Holocene paleoceanography and climate variability in the Western Arctic Ocean

北冰洋是气候变化的敏感反应者，也是全球和区域大气和海洋环流模式的积极推动者。为了记录北冰洋长期的自然气候循环和预测未来的气候趋势，需要重建锁定在沉积记录中的海洋动力学，在沉积记录中，水文和海洋学对气候变化的反应表现为沉积和地球化学示踪剂的可变性。在这些示踪剂中，来自海洋沉积物的粘土矿物(如伊利石、高岭石、绿泥石和蒙皂石)、放射性同位素[如钕(ND)、铅(Pb)和锶(Sr)]和沉积钚-231/钍-230(231Pa/230th)记录是重建古海洋和古气候的有用工具。在这一背景下，这项研究计划的总体目标是使用一种强大的多指标方法，结合粘土矿物组成、元素地球化学、粘土粒度组分和自生(海水来源)铁锰涂层中的放射性同位素组成，以及来自加拿大博福特海和楚科奇海大陆边缘的相同沉积物岩心样品的沉积231Pa230th比值，以记录与气候变化有关的大陆输入、北极深海环流和海流输送的全新世变化。因此，由于加拿大博福特海和楚科奇海大陆边缘的全新世沉积速率高达120厘米/卡，这一创新的研究计划将提供一个独特的机会，以十年至千年的时间尺度重建过去10,000年来北冰洋西部气候和海洋条件的自然演变和变化。这些结果不仅有助于显著提高我们对未来北极气候和海洋动力学的理解，而且还将提供高时间分辨率的数据，有助于更好地约束区域气候模型。最后，这一独特的矿物学和地球化学工具库还将为高素质人员提供一个充满活力的培训环境，使他们能够获得不同海洋地质和地球化学领域的专门知识。

The Arctic Ocean is a sensitive responder to climate changes as well as active driver of global and regional atmospheric and oceanic circulation patterns. In order to document long-term natural climate cycles and predict future climate trends for the Arctic Ocean, one needs to reconstruct the oceanic dynamics locked in sedimentary records in which hydrologic and oceanographic responses to climatic changes are represented by the variability of sedimentary and geochemical tracers. Among these tracers, the clay minerals (e.g., illite, kaolinite, chlorite and smectite), radiogenic isotopes [e.g., neodymium (Nd), lead (Pb) and strontium (Sr)] and sedimentary protactinium-231/thorium-230 (231Pa/230Th) records from marine sediments are useful tools for paleoceanographic and paleoclimatic reconstructions. Under this context, the overall objective of this research program is to use a powerful multi-proxy approach combining clay mineral composition, elemental geochemistry, radiogenic isotope compositions (Nd, Pb and Sr) in both the clay-size fraction and authigenic (seawater-derived) ferromanganese coatings, and sedimentary 231Pa/230Th ratios from identical sediment core samples from the continental margins of the Canadian Beaufort and Chukchi seas, in order to document Holocene changes in continental inputs, deep-Arctic circulation and current transport related to climate change. Hence, because Holocene sedimentation rates in the continental margins of the Canadian Beaufort and Chukchi seas reach up to 120 cm/ka, this innovative research program will offer a unique opportunity to reconstruct the natural evolution and variability of climatic and oceanographic conditions in the Western Arctic Ocean during the last 10,000 years at decadal to millennial timescales. These results not only will help to significantly advance our understanding on the future Arctic climate and oceanographic dynamics, but will also provide high temporal resolution data that will help to better constrain the regional climate models. Finally, this unique pool of mineralogical and geochemical tools will also offer a dynamic training environment for highly qualified personnel with access to expertise in different fields of marine geology and geochemistry.