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: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710179
• 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.

新世第四纪(上新世-更新世)大约在280万到245万年前发生转变，代表着地球气候系统的根本性转变。以我们最近的气候为特征的极端冰川-间冰期振荡此时出现，尽管原因尚不确定。深海沉积物由于其连续性和年代确定的特点，以及海洋本身是至关重要的热源和二氧化碳源/汇，以及为冰盖生长提供水分的来源，为气候历史提供了线索。对北大西洋沉积物的广泛研究表明，大约在274万到260万年前，巨大的冰盖覆盖了北部高纬度地区。 虽然研究主要集中在北大西洋，但可信的证据表明，北太平洋为北美北部提供了水分，使得274万年前冰盖得以生长。这项拟议的研究针对从白令海到南中国海的一条断面上的五个深海岩芯，旨在阐明太平洋在新世第四纪过渡期间的气候演变中的作用。它专门研究了274年和260万年前冰盖的扩张，并探索了相关的表面洋流模式。它还研究了北方高纬度冰盖与东亚冬季风系统之间的遥相关，这一联系反映在日本边缘海和南中国海的沉积物中。这种季风的加强在中国黄土序列中可见，并由北亚地区的冷却驱动。因此，对测年准确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。 拟议的研究中主要使用的工具是甲藻的化石包囊：已知对环境变化敏感的单细胞微型浮游生物，以及作为一组对大范围盐度耐受的生物。这些包囊(“包囊”)不溶于酸，不易溶解，被用作水团的示踪物和海冰范围的指示器。Acritarchs也有待研究，它们出现在与胞囊相同的制剂中，但具有未知的生物亲和力。它们在北部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下更新世沉积中，对恐囊和闪石进行了广泛的研究，但在太平洋地区却基本上被忽视了。 研究结果将对古气候和古海洋学领域以及气候模型师具有特别重要的意义，他们用基于证据的古气候重建来测试未来气候模型。结合其他古环境指标对恐囊和鞭毛虫进行详细研究，将加强这一微化石群在太平洋和其他地方未来应用的效用。