22 Undergraduate Research Poster Session II

Saturday, 29 March 2025
8:30 AM - 5:30 PM
North Great Hall

DOES A GRAY PUMICE RICH LAPILLI TUFF FROM A FOSSIL LOCATION IN CENTRAL LEE ADOYTA, WITHIN LGRP, GEOCHEMICALLY CORRELATE TO A KNOWN DATED TUFF CALLED THE GURUMAHA TUFF?

Paper number: 22-31
Program: Theme Sessions
Time: 8:30 AM – 5:30 PM

Authors

Abstract

Tephra deposits in sedimentary layers can be geochemically analyzed and correlated across long distances. Volcanic glass and feldspar grains present in the tephra are representative of the composition of the volcanic eruption and can be used to date the eruption. In the Afar depression, Ethiopia tephra deposits are important for dating fossils and correlating layers to study paleoenvironments. At the Ledi-Geraru project site in Ethiopia, fossils of early humans were discovered overlying a gray lapilli tuff near a fault. The tuff is thought to be the Gurumaha Tuff - a tuff dated to ~2.8 Ma and geochemically fingerprinted from samples elsewhere in the region. Correlating this tuff would help confirm the unit and date it – providing age estimates for the fossils. Here we use electron microprobe data of feldspar phenocrysts to assess its correlation with samples of the Gurumaha Tuff. Electron microprobe data allows us to make comparisons to previous samples of the Gurumaha Tuff that were dated and analyzed for geochemistry. This investigation will improve geologic mapping in the region by characterizing unidentified tuffs and improve our ability to constrain the age of important fossil discoveries.

Geological Society of America Abstracts with Programs. Vol. 57, No. 3

doi: 10.1130/abs/2025NE-409084

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