Ice volume as a trigger for the amplification of Pleistocene millennial-scale climate fluctuations? A terrestrial perspective from Central Asia (Qaidam Basin)

千禧年尺度的气候波动越来越被认为是最晚上新世和早更新世气候变暖的持久特征。然而，与众所周知的晚更新世千年尺度波动相比，气候变暖下的千年尺度波动表现出明显较低的幅度，与冰期-间冰期变化缺乏相关性(即，与间冰期相比，冰期期间缺乏较高的幅度)。解释这种差异的一个假设是，冰量阈值放大了千年尺度的气候波动，在中更新世过渡(约1.2-0.7 Ma)之前没有达到。然而，关于千年尺度气候波动放大的拟议阈值的存在以及北半球冰盖作为驱动机制的确切作用，仍然是一个有争议的问题，特别是对于北半球冰川作用的加剧(inHg；约2.8-2.3 Ma)。要切实评估北半球冰盖对千年尺度气候变化放大的影响，迫切需要对海洋和陆地记录进行复杂的分析。虽然海洋记录变得越来越多，但仍然缺乏基于陆地的汞气候记录。因此，它计划产生高分辨率(约200a)柴达木盆地(青藏高原东北部)SG-1b钻孔的沉积学(粒度、XRF扫描)和孢粉学分析。柴达木盆地位于西伯利亚高压的直接影响下，而西伯利亚高压又与北半球储存的冰量直接相关。此外，SG-1b岩芯提供了在极高分辨率和最高地层精度的基础上工作的机会，以回答以下概述的问题。因此，它为揭示北半球冰盖作为千年尺度气候波动幅度变化的触发因素所起的作用提供了一个理想的目标。拟议研究的主要目的是(I)澄清柴达木记录在inHg的最后阶段(即在MIS104-94年期间)是否存在不同幅度的千年尺度气候波动；(2)如果是的话，(2)查明它们是否与冰川-间冰期变化有关，(3)澄清在早更新世期间是否存在触发千年尺度大范围气候波动的冰量阈值，(4)将由此产生的陆地数据与海洋领域的现有结果进行比较，以及(5)破译早更新世冰川在多大程度上可与晚更新世冰川相媲美。

Millennial-scale climate fluctuations have increasingly become recognized as a persistent feature of the warmer climates of the latest Pliocene and Early Pleistocene. However, when compared to the well-known millennial-scale fluctuations of the Late Pleistocene, the millennial-scale fluctuations under a warmer climate show markedly lower amplitudes and a lack of correlation to glacial-interglacial changes (i.e., lack of higher amplitudes during glacials compared to interglacials). One hypothesis to explain this difference is an ice-volume threshold that amplifies millennial-scale climate fluctuations and was not reached prior to the Mid-Pleistocene Transition (~1.2-0.7 Ma). The existence of the proposed threshold for the amplification of millennial-scale climate fluctuations and the exact role of northern hemisphere ice sheets as driver mechanisms, however, is still a matter of debate, especially for the intensification of northern hemisphere glaciation (iNHG; ~2.8-2.3 Ma). A solid evaluation of the influence of northern hemisphere ice sheets on the amplification of millennial-scale climate change urgently needs a sophisticated analysis of both marine and terrestrial records. While marine records get more and more available, there is still a lack of terrestrial-based climate records for iNHG. Therefore, it is planned to generate high-resolution (approx. 200 years) sedimentological (grain-size, XRF scanning) and palynological analyses of drill core SG-1b from the Qaidam Basin (NE Tibetan Plateau). The Qaidam Basin is located under the direct influence of the Siberian High, which is in turn directly linked to the amount of ice stored in the northern hemisphere. In addition, core SG-1b provides the opportunity to work at very high resolution and on the basis of maximum stratigraphic precision to answer the questions outlined below. It therefore provides an ideal target to unravel the role of northern hemisphere ice sheets as a trigger for amplitude changes in millennial-scale climate fluctuations. The main objectives of the proposed study are (i) to clarify if there are millennial-scale climate fluctuations of different amplitude in the Qaidam record during the last phase of iNHG (i.e., during MIS 104-94; 2.62-2.38 Ma), (ii) if yes, to figure out if they are related to glacial-interglacial changes, (iii) to clarify if an ice-volume threshold as a trigger for large-amplitude millennial-scale climate fluctuations exist during the early Pleistocene, (iv) to compare the resulting terrestrial data with available results from the marine realm, and (v) to decipher to what extent early Pleistocene glacials are comparable to those from the late Pleistocene.