Degree Granting Department
Benjamin P. Flower, Ph.D.
Terrence M. Quinn, Ph.D.
Michael Howell, Ph.D.
climate change, sea surface temperature variability, freshwater floods
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 v 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 ∆ 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.
Scholar Commons Citation
LoDico, Jenna Meredith, "Sub-Centennial Scale Climatic and Hydrologic Variability in the Gulf of Mexico during the Early Holocene" (2006). USF Tampa Graduate Theses and Dissertations.