Radiocarbon ages and clay minerals in sediment cores obtained during a 2009 Jan Mayen cruise to the Norwegian Sea

The origin of two acoustic sediment units has been studied based on lithological facies, chronology and benthic stable isotope values as well as on foraminifera and clay mineral assemblages in six marine sediment cores from Kveithola, a small trough west of Spitsbergenbanken on the western Barents Sea margin. We have identified four time slices with characteristic sedimentary environments. Before c. 14.2 cal. ka, rhythmically laminated muds indicate extensive sea ice cover in the area. From c. 13.9 to 14.2 cal. ka, muds rich in ice-rafted debris were deposited during the disintegration of grounded ice on Spitsbergenbanken. From c. 10.3 to 13.1 cal. ka, sediments with heterogeneous lithologies suggest a shifting influence of suspension settling and iceberg rafting, probably derived from a decaying Barents Sea Ice Sheet in the inner-fjord and land areas to the north of Kveithola. Holocene deposition was episodic and characterized by the deposition of calcareous sands and shell debris, indicative of strong bottom currents. We speculate that a marked erosional boundary at c. 8.2 cal. ka may have been caused by the Storegga tsunami. Whilst deposition was sparse during the Holocene, Kveithola acted as a sediment trap during the preceding deglaciation. Investigation of the deglacial sediments provides unprecedented details on the dynamics and timing of glacial retreat from Spitsbergenbanken.本研究基于采自巴伦支海西部陆缘斯匹次卑尔根浅滩（Spitsbergenbanken）西侧小型槽谷Kveithola的6根海洋沉积岩芯，通过岩相、年代学、底栖稳定同位素值以及有孔虫（foraminifera）和黏土矿物组合特征，对两套声学沉积单元的成因展开了分析。我们识别出四个具有典型沉积环境特征的时间时段：约14.2校准千年（cal. ka）之前，韵律层状泥质沉积物指示该区域存在广泛的海冰覆盖；约13.9至14.2校准千年期间，斯匹次卑尔根浅滩上的固着冰解体阶段沉积了富含冰筏碎屑（ice-rafted debris）的泥质沉积物；约10.3至13.1校准千年期间，岩性不均一的沉积物指示悬浮沉降与冰山搬运的影响此消彼长，该沉积物可能源自Kveithola以北峡湾内部及陆地区域衰退的巴伦支冰盖；全新世沉积具有间歇性特征，以钙质砂与贝壳碎屑的沉积为标志，指示当时存在强劲的底流活动。我们推测，约8.2校准千年处的显著侵蚀界面可能由斯托雷加海啸（Storegga tsunami）引发。尽管全新世期间沉积作用较为稀疏，但Kveithola在此前的冰消期内充当了沉积阱。对冰消期沉积物的研究为斯匹次卑尔根浅滩的冰川退缩动力学过程与时间节点提供了前所未有的详细信息。