Post-glacial paleoenvironments of the Lake Winnebago basin, east central Wisconsin, based on ostracodes

Conference · Fri Apr 01 04:00:00 EST 1994 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:6924875

Fielder, R F; Smith, G L; Fitzgerald, T M ^[1]

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1. Lawrence Univ., Appleton, I (United States). Dept. of Geology

Ostracodes were used to determine post-glacial paleoenvironments of the Lake Winnebago Basin. Following the retreat of the Wisconsinian Green Bay Lobe, Glacial Lake Oshkosh was dammed behind the ice sheet. As the modern Fox River was established, Glacial Lake Oshkosh shrank to form modern Lake Winnebago. Ostracodes were sampled from four vibracores in attempts to correlate sedimentary units and determine paleoenvironments. The oldest unit identified in their vibracores is grayish red clay that is thought to be reworked glacial till that was deposited in a lacustrine setting. This clay is dominated by Candona rawsoni, an ostracod species that prefers cold and deep water. The broken and eroded carapaces of the C. rawsoni in the greyish-red clay suggest reworking and transport, perhaps from the Lake Superior Basin. The contact between the clay and overlying sediments is an erosional unconformity, overlain in some places by gravel. The clay is overlain by coarsening-upward from sandy-silt to medium-grained sand, suggesting a decrease in lake levels and water depths. Raised shorelines 20 and 60 ft above present lake level constitute the geomorphic evidence for higher lake levels. Offshore, at depths of ten to twenty feet, the sediment type above is an olive black organic-rich mud where juveniles of C. rawsoni are the dominant species.

• OSTI ID: 6924875
• Report Number(s): CONF-9404217--
• Conference Information: Journal Name: Geological Society of America, Abstracts with Programs; (United States) Journal Volume: 26:5
• Country of Publication: United States
• Language: English

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58 GEOSCIENCES
580000* -- Geosciences
ANIMALS
AQUATIC ORGANISMS
DEPOSITION
DEVELOPED COUNTRIES
GEOLOGIC STRUCTURES
GEOLOGY
INVERTEBRATES
MOLLUSCS
NORTH AMERICA
PALEONTOLOGY
PETROLOGY
SEDIMENTARY BASINS
STRATIGRAPHY
USA
WISCONSIN