Source change of surface water in the western Arctic Ocean recorded by neodymium isotopes since 76 kyr BP

paleoclimate;freshwater;surface water;N. Pacific Ocean;western Arctic ocean;neodymium isotope

자연과학대학 지구환경과학부 ;

University:서울대학교 대학원

关键词: paleoclimate;    freshwater;    surface water;    N. Pacific Ocean;    western Arctic ocean;    neodymium isotope;   

Others  :  http://s-space.snu.ac.kr/bitstream/10371/131350/1/000000005267.pdf

美国|英语

来源: Seoul National University Open Repository

【 摘 要 】

The freshwater budget of the Arctic Ocean is an important component of the global climate system. Meltwater input, riverine discharge, and Pacific water inflow decrease the salinity of the Arctic Ocean and weaken the formation of the North Atlantic Deep Water (NADW) (Schlosser et al., 1991). Here I report continuous record of authigenic neodymium (Nd) isotopes on the Mendeleev Ridge from which I reconstruct prominent freshwater discharge events at 46-51, 35-39 and 13-19 ka BP. At 46-51 ka BP, there was freshwater input from bursting of ice-dammed lakes accompanying the collapse of the Barent-Kara Ice Sheet during Middle Weichselian glaciation (Mangerud et al., 2004) releasing radiogenic Nd. The cyclonic surface circulation in the eastern Arctic Ocean was stronger than at present. At 35-39 and 13-19 ka BP, the Laurentide ice sheet (LIS) supplied freshwater which remobilized the unradiogenic Nd accumulated on the shelves. During both intervals the configuration of anticyclonic circulation in the western Arctic was expanded eastward or similar to today. Simple mass balance calculation suggests that 6,300, 10,600, and 4,800 km3 of freshwater contributed these εNd variations, implying that amount of freshwater could have also affected the formation of NADW. During late Holocene, the radiogenic trend toward the upper sediment layer imply that Pacific inflow to the Arctic Ocean was increased owing to sea-level rise. Two unradiogenic troughs were questionable due to lack of age and geochemical information.