T219 130 Years of Research in the Turkana Basin, Kenya: Insights into Earth, Climate, and Life in Eastern Africa Topical Session

Tuesday, 24 September 2024
1:30 PM - 5:30 PM
207A

MIOCENE LANDSCAPE RECONSTRUCTION AND FAUNAL EVOLUTION IN KENYA’S TURKANA BASIN: A REPORT FROM THE TURKANA MIOCENE PROJECT

Paper number: T219-5
Program: Technical Sessions
Time: 2:20 PM – 2:35 PM

Authors

Abstract

A central goal of the paleosciences is to assign causality to macroevolutionary changes in the paleontological record using the geologic toolkit, including field observations, geophysical data, geodynamic modeling, geochronology, geochemical proxies, and paleoclimate simulations. Inherent challenges exist, however, when trying to develop records and predictions at the same temporal resolution while studying terrestrial rocks at the regional scale. The East African Rift System (EARS) offers an exceptional setting for these efforts due to the availability of outcropping sedimentary rocks and the richness of the faunal record, and provide an opportunity to illuminate the conditions that influenced the origin of our own lineage. Here we present the design, progress, and early results from the Turkana Miocene Project (TMP). The TMP is a highly interdisciplinary team investigating the relationship between tectonics, climate, and the transformation of terrestrial vegetation and faunal assemblages in the Turkana Basin, Kenya, from the latest Oligocene through the Late Miocene (~28 to 5 Ma). The TMP’s integrative research approach combines geophysical, sedimentological, geochemical, and fossil data from the field with cutting-edge global and regional climate simulations of the Miocene that provide direct model-proxy comparisons and a 4D forward thermo-mechanical geodynamic model to assess the tectonic evolution of the basin. The Oligo-Miocene sedimentary rocks in Turkana span an intermediate interval of long-term Neogene cooling, punctuated by the Miocene Climatic Optimum from 17 to 15 Ma. They also cover consequential regional tectonic events like the docking of Africa with Eurasia and the closure of the Tethys seaway, which allowed faunal interchange between the two continents. Initiation of the EARS during the Early Miocene led to increased volcanism and the creation of topographic heterogeneity that supported heterogeneous habitats. This coincided with the rise of apes, and the first hominins - the tribe containing modern humans and their extinct ancestors - emerged in the Late Miocene. The global rise of C4 grasslands, and especially in eastern Africa at ~9.5 Ma, matches closely with the origin of mammal lineages that make up modern Africa’s iconic fauna.

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

doi: 10.1130/abs/2024AM-402921

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