Positive correspondence between the completeness of Late Quaternary fossiliferous lacustrine successions in Illinois and the basin index
- Illinois State Geological Survey, Champaign, IL (United States)
The basin index, defined as the ratio of the maximum area of a paleolake versus the area of the catchment (A[sub L]/A[sub C]), initially was used to compare the moisture balance of pluvial lakes in closed and semi-closed basins under arid climates. In this study the basin index also corresponds to the completeness of ostracode and pollen successions preserved in the basins. The basin indices of four breached kettles located in south-central Illinois as well as the thickness of fossiliferous zones determined from cores are compared. Collectively, the basins contain ostracode and pollen records spanning from the late Illinoian ([approx] 150 ka) to the Holocene. Hopwood Farm has the smallest index (0.03) and has a fossil record that terminates in Sangamonian clay. The fossil succession at Bald Knob Basin, with an intermediate basin index of 0.4, contains several lacuna in post-Sangamonian sediment and poorly preserved pollen in Holocene material. Raymond and Pittsburg Basins have indices > 1.0 and contain the most complete fossil records. The data indicate that the basin index is a useful guide for choosing sites with the greatest potential for yielding cores with conformable sediment successions.
- OSTI ID:
- 6974953
- Report Number(s):
- CONF-9404217-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 26:5; Conference: 27. annual conference of the North-Central Section of the Geological Society of America (GSA), Kalamazoo, MI (United States), 28-29 Apr 1994; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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