North-Central Section - 35th Annual Meeting (April 23-24, 2001)
Paper No. 26-0
Presentation Time: 1:00 PM-4:30 PM

CARBON ISOTOPE CHEMOSTRATIGRAPHY OF ORDOVICIAN CARBONATES OF THE PLATTEVILLE, DECORAH, AND DUNLEITH FORMATIONS IN THE BIG SPRING #4 CORE, CLAYTON COUNTY, IOWA

HASIUK, Franciszek J.1, LUDVIGSON, Greg A.2, WITZKE, Brian J.3, CARPENTER, Scott J.4, and GONZALEZ, Luis A.4, (1) Geoscience, Univ of Iowa, 121 Trowbridge Hall, Iowa City, IA 52242-1379, fhasiuk@blue.weeg.uiowa.edu, (2) Iowa Geological Survey, Iowa Dept. Nat Rscs, 109 Trowbridge Hall, Iowa City, IA 52242-1319, (3) Iowa Dept. Natural Resources, Geol Survey Bureau, Iowa City, IA 52242, (4) Geoscience, Univ of Iowa

The Big Spring #4 drillcore in Clayton County, northeast Iowa, was sampled for carbon isotopic values of micritic carbonates as part of a regional study of the chemostratigraphy of Ordovician units in the Upper Mississippi Valley. Starting out from baseline values in the Platteville Formation of around -2 o/oo VPDB, the d13C rises to a peak of near 0 o/oo before falling to values of -2.5 to -3 o/oo in the uppermost few meters of the unit. Moving up into the Decorah Formation, values rise to around +0.5 o/oo in the Spechts Ferry Member. Then they dip to -0.5 o/oo before rising again to about +1 o/oo in the Guttenberg Member. In the Ion Member, the d13C stabilizes out to roughly -0.5 o/oo, which continues upward through our sampled interval of the Dunleith Formation.

North-Central Section - 35th Annual Meeting (April 23-24, 2001)
General Information for this Meeting
Session No. 26--Booth# 23
Undergraduate Research Sedimentology, Stratigraphy and Paleontology (Posters)
Bone Student Center, Illinois State University: Ballroom
1:00 PM-4:30 PM, Tuesday, 24 April 2001

Geological Society of America Abstracts with Programs, Vol. 33, No. 4, March 2001, p. 52

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