T161 Sedimentary Geology Division/SEPM Student Research Poster Competition: Dynamics of Stratigraphy and Sedimentation (Posters)

Tuesday, 12 October 2021
9:00 AM - 1:00 PM
Exhibit Hall A

RESOLVING ALONG-STRIKE ANDEAN THRUST FRONT EVOLUTION USING THE FORELAND BASIN RECORD IN THE FLAT SLAB REGION OF ARGENTINA

Paper number: T161-16
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

The Neogene Bermejo Basin of west-central Argentina is a classic example of a broken foreland basin system characterized by basement-involved uplifts of the Sierras Pampeanas and thin skinned Central Precordillera fold-thrust belt partitioning the once continuous foreland basin. However, the kinematic relationship between the Sierras Pampeanas, the Central Precordillera, and the enigmatic west-vergent Eastern Precordillera thrust front remains debated. End member tectonic models for Eastern Precordillera deformation include: (1) thin-skinned deformation at 8-6 Ma associated with the Central Precordillera fold-thrust belt to the west, and (2) thick-skinned deformation at <5 Ma linked to Sierras Pampeanas deformation to the east. Our study seeks to constrain the along-strike Neogene tectonics for the Eastern Precordillera by integrating new structural geology, stratigraphic, detrital zircon U-Pb geochronology provenance, and detrital apatite low temperature thermochronology datasets from the Bermejo Basin. New data from a ~1.8 km thick Neogene stratigraphic section in southern Bermejo Basin constrains deposition between ~13-5 Ma with dominant fluvial-lacustrine mudstones, siltstones and sandstones, that transition into fluvial/alluvial fan conglomerate facies around 7 Ma. New detrital apatite thermochronology ages from the base of the measured section record mean age of ~7 Ma, suggesting a kinematic linkage to thin-skinned deformation in the Central Precordillera. When we compare our new data with published data from northern Bermejo Basin, we observe a north to south: (1) decrease in stratigraphic thicknesses, and (2) increase in exhumation ages along strike. To further investigate these along-strike variations, we will measure additional stratigraphic sections in southern Bermejo Basin coupled with detailed mapping and sample collection for geo-thermochronology analyses.

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-365602

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