IGCP 433 -Caribbean Plate
ITALIAN CARIBBEAN WORKING GROUP (Universities of Palermo, Ferrara, Firenze, Pisa)
G.L.O.M. - Italian Gruppo di Lavoro sulle Ofioliti Mediterranee
C.N.R. - Italian National Council of Researches
SOCIEDAD GEOLOGICA DE GUATEMALA
CESEM Centro Estudios Sup. Energia y Minas, Fac. Ingegneria USAC, Guatemala
2° ITALIAN-LATIN AMERICAN GEOLOGICAL MEETING ON:
THE MOTAGUA SUTURE ZONE OF GUATEMALA
January, 28-31, 2002
First circular
The meeting will be held in the context of the IGCP-433. It will be aimed at contributing to the debate on the origin and evolution of the Caribbean Plate, summarising the main results achieved by the Italian-Caribbean Group through systematic investigation on the regional geometry, magma affinity, and tectono-magmatic significance of the ophiolitic units of the peri-Caribbean deformed margins.
The field trip will regard a transect through the main Jurassic-Cretaceous ophiolitic units involved in the Caribbean Plate north-western deformed margin, represented by the Motagua Suture Zone of Guatemala.
GEOLOGICAL OUTLINE OF THE MOTAGUA SUTURE ZONE
In Guatemala the northwestern deformed margin of the Caribbean Plate crops out along the Motagua Suture Zone (MSZ). Starting from the Miocene, a west-east trending fault system, with a sinistral component of mouvement, links up the Middle American trench, to the west, with the Cayman ridge, to the east, from the Pacific to the Caribbean. The MSZ represents a typical trans-pressional "flower structure" characterised by remarkable W-E trending uplift structures and pull-apart basins, as well as N-S trending grabens; it has been built, from the Cretaceous, in a sinistral shear-zone between Maya and Chortis continental bloks, belonging respectively to the North America and Caribbean Plates.
Several main ophiolitic units can be recognised in the MSZ:
- the Sierra de Santa Cruz (SSC) and Baja Verapaz (BVP) units, in the MSZ northern area, and the Juan de Paz (JPZ) unit, in the MSZ central zone, all overthusting the Maya Block. From a lithological point of view, these units consist of generally serpentinized mantle harzburgites, layered gabbros, dolerites and basalts. Reduced terrigenous and andesitic-dacitic volcanoclastic sequences, as well as, mafic and andesitic breccias, passing upward to reefal limestones and calcarenites are also present. The island arc tholeiitic (IAT) and calk-alcaline (CA) magmatic affinities of the Cretaceous volcanics of both the JPZ and SSC units, testifies the presence of an island arc related to an intra-oceanic subduction.
- the South Motagua (SM) and North Motagua (NM) units overthrust the Chortis and the Maya Blocks, in the southern and central MSZ areas, respectively. These units are represented by: serpentinized peridotites and foliated gabbros, thick basaltic pillow-lava flows, cherts, siltites and arenites interlayered by basaltic flows. The clear normal mid-ocean ridge (N-MOR) magmatic affinity of Late Jurassic-Early Cretaceous basalts, from both the SM and NM units, indicate that these sequences have been generated in an oceanic spreading centre environment.
Penetrative deformations associated to greenschist/amphibolite or blueschist/eclogite facies metamorphism have been observed in several tectonic sheets, generally related to SSC, SM and NM units.
Attempting to draw a synthetic geodynamic model, the available data on the MSZ ophiolites suggest that the SM and NM units represent remnants of an oceanic basin generated, during Jurassic-Early Cretaceous (proto-Caribbean phase), between the Maya and Chortis blocks. Starting from the Early Cretaceous (eo-Caribbean phase), an intra-oceanic convergence interested the western sector of the proto-Caribbean domain, as testified by the orogenic tectono-metamorphic imprint of the SM and NM units, as well as by the development of IAT and CA magmatism, recorded by the SSC and JPZ units. From the Late Cretaceous, the continuous, compressive stress-field give rise to a strong, sinistral, trans-pressional setting, which allowed both the overthrust of the oceanic deformed units onto the Maya and Chortis blocks and the dismembering of the eo-Caribbean units of Guatemala along the tectonic belt, up to reached the present-day MSZ settlement.
