T202 Climate and Tectonic Interactions from Bedrock to Basins (Posters)

Tuesday, 24 September 2024
8:00 AM - 5:30 PM
Hall D

OROGENIC COLLAPSE AND EVOLUTION OF THE WESTERN ANATOLIA MIGRATION CORRIDOR

Paper number: T202-3
Program: Technical Sessions
Time: 8:00 AM – 5:30 PM

Authors

Abstract

Fossil records suggest a delay of 2–3 Myr between the establishment of the “Gomphotherium Landbridge” and the dispersal of hominoids to central Anatolia, but only 1-2 Myr between the establishment of the landbridge and the appearance of hominoids at a far more remote location in China. In addition, vast differences existed between the small mammal populations of Europe and Anatolia in the early Miocene. Airy isostacy, applied to crustal thicknesses based on mineral barometry and structural restorations, indicates elevations of 3.5–4.1 km in western Anatolia during the early Miocene. These observations lead to the hypothesis that extreme elevations in western Anatolia presented migration barriers in the early Miocene.

To investigate how high western Anatolia was in the early Miocene, we collected δD data from 14 volcanic glass samples and δ18O data from 18 carbonate samples. Paleowater isotopic compositions were calculated assuming standard isotopic fractionation during precipitation and a 15°C precipitation temperature for CO3. δ18Opaleowater(pw) values range from -6.1 to -12.9‰ and δDpw values of volcanic glass samples range from -113.7 to -68.7‰. A weak negative trend between δD and wt% H2O reflects hydration by dominantly environmental waters instead of magmatic water. The δ18O, δ13C, and microphotographs of alluvial carbonate samples show that these samples are not diagenetic. Volcanic glass samples with wt% H2O> 2 and alluvial carbonate samples were used to calculate paleoelevation. We used a 16 Ma paleosol sample formed in a marginal marine environment as a low-elevation baseline for calculating Miocene paleoelevations. The most negative values of the δ18Opw and δDpw are -13.2‰ and -113.7‰, which yield elevations of 3.6 ± 0.7 and 4.3 ± 0.9 km, respectively. These results from independent isotopic systems confirm that early Miocene topography in western Anatolia was ~3 km higher than the modern. Furthermore, the calculated elevations are consistent with independent estimates based on Airy isostactic considerations. All of these are consistent with the hypothesis that elevated topography posed formidable barriers to faunal dispersion in the early Miocene and may explain the delay in faunal dispersion in western Anatolia. If that is the case, a Miocene-Pliocene decrease in elevation which accompanied extension may have produced faunal migration corridors.

Geological Society of America Abstracts with Programs. Vol. 56, No. 5

doi: 10.1130/abs/2024AM-402665

© Copyright 2024 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.