Graduation Year

2006

Document Type

Thesis

Degree

M.S.

Degree Granting Department

Marine Science

Major Professor

Benjamin P. Flower, Ph.D.

Co-Major Professor

Terrence M. Quinn, Ph.D.

Committee Member

Michael Howell, Ph.D.

Keywords

climate change, sea surface temperature variability, freshwater floods

Abstract

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.

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