TY - JOUR T1 - Sediment Cd and Mo accumulation in the oxygen-minimum zone off western Baja California linked to global climate over the past 52 kyr JF - Paleoceanography Y1 - 2006 A1 - Dean, W. E. A1 - Zheng, Y. A1 - Ortiz, J. D. A1 - van Geen, A. KW - continental-margin KW - enhanced preservation KW - late pleistocene KW - marine-sediments KW - nitrogen isotope KW - northeast pacific waters KW - organic-carbon preservation KW - productivity variations KW - santa-barbara basin KW - suboxic sediments AB - [ 1] Concentrations of organic carbon (orgC), cadmium (Cd), and molybdenum (Mo) were measured in two sediment cores raised from depths of 430 and 700 m within the oxygen-minimum zone (OMZ) off southern Baja California at a temporal resolution of similar to 0.5 kyr over the past 52 kyr. These records are supplemented with diffuse spectral reflectance (DSR) measurements obtained on board ship soon after collection at a resolution of similar to 0.05 kyr. In the core from 700 m depth, a component extracted from the DSR data and the three geochemical proxies generally vary in concert with each other and over a wide range ( 4 - 22% orgC; 1 - 40 mg/kg Cd; 5 120 mg/kg Mo). Intervals of increased orgC, Cd, and Mo accumulation generally correspond to warm periods recorded in the oxygen-isotopic composition of Greenland ice, with the exception of the Bolling/Allerod which is only weakly expressed off Baja California. Concentrations of the biogenic proxies are higher in the core from 430 m depth, but erratic sediment accumulation before 15 ka precludes dating of the older intervals that are laminated and contain elevated orgC, Cd, and Mo concentrations. The new data provide further evidence of an intimate teleconnection between global climate and the intensity of the OMZ and/or productivity along the western margin of North America. On the basis of a comparison with Cd and Mo records collected elsewhere in the region, we conclude that productivity may actually have varied off southern Baja California by no more than a factor of 2 over the past 52 kyr. VL - 21 SN - 0883-8305 IS - 4 N1 - 110idTimes Cited:34 Cited References Count:68 JO - Paleoceanography ER - TY - JOUR T1 - Last deglaciation in the Okinawa Trough: Subtropical northwest Pacific link to Northern Hemisphere and tropical climate JF - Paleoceanography Y1 - 2005 A1 - Sun, Y. B. A1 - Oppo, D. W. A1 - Xiang, R. A1 - Liu, W. G. A1 - Gao, S. KW - cal kyr bp KW - deep-ocean circulation KW - equatorial current KW - kuroshio current KW - late pleistocene KW - oxygen-isotope KW - planktonic-foraminifera KW - radiocarbon age calibration KW - south china sea KW - surface-water AB - [1] Detailed deglacial and Holocene records of planktonic delta O-18 and Mg/Ca - based sea surface temperature (SST) from the Okinawa Trough suggest that at similar to 18 to 17 thousand years before present (kyr B. P.), late spring/ early summer SSTs were approximately 3 degrees C cooler than today, while surface waters were up to 1 practical salinity unit saltier. These conditions are consistent with a weaker influence of the summer East Asian Monsoon (EAM) than today. The timing of suborbital SST oscillations suggests a close link with abrupt changes in the EAM and North Atlantic climate. A tropical influence, however, may have resulted in subtle decoupling between the North Atlantic and the Okinawa Trough/EAM during the deglaciation. Okinawa Trough surface water trends in the Holocene are consistent with model simulations of an inland shift of intense EAM precipitation during the middle Holocene. Millennial-scale alternations between relatively warm, salty conditions and relatively cold, fresh conditions suggest varying influence of the Kuroshio during the Holocene. VL - 20 SN - 0883-8305 UR - http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcAuth=Alerting&SrcApp=Alerting&DestApp=WOS&DestLinkType=FullRecord;UT=WOS:000232654500001 IS - 4 N1 - 975ipTimes Cited:53 Cited References Count:55 JO - Paleoceanography ER - TY - JOUR T1 - Biomass burning and oceanic primary production estimates in the Sulu Sea area over the last 380 kyr and the East Asian monsoon dynamics JF - Marine Geology Y1 - 2003 A1 - Beaufort, L. A1 - de Garidel-Thoron, T. A1 - Linsley, B. A1 - Oppo, D. A1 - Buchet, N. KW - arabian sea KW - atlantic KW - climatic-change KW - EARLY HOLOCENE KW - EQUATORIAL KW - fire KW - GLACIAL MAXIMUM KW - indian-ocean KW - late pleistocene KW - Late Quaternary KW - monsoon KW - nannoplankton KW - Pleistocene KW - SOUTH CHINA KW - Sulu Sea KW - WEST-JAVA AB - Coccolithophorid assemblages and micro-charcoal content were analysed in giant piston core MD97-2141 recovered in the Sulu Sea (Philippines). These proxies help to reconstruct respectively the dynamics of the oceanic primary production (PP) and biomass burning in that area. PP in the Sulu Sea intensifies during the East Asian winter monsoon (EAWM) and therefore PP constitutes a proxy for EAWM dynamics. Most of the precipitation in the Sulu Sea region occurs during the East Asian summer monsoon (EASM). Because the intensity of biomass burning is related to dryness of the surrounding area, the sedimentary micro-charcoal content can be used as an inverse proxy for EASM intensity. Our results show that the EAWM intensifies during glacial times in agreement with previous studies. Precessional forcing appears to act directly on EAWN because of the early response of PP in that frequency