T19 New Insights into Controls on the Behavior of Orogenic Systems and their Associated Basins

Sunday, 15 October 2023
8:00 AM - 12:00 PM
326

INTENSIFICATION OF THE SOUTH AMERICAN MONSOON AT THE START OF THE MIDDLE MIOCENE CLIMATIC OPTIMUM IN THE CENTRAL ANDES AS A MODULATOR OF OROGENIC SHORTENING

Paper number: T19-3
Program: Technical Sessions
Time: 8:20 AM – 8:40 AM

Authors

Abstract

Climate exerts critical controls on the behavior of orogenic systems by regulating erosion, which in turn influences fold-thrust belt behavior. We investigate the stratigraphic and orogenic response to pronounced climatic warming during the Middle Miocene Climatic Optimum (ca. 17-14 Ma) in the southern Central Andes. We present stratigraphic and geochronologic data from a series of basins at ~25-35°S that occupied both high and low elevation positions during basin filling. Regionally ubiquitous eolianite deposition from 23-17 Ma supports arid conditions on the eastern flank of the Central Andes leading up to the Middle Miocene Climatic Optimum. A rapid and regional shift from eolian dune fields to fluvial-lacustrine conditions occurs near the onset of the Middle Miocene Climatic Optimum over 1000 km along-strike. These results support a change from arid to more seasonal and humid conditions during the Middle Miocene Climatic Optimum. Stratigraphic constraints are corroborated by climate models which indicate increased seasonality and moisture availability on the eastern flank of the Andes during increasing pCO2, likely driven by an intensification of the South American Monsoon. We compare our results with published sequentially restored, regional cross-sections to explore linkages between the climatic shift and orogenic growth.

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

doi: 10.1130/abs/2023AM-392282

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.