Abstract
Little is known about the potential of organic substances found within cave sediments to provide useful reconstructions of past climatic changes. Here, we present a study of the carbon isotopes of fulvic acids extracted from sediments from a cave in west-central Florida. Fulvic acids are the most contemporaneous representation of soil humic substances derived from vegetation growing above the cave. Radiocarbon dating of these sediments constrains their depositional period to be late-Holocene. The range of the fulvic acid δ 13 C record shows the dominance of C 3 vegetation during this period, but with changes in abundance and the shifting presence of C 4 plants. The δ 13 C values record both the Little Ice Age and Medieval Climate Anomaly which produce drier and wetter conditions for Florida, respectively. Our conclusion that the stable carbon isotopic values of the cave sediment record as a proxy for vegetation change as driven by variability in precipitation is strongly supported by a comparison with the δ 13 C and δ 18 O values of two uranium-series dated speleothems from this part of Florida, with both being proxies for precipitation change.
Original language | American English |
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Journal | Chemical Geology |
Volume | 360-361 |
DOIs | |
State | Published - Dec 1 2013 |
Keywords
- Cave sediments
- Paleoclimate
- Fulvic acids
- Speleothems
- Precipitation
- Vegetation change
Disciplines
- Earth Sciences