Trace element investigation of tephras from the Ledi-Geraru paleontological site in Afar, Ethiopia
Abstract
The history of explosive volcanism in the highly extended Afar region of Ethiopia is recorded in Neogene to Quaternary tephra deposits in stratigraphic sequences exposed along the course of the Awash River and its tributaries. High extension rates and complex extension patterns in the Afar have resulted in faulted or discontinuous strata that require tephra correlation methods for linking rock records. Geochemical fingerprinting of tephras has traditionally been accomplished using major element data collected using electron microprobes. However, recent improvements to the laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) methodology allow minor and trace elements of small (20 μm), discrete, volcanic glass shards to be analyzed that increase the database for correlation and magmatic evolution studies. While discrete grain LA-ICP-MS has been successfully used in tephrochronology studies in places such as Antarctica, Indonesia, and the US, there has been limited application of the method to paleoanthropological sites in eastern Africa. Here we present results of trace and minor element glass analysis measured using LA-ICP-MS of a subset of tephras from the Ledi-Geraru project area in Afar where the earliest fossil of the genus Homo was recently discovered. Generating new and more robust tephra correlations improves stratigraphic links and age models at Ledi-Geraru for dating fossil and artifact sites. These data also serve as a promising first step in building a discrete grain LA-ICP-MS database to study the physical and chemical magmatic evolution of this part of Afar.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.T51C2919D
- Keywords:
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- 1037 Magma genesis and partial melting;
- GEOCHEMISTRYDE: 1209 Tectonic deformation;
- GEODESY AND GRAVITYDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8109 Continental tectonics: extensional;
- TECTONOPHYSICS