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Colleagues,
Below you will find the "Outline" (in plain English for non specialists, as required by IUGS) of a project that Uwe Martens (U. Stanford) and I wish to submit to the IUGS International Geoscience Program (IGCP).
The deadline for submission is next Sunday! We started thinking about it last Monday, and we have been working hard the last few days to have the proposal ready and, hopefully, we shall put in on the mail tomorrow. If the proposal is not approved, we shall submit it next year.
Our aim is correlating high-pressure metamorphic complexes along the Caribbean and Central America in an effort to resolve the history of subduction in the region.
Our aim is correlating high-pressure metamorphic complexes along the Caribbean and Central America in an effort to resolve the history of subduction in the region.
Five workshops and fieldtrips (Guatemala -Motagua and Chuacus-, Cuba -central and eastern-, Dominican Rep. -Samana and Rio San Juan-, Venezuela -Margarita, VdelCura, CCosta-, and Nicaragua -recently discovered HP rocks in the Siuna terrane-) distributed in five years constitute the main activities of the project. Research in progress shall be presented in the workshops, but we shall propose organizers of international congresses to include sessions devoted to the project.
Key points to be addressed in the workshops and fieldtrips are:
* Nature of metamorphosed protoliths
* P-T conditions and paths
* Fluid flow and processes
* Timing of subduction and exhumation
* Structure of metamorphic complexes
* Exhumation mechanisms
* Nature of metamorphosed protoliths
* P-T conditions and paths
* Fluid flow and processes
* Timing of subduction and exhumation
* Structure of metamorphic complexes
* Exhumation mechanisms
We have already offered individuals (petrologists, structural geologists and geochronologists) involved in the region joining us. If the proposal is of your interest, we would appreciate receiving a support letter from you. Please send emails to me and a copy to Uwe Martens (umartens@...) as soon as possible, and if you cannot do it so before next Friday, please send it to (+copy to Antonio):
Subject: IGCP proposal "Subduction zones in the Circum-Caribbean" support
Email: igcp@...
IGCP Secretariat
Division of Ecological and Earth Sciences
UNESCO
1 rue Miollis
F-75732 Paris Cedex 15
France
IGCP Secretariat
Division of Ecological and Earth Sciences
UNESCO
1 rue Miollis
F-75732 Paris Cedex 15
France
Don’t hesitate to contact us for further information, and invite your colleagues and students who may be interested!
Very best regards
Antonio and Uwe
--
Antonio Garcia-Casco
Departamento de Mineralogia y Petrologia
Facultad de Ciencias, Universidad de Granada
Fuentenueva s/n
18002 Granada
España/Spain
Tel: + 34 958 246613
Fax: + 34 958 243368
email: agcasco@...
Departamento de Mineralogia y Petrologia
Facultad de Ciencias, Universidad de Granada
Fuentenueva s/n
18002 Granada
España/Spain
Tel: + 34 958 246613
Fax: + 34 958 243368
email: agcasco@...
Uwe Martens
Department of Geological & Environmental Sciences
Stanford University
450 Serra Mall, Bldg 320
Stanford, CA 94305
Tel: + 1 650 725 0045
E-mail: umartens@...
Stanford University
450 Serra Mall, Bldg 320
Stanford, CA 94305
Tel: + 1 650 725 0045
E-mail: umartens@...
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SHORT TITLE: Subduction zones in the Circum-Caribbean
OUTLINE
Oceanic trenches, located generally adjacent to continental masses, constitute the largest physiographical construction in the surface of Planet Earth, with >55.000 km of aggregated length. They form as lithosphere is consumed, a process called subduction, and the resulting plate-scale structure is a convergent margin where intense seismic activity and volcanism take place. Subducted material recrystallizes in response to increased pressure into dense rocks such as blueschist and eclogite, which sink down into the Earth’s mantle responding to negative buoyancy forces. Under favorable tectonic conditions, these rocks are exhumed to the surface. Collisions of plates and lithospheric blocks cease subduction zones, leaving its relics as a suture in orogenic belts. Analysis of high-pressure rocks from sutures around the world has demonstrated the non-steady thermal state of subduction zones, both in time and space, which ultimately controls the distribution of earthquakes and the generation of magma that feeds chains of volcanoes.
The Caribbean plate is limited by the active Central American and the Antillean subduction zones, which cause intense seismic activity and volcanism in the region. This region also presents a number of Mesozoic-Tertiary sutures documenting former subduction. Establishing the link between ancient and current subduction is critical for a well founded understanding of the tectonic evolution of the associated convergent plate-margins, shedding light on the geodynamics of such populated and geologically hazardous region. Current studies on HP rocks found within these sutures have identified an unusually wide range of ages, conditions and episodes of subduction that started ~ 120 My ago: (a) Very cold subduction of oceanic lithosphere recorded in lawsonite-bearing eclogites south of the Motagua suture (Guatemala) and the Samaná peninsula (Dominican Republic); (b) Cold- (normal) to hot-subduction of oceanic lithosphere (including volcanic arc material) recorded in blueschists, eclogites and garnet amphibolites in the Villa del Cura-Cordillera de la Costa-Margarita island (Venezuela), Puerto Rico forearc, Samaná Peninsula, Blue Mountains (Jamaica), Purial complex (eastern Cuba), northern serpentinite belt (west-central Cuba), the northern Motagua suture (Guatemala), and the Río San Juan complex (Dominican Republic); (c) Very hot subduction of oceanic lithosphere recorded in partially melted garnet-amphibolites in eastern Cuba; (d) subduction of continental material of the Chuacús (Guatemala), Guaniguanico, Isle of Pines, and Escambray massifs (Cuba); (e) Garnet-bearing mantle peridotites that record extraordinary depth of formation at Rio San Juan (Dominican Republic). Although many local studies have been carried out in the past few years, the precise timing of subduction-related metamorphism and precise thermobaric structure of subduction zones have not been established in many of the sutures. In addition the relations between oceanic and continental HP belts are poorly understood, and few studies have integrated information from this wide range of HP occurrences for a systematic comparison. As a consequence, it is unknown whether the aforementioned HP occurrences correspond to one or several subduction zones that evolved in time and space, leading to considerable speculation in plate-tectonic models for the region.
In order to address the above questions, scientific collaboration between researchers working in local projects in the Caribbean is critical. We propose bringing together these scientists by organizing workshops in 5 key countries bearing a variety of field occurrences of HP rocks: Cuba, Dominican Republic, Guatemala, Nicaragua and Venezuela. Meetings will combine a scientific conference and a fieldtrip, allowing experts on individual regions and suture zones to share their scientific findings and establish differences, similarities and links between HP belts all along the Caribbean realm in order to establish clear correlations and resolve the history of subduction in the region.
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