2014 GSA Annual Meeting in Vancouver, British Columbia (19–22 October 2014)

Paper No. 149-9
Presentation Time: 3:30 PM

HIGH RESOLUTION CORRELATION OF EOCENE LAKE DEPOSITS (GREEN RIVER FORMATION, WYOMING) USING SR –ISOTOPE CHEMOSTRATIGRAPHY


BADDOUH, M'bark1, CARROLL, Alan R.2, MEYERS, Stephen R.3, BEARD, Brian4 and JOHNSON, Clark4, (1)Department of Atmospheric, Oceanic and Earth Sciences, George Mason University, 44000 University Dr, Farifax, VA 22030, (2)Department of Geoscience, University of Wisconsin-Madison, 1215 W. Dayton St., Madison, WI 53706, (3)Department of Geoscience, University of Wisconsin-Madison, 1215 West Dayton St, Madison, WI 53076, (4)Department of Geoscience, University of Wisconsin-Madison, NASA Astrobiology Institute, 1215 W. Dayton St, Madison, WI 53706

Lacustrine deposits are often difficult to accurately correlate, due to their intrinsically high spatial and temporal variability. In this study we investigate the use of Sr-isotope chemostratigraphy to develop a high-resolution correlation between two rock cores of the Eocene Green River Formation (Black Fork core #1 and White Mountain core #1). In the Black Forks core # 1, 87Sr/86Sr ratios range from 0.71156 to 0.71482, with an average of 0.71252. In the White Mountain core #1, 87Sr/86Sr ratios range from 0.71154 to 0.71504, with an average of 0.71268. Lower ratios consistently correspond to deeper (profundal) lacustrine facies, and higher ratios correspond to shallower (littoral and lake plain) facies. 87Sr/86Sr ratios do not correlate to sample mineralogy. We therefore conclude that they record changing provenance of Eocene Lake Gosiute waters during lake level fluctuations, rather than fractionation during carbonate precipitation.

We infer from these results that Sr was well mixed in the central part of Eocene Lake Gosiute, across spatial scales of at least tens of km. 87Sr/86Sr in the carbonate-rich lake deposits therefore provides a unique means of establishing temporal correlations within lacustrine strata, based on changes in lake water provenance through time.

Session No. 149

T34. Modern and Ancient Continental Depositional Environments: Linking Landscape Evolution with Fluvial Systems and Lacustrine Basins through the Cenozoic
Monday, 20 October 2014: 1:00 PM-5:00 PM
211 (Vancouver Convention Centre-West)
Geological Society of America Abstracts with Programs. Vol. 46, No. 6, p.379
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