band. The micro-charcoal record exhibits complex dynamics, which we attribute to the competing influence of the long-term El Nino Southern Oscillation (ENSO)-like forcing and the glacial/interglacial cycle on EASM. These influences create an unusual frequency spectrum with power around 30 kyr and 19 kyr attributed to the non-linear response to the 100-kyr cycle (glacial) and the 23-kyr (ENSO) cycle. A factor of two increase in the amplitude of the micro-charcoal variability between 51 and 10 ka BP could correspond to Homo sapiens biomass burning in the style of the fire-stick farming of the Australian Aborigines. We also find, on precession cycles, an opposite phase between EASM and EAWM records and an advance of -delta(18)O and delta(18)O respectively by 2000 yr. (C) 2003 Elsevier B.V. All rights reserved. VL - 201 SN - 0025-3227 IS - 1-3 N1 - Symposium on Asian Monsoons and Global Linkages on Milankovitch and Sub-Milankovitch Time ScalesMAY 09-11, 2001 BEIJING, PEOPLES R CHINA 70 JO - Mar. Geol. ER - TY - JOUR T1 - East Asian monsoon forcing of suborbital variability in the Sulu Sea during Marine Isotope Stage 3: Link to Northern Hemisphere climate JF - Geochemistry Geophysics Geosystems Y1 - 2003 A1 - Dannenmann, S. A1 - Linsley, B. K. A1 - Oppo, D. W. A1 - Rosenthal, Y. A1 - Beaufort, L. KW - 1620 global change : climate dynamics (3309) KW - 4267 oceanography : general : paleoceanography KW - dissolution KW - equatorial pacific KW - eurasian snow cover KW - isotope stage 3 KW - last glacial period KW - late pleistocene KW - Mg/Ca KW - millennial-scale climate change KW - oxygen isotopes KW - paleoceanography KW - planktonic-foraminifera KW - records KW - se asian monsoon KW - south china sea KW - summer monsoon KW - surface temperature-variations AB - [1] We have generated a new high-resolution record of variations in planktonic foraminiferal oxygen isotopes (delta(18)O) and Mg/Ca from a sediment core (IMAGES 97-2141) in the Sulu Sea located in the Philippine archipelago of western tropical Pacific. This record reveals distinct, suborbital-scale delta(18)O changes, most notably during Marine Isotope Stage 3 (MIS3) (similar to30,000 to 60,000 years B.P.). The amplitudes of these delta(18)O fluctuations (0.4 to 0.7parts per thousand) exceed that which can be attributed to sea level changes and must be due to changes in sea surface conditions. In the same interval, variations in planktonic foraminifera Mg/Ca suggest that suborbital surface ocean temperature variations of 1 to 1.5degreesC in the Sulu Sea were not in phase with delta(18)O. Combined, this evidence indicates that the MIS3 millennial delta(18)O events in the Sulu Sea were primarily the result of changes in surface water salinity, which today is directly related to the East Asian Monsoon (EAM) and its influence on the balance between surface water contributions from the South China Sea and Western Pacific Warm Pool (WPWP). Within dating uncertainties the MIS3 Sulu Sea delta(18)O suborbital variability indicates that times of fresher surface conditions in the Sulu Sea coincide with similar conditions in the WPWP [Stott et al., 2002] and also with intensifications of the summer EAM as recorded in the U-Th dated Chinese (Hulu Cave) speleothem delta(18)O record [Wang et al., 2001] and thus by inference with interstadials in the Greenland Ice core records. Combined, these results indicate that pronounced suborbital variability in the summer EAM and Intertropical Convergence Zone (ITCZ) during MIS3 was tightly coupled with climate conditions in the northern high latitudes. VL - 4 SN - 1525-2027 N1 - 631mwTimes Cited:41 Cited References Count:53 JO - Geochem Geophy Geosy ER - TY - JOUR T1 - Postglacial climate and vegetation history, north-central Kola Peninsula, Russia: pollen and diatom records from Lake Yarnyshnoe-3 JF - Boreas Y1 - 2000 A1 - Snyder, J. A. A1 - MacDonald, G. M. A1 - Forman, S. L. A1 - Tarasov, G. A. A1 - Mode, W. N. KW - atlantic KW - finnish lapland KW - Holocene KW - late pleistocene KW - norway KW - sea KW - sediments KW - varanger-peninsula KW - western part KW - younger-dryas AB - A sediment core from Lake Yamyshnoe-3 (69 degrees 04'N; 36 degrees 04'E), an emerged coastal lake from the tundra of the north-central Kola Peninsula, has been analyzed for fossil pollen and diatoms. The pollen record shows the Younger Dryas event marked by increasing Artemisia coupled with decreases in Poaceae, Cyperaceae and Salix at c. 10 700 to 10 000 BP. This core provides the first well-defined palynological record of the Younger Dryas event on the Kola Peninsula. Stomates from Pinus were recovered from the core interval between 8000 and 6000 BP. The stomates, coupled with elevated values of pine pollen, indicate that Pinus sylvestris grew near the arctic coastline of the central Kola Peninsula in the middle Holocene. However, the small number of stomates suggests that pines were not plentiful. The diatom record from the core reflects basin isolation from the sea and indicates additional limnological changes during the climate transition between c. 5000 and 4000 BP. The broadly similar climate and vegetation history on the north-central Kola Peninsula and in Fennoscandia demonstrates the propagation of late glacial and Holocene climate events from the North Atlantic region into the Eurasian Arctic. VL - 29 SN - 0300-9483 IS - 4 N1 - 378dxTimes Cited:28 Cited References Count:82 JO - Boreas ER -