Abstract
Combining speleothem carbon and faunal assemblages to examine vegetation change in the southern Midwest
Abstracts with programs - Geological Society of America, Vol.30(7), p.167
Geological Society of America, 1998 annual meeting
1998
Abstract
Speleothems from southern Missouri and northern Arkansas contain several shifts in carbon isotopic composition throughout the Holocene. Based on preliminary research, we interpret these changes as reflecting rapid vegetation changes over the cave with prairie, forest, and forest border/parkland migrating in response to climatic change. In the absence of a well-documented vegetation record, it is difficult to distinguish vegetation types based solely on the carbon isotopic composition of speleothem calcite. Pollen records are sparse in the southern Midwest, but numerous archeological sites have been examined and dated in detail. Extracting site-specific paleovegetational information from archeological sites is problematic, however, because several habitats likely existed simultaneously (e.g., prairies on dry hilltops, forests along moist valley floors) and because prairie environments may be underrepresented in the fauna from archeological sites. Speleothems may allow a more precise investigation of the timing and nature of Holocene vegetation shifts along the southern margin of the Prairie Peninsula. The carbon isotopic composition of speleothem calcite is closely linked to the type of vegetation overlying the cave. Prairies are rich in C4 grasses which respire carbon dioxide that is isotopically heavier than C3 vegetation (e.g., trees). Comparing the faunal assemblages at these sites to the carbon isotopic record aids in calibrating the relationship between the 13-C of speleothems and dominant flora. Speleothems from Bridal Cave, southcentral MO, exhibit pronounced (<3 per mil) shifts in carbon isotopic composition with maxima from 10,00-9200 YBP, 7900-7400 YBP (limited by top of stalagmite), and 2500-1200 YBP. This record partly coincides with faunal-based paleoenvironmental reconstructions from Rodgers Shelter, westcentral Missouri and Modoc Rock Shelter, southwestern Illinois. At Rodgers Shelter, numbers of prairie taxa peaked between 9800-7200 YBP and 3200-1700 YBP. Cessation of stalagmite growth corresponds with abandonment of Rodgers Shelter between 7200-3200 YBP. A similar correlation exists from faunal remains at Modoc, where steppe taxa increase in abundance relative to arboreal species from 8530-4700 YBP.
Details
- Title: Subtitle
- Combining speleothem carbon and faunal assemblages to examine vegetation change in the southern Midwest
- Creators
- Rhawn F Denniston - University of IowaLuis A GonzalezHolmes A SemkenMark K ReaganYemane Asmerom
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.30(7), p.167
- Conference
- Geological Society of America, 1998 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 1998 annual meeting
- Language
- English
- Date published
- 1998
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240882502771
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