962, #1029
Paired carbon-14 (14C) and thorium-230(230Th) ages were determined on fossil corals from the Huon Peninsula, Papua New Guinea. The ages were used to calibrate part of the 14C time scale and to estimate rates of sea-level rise during the last deglaciation. An abrupt offset between the 14C and 230Th ages suggests that the atmospheric 14C/12C ratio dropped by 15 percent during the latter part of and after the Younger Dryas (YD). This prominent drop coincides with greatly reduced rates of sea-level rise. Reduction of melting because of cooler conditions during the YD may have caused an increase in the rate of ocean ventilation, which caused the atmospheric 14C/12C ratio to fall. The record of sea-level rise also shows that globally averaged rates of melting were relatively high at the beginning of the YD. Thus, these measurements satisfy one of the conditions required by the hypothesis that the diversion of meltwater from the Mississippi to the St. Lawrence River triggered the YD event.
Prentice, C. S., P. Mann, F. W. Taylor, G. S. Burr, and S. Valastro, Paleoseismicity of the North American-Caribbean plate boundary (Septentrional Fault), Dominican Republic, Geology, 21, 49-52, 1993, 23 citations, doi:10.1130/0091-7613(1993)021<0049:POTNAC>2.3.CO;2, #976
The Septentrional fault zone, the major North American-Caribbean plate-boundary fault in Hispaniola, is a likely source of large earthquakes in the Dominican Republic. An excavation into a Holocene alluvial fan deposited across the fault in the central Cibao Valley, Dominican Republic, provides evidence that it has been at least 430 yr and probably more than 730 yr since the last ground-rupturing earthquake along this segment of the fault. On the basis of these data and published estimates of the plate-tectonic slip rate, we propose that the Septentrional fault is a source of high seismic potential in the densely populated and rapidly developing Cibao Valley in the northern Dominican Republic.
Quinn, T. M., F. W. Taylor, and T. J. Crowley, A 173 year stable isotope record from a tropical South Pacific coral, Quaternary Sci. Rev., 12, 407-418, 1993, 59 citations, doi:10.1016/S0277-3791(05)80005-8, #1017
We have generated a 173 year-long time series (A.D. 1806 to 1979) of changes in the δ18O and δ13C composition of a coral head (Platygyra lamellina) to investigate environmental change in the climatologically sensitive region of the tropical South Pacific. Little is known about decadal- and centennial-scale climate change at sea level in this region. Our coral is from near the south coast of Espiritu Santo Island (15°S, 167°E), Republic of Vanuatu. The stable isotope record from this coral is consistent with meteorological and oceanographic records during the period of overlap in the records (1964â1978): δ18O values positively correlate with SST (r=0.77) and δ13C values are highly coherent with rainfall (r=0.82) at the annual cycle. These relations suggest that the δ18O signal in this coral is a function of variations in SST and rainfall-induced changes in SSS, whereas the δ13C signal may be related to rainfall and cloud cover modulation of photosynthesis in the coral. δ18O and δ13C values are positively correlated over the entire length of the record (r=0.65), a relation that is even stronger between 1806 and 1866 (r=0.81), i.e. prior to the time of possible anthropogenic influence on the δ13C record. Because of the positive correlation between temperature and rainfall in this region, we interpret the long-term record of δ18O in terms of joint variations of these two variables. The most significant cool/dry excursion in the Santo record occurs during the nineteenth century (1832â1866) and ends abruptly in 1866 with a change to modern values. Superimposed on this pattern is a slight (0.2%.), cooling/drying toward the end of the twentieth century. Cross-spectral analysis of the δ18O and δ13C records indicates a strong concentration of variance at the quasi-biennial (2 years) and El Nino/Southern Oscillation (ENSO) (4â5 years) frequency bands, in addition to a 15 year peak found also in global temperature records. Cross-spectral analysis of coral isotope records from Santo and the Philippine Sea, indicate a concentration of variance at ENSO (4â5 years) frequency bands. However, comparison of the Santo coral isotope record with high-latitude northern hemisphere temperature records indicates that the major cool/dry excursion in the Santo record (1832â1866) is not seen in the northern hemisphere record. If verified in other tropical South Pacific coral records, the results have implications concerning the global scale of cooling for Little Ice Age events.
