29 Cenozoic Tectonics in Asia and North America: Linking Processes Across Scales

This session invites research integrating geologic, geomorphic, and paleoclimate data to advance understanding on orogenesis, seismic hazards, and global change.

Tuesday, 19 May 2026
1:30 PM - 4:30 PM
Alvarado A

Understanding the history of Altai uplift using stable and clumped isotope analysis in western Mongolia

Paper number: 29-3
Program: Technical Sessions
Time: 2:30 PM – 2:50 PM

Authors

Abstract

Understanding the surface uplift of mountain ranges is crucial for deciphering deep Earth processes, as well as changes in global biochemical cycles and biodiversity. Proxies for past climate shifts are commonly employed to generate surface uplift reconstructions given the close relationship between topography and climate. However, discrepancies between paleoclimatic and sedimentological records of uplift can complicate their interpretations, such as is the case for the Altai Mountains in western Mongolia. The Altai Mountains potentially have played a significant role in global climate change since the Middle Miocene because of their geographic location, extent, high elevation, and role in the aridification of Central Asia, leading to dust-fertilization of the Pacific Ocean. To better understand the paleoclimatic and sedimentological discrepancies, we generated new records of stable and clumped δ18O and δ13C isotopes from paleosol carbonates collected in two basins east of the Altai Mountains: the Khyargas Nuur Basin in the immediate lee of the range and two sections of the Zereg Basin located approximately 200 km leeward. The formation of a rain shadow by the Altai should have generated a detectable change in precipitation in leeward basin paleoclimate records; Khyargas Nuur is influenced by moisture coming directly over the mountain, though Zereg is also influenced by moisture that travels south around the main portion of the Altai Mountains. We discover a decrease in Khyargas Nuur δ18O values in the Pliocene (~ 5-2 Ma), which may be linked to elevated upwind topography. In both basins, there is a gradual increase in δ13C starting at ~6 Ma suggesting a more arid environment. Preliminary CIA-K data supports these results by showing a decrease in weathering. Our new clumped isotope data show a 5-10°C decrease in carbonate formation temperatures during the Late Miocene, approximately at the same stratigraphic position in the sections as the lower δ13C values. We suggest that the combination of lower temperatures and δ13C could be a result of global cooling that occurred during the Late Miocene. These results suggest that the Altai were likely high enough by the Late Miocene to substantially influence climate in the lee of the range.

Geological Society of America Abstracts with Programs. Vol. 58, No. 4

doi: 10.1130/abs/2026RM-410574

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