HR: 0800h
AN: PP11A-0219    [Abstracts]
TI: Glacial and Interglacial Climate Variability in Guaymas Basin (Gulf of California) from a Varved Record
AU: * Thurow, J
EM: j.thurow@ucl.ac.uk
AF: Department of Earth Sciences, UCL, Gower Street, London, Wc1E 6BT, United Kingdom
AU: Brumsack, H
AF: ICBM, Oldenburg University, P.O. Box 2503, Oldenburg, D-26111, Germany
AU: Ganeshram, R
AF: School of Geosciences, Univ. Edinburgh, John Murray Laboratories, The King's Buildings, West Mains Road, Edinburgh, EH9 3JW, United Kingdom
AU: Kemp, A E
AF: NOC, Southampton, University of Southampton Waterfront Campus, European Way, Southampton, Southampton, SO14 3ZH, United Kingdom
AU: Nederbragt, A
AF: Department of Earth Sciences, UCL, Gower Street, London, Wc1E 6BT, United Kingdom
AU: Pearce, R
AF: NOC, Southampton, University of Southampton Waterfront Campus, European Way, Southampton, Southampton, SO14 3ZH, United Kingdom
AB: To test for interaction between long and short climate cycles it is necessary to reconstruct records of interannual to decadal variability over sufficiently long time periods. Marine varved sediments are one of the few archives with the necessary resolution. The latest Quaternary in sediment core MD02-2515 (65m, 7 to 38 kyr) from the Gulf of California is predominantly varved with few bioturbated intervals (e.g. the Younger Dryas). The Guaymas Basin allows reconstruction not only of regional upwelling and precipitation but also of ocean circulation in the North Pacific (intermediate water) and equatorial Pacific (subsurface water). The material is therefore ideally suited to test for interaction between all scales of climate variability, from orbital scales (glacial/interglacial) via millennial (D/O cycles) to interannual oscillations (ENSO). A varve age model has been compiled, supported by correlation of delta15Norg data with the GISP-record, allowing estimation of biogenic and lithogenic fluxes at annual to near annual resolution. During the last glacial the rates of opal, TOC and lithogenic material were 2-3 times higher than during the Holocene, indicating that total mass fluxes control the export production of carbon. Dysoxia in the basin is mainly controlled by regional productivity (as opposed to intermediate water circulation) as seen from a strong correlation between opal and delta13C in benthic foraminifers. The distribution pattern of opal does not correlate with typical North Atlantic patterns (e.g. D/O cycles). Annual resolution records of opal content and delta15N in laminated intervals from the last glacial, Bolling/Allerod, and Holocene all show ENSO-like variability but there is no consistent change in strength or frequency.
DE: 4912 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 1615, 4805)
DE: 4922 El Nino (4522)
DE: 4964 Upwelling (4279)
DE: 9355 Pacific Ocean
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting