Sediment core MD02-2550 from Orca Basin located in the northern Gulf of
Mexico (GOM) provides a high-resolution early Holocene record of climatic and
hydrologic changes from ~10.5 to 7 thousand calendar years before present (ka). Paired
analyses of Mg/Ca and
δ18O on the planktonic foraminifer Globigerinoides ruber (white
variety, 250-355
μm) sampled at ~ 20 year resolution were used to generate proxy
records of sea surface temperature (SST) and the
δ18O of seawater in the GOM (δ18OGOM).
The Mg/Ca-SST record contains an overall ~1.5 °C warming trend from 10.5 to 7 ka that
appears to track the intensity of the annual insolation cycle and six temperature
oscillations (0.5-2 °C), the frequency of which are consistent with those found in records
of solar variability. The
δ18OGOM record contains six ~ 0.5 ‰ oscillations from 10.5 to 7
ka that bear some resemblance to regional hydrologic records from Haiti and the Cariaco
Basin, plus a -0.8 ‰ excursion that may be associated with the “8.2 ka event” recorded in
Greenland air temperatures. The
δ18OGOM record, if interpreted as a salinity proxy, suggest
large salinity fluctuations (> 2 ‰) reflecting changes in evaporation-precipitation (E-P)
and Mississippi River input to the GOM. Percent
Globigerinoides sacculifer records from
three cores in the GOM exhibit remarkably coherent changes, suggesting episodic
centennial-scale incursions of Caribbean waters. Spectral analysis of the Mg/Ca-SST and
the
δ18OGOM time series indicate that surface water conditions may be influenced by solar
variations because they share significant periods of variability with atmospheric
Δ 14C
near 700, 200, and 80-70 years. Our results add to the growing body of evidence that the
sub-tropics were characterized by significant decadal to centennial-scale climatic and
hydrologic variability during the early Holocene.
| Identifer | oai:union.ndltd.org:USF/oai:scholarcommons.usf.edu:etd-5063 |
| Date | 20 January 2006 |
| Creators | LoDico, Jenna Meredith |
| Publisher | Scholar Commons |
| Source Sets | University of South Flordia |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Graduate Theses and Dissertations |
| Rights | default |
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