Schutz, B. E., M. G. Bevis, F. W. Taylor, D. Kuang, P. Abusali, M. Watkins, J. Recy, B. Perin, and O. Peyroux, The southwest Pacific GPS project: Geodetic results from burst 1 of the 1990 field campaign, Bull. Geodesique, 67, 224-240, 1993, 5 citations, #981
Beck, J. W., R. L. Edwards, E. Ito, F. W. Taylor, J. Recy, F. Rougerie, P. Joannot, and C. Henin, Sea-surface temperature from coral skeletal strontium/calcium ratios, Science, 257, 644-647, 1992, 353 citations, doi:10.1126/science.257.5070.644, #956
Seasonal records of tropical sea-surface temperature (SST) over the past 105 years can be recovered from high-precision measurements of coral strontium/calcium ratios with the use of thermal ionization mass spectrometry. The temperature dependence of these ratios was calibrated with corals collected at SST recording stations and by 18O/16O thermometry. The results suggest that mean monthly SST may be determined with an apparent accuracy of better than 0.5°C. Measurements on a fossil coral indicate that 10,200 years ago mean annual SSTs near Vanuatu in the southwestern Pacific Ocean were about 5°C colder than today and that seasonal variations in SST were larger. These data suggest that tropical climate zones were compressed toward the equator during deglaciation.
Burr, G. S., R. L. Edwards, D. J. Donahue, E. R. M. Druffel, and F. W. Taylor, Mass spectrometric 14C and U-Th measurements in coral, Radiocarbon, 34, 611-618, 1992, 34 citations, #891
Taylor, F. W., Quaternary vertical tectonics of the central New Hebrides island arc, Proc. Ocean Drilling Prog., Init. Rept., 134, 33-42, 1992, #883
Collot, J.-Y., H. G. Greene, L. Srokking, K. Akimoto, M. V. S. Ask, P. E. Baker, L. Briqueu, T. Chabernaud, M. Coltorti, M. A. Fisher, M. Good, T. Hasenaka, M. Hobart, A. Krammer, J. Leanard, J. B. Martin, J. I. Martinez-Rodriguez, S. Menger, M. Meschede, B. Pelletier, R. C. B. Perembo, T. M. Quinn, P. Roperch, P. Reid, W. R. Riedel, T. S. Sraerker, F. W. Taylor, and X. Zhao, Resultats preliminaires du Leg 134 de l'ocean drilling program dans la zone de collision entre l'arc insulaires des Nouvelles-Hebrids et la zone d'Entrecasteaux, C. R. Acad. Sci. Paris, 313, Ser. II, 539-546, 1991, #874
Taylor, F. W., and P. Mann, Late Quaternary folding of coral reef terraces, Barbados, Geology, 19, 103-106, 1991, 17 citations, doi:10.1130/0091-7613(1991)019<0103:LQFOCR>2.3.CO;2, #735
Uplifted late Ouaternary coral reefs on the island of Barbados record folding of the emergent crest of the Lesser Antilles accretionary prism (Barbados Ridge complex) since ca. 1 Ma. Three northeast striking folds are defined by systematic changes in altitudes in the crest of First High Cliff, a mostly constructional reef terrace about 125 ka, and Second High Cliff, a partially erosional reef terrace about 500 ka. The folds have wavelengths of 6 to 8 km and fold axes extend about 10 km. The largest anticline rises to the northeast, where it has been breached by erosion exposing highly deformed Eocene to lower Miocene rocks of the Scotland District. Uplift rates based on heights of the last interglacial First High Cliff range from 0.07 to 0.44 mm/yr. Quaternary folding on Barbados indicates that the crest of the accretionary prism continues to be an active fold belt undergoing northwestsoutheast shortening.
