Late Quaternary paleoproductivity history on the Vancouver Island margin, western Canada: a multiproxy geochemical study
Late Quaternary paleoproductivity history on the Vancouver Island margin, western Canada: a multiproxy geochemical study
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DOI：
10.1139/e08-038
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发表时间：
2008-11-01
影响因子：
1.4
通讯作者：
Hendy, Ingrid L.
中科院分区：
文献类型：
--
作者：
Chang, Alice S.;Pedersen, Thomas F.;Hendy, Ingrid L.
对从温哥华岛边缘（北纬 48.97 度，西经 127.04 度，水深 1243 英寸）回收的 38 m 长沉积岩芯进行多代理分析，得出了过去类似于 50 ka 的千年规模的上升流和出口生产历史。较高浓度的海洋有机碳、蛋白石和微量钼表明，在温暖的全新世、博林-阿勒罗德和 31 至 44 ka BP 之间的间质事件期间，产量更高，沉积孔隙水更缺氧。陆源有机质的产量相对较低，输入量较高，发生在末次冰期（14.7-31 ka BP；靠近取芯地点的科迪勒拉冰盖，大约为 19.5 ka BP）和 44-50.4 ka BP。间质事件期间沉积三角洲 N-15 的富集被解释为反映了重同位素硝酸盐间歇性输送和上涌至地表水，并随后通过沉降的浮游碎屑引导至海底。类似的模式也出现在南加州和北美西缘的其他地区，这意味着热带北太平洋东部反硝化作用产生的较重的硝酸盐过去曾被加州暗流带向北方，至少远至温哥华岛中部。这一推论与该地区的现代水文学观测结果是一致的。将温哥华岛、俄勒冈州、加利福尼亚州和墨西哥西北部边缘记录与格陵兰岛晚更新世气候历史进行比较，强化了这样的结论：北大西洋和北美边缘水域（包括温哥华岛附近的边缘水域）之间存在紧密的物理和生物地球化学耦合至少 50ka。
Multiproxy analysis of a 38 m long sediment core recovered from the Vancouver Island margin (48.97 degrees N, 127.04 degrees W, water depth 1243 in) has yielded a millennial-scale history Of upwelling and export production over the last similar to 50 ka. Higher concentrations of marine organic carbon, opal, and trace Mo suggest that production was higher, and sedimentary pore waters more anoxic, during the warm Holocene, Bolling-Allerod, and interstadial events between 31 and 44 ka BP. Relatively lower production and higher inputs of terrigenous organic matter occurred during the last glacial (14.7-31 ka BP; Cordilleran ice sheet proximal to coring site at similar to 19.5 ka BP) and from 44-50.4 ka BP. Enrichments in sedimentary delta N-15 during interstadial events are interpreted to reflect episodic delivery and upwelling of isotopically heavy nitrate to the surface waters and subsequent vectoring to the seafloor via settling planktonic detritus. Similar patterns are seen in Southern California and other areas along the western margin of North America, implying that heavier nitrate generated by denitrification in the Eastern Tropical North Pacific has in the past been carried northward in the California Undercurrent at least as far as central Vancouver Island. This inference is consistent with modern hydrographic observations in the region. Comparison of the coherent Vancouver Island, Oregon, California, and northwest Mexico margin records with late Pleistocene climate history in Greenland reinforces the conclusion that a tight physical and biogeochemical coupling has existed for at least 50 ka between the North Atlantic and North American margin waters, including those off Vancouver Island.