Ice rafted detritus and grain size records on the northern Mendeleev Ridge,central Arctic Ocean over

• 作 者: Rujian Wang Weiguo Wang Jing Mei Wenshen Xiao Boo-Keun Khim Leonid Polyak
• 机 构: State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China
• 出 处: 2015中国极地科学学术年会
• 发表日期: 2015年5期

　　The spatial distribution of ice rafted debris(IRD)in the Arctic Amerasian Basin nowadays is mainly controlled by the Beaufort Gyre that deliver large amounts of IRD from the Canadian and Alaskan Arctic coastal areas(Darby and Zimmerman,2008).Ice-sheet collapse events are documented by the IRD peaks in the sediment(Stein et al.,2010).When tracked across the basin,these events provide valuable information on the condition of ice sheets and the concomitant Arctic Ocean circulation(St?rz,et al.,2012).Core ARC5-MA01 from the northern Mendeleev Ridge,central Arctic Ocean,collected during the 5th Chinese National Arctic Expedition,provide important information about the Arctic Ocean circulation and ice sheet stability of the past~920 ka.The core stratigraphy was established based on a combination of AMS 14C,XRF Ca and Mn variations,foraminifera/ostracode abundances correlation to other central Arctic records,paleomagnetic inclination correlation to ACEX record from the Lomonosov Ridge(ORegan et al.,2008),and relative paleo-intensity(RPI)to global PISO-1500 stack(Channell et al.,2009).The core ARC5-MA01 extends back to MIS 23,with estimated base age of about 920 ka.21 IRD events were identified in the core,with the earliest event occurred at boundary between MIS 22 and MIS 21.Ten IRD peaks correspond to Ca peaks,implying their Canadian Arctic Archipelago sources of carbonate rock outcrops.And the first occurrence of carbonate IRD in our record is located at boundary between MIS 19 and MIS 18,earlier than previous estimations(Cronin et al.,2013).While other high IRD intervals could be derived from the various circum-Arctic sources(Darby et al.,2011).Strong variations of silt and clay fractions occur since the MIS 18,close to the Mid Pleistocene Transition(MPT),which could suggest the responses to stronger glacial-interglacial amplitude after the MPT.