Taylor, F. W., J. Recy, B. M. Larue, M. G. Bevis, and B. E. Schutz, A geodetically positioned shallow platform for tectonics and oceanographic research, in Marine Positioning into the 1990's, edited by M. Kumar and G. A. Maul, PIP, 278-287, 1991, #913
Taylor, F. W., R. L. Edwards, G. J. Wasserburg, and C. Frohlich, Seismic recurrence intervals and timing of aseismic subduction inferred from emerged corals and reefs of the central Vanuatu (New Hebrides) frontal arc, J. Geophys. Res., 95, 393-408, 1990, 39 citations, #787
The recognition and dating of corals that have been killed by tectonic uplift allow us to date paleoseismic uplifts in the Vanuatu island arc. We recognize corals that record paleouplifts by their similarity to those known to have died during contemporary sudden uplifts and date them (1) by counting annual coral growth bands (only if part of the coral is alive at the time of collection) or (2) by newly developed techniques for obtaining 230Th ages by mass spectrometry. The mass spectrometric method produces isotopic ages with precisions of ±3 to ±9 years (2σ) in the 0â1000 years B.P. time range. The 230Th ages in this time range appear to be accurate. Samples whose ages are known by counting coral growth bands give 230Th ages that are indistinguishable from their growth band ages. By dividing the average increment of uplift for the latest Holocene uplifts by the mean Holocene uplift rate, we can estimate average seismic uplift recurrence intervals for the past 6000 years. The results for each of four central Vanuatu arc segments are (1) North Santo emerged 1.2 m in 1866 A.D. and 0.6 m 107 years later in 1973 A.D. The average coseismic uplift of 0.9 m and mean Holocene uplift rate of 4.3 mm yr−1 suggest a longer recurrence interval of 212 years. (2) South Santo emerged 0.29 m in 1946 and 0.26 m 19 years later in 1965, including the related 1971 event. Here the mean Holocene uplift rate is 5.5 mm yr−1. The uplift data suggest a longer average recurrence interval of about 51 years. (3) North Malekula emerged 1.23 m near 1729 A. D. and 1.05 m 236 years later in 1965. The mean Holocene uplift rate of 2.7 mm yr−1 and mean coseismic uplift of 1.14 m for dated events suggest a longer recurrence interval of 422 years. (4) Part of southernmost Malekula has uplifted continuously or episodically by about 0.35 m from about 1957 until at least mid-1983 A.D. The maximum uplift of 2.7 mm yr−1 occurs near a nest of small earthquakes. Both the earthquakes and rapid uplift suggest that interplate slip beneath south Malekula may be continuous, rather than episodic. Episodes of 0.35 m uplift would have to recur every 130 years to maintain the 2.7 mm yr−1 uplift rate. In contrast, we find no evidence of interseismic vertical movements for the other three blocks. The most reasonable interpretation of these results is that the seismic recurrence intervals and processes for accommodation of slip are quite different on adjacent arc segments. We have used the most widely accepted momentmagnitude relationship to evaluate the accumulated seismic slip caused by large earthquakes occurring since 1920. In all four arc segments this analysis suggests that the seismically radiated moments account for less than one-third to one-tenth of the slip associated with plate convergence. The similarity between the paleoseismic record of uplifts and the contemporary record of coseismic uplifts suggests that this analysis can be generalized to times before 1920. For the northern three segments of central Vanuatu, aseismic slip probably occurs in the same years as large earthquakes because the contemporary coral record records uplifts only in years having large historic earthquakes. This suggests that aseismic slip is not continuous and does not occur at rates which vary slowly over the course of the earthquake cycle. The south Santo segment may have the highest proportion of seismic slip because the mean recurrence interval of 51 years is shortest and the mean Holocene uplift rate of at least 5.5 mm yr−1 is the fastest.
