A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years
A multiproxy approach to reconstruct the environmental changes along the Eurasian continental margin over the last 150 000 years
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多代理方法重建过去 15 万年欧亚大陆边缘的环境变化
DOI：
10.1016/s0025-3227(99)00106-1
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发表时间：
2000
期刊：
影响因子：
2.9
通讯作者：
R. Stein
中科院分区：
文献类型：
--
作者：
J. Knies;N. Nowaczyk;C. Müller;C. Vogt;R. Stein
沉积物岩心位于沿着欧亚大陆边缘（北冰洋）进行了研究，重建的环境变化方面的盈亏的巴伦支海/喀拉海冰盖，大西洋水流入，海冰分布在过去的150 kyr。岩心的地层学是基于稳定氧同位素、AMS 14 C和古地磁数据。我们研究了海洋和陆源输入的多代理方法的变化，涉及直接比较沉积学和有机地球化学数据。海洋同位素阶段（MIS）6和2期间北方巴伦支海冰盖生长的广泛事件至少得到了大西洋地下水流入、含水风暴、夏季低日照和最小冰崩解的支持。MIS 4期间的冰推进可能仅限于浅水陆架。在MIS 4和MIS 2之间，大的冰盖波动对应于当代劳伦潮涌动事件，并表明北冰洋的短期气候变化，如低纬度地区所记录的那样。相比之下，在欧亚大陆东部的低降水地区，冰川活动相当有限。只有不同的冰筏碎片（IRD）的输入，在终端II和早期MIS 3反映严重的冰川在北方塞姆利亚边缘MIS 6和MIS 4。我们的结论是：（1）欧亚大陆东部边缘的冰盖振荡沿着比欧亚大陆西部边缘等有持续水分供应的地区要少;（2）喀拉海冰盖在过去15万年的主要波动显然是跟随着主要的间冰期/冰期MIS 5/4和MIS 7/6的转变，而不是岁差（23 kyr）和倾斜（41 kyr）分别对斯堪的纳维亚（SIS）和斯瓦尔巴特群岛冰盖观测到的地球轨道的周期性[Mangerud，J.，Jansen，E.，Landvik，J.Y.，1996.斯堪的纳维亚和巴伦支海冰盖的晚新生代历史。In：Solheim，A.，Riis，F.，Elverhøi，A.，Faleide，J.J.，詹森，L.N.，Cloetingh，S.（编），冰川对盆地演化的影响：来自挪威边缘和邻近盆地的数据和模型。全球和行星的机会，特别问题12，pp。11-26.]。在过去的150 kyr期间，表层和/或次表层大西洋水体与季节性无冰条件相结合，至少持续渗透到弗朗兹维多利亚海槽。然而，开放水域的持续时间主要限于子阶段5.5，5.1和全新世，由明显的碳酸盐溶解和海洋有机质（CO2）的积累较高。沿塞姆利亚北部北方边缘沿着周期性开放水域条件的信号不太重要。有孔虫产量较高，可能是由于大西洋水流入38和1214 C Kyr之间发生，并对应于定期大西洋水平流渗透到北冰洋。然而，海洋有机代理表明，由于在过去的150 kyr更广泛的海冰覆盖，从西部到东部的欧亚大陆边缘的地表水生产力的持续下降。
Sediment cores located along the Eurasian continental margin (Arctic Ocean) have been studied to reconstruct the environmental changes in terms of waxing and waning of the Barents/Kara Sea ice-sheets, Atlantic water inflow, and sea-ice distribution over the last 150 kyr. The stratigraphy of the cores is based on stable oxygen isotopes, AMS14C , and paleomagnetic data. We studied variations in marine and terrigenous input by a multiproxy approach, involving direct comparison of sedimentological and organo-geochemical data. Extensive episodes of northern Barents Sea ice-sheet growth during marine isotope stages (MIS) 6 and 2 have been supported by, at least, subsurface Atlantic water inflow, moisture-bearing storms, low summer insolation, and minimal calving of ice. Ice advance during MIS 4 was probably restricted to the shallow shelf. Between MIS 4 and MIS 2, large ice-sheet fluctuations correspond to contemporary Laurentide surging events and indicate short-term climatic changes in the Arctic Ocean as has been recorded in lower latitudes. In contrast, in low precipitation areas in eastern Eurasia, glacial activity was rather limited. Only distinct ice-rafted debris (IRD) input during Termination II and early MIS 3 reflects severe glaciations on the northern Severnaya Semlya margin during MIS 6 and MIS 4. We conclude that (1) oscillations of ice-sheets are less frequent along the eastern Eurasian margin than in areas with continuous moisture supply like the western Eurasian margins and that (2) major fluctuations of the Kara Sea ice-sheet during the last 150 kyr apparently followed the major interglacial/glacial MIS 5/4 and MIS 7/6 transitions rather than the precession (23 kyr) and the tilt (41 kyr) cyclicity of the Earth's orbit as observed for the Scandinavian (SIS) and the Svalbard ice-sheets, respectively [Mangerud, J., Jansen, E., Landvik, J.Y., 1996. Late Cenozoic history of the Scandinavian and Barents Sea ice-sheets. In: Solheim, A., Riis, F., Elverhøi, A., Faleide, J.J., Jensen, L.N., Cloetingh, S. (Eds.), Impact of Glaciations on Basin Evolution: Data and Models from the Norwegian Margins and Adjacent Basins. Global and Planetary Chance, Special Issue 12, pp. 11-26.]. Surface and/or subsurface Atlantic water masses coupled with seasonally ice-free conditions penetrated continuously to at least the Franz Victoria Trough during the last 150 kyr. However, sustained periods of open water were largely restricted to substages 5.5, 5.1, and the Holocene as indicated by distinct carbonate dissolution and higher accumulation of marine organic matter (MOM). Signals of periodic open-water conditions along the northern margin of Severnaya Semlya are of less importance. Higher production of foraminifera, probably due to Atlantic water inflow occurred between 38 and 1214C kyr and corresponds to periodic Atlantic water advection penetrating into the Arctic Ocean. However, marine organic proxies indicate a continuous decrease of surface-water productivity from the western to the eastern Eurasian continental margin due to a more extensive sea-ice cover over the last 150 kyr.