T86 Advances and New Voices in Marine and Coastal Geoscience

Monday, 16 October 2023
8:00 AM - 12:00 PM
325

GEOHAZARDS ALONG THE NE CARIBBEAN TRANSPRESSIONAL PLATE BOUNDARY

Paper number: T86-6
Program: Technical Sessions
Time: 9:15 AM – 9:30 AM

Authors

Abstract

Transform plate boundaries accommodate motion between two tectonic plates and can undergo compressional and extensional forces. Along the northern Caribbean transform plate boundary the motion between the Caribbean and North American plate is transpressional and there are several faults that accommodate this motion. The Enriquillo-Plantain-Garden Fault has recently ruptured along Hispaniola in two catastrophic earthquakes that present a high geohazard risk to the region. The 2010 Mw 7.0 and 2021 M7.2 ruptured the EPGF along the southern peninsula in Haiti. As part of an NSF RAPID reponse we surveyed the EPGF in the Jamaica Passage, west of Hispaniola. High-resolution subbottom profiles and 47 sediment cores were recovered from the R/V Pelican in water depths of 3000 m to characterize the paleoearthquake record. Not much is known about the historic and prehistoric earthquakes along the EPGF in the Jamaica Passage. The Passage forms an elongated trough extending for ~150 km from E-W. It is 3000 m deep and contains three main basins relics from a Paleocene-Eocene extensional regime, which are from E-W: Matley, Navassa and Morant. Compression began in the Neogene.

We present geochemical, lithologic and age data that reveal the sedimentation is dominated by iron-rich sediments and calcium carbonate pelagic sediments mainly composed of foraminifers and pterapods. A marked change occurs in the mafic-rich lithology from the late Pleistocene to the Holocene showing a transition where redox elements such as Mn and Fe reveal a change to more oxygenated conditions, and microfossil assemblages show an increase in numbers. These changes are consistent with a decrease in the Fe-Ca ratio and other element trends. The sediment structures and contrasting color and density of the lithology allow us to identify sediment transport deposits composed of stacked turbidites up to 1 m thick. The ages reveal recurrence intervals of ~500-1000 years for individual segments, and some of these events can be correlated throughout the three basins suggesting either large-scale ruptures of the plate boundary or more likely sequential events.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-391891

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