Austin, J. A., F. W. Taylor, and C. D. Cagle, Seismic stratigraphy of the central Tonga Ridge, Marine Petroleum Geol., 6, 71-92, 1989, 10 citations, doi:10.1016/S0264-8172(89)90077-9, #667
Edwards, R. L., F. W. Taylor, and G. J. Wasserburg, Dating earthquakes with high-precision thorium-230, ages of very young corals, Earth Planet. Sci. Lett., 90, 371-381, 1988, 60 citations, doi:10.1016/0012-821X(88)90136-7, #751
Mass spectrometric techniques have recently yielded significant increases in precision and sensitivity over previous methods for measuring230Th abundance in corals. To assess the accuracy of230Th ages, three corals from Vanuatu, whose ages were known from counting annual growth bands, were analyzed. For each sample, the date of growth determined by230Th analysis (A.D.1969 ± 3, 1932 ± 5,and1806 ± 5; 2σ uncertainties based on analytical error) was indistinguishable from the date determined by counting bands (A.D. 1971â1973, 1935â1937, and 1804â1810), indicating that the230Th dates are accurate.230Th dates were also determined for two adjacent emerged heads from Santo Is., Vanuatu, which were thought to have died when they were raised above sea level during coseismic uplift. The dates (A.D.1864 ± 4, 1866 ± 4) were the same, indicating that the heads died at the same time and consistent with the idea that they were killed by coseismic emergence around A.D. 1865. The difference between this date and the date of the only major historically documented earthquake that caused uplift (A.D. 1973,Ms = 7.5), suggests a seismic recurrence interval of108 ± 4y for Santo. Analogous emerged corals from Malekula Is., Vanuatu yielded230Th dates that were similar to each other (A.D.1729 ± 3, 1718 ± 5) and are inferred to have died during coseismic emergence around A.D. 1729. In conjunction with the date of the only large historically documented earthquake that caused uplift (A.D. 1965,Ms = 7.5), the recurrence interval for Malekula is236 ± 3y. If similar emerged corals can be found, this appraoch may be extended back in time and to other localities because it appears that such features can now be dated both accurately and precisely.
Edwards, R. L., F. W. Taylor, J. H. Chen, and G. J. Wasserburg, High precision thorium-230 dating of corals using thermal ionization mass spectrometry: Applications to paleoseismology, in Directions in Paleoseismology, edited by A. J. Crone and E. M. Omdahl, U. S. Geol. Surv. Open File Report, 87-673, 30, 1987, #1090
Taylor, F. W., C. Frohlich, J. Lecolle, and M. R. Strecker, Analysis of partially emerged corals and reef terraces in the central Vanuatu arc: Comparison of contemporary coseismic and nonseismc with Quaternary vertical movements, J. Geophys. Res., 92, 4905-4933, 1987, 74 citations, #683
n the central Vanuatu arc, living and recently deceased reef corals act as natural tide gauges which have allowed us to map vertical tectonic deformation patterns. As corals grow, the density of the aragonite coral skeletons varies on an annual cycle, producing annual growth bands similar to tree rings. Using coral growth bands, we can determine the year coral surfaces died due to emergence. We interpret four major coral emergence events as coseismic uplifts that occurred near the epicenters and times of large shallow earthquakes on January 5, 1946 (MS = 7.3), August 11, 1965 (MS = 7.5), October 27, 1971 (MS = 7.1) and December 29, 1973 (MS = 7.5). The 1965 and 1973 events caused maximum uplifts of 120 and 60 cm, respectively, in the frontal arc. Also related to these events are uplifts of 10 cm and 6 cm in the back arc on Pentecost and Maewo islands, which lie east of the volcanic chain and the primary forearc zones of uplift and subsidence. Similar secondary zones of uplift occurred with the great 1960 Chile and 1964 Alaska earthquakes. The amplitude of these secondary uplifts is significantly larger than that predicted by models having a single fault in an elastic half-space. However, the amount of secondary uplift is comparable to that predicted if the fault occurs in a plate of constant thickness overlying a viscoelastic half-space. At various places in 1957, 1969ââ¬â1970, 1977, and 1978ââ¬â1981 there was about 5ââ¬â10 cm of emergence not associated with major earthquakes, which may indicate nonseismic tectonic uplift. However, oceanographically lowered sea levels, as in El Niños, may have determined the times when corals died and recorded these events. Nevertheless, the accumulation of emergence, its persistence, the limited geographic extent of each event, and occurrence in areas of rapid Holocene uplift suggest that the causes of the uplifts are tectonic. These events suggest that in some areas a third or more of the total accumulated uplift in central Vanuatu takes place as aseismic motion. However, in some areas we find only coseismic emergence. In central Vanuatu, contemporary coseismic vertical deformation, Holocene uplift, and topography have remarkably similar patterns. This suggests that the mechanisms and processes causing vertical deformation have varied little over the last 106years. Apparently, the topography, structure, and seismotectonics are controlled by the subduction of the d'Entrecasteaux ridge, a major bathymetric feature underthrusting this part of the arc. The influence of this ridge may have been especially extensive because it migrates very slowly along the arc trend, and thus it interacts for a long time with a single portion of the arc system. Our previous studies of reef terraces indicated the existence of at least four seismotectonic arc segments or blocks along the Santo-Malekula interval of the arc, and our present results further support this conclusion. Each block has uplifted at different times, by different amounts, at different rates, and tilted in a different direction. Boundaries between the north Santo and the south Santo segment and between the north Malekula and the south Malekula segment correlate with the north and south flanks of the d'Entrecasteaux ridge, as does the absence of a physiographic trench west of Santo.
Strecker, M. R., A. L. Bloom, L. M. Gilpin, and F. W. Taylor, Karst morphology of uplifted Quaternary coral limestone terraces: Santo Island, Vanuatu, Z. Geomorph., N. F., 30, 387-405, 1986, 6 citations, #1088
Taylor, F. W., P. Mann, S. Valastro, and K. Burke, Stratigraphy and radiocarbon chronology of a subaerially exposed Holocene coral reef, Dominican Republic, J. Geology, 93, 311-332, 1985, 24 citations, doi:10.1086/628954, #604
Emerged reef terraces record the extraordinarily rapid Holocene uplift rate of the fault-bounded Yenkahe resurgent block (YRB), located within a partially submerged Quaternary caldera on Tanna Island, Vanuatu, southwest Pacific. The presently active volcano, Yasur, is located at the western end of the YRB. Episodic uplift of the YRB is probably associated with the movement of magma below the Yenkahe area. A historically recorded uplift at Port Resolution Bay in a.d. 1878 raised the shoreline ~ 15 m. This a.d. 1878 event was accompanied by a local earthquake and a tsunami that reached ~ 12 m elevation. Coral samples from terraces at mean altitudes of 155 m and 15 m above present sea level yield [tex-math]$^{230}Th/^{234}U$[/tex-math] dates of a.d. [tex-math]$1002 \pm 10$[/tex-math] and a.d. [tex-math]$1868 \pm 4$[/tex-math], respectively. These ages imply a mean uplift of 156 mm/yr for the YRB since a.d. 1002 until a.d. 1992. This volcanically related uplift occurs within the context of regional uplift of the southern New Hebrides arc. The late Holocene uplift rate, ~ 1 mm/yr, was determined from emerged terraces on the north and west coasts of Tanna. There have been several large volcanic eruptions in the geological history of Tanna; continued emplacement of magma at shallow levels below the YRB poses a possible volcanic hazard to the population there. Numerous faults in the weakly consolidated YRB strata and relief created by rapid uplift increase the probability of hazards from landslides and tsunamis.
