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Geological Sciences Seminar: Jon Husson, University of Victoria - "The nature of the rock record and its implications for Earth history"

Date and Time: 
October 17, 2017 -
12:00pm to 1:00pm
Location: 
GeoCorner, Room 220
Contact Email: 
julieh1@stanford.edu
Contact Phone: 
650-724-8437
Event Sponsor: 
Department of Geological Science

For over 100 years, geoscientists have appreciated that Earth's climate and surface chemistry is mediated by mass exchange with the lithosphere. Due to the challenges of direct quantification of sedimentary mass fluxes, especially at fine temporal scales, geochemical proxy study of well-constrained stratigraphic sections has emerged as a dominant mode to study ancient climate and biogeochemical cycling. This approach has found remarkable success, and underpins our modern hypotheses for how Earth's surface has evolved across geologic time. Interpretations of geochemical time series, however, are often non-unique, leading to uncertainty in their implications for Earth history. Here, we present analyses from Macrostrat (https://macrostrat.org), a relational geospatial database that describes the chronological age and spatial distribution of rocks and sediments in the upper crust. Macrostrat thus allows one to model sedimentary mass fluxes into and out of the lithosphere on geological timescales. Our analyses (i) challenge long-standing models that have previously described the nature of the rock record and (ii) have clear and important implications for climate and biogeochemical evolution across Earth history. In particular, we will discuss new insights about the geologic histories of atmospheric O2 and CO2, derived from our empirical analysis of the sedimentary rock record.