8.2 ka event North Sea hydrography determined by bivalve shell stable isotope geochemistry
8.2 ka event North Sea hydrography determined by bivalve shell stable isotope geochemistry
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DOI：
10.1038/s41598-019-43219-1
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发表时间：
2019-05-01
影响因子：
4.6
通讯作者：
Butler, Paul G.
中科院分区：
文献类型：
--
作者：
Estrella-Martinez, Juan;Ascough, Philippa L.;Butler, Paul G.
格陵兰岛和北大西洋的记录中广泛描述了这一突如其来的8.2卡冷事件。然而，它在陆架海中的表现很少有文献记载，而且大多数海洋记录的时间分辨率不足以准确确定重大事件的年表。稳健的水文重建可以提供对大西洋经向翻转环流扰动的气候反应时间的洞察。在这里，我们提出了一个年分辨温度和水柱层结重建基于稳定同位素地球化学从弗拉登地面(北海北部)与格陵兰冰芯记录的时间一致。我们的年龄模型是基于从覆盖8290-8100卡BP区间的四个放射性测年贝壳获得的生长增量年代学。结果表明，8320-8220cal BP之间发生了海平面突然上升(SSLR)事件驱动的柱状层结。30年后，寒冷的条件阻止了水柱分层，但亚北极水域最终侵入北海，重新建立了密度驱动的分层。在SSLR发生55年后，水温达到了类似3.7摄氏度的最低水平。当亚北极水域退去时，断断续续的混合条件后来被建立起来。
The abrupt 8.2 ka cold event has been widely described from Greenland and North Atlantic records. However, its expression in shelf seas is poorly documented, and the temporal resolution of most marine records is inadequate to precisely determine the chronology of major events. A robust hydrographical reconstruction can provide an insight on climatic reaction times to perturbations to the Atlantic Meridional Overturning Circulation. Here we present an annually-resolved temperature and water column stratification reconstruction based on stable isotope geochemistry of Arctica islandica shells from the Fladen Ground (northern North Sea) temporally coherent with Greenland ice core records. Our age model is based on a growth increment chronology obtained from four radiometrically-dated shells covering the 8290-8100 cal BP interval. Our results indicate that a sudden sea level rise (SSLR) event-driven column stratification occurred between ages 8320-8220 cal BP. Thirty years later, cold conditions inhibited water column stratification but an eventual incursion of sub-Arctic waters into the North Sea re-established density-driven stratification. The water temperatures reached their minimum of similar to 3.7 degrees C 55 years after the SSLR. Intermittently-mixed conditions were later established when the sub-Arctic waters receded.