Taylor, F. W., C. Jouannic, and A. L. Bloom, Quaternary uplift of the Torres Islands, northern New Hebrides frontal arc: Comparison with Santo and Malekula Islands, central New Hebrides frontal arc, J. Geology, 93, 419-438, 1985, 36 citations, doi:10.1086/628964, #605
Coral reef terraces on the Torres Islands have recorded the Quaternary uplift of part of the northern New Hebrides frontal arc. These isles lie about midway between the volcanic chain and trench axis, where the Indian plate underthrusts the arc from the west. [tex-math]$^{14}C$[/tex-math] and [tex-math]$^{230}Th/^{234}U$[/tex-math] ages for Torres fossil corals indicate that for approximately the past 100,000 years the islands uplifted at a constant rate ranging geographically from 0.7 to 0.9 mm/yr. The occurrence of similar uplift rates and eastward-tilting directions and the absence of major crosscutting structures or rupture zone boundaries suggest that the islands may be part of a single tectonic block or arc segment. The frontal arc morphology in the Torres area is typical of frontal arcs. Farther south, the central New Hebrides frontal arc has no physiographic trench at the plate boundary west of Santo and Malekula Islands, and the axes of the maximum uplift rate are at the seaward edge of the plate. The d'Entrecasteaux Ridge (DR), a massive E-W trending bathymetric feature on the Indian plate, is underthrusting Santo and Malekula. The eastern parts of Santo and Malekula are physiographically equivalent to the Torres Islands and seem to have been on a former axis of maximum uplift rate. However, in response to subduction of the DR, the uplift axes of Santo and Malekula may have shifted westward. In a few hundred thousand years the new uplift axes caused the western parts of these islands to achieve their present topographic dominance over the earlier uplift axes. Holocene uplift rates on southern Santo and northern Malekula are about twice the average rates of the previous 100,000 years. The accelerated Holocene uplift could be explained if a particularly prominent part of the DR has recently underthrust Santo and Malekula.
Mann, P., F. W. Taylor, K. Burke, and R. Kulstad, Subaerially exposed Holocene coral reef, Enriquillo Valley, Dominican Republic, Geol. Soc. Amer. Bull., 95, 1084-1092, 1984, 16 citations, doi:10.1130/0016-7606(1984)95<1084:SEHCRE>2.0.CO;2, #555
An extremely well-preserved Holocene fringing coral reef occurs at an average elevation of 5 m below sea level around the margins of the central Enriquillo Valley, Dominican Republic. The reef records the latest marine incursion from the east into an 85-km-long, 12-km-wide tectonic depression and appears to represent a unique preservation. Excellent cross sections of the reef exposed in erosional gullies reveal a composition and zonation typical of modern Caribbean reefs that are found in offshore low-energy environments. Radiocarbon age determinations (2) indicate that reef growth coincided with sea-level rise following the last ice age (5,930 ± 100 to 4,760 ± 90 yr B.P.). Deltaic deposition and possible vertical movements on active fault scarps dammed the eastern mouth of the valley and created Lago Enriquillo, the level of which was then rapidly lowered by evaporation in an arid climate to produce a saline lake ∼40 m below sea level. Stratigraphic studies of rocks along the valley edge and data from drill holes in the basin center indicate that there were earlier post-Miocene marine incursions similar to that described here.
