HR: 16:30h
AN: PP14B-03    [Abstracts]
TI: Geochemical and sedimentological evidence of varying intense hurricane activity and precipitation patterns from the Caribbean during the late Holocene
AU: * Woodruff, J D
EM: jwoodruff@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Donnelly, J P
EM: jdonnelly@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Tierney, J
EM: jtierney@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AU: Scileppi, E
EM: elyse_scileppi@brown.edu
AF: Brown University, Brook Street, Providence, RI 02912 United States
AU: Giosan, L
EM: lgiosan@whoi.edu
AF: Woods Hole Oceanographic Institution, 360 Woods Hole Road, MS22, Woods Hole, MA 02543 United States
AB: Coastal lagoons are relatively unique systems because they have the potential for recording both marine and terrestrial paleo-climate signals. An analysis of sediment cores collected from a backbarrier lagoon in the Northeastern Caribbean (Laguna Playa Grande, Vieques, Puerto Rico) reveal paleoclimatic records of intense hurricane activity, sea-level elevation, and shifts in regional precipitation and vegetation. Coarse-grain laminae preserved within the 5000 year fine-grained sedimentary record at the site consist of beach and nearshore sediments and provide evidence of past intense hurricane strikes. Sediment ages based on C-14 dating indicate a relatively constant long-term sedimentation rate in the basin appears to be in steady state with sea-level rise. X-ray fluorescences (XRF) analyses of surficial terrestrial and barrier-beach samples show that they are distinct in their elemental composition with terrestrial samples containing high concentrations of Fe, Ti and Mn, while Ca and Sr dominate the composition for samples collected from the barrier beach. XRF scans of cores collected from the lagoon indicate that the observed coarse-grain strata contain high concentrations of Ca and Sr confirming the seaward origin of this material, while fine-grained sediments are high in Fe, Ti and Mn indicating its terrestrial source. A transition from high to low intense hurricane activity occurred at the site approximately 1250 yr BP. XRF results reveal a dramatic increase in the concentration of terrestrial elements (Ti, Fe and Mn) throughout the basin after this 1250 yr BP horizon indicating an abrupt transition from a more arid to a more humid local climate. An additional increase in Ti, Fe and Mn concentrations is observed within sediments deposited in the 18th century A.D. and is most likely associated with anthropogenic land-use changes. The earlier 1250 yr BP transition from low to high precipitation is consistent with records from other sites within the Caribbean. Surprisingly, this increase in precipitation is also concomitant with a decrease in hurricane activity in the Northeastern Caribbean and possibly throughout the Western North Atlantic. In addition fluctuations in hurricane activity over the last 4000 yrs are strongly correlated with proxy records for El Nino/Southern Oscillation (ENSO) variability and may indicate that ENSO has been a dominant control of hurricane activity in the North Atlantic during the late Holocene.
DE: 1605 Abrupt/rapid climate change (4901, 8408)
DE: 1817 Extreme events
DE: 1821 Floods
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4901 Abrupt/rapid climate change (1605)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005