Searching the proposed Northern Source of the MPT start of the 100-ka climate cyclicity

中更新世-过渡期（MPT）是一个神秘的气候时期，在此期间，在天文强迫没有发生重大变化的情况下，气候周期发生了从~ 41-ka到100-ka的摆动。最近的研究结果表明，在旋回性转变之前，北半球冰川侵蚀/风化风化发生了变化，大西洋经向翻转环流（AMOC）大量减少。此外，北半球冰盖的快速扩张伴随着高达57°N的明显地下热量积累阶段。所需的额外热量被认为反映了地中海流出量（MOW）的增加或北大西洋洋流（NAC）的加强。所有机制都有一个共同点，即必须跨越临界点，这是很难确定的时间和机制。然而，所有的观测和模型都没有预测到单次跃迁。最近对北大西洋东部冷水珊瑚框架形成的研究遵循了类似的气候影响和物理过程。珊瑚的出现与极地和亚热带锋面的热历史和生产力位移有关。MOW和NAC对珊瑚的生长和扩张起着重要作用。豪猪海带的挑战者丘横跨MPT演变而来，因此是唯一允许测试气候冷却机制、翻转变化（纬向热通量）和风化风化与海洋记录耦合的地点。间断珊瑚生长的间断观测不太可能提供北半球进入100 ka周期的“冷阈值”的独特证据，但是，由于最近在234U/238U和U/Pb定年方面的进展，珊瑚对气候变化和水体结构变化的响应可能精确定年。此外，通过对不同地点（ODP 982、IODP U1304和IODP U1388/1386）的珊瑚（IODP U1317 -挑战者丘）和北半球沉积物的综合研究，我们将测试风化层风化增强、气候冷却以及MOW或NAC跨越双分支进入新的全球气候状态的假设。为了实现这一目标，该项目有两个数据流：(1)通过创新珊瑚定年和重新考察土堆演化来更精确地确定事件的时间；(2)使用温度地球化学示踪剂（Li/Mg）和放射性成因Nd重建热历史、水团物源和风化模式。通过综合所有新发现和以往对东北大西洋冰盖动力和热结构的评述，我们将建立一个新的阈值穿越概念模型及其可能的北半球源区。该项目应由一名早期博士后研究员进行，并以海德堡大学和法兰克福大学的专家团队为基础，提供独特的研究环境和基础设施。

The Mid-Pleistocene-Transition (MPT) is an enigmatic climate period during which, without substantial changes in astronomical forcing, swing from ∼41-ka to 100-ka climate cyclicity occurred. Recent findings indicate changes in Northern Hemispheric glacial erosion/weathering of Regolith preceding the cyclicity shift and a massive reduction of the Atlantic Meridiornal Overturning circulation (AMOC). Furthermore, the rapid expansion northern hemisphere ice-sheets was accompanied by phases of pronounced subsurface heat accumulation at up to 57°N. The required extra heat is thought to reflect increased outflow of the Mediterranean Sea (MOW) or strengthening of the North Atlantic current (NAC). All mechanisms is in common that tipping points must be crossed, which are difficult to determine regarding the timing and mechanisms. None of the observations and models, however, predict a singular transition. Recent studies of framework forming cold-water corals in the eastern North Atlantic follow similar climate influence and physical processes. The occurrence of corals has been linked to the thermal history and productivity displacements of the polar and subtropical fronts. A significant role of MOW and NAC on coral growth and expansion has been invoked. Challenger Mound in the Porcupine Seabight evolved across the MPT and thus is the only site permitting to test mechanisms of climate cooling, overturning changes (latitudinal heat fluxes), and regolith weathering coupled to marine records. Punctuated observations of discontinuous coral growth are unlikely to provide unique evidence of the northern hemisphere “cold-threshold” into the 100-ka cycles, But, thanks to recent advance towards 234U/238U and U/Pb dating, coral responses to climate change and water mass configuration changes may be precisely dated. Moreover, through a comprehensive study of corals (IODP U1317 - Challenger Mound) and northern hemisphere sediments from various sites (ODP 982, IODP U1304, and IODP U1388/1386) we intent to test the hypothesis of enhanced Regolith weathering, climate cooling, and MOW or NAC advances across the bi-furcation into new global climate states. To achieve this goal the project has two data streams: (1) More precise timing of events through innovation of coral dating and revisiting mound evolution and (2) Reconstruction of the thermal history and water mass provenance and weathering patterns using geochemical tracers of temperature (Li/Mg) and radiogenic Nd. Through a synthesis of all new findings and previous reviews on the ice-sheet dynamic and thermal structure of the northeast Atlantic we will build a new conceptual model of threshold crossing and its possible northern hemisphere source region. The project should be conducted by an early stage postdoctoral researcher and build on the combined forces of expert teams at Heidelberg University and University Frankfurt providing a unique research environment and infra-structure.