Back to
more links to Puerto Rico researchJ van Gestel (Dept. of Geological
Sciences, Univ. of Texas at Austin, Austin, TX, 78713; 512-471-0452;
jpges@utig.ig.utexas.edu; Sponsor: P Mann)
P Mann (Inst. for Geophysics, Univ. of Texas at Austin, Austin, TX 78759); N Grindlay,
(Dept. of Geology, Univ. of Puerto Rico, Mayaguez, Puerto Rico 00681); J Dolan, (Dept.
Geol. Sci., Univ. of Southern California, Los Angeles CA, 90089)
An Oligocene-early Pliocene carbonate platform covers an extensive region of the
oblique-slip Caribbean-North America plate boundary in and around the Virgin Islands,
Puerto Rico (PR), the Mona Passage, and the Dominican Republic (DR). Integration of
onshore data compiled from previous studies and the results of single channel seismic
reflection data collected by the RV Maurice Ewing in 1996 improve the identification and
correlation of this remarkable carbonate datum throughout the region. Similarities in the
present-day elevation and deformational style of this unit, whose age ranges and
depositional water depths are generally known from onland studies, are used to subdivide
the NE edge of the Caribbean plate into five structural provinces that record post-early
Pliocene deformation related to oblique subduction and strike-slip faulting: 1) Deeply
drowned and tectonically eroded province adjacent to the Virgin Islands and eastern PR
shelf margins; 2) Deeply drowned and less tectonically eroded province adjacent to western
PR; 3) Drowned and rifted province in the Mona Canyon area, where the carbonate platform
floors NS-striking grabens; 4) Drowned and folded province in the northeastern DR; and 5)
Uplifted and folded province in the northern DR; anticlinal crests of folded early
Pliocene rocks reach elevations of 1200 m ASL.
These five structural provinces are interpreted as the result of east to west, Miocene
to recent, time-transgressive deformation related to the oblique subduction of the
southeastern margin of the Bahama Platform beneath the Virgin Islands, PR and the DR.
Drowning of provinces 1 and 2 reflect tectonic erosion and collapse of the overriding
plate as the SE Bahama Platform migrated from east to west.