Research Summary:

This work has involved an examination of the carbonate diageneis from seven Ordovician reefal deposits from the United States and Sweden. Characterization of marine, meteoric (fresh water), and burial diagenetic phases using minor element and stable isotopic analyses was completed. This work served as a foundation for determining Ordovician surface seawater temperatures and the nature of pre-vascular plant freshwater (meteoric) diagenesis.

Funding Record:

Walker, K.R., and Tobin, K.J., Feb. 1994 to Jan. 1997, $154,960, Isotopic composition of early diagenetic carbonate from the Ordovician: implications for greenhouse paleoceanography and paleoclimate and pre-vascular plant meteoric diagenesis. National Science Foundation.

Papers:

Tobin, K.J., and Walker, K.R., 1998, Diagenetic calcite from the Chazyan Group (Vermont): an example of aragonite alteration in a greenhouse ocean. Sedimentary Geology. 121: 277-288.

Tobin, K.J., et al., 1997, Burial diagenesis of Middle Ordovician carbonate buildups (Alabama, U.S.A): Documentation of the dominance of shallow burial conditions. Sedimentary Geology, 114: 223-236.

Tobin, K.J., and Walker, K.R., 1996, Ordovician low-to-intermediate Mg calcite from Sweden: an example of marine stabilization and implications for Ordovician stable C-O marine isotopes. Sedimentology, 43: 719-735.

Tobin, K.J., 1996, Book Review of Johannes Walther on reefs: pioneering concepts of biogeology 1885-1910. Earth Science History, 15: 83-84.

Tobin, K.J., et al., 1996, Fibrous calcite from the Ordovician of Tennessee: Preservation of marine oxygen isotopic composition and its implications. Sedimentology, 43: 235-251

Tobin, K.J., and Walker, K.R., 1995, Meiklejohn Peak fibrous calcite: implications for the Ordovician d18O marine record. In: Cooper, J.D., Droser, M.L., and Finney, S.C., eds., Ordovician Odyssey: Short Papers for the Seventh International Symposium on the Ordovician System, Pacific Section Society for Sedimentary Geology (SEPM), p. 385-388.

Tobin, K.J., and Walker, K.R., 1994, Early diagenesis of below a submerged platform: implications for d13C compositions prior to pre-vascular plant evolution, Middle Ordovician, Alabama, U.S.A. Sedimentary Geology, 90: 95-111.

Abstracts:

Tobin, K.J., 2002, Diagenetic influences on Early Paleozoic marine oxygen isotopes. American Association of Petroleum Geologists Annual Convention.

Tobin, K.J. and Walker, K.R., 1998, Ordovician carbon isotope stratigraphy: some lessons from detailed unit characterization. American Association of Petroleum Geologists Annual Convention, Extrended Abstracts, Vol. 2, p. A660.

Tobin, K.J. and Walker, K.R., 1996, Recognition of original marine cements from the Effna Formation (Ordovician, Virginia) using multiple lines of evidence, GSA Abstract, 28(7): 338.

Steinhauff, D.M., Srinivasan, K., Tobin, K.J., and Walker, K.R., 1996, Cambrian and Ordovician drowning unconformities: examples from east Tennessee, GSA Abstract, 28(2): 45.

Tobin, K.J. and Walker, K.R., 1995, Fibrous calcite from the Middle Ordovician of Sweden: A tale of three calcites. 1st SEPM Congress on Sedimentary Geology, 1: 122.

Tobin, K.J., and Walker, K.R., 1995, Primary, low-magnesium bladed-to-fibrous calcite from Chickamauga Fm. (Middle Ordovician) in Alabama: not a reflection of calcite sea. GSA Abstract, 27(2): 92.

Tobin, K.J., et al., 1994, Post-Devonian diagenesis of Middle Ordovician carbonate buildups (Alabama, U.S.A.): implications for the timing of fluid migration in the Alleghanian foreland basin. American Association of Petroleum Geologists Annual Meeting, 3: 272.

Tobin, K.J., et al., 1993, Burial alteration of ooids and fibrous calcite cement from platform-marginal Ottosee Formation (Middle Ordovician) east Tennessee: Is there no place to hide? GSA Abstract, 25(7): 228.

Tobin, K.J., and Walker, K.R., 1993, Fibrous calcite from the Middle Ordovician Holston Formation (east Tennessee). GSA Abstract, 25(4): 74.

Tobin, K.J., Walker, K.R., and Srinivasan, K., 1992, Repetitive, multistage near surface, and subsequent burial diagenesis in the Middle Ordovician Chickamauga organic buildups from Alabama. GSA Abstract, 24(7): 56.

Tobin, K.J., et al., 1991, Comparison of on-platform with down slope organic buildups from the Middle Ordovician Ottosee and Holston formations, east Tennessee. GSA Abstract, 23(3): 139.