Speaker: Colin Robins, Keck Science Department (CMC/PIT/SCR)
Title: “Mineralogical and Soil-Geomorphic Insights from a ~4-5 million-year-old Mojave Desert Soilâ€
Please join us: Tuesday, September 17th @ 11AM in Edmunds 130
Abstract: Sometimes called calcretes or caliches, carbonate-cemented soil horizons cap geomorphic surfaces in modern, arid to semi-arid landscapes worldwide, and they also mark unconformities in the rock record. Calcic soils and paleosols are highly attractive for paleoenvironmental study because of known relationships between climate, soil chemistry, and soil mineralogy, and because of the diversity of authigenic minerals now being recognized in such soils. However, the difficulty of extracting intact, mineralogically homogenous, authigenic crystals from cemented soil for isotopic analysis poses a significant obstacle to quantifying rates of soil genesis or constraining the timing of landscape response to climate change in arid regions.
My research on ‘critical zone’ carbonates is focused on (1) using micromorphological and chemical analyses to identify authigenic minerals or features that might act as isotopically closed, sequentially grown systems, and (2) testing the applicability of existing geochronologic techniques to those minerals and features. I’ll discuss some of the lessons I’ve learned so far, as well as a few new directions for this field and laboratory research in geology, soil science, and environmental analysis.