Constraining the temperature conditions of paleo-subduction plate interfaces, Part I: Petrologic case study of the Rio San Juan Complex (Dominican Republic)
Abstract
Pressure-temperature (P-T) estimates from exhumed metamorphic rocks are often used to constrain the thermal conditions of paleo-subduction zone plate interfaces. However, the exhumed rock record on average indicates temperatures 200-300°C warmer than those predicted by geodynamic models for modern subduction zones. In this study, we use quartz-in-garnet and zircon-in-garnet elastic thermobarometry combined with equilibrium thermodynamics to evaluate the P-T history of four tectonic blocks within mélange zones of the Rio San Juan Complex, which was exhumed from a subduction system involving the Caribbean, North American and South American plates during the mid-Cretaceous to mid-Eocene period. Previous work suggests that this subduction complex is a warm end-member relative to other exhumed terranes. Mélange zones within the Rio San Juan Complex preserve a near-continuous record of its P-T history during subduction and exhumation. The selected blocks range in metamorphic grade from garnet blueschist to eclogite facies, and have been previously interpreted to record circa 200°C of secular cooling of the subduction interface following subduction initiation. Preliminary results appear to support this model. To better understand the physical controls on paleo-subduction zone thermal structures, these estimates are compared to 2-D coupled kinematic-dynamic models that capture key features of the tectono-metamorphic evolution of the region.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.T41J0279H
- Keywords:
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- 7230 Seismicity and tectonics;
- SEISMOLOGY;
- 8158 Plate motions: present and recent;
- TECTONOPHYSICS;
- 8170 Subduction zone processes;
- TECTONOPHYSICS;
- 8488 Volcanic hazards and risks;
- VOLCANOLOGY