245 D35. Recent Advances in Structural Geology and Tectonics (Posters)

Wednesday, 12 October 2022
9:00 AM - 1:00 PM
Exhibit Hall F

DEFORMATION AND EXHUMATION AT OBLIQUE MARGINS: A STUDY OF THE NORTHERN CARIBBEAN PLATE BOUNDARY IN THE DOMINICAN REPUBLIC, HISPANIOLA

Paper number: 245-18
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

The evolution of obliquely convergent margins tends to experience temporally and spatially variable deformation patterns due to time-varying convergence rates, obliquity, and strain partitioning. In particular, the origin and temporal evolution of topography and deformation during progressive convergence at oblique plate boundaries remain debated. To fully understand their current and evolving signatures, we must reconstruct and unravel margin evolution for variable tectonic scenarios. Here, we explore how a convergent margin progresses from pure shear to wrench-dominated transpression using the northern Caribbean Plate Boundary (NCPB) as a natural laboratory. To investigate the evolving style and magnitude of deformation and the exhumation and landscape evolution response, we integrate structural geology and geomorphology with zircon and apatite (U-Th)/He low-temperature thermochronology. We focus on the Dominican portion of the Greater Antilles Island of Hispaniola, where the NCPB is well exposed. Structural analyses in the northern and central Cordilleras point to a multistage deformation pattern with marked spatial variation in style and geometry. Slickenline orientations point to a west-to-east increase in extension corresponding to along-strike changes in fault geometry and magnitude of exhumation. Structural overprinting in both Cordilleras indicates potential temporal changes in fault slip direction of >70º, likely accompanying local stress reorientations as the boundary transitioned to wrench-dominated transpression. Stream and topographic analyses suggest that the southwestern portion of the island accommodates most of the uplift and topographic response, while thermochronometric results constrain the timing, spatial magnitudes of exhumation, and the control of major faults on spatial trends in exhumation rates. Based on these integrated analyses, we propose that the NCPB experienced multistage adjustments in strain partitioning during the plate boundary's transition, reflected by changes in fault kinematics and geometry, spatiotemporal exhumation trends, and the development of topography. Deformation appears to have intensified in the Miocene related to the accretion of thick Caribbean crust, rejuvenating deformation and exhumation across the island.

Geological Society of America Abstracts with Programs. Vol. 54, No. 6

doi: 10.1130/abs/2022AM-380024

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