An improved methodology for high-resolution LA-ICP-MS trace-element fingerprinting of tephra layers: Insights from the Upper and Lower Nariokotome Tuffs, Turkana Basin, Kenya

Abstract

Single grain, laser-ablation inductively-coupled-plasma mass spectrometry (LA-ICP-MS) trace element analysis of volcanic glass shards has emerged as a valuable tool in constructing regional tephrostratigraphic frameworks for paleoanthropological sites. The limiting factors in analysing single shards for trace element compositions are a) analytical precision (% RSD), which is dependent on the size and homogeneity of the area available for analysis, and b) accuracy (% bias), which is dependent on compositional differences between natural rhyolitic samples and available reference materials. The limited vertical thickness of the tephra glasses, the small surface areas accessible for ablation and..