Jouannic, C., F. W. Taylor, and A. L. Bloom, Sur la surrection et la deformation d'un arc jeune: L'arc des nouvelles hebrides, in Contribution a l'etude Geodynamique du Sud-Ouest Pacifique, Travaux et Documents de L'ORSTOM, 147, 223-246, 1982, #581
Taylor, F. W., C. Jouannic, L. M. Gilpin, and A. L. Bloom, Coral colonies as monitors of change in relative level of the land and sea: Applications to vertical tectonism, Proc., 4th Int. Coral Reef Symp., 2, 486-491, 1982, #478
Buskirk, R. E., F. W. Taylor, W. P. O'Brien, P. Maillet, and L. M. Gilpin, Seasonal growth patterns and mortality of corals in the New Hebrides (Vanuatu), Proc., 4th Int. Coral Reef Symp., Manila, 2, 197-200, 1981, #490
Gaven, C., M. Bernat, C. Jouannic, and F. W. Taylor, Mouvement verticaux des nouvelles-Hebrides pendant les derniers 120,000 ans. Datations de coraux par la methode Io-U, C. R. Acad. Sci. Paris, 290D, 175-178, 1980, #1342
Jouannic, C., F. W. Taylor, and A. L. Bloom, Late Quaternary uplift history from emerged reef terraces on Santo and Malekula Islands, central New Hebrides island arc, UN ESCAP, CCOP/SOPAC, Tech. Bull., 3, 91-108, 1980, #1340
Taylor, F. W., B. L. Isacks, C. Jouannic, A. L. Bloom, and J. Dubois, Coseismic and Quaternary vertical tectonic movements, Santo and Malekula Islands, New Hebrides island arc, J. Geophys. Res., 85, 5367-5381, 1980, 80 citations, #1341
Emerged late Quaternary coral reefs show that on the 103 to 105 years time scale the western part of the central New Hebrides arc is divided into several semi-independent uplifted blocks. The blocks are separated by tectonic discontinuities, oriented approximately normal to the arc trend, across which tilt directions or uplift change suddenly. However, none of the blocks is tilted in a direction normal to the arc trend of N20° W. Two of the discontinuities, across Santo and Malekula Islands, occur near the places where ridges on the north and south flanks of the d′Entrecasteaux fracture zone, a major bathymetrie feature on the underthrusting plate, intersect the arc. Each of these tectonic discontinuities approximately coincides with one end of the rupture zone inferred for a shallow thrust-type earthquake sequence in 1965. The discontinuity across Santo also nearly coincides with the south end of the rupture zone inferred for another earthquake sequence in 1973â1974. Uplift of north Malekula, imposed during the 1965 earthquakes, was recorded by emergence of shallow water corals and closely resembles the uplift pattern shown by reef terraces on the 103 to 105 years time scale. Uplift of south Santo that occurred in recent years, possibly 1965, also resembles the long-term uplift pattern of that island. These observations indicate that the subducting topography of the d′Entrecasteaux fracture zone has controlled segmentation of the central New Hebrides arc both in terms of seismicity on the 101 years time scale and deformation on the 105 years time scale. Plausible models for buried thrust faults can be made to account for the 1965 uplift pattern. However, there are reasons why a simple elastic dislocation model may be misleading. For example, (1) the uplift data do not adequately constrain the model so that unique fault parameters need be chosen, (2) the block-controlled uplift pattern may interfere with a simple elastic response to faulting, and (3) possible movement on surface faults in north Malekula may have affected the displacement pattern. The upper plate in the Santo-Malekula area might best be viewed as a series of loosely coupled blocks whose movements are dominated by underthrusting of rugged topography on the descending plate. Given the Holocene uplift rates for Malekula and the 1965 example of coseismic uplift, it is possible to consider possible recurrence intervals for earthquakes of the same magnitude and uplift as that of 1965. Many assumptions are inherent in this estimate, but it offers valuable perspective. On Malekula, where there was 1.2 m of uplift in 1965, the Holocene uplift rate is 3.5 m/1000 years. Therefore, every 340 years, there must be 1.2 m of uplift to maintain such an average uplift rate. Interseismic recovery of coseismic uplift could shorten considerably the recurrence interval required to maintain this uplift rate. The convergence rate of 11 cm/yr at the New Hebrides arc implies fault slip of 37 m per 340 years. Since this amount of slip is unlikely for the 1965 earthquakes or their predecessors, either some aseismic slip or a seismic recurrence interval of less than 340 years is suspected.
Bender, M. L., R. G. Fairbanks, F. W. Taylor, R. K. Matthews, J. G. Goddard, and W. S. Broecker, Uranium-series dating of the Pleistocene reef tracts of Barbados, West Indies, Geol. Soc. Amer. Bull., 90, 577-594, 1979, 144 citations, doi:10.1130/0016-7606(1979)90<577:UDOTPR>2.0.CO;2, #1343
Detailed studies of reef-tract stratigraphy in the southwestern part of Barbados have revealed nine, seven, and ten reef tracts in the Christ Church, Clermont Nose, and Saint George's Valley sections, respectively. The reefs have been projected onto standard traverses, and present elevations are reported for each reef crest.