In this
scenario several geodynamic problems can be outlined and proposed for
discussion:
1) the position and trend of the Jurassic-Cretaceous oceanic seaway, testified by
the SM and NM ophiolites, as well as of the surrounding continental microplate
(Maya and Chortis Blocks);
2) the position of the island arc (SSC and JPZ units)
during the Cretaceous convergence phases, in relation to the subduction
direction;
3) the mechanism of ophiolite obduction and the kinematic evolution
of the MSZ belt during the Cretaceous-Paleocene;
4) the spatial-temporal
definition of the main evolutionary stages of the MSZ ophiolites in order to
restore the paleogeography of the kinematic elements of the Caribbean Plate.
PRELIMINARY PROGRAMME
1st day (28/1/2002)
Ciudad de Guatemala - Italian Cultural Institute of the Italian Embassy
IGCP
433 Workshop on the evolution of the Caribbean Plate northwestern margin
(session in honour of Gabriel Dengo). Speakers will be defined
as soon as possible.
Overnight stay in Ciudad de Guatemala
2nd day (29/1/2002) Ciudad de Guatemala Valle de Motagua Jalapa
Geological
overview of the Motagua Valley and cross-section through the South Motagua Unit
(N-MORB affinity).
Overnight stay in the Motagua valley area
3rd day (30/1/2002) Valle de Motagua Juan de Paz Lago Izabal
Cross-section through the North
Motagua Unit (N-MORB affinity), and the Juan de Paz Unit (IAT and CA
affinities).
Overnight stay in Lake Izabal area
4th day (31/1/2002) Lago Izabal Sierra Santa Cruz
Cross-section through the Sierra Santa Cruz Unit (IAT and CA affinities).
Overnight stay in Lake Izabal area. Transport to Ciudad de Guatemala is assured on
February 1st 2002.
GENERAL INFORMATION
No registration fee is foreseen for the workshop. A list of hotels in Ciudad de Guatemala will be provided in the second circular, so the participants can book their own accommodation.
The field trip participation fee shall include transport in 4 driving wheel cars, hotel accommodation, and meals. It will be communicated in the second circular; however, the fee total amount depends on both the facilities offered by the Guatemalan institutions and the number of participants, which should not exceed 25.
Funding may be available for some participants: please contact the IGCP 433 project leader, Manuel Iturralde-Vinent ( iturralde@mnhnc.inf.cu), for further details.
For the Italian participants, economically-priced flight reservations can be arranged through our confidential travel agency.
If you have any more queries, please do not hesitate to contact the organizing secretary.
Conveners:
GIUSEPPE GIUNTA
Dipartimento di Geologia, Università di Palermo.
Corso Tukory 131, 90134 Palermo, Italy.
Tel. +39 0917041017; fax +39 0917041041
e-mail: giuntape@unipa.it
LUIGI BECCALUVA
Dipartimento di Scienze della Terra, Università di Ferrara.
Corso Ercole I d’Este 32, 44100 Ferrara, Italy.
Tel. +39 0532293744
e-mail: bcc@dns.unife.it
Organizing secretary:
ELISA PADOA
Dipartimento di Scienze della Terra, Università di Firenze.
Via G. La Pira 4, 50121 Firenze, Italy.
Tel.: +39 3494750195; Fax: +39 055 218628
e-mail: padoae@geo.unifi.it
To send, before September 10th , 2001, to:
ELISA PADOA
Dipartimento di Scienze della Terra, Università di Firenze.
Via G. La Pira 4, 50121 Firenze, Italy.
Tel.: +39 3494750195; Fax: +39 055 218628
e-mail: padoae@geo.unifi.it
IGCP 433
2° ITALIAN-LATIN AMERICANGEOLOGICAL MEETING ON:
THE MOTAGUA SUTURE ZONE OF GUATEMALA
January, 28-31, 2002
APPLICATION FORM
Surname:__________________________ Name:___________________
Institution:________________________________________________________
Address:____________________________ City:___________________ State:___________
e-mail:______________________________________________________________________
tel./fax_______________________________________________________________________
Workshop (28/1/2002) participation: Yes
Oral presentation or poster: Yes
Author(s):_____________________________________________________________________
Title:_________________________________________________________________________
_______________________________________________________________________________Field trip (29-31/1/2002) participation: Yes
This page last modified: June 4, 2001