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Carbon isotopes were first shown to be effective for stratigraphic correlation in Neogene and Paleogene sections (e.g., Cramer et al., 2003; Dupuis et al., 2003; Woodruff and Savin, 1991). d¹³C stratigraphy is now recognized as critical in older records, especially where magnetobiostratigraphy is insufficient to accurate correlate high-resolution datasets (e.g., Cramer and Saltzman, 2005; Grocke, 2006; Muttoni et al., 2004; Weissert et al., 1998). My grant research focuses on identifying d¹³C events recorded in marine carbonates and organic carbon that can be used for correlation in Triassic sections.

Grant funds were received in Dec. 2010. Although this was too late to recruit a new graduate student for this project in the 2009-2010 academic year, I began isotopic analyses on Barents Sea cores myself immediately. By the end of March, I successfully recruited a very promising graduate student, David Mosher (B.S. St. Lawrence U., May 2010). 

David started his thesis research on Tethyan Triassic carbonate sections at RPI in June. While at St. Lawrence, David completed an undergraduate honors thesis on the Marcellus Shale with Dr. Jeff Chiarenzelli, supported by an ACS-PRF grant.  David’s goal is to go into the oil and energy industry.  Just a week after attending the student expo in Houston, Dave is already being heavily recruited for an internship by 6 oil companies.  David is an excellent example of the important role ACS-PRF plays in supporting students.  Without the ACS-PRF grants, Dave would not have had the opportunity to be involved in either of these research projects.

This project has allowed my to establish new collaborations (including international collaborations) with Dennis Kent (Rutgers U.), Giovanni Muttoni (Univ. of Milan), and Atle Mørk (SINTEF Petroleum Research, and Norwegian University of Sciences and Technology). In addition, I have been able to renew an old collaboration with Allen Milligan (Oregon State University), on a new research topic.

In spite of the short time that we have had the funds available to conduct grant-related research, we have preliminary results and we submitted two abstracts for the 2011 AAPG annual meeting, summarized below.

1. Katz, M.E., Mørk, A., Milligan, A.J., Triassic Carbon Isotope Stratigraphy – Correlations between Panthalassic and Tethyan Sections.

In this study, we build on published high-resolution d¹³C records of carbonates (d¹³C_carb)(Korte et al., 2005; Muttoni et al., 2004a; Payne et al., 2004), which provide important glimpses of carbon cycle dynamics and potential for d¹³C stratigraphic correlation during the Triassic, which began and ended with large d¹³C excursions. Large d¹³C_carb fluctuations (up to 8‰) in the Tethys accompanied the Early Triassic reorganization of marine ecosystems over 4-8 myr (Payne et al., 2004), followed by more stable values punctuated by occasional smaller events through the rest of the Triassic (Korte et al., 2005; Muttoni et al., 2004a). Although geographically restricted to the Tethys (Europe and China), these Triassic isotopic records demonstrate the potential to establish d¹³C events that could be used in stratigraphic correlation.

We expand on these published Tethyan d¹³C_carb records both geographically and geochemically, with Early to Middle Triassic (Induan-Ladinian) d¹³C_carb and d¹³C_org from the Panthalassic Ocean. We use 11 cores drilled by IKU/SINTEF along a depth transect on Svalis Dome (Barents Sea), recovering 315m of a 650m section of deep shelf to basinal siltstones and shales (Mork and Elvebakk, 1999). The Svalis Dome succession contains an excellent hydrocarbon-rich source rock in the late Olenekian and Anisian with TOC values of 2 to 7%. Ammonoids and palynomorphs provide good age control (Vigran et al., 1998). Our d¹³C_carb and d¹³C_org data both show large fluctuations that are similar to coeval d¹³C_carb changes reported from China (Payne et al., 2004), supporting the utility of carbon isotopes for stratigraphic correlation in Triassic sections. 

2. Mosher, D., Katz, M.E., Muttoni, G., Kent, D.V., Development of High-Resolution d¹³C Records in Tethyan Limestones from the Anisian to Early Norian.

In this study, we present new high resolution (100 ky) d¹³C records of bulk sediment carbonates from Tethyan Triassic sections with excellent biomagnetostratigraphy. Our goal is to establish d¹³C event stratigraphy that can be used for correlation in sections that lack good biomagnetostratigraphy.

We analyzed an Anisian-Ladinian (~240-231 Ma) limestone section from Seceda (northwestern Dolomites, Italy) that spans the entire Buchenstein Beds Formation. These limestones contain radiometrically-dated tuff layers (~238.0-241.2 Ma) (Mundil et al., 1996; Brack et al., 1996). Through U-Pb age dating, a sediment accumulation rate of ~10 m/m.y. was determined, this rate doubled in the Bänderkalke member; where turbidite beds became more prevalent (Maurer el al., 2003). The magnetostratigraphy from this core has been used to define the base of the Ladinian for the Global Stratigraphic Section and Point (GSSP), and to complete the Middle Triassic magnetic polarity time scale; in addition, conodont biostratigraphy has been directly tied to the Seceda core from locations throughout the Dolomites and Alps (Muttoni et al., 2004). This published integrated biomagnetostratigraphic framework makes Seceda the best section to use for our Middle Triassic d¹³C stratigraphy. In addition, we analyzed a section from Hydra Aghia Marina (Greece) to check Seceda results when the two sections overlap; the Aghia Marina is from Adhami Formation; condont biostratigraphy indicates late Ladinian to early Norian ages.