HR: 15:25h
AN: PP33C-08    [Abstracts]
TI: A 1400 Year Multi-Proxy Record of Hydrologic Variability in the Gulf of Mexico: Exploring Ocean- Continent Linkages During the Late Holocene
AU: * Flannery, J A
EM: flannery@marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 7th Ave South, St. Petersburg, FL 33701, United States
AU: Richey, J N
EM: jrichey@marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 7th Ave South, St. Petersburg, FL 33701, United States
AU: Meckler, A N
EM: ameckler@gps.caltech.edu
AF: California Institute of Technology, MC 100-23, 1200 East California Blvd., Pasadena, CA 91125, United States
AU: Hollander, D J
EM: davidh@marine.usf.edu
AF: College of Marine Science, University of South Florida, 140 7th Ave South, St. Petersburg, FL 33701, United States
AB: The timing and phasing of variations in hydrologic conditions between the North American (NA) continent and the Gulf of Mexico (GOM) during the Late Holocene are critical to understanding current and future responses to natural and anthropogenic climate changes. The Pigmy Basin in the northern GOM is ideally situated to record inputs from the Mississippi River (MR), and, thus, can provide a coherent, decadal-scale assessment of oceanic and continental responses to changing hydrologic conditions over NA and in the GOM. This study focuses on the sedimentary record spanning the last 1400 years and utilizes a multi-proxy approach incorporating organic and inorganic geochemical analyses to define intervals of varying continental inputs and to assess changes in the moisture balance (E/P) within the GOM. Results show multi-decadal episodes of significantly increased terrestrial inputs and enhanced MR discharge (flood intervals) centered at 1500 and 1000 A.D. that coincide with intervals of increased δ¹⁸O seawater indicative of higher salinity recorded in the Pigmy Basin. Episodes of lower continental inputs (i.e. drought intervals) at 1850, 1150 and 600 A.D. are associated with decreased salinity in the GOM. Since the continental inputs and salinity variations are synchronous, we hypothesize that hydrologic variability recorded over the NA continent is directly dependent on the moisture balance (E/P) over the sub-tropical GOM (a major source of moisture to the NA continent). For example, increased evaporation over the GOM leads to enhanced precipitation over the NA continent, due to the intensification of the atmospheric Hadley cell circulation, which influences meridional moisture flux from the GOM to the NA continent. Additional regional marine and terrestrial hydrologic records from the sub-tropics and the NA continent are in strong agreement with these hydrologic records, further supporting the hypothesis.
DE: 1812 Drought
DE: 3354 Precipitation (1854)
DE: 4215 Climate and interannual variability (1616, 1635, 3305, 3309, 4513)
DE: 4825 Geochemistry
DE: 4904 Atmospheric transport and circulation
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting