Reports: DNI853196-DNI8: Resolving the Silurian Petroleum System on the Western Margin of the Appalachian Basin: Integrated High-Resolution d13C, Conodont, and Chitinozoan Bio-Chemostratigraphy and the Continuing Search for the Source of Silurian-Hosted Hydrocarbon Resources

Bradley D. Cramer, PhD, University of Iowa

Following the one-year hold on the grant as I waited for my post-doc to graduate, we are now well underway on the grant and, as discussed last year, I request a no-cost extension of one year to complete the project. Dr. Alyssa Bancroft (the post-doc on this project) has been working very well on the project and is making tremendous progress on the Conodont Alteration Index (CAI) map for the Silurian of the Appalachian Basin. This past fall (Fall 2014) we received the complete conodont collection of Charles Helfrich, courtesy of Virginia Tech University. This collection is critical to this study as it is likely the largest single collection of conodonts from the Silurian of the Appalachian Basin and it expedited the process of constructing a CAI map by providing over a hundred samples from West Virginia, Virginia, and Maryland. Producing a similar amount of samples from scratch would have taken well over a year to accomplish and retrieving the collection from VT was a great boon to the project. The samples, and their identifications, were all part of Helfrich’s work in the late 1970’s and early 1980’s and therefore require all of the taxonomy to be updated, specimen by specimen, to be useful for modern biostratigraphic analysis. Dr. Bancroft is in the process of updating all of the specimens into modern taxonomic nomenclature and simultaneously providing a CAI determination of each specimen. The net result of this work will be a new biostratigraphic zonation of the Silurian of the Appalachian Basin that includes the Helfrich collection, the collections of project collaborator Dr. Mark Kleffner (The Ohio State University) as well as Silurian Appalachian Basin samples contained in the University of Iowa repository that were originally part of the AMOCO collection. The exceptionally large number of specimens in the Helfrich collection has required most of her time during the last year to update successfully. This process should be completed in the next month or so (by the end of October 2015 at the latest).

A deep drill core was sampled for carbon isotope stratigraphy from south-central Ohio. Access to the core through the Ohio Geological Survey required payment from the project, but a negotiated cost provided a reduced price of $750 for access to the entire core. The OGS waived the core handling fees as well as the use of the facilities fees and only charged a reduced fee of $1/sample for this project. This cost shows up as ‘Expendable Supplies/Services’ in the financial report. The sampled core is the longest, most continuous Silurian core held by the Ohio Geological Survey and should contain at least Aeronian through Ludfordian strata. Such a complete succession has never been sampled from Ohio and we are eagerly awaiting the results from the laboratory. The core was sampled in April of 2015 and the samples are in the laboratory queue at the Stable Isotope Laboratory of Iowa State University. The data should be returned by late September/early October 2015. The cost for carbon isotope analysis will be billed after the data are returned.

A suite of chitinozoan samples were sent to project collaborator Dr. Thijs Vandenbroucke from upper Silurian stratigraphy of New York. The position of the Silurian-Devonian boundary in the Appalachian Basin has been notoriously difficult to identify, largely the result of a lack of sufficient biostratigraphic information. The samples sent to Dr. Vandenbroucke come from a suite of samples collected from New York by project collaborator Dr. Kleffner and help to constrain the recently produced radioisotopic date from the so-called ‘Kalkberg Bentonite’ that is currently the only radioisotopic date constraining the calibration of the Silurian-Devonian boundary. The samples provided some useful biostratigraphic information from near the bentonite, however, the most interesting information from the samples is that what had previously been considered middle to late Pridoli in New York State is likely no higher than late Ludlow. This will require significant further testing to fully demonstrate and new sampling to be undertaken this fall (2015) will begin to address this question.

Travel funds for meetings were used by the Post-Doc (Dr. Bancroft) to attend the 5th Annual Meeting of IGCP 591 this past summer (2015) in Quebec City, Quebec, Canada. The meeting also included field trips to the Gaspé Peninsula as well as Anticosti Island. These trips were critical to be able to provide her with the opportunity to see these exceptional sections and fill in the northern portion of the Appalachian Basin in our understanding of the basin as a whole and she was offered several future post-doc positions during the meeting.

The work done during the past year sets the table for the field work to be conducted in the next several months as well as in the following spring of 2016. The OGS core data will provide critical new information about the continuity and stratigraphic completeness of the Silurian in the Appalachian Basin and the results will dictate what other cores are to be analyzed from their collection. A field run to upstate New York will be carried out in October to collect the Salina Group strata, particularly the Camilus Shale and Vernon Shale for carbon isotope, conodont biostratigraphy, and TOC analysis. We have spent the past six months improving conodont processing methods from Silurian organic shales (mostly from the Welsh Basin) in preparation for how we will deal with these New York samples. The Helfrich collection is being plotted against Appalachian Basin stratigraphy and the updated biozonation information will dictate where additional sampling for carbon isotope and biostratigraphy will be conducted in the last year of this project. The first anticipated publications from this project will be submitted in the summer of 2016 and several more will follow in the fall/winter 2016 and beyond. The length of time required for conodont processing and lab queues at the stable isotope lab place a typical 1-2 year delay on publication outcomes. I anticipate a minimum of three publications in international peer-reviewed journals to result from this work.