Plio-Pleistocene paleoceanography of the northern and western Pacific

北太平洋和西太平洋的上里奥-更新世古海洋学

• 批准号: RGPIN-2016-06371
• 负责人: Head, Martin
• 金额: $ 2.4万
• 依托单位: Brock University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=684931
• 关键词: Plio; Pleistocene; paleoceanography; northern; western

The NeogeneQuaternary (Pliocene-Pleistocene) transition around 2.8 to 2.45 million years ago represents a fundamental shift in Earth's climate system. The extreme glacial-interglacial oscillations that characterize our more recent climate emerged at this time, although the causes remain uncertain. Deep-ocean sediments offer clues to climate history owing to their continuous and well-dated character, and because the oceans themselves are crucial heat and CO2 sources / sinks as well as being suppliers of moisture for ice sheet growth. Extensive research on North Atlantic sediments has revealed that large ice sheets covered the high northern latitudes around 2.74 and 2.6 million years ago.***While research has focused mostly on the North Atlantic, plausible evidence holds that the northern Pacific Ocean supplied moisture to northern North America allowing the growth of ice sheets 2.74 million years ago. The proposed research targets five deep-sea cores along a transect from the Bering Sea to the South China Sea, and aims to elucidate the Pacific Ocean's role in climate evolution during the NeogeneQuaternary transition. It specifically addresses ice sheet expansion 2.74 and 2.6 million years ago, and explores the associated surface current patterns. It also examines teleconnections between high northern latitude ice sheets and the East Asian winter monsoon system, as reflected in sediments of the marginal Sea of Japan and South China Sea. The intensification of this monsoon is seen in Chinese loess sequences and is driven by cooling in northern Asia. The examination of well-dated ocean sediments may therefore resolve uncertainties in the timing of Chinese loess deposition.***The tools used primarily in the proposed research are the fossilized cysts of dinoflagellates: single-celled microplankton known to be sensitive to environmental change, and as a group tolerant of a wide range in salinities. The cysts (“dinocysts”) are acid-insoluble and resistant to dissolution, and are used as tracers of water masses and indicators of sea-ice extent. Acritarchs, also to be studied, occur in the same preparations as dinocysts but are of unknown biological affinity. They are abundant and relatively diverse in high northern latitudes, and have strong potential for paleoenvironmental analysis over the selected time interval. Dinocysts and acritarchs have been studied extensively in Pliocene and lower Pleistocene deposits of the North Atlantic, but have been largely neglected for the Pacific.***Results will be of particular importance to the paleoclimate and paleoceanography communities, and to climate modelers who test models of future climate against evidence-based paleoclimate reconstructions. The detailed study of dinocysts and acritarchs in tandem with other paleoenvironmental proxies will enhance the utility of this microfossil group for future applications in the Pacific and elsewhere.**

大约280万至245万年前的更新世-第四纪（上新世-更新世）过渡代表了地球气候系统的根本转变。 作为我们近代气候特征的极端冰川-间冰期振荡就出现在这个时期，尽管其原因仍然不确定。 深海沉积物提供了气候历史的线索，因为它们具有连续性和日期明确的特点，而且海洋本身是重要的热和二氧化碳源/汇，也是冰盖生长的水分供应者。对北大西洋沉积物的广泛研究表明，大约在274万年和260万年前，大冰盖覆盖了北方高纬度地区。虽然研究主要集中在北大西洋，但有可信的证据表明，北方太平洋为北方北美洲提供了水分，使274万年前的冰盖得以生长。拟议的研究目标是沿沿着从白令海到南中国海的一个断面的五个深海岩心，目的是阐明太平洋在新近纪-第四纪过渡期气候演变中的作用。 它专门讨论了274万年和260万年前的冰盖扩张，并探索了相关的表面电流模式。 它还研究了北方高纬度冰盖和东亚冬季风系统之间的遥相关，如日本海和南海边缘沉积物中所反映的。 这种季风的加强在中国黄土序列中可见，并受到北方亚洲冷却的驱动。 因此，对年代确定的海洋沉积物的研究可能会解决中国黄土沉积时间的不确定性。在拟议的研究中主要使用的工具是甲藻的藻化包囊：已知对环境变化敏感的单细胞微型浮游生物，并且作为一个群体耐受各种盐度。 囊（“dinocysts”）是酸不溶性的，耐溶解，并被用作水团的示踪剂和海冰范围的指标。 疑源类，也要研究，出现在相同的准备工作作为dinocysts，但未知的生物亲和力。 它们在北方高纬度地区丰富且相对多样，在选定的时间间隔内具有很强的古环境分析潜力。 在北大西洋的上新世和更新世早期沉积物中，人们已经广泛地研究了棘孢囊和疑源类，但在太平洋却基本上被忽视了。结果将是特别重要的古气候和古海洋学社区，气候建模谁测试模型的未来气候对证据为基础的古气候重建。 对dinocysts和acritarchs的详细研究与其他古环境代用品一起将提高这一微体化石群在太平洋和其他地方未来应用的实用性。