61st Annual Report on Research 2016

     The main goal for the first year of this grant was to recruit a high quality PhD candidate.  I was extremely successful in this by bringing on my top candidate, Alexander Conti, who completed his MS in Geology at Ohio University under the direction of Elizabeth Gierlowski-Kordesch in May 2016.  Alex’s MS project was focused on the sedimentology, stratigraphy, and organic geochemistry of lacustrine rocks deposited in the Hartford Basin of New England.  His knowledge in these areas is already proving to be a valuable asset to this project. 

     While I didn’t have a student working directly on this project during the 2015-2016 reporting period, I did have a MS student studying cores of the Green River Formation in the Uinta Basin of Utah (Figure 1).  His project helped to identify numerous correlatable organic-rich mudstone beds from two cores that are separated by 16 km.  One bed was sampled in both wells (Figure 2) which contains a volcanic tuff, providing further confidence in our chronostratigraphic correlation.  A second tuff, the Skyline ash, located a few feet below (Figure 2) was recently dated using ⁴⁰Ar/³⁹Ar geochronology (Smith and Carroll, 2015).  This sample set will allow us to address three of the five primary objectives of the proposed research: 1) investigate the control of organic matter type on Re and Os concentrations and Re/Os isotope ratios in lacustrine organic-rich mudstones, 2) determine the initial ¹⁸⁷Os/¹⁸⁸Os ratio (Os_i) from an individual organic-rich mudstone bed separated by more than 10 km to investigate how robust Os_i measurements are as chemostratigraphic indicators, and 3) compare Re/Os isochron age determinations of organic-rich mudstones to high precision ⁴⁰Ar/³⁹Ar age determinations of interbedded volcanic tuffs.

     Currently, aliquots of these samples are being processed by the USGS in Denver, CO for RockEval and TOC analysis to help determine the type and diversity of organic-matter present.  Additional aliquots will be analyzed for biomarkers in early 2017 to further elucidate the organic matter type.  Alex is now preparing the samples for Re and Os isotope analysis in Dr. David Selby’s TOTAL Laboratory for Source Rock Geochronology at Durham University.  Results from this sample set should allow us to prepare a manuscript for submission in 2017 to a peer-reviewed journal, and provide focus for a follow up grant proposal to the NSF. 

References:

Smith, M.E., and Carroll A.R., 2015, Introduction to the Green River Formation, in Smith, M.E., and Carroll A.R., eds., Stratigraphy and paleolimnology of the Green River Formation, Western USA: Springer, Syntheses in Limnogeology 1, p. 1-12.

Figure 1.  Map showing the location of sampled cores within the eastern portion of the Uinta Basin (U).  The Greater Green River Basin (G) and Piceance Creek Basin (P) are also shown.

Figure 2.  Core photographs showing the correlation of the sampled interval and volcanic tuffs between Skyline 16 and PR15-7c.  See Figure 1 for location of cores.