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

搜索 100ka 气候周期 MPT 起始的拟议北方源

• 批准号: 527457453
• 负责人: Professor Dr. Norbert Frank
• 金额: --
• 依托单位: Institut für Umweltphysik
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/527457453?language=en
• 关键词: Searching; proposed; Northern; Source; MPT

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.

中更新世过渡期（MPT）是一个神秘的气候时期，在此期间，天文强迫没有发生重大变化，气候周期发生了从~41ka到100ka的转变，最近的发现表明北半球冰川侵蚀/风化的变化。风化层发生在周期性变化和大西洋经向翻转环流（AMOC）大幅减少之前，此外，北半球冰盖迅速扩张。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 (MOW) 的流出量增加或北大西洋洋流 (NAC) 的加强。必须跨越临界点，但在时间和机制方面都很难预测，但最近对北大西洋东部冷水珊瑚框架形成的研究都遵循类似的气候影响确定和确定。珊瑚的出现是物理过程。与极地和亚热带锋面的热历史和生产力位移有关的MOW和NAC对珊瑚生长和扩张的重要作用已被援引，挑战者土墩在整个MPT中演变，因此是唯一允许进行测试的地点。气候变冷、翻转变化（纬度热通量）和风化层风化的机制与海洋记录相结合，对不连续珊瑚生长的间断观察不太可能提供北方的独特证据。半球“冷阈值”进入 100ka 周期，但是，由于最近在 234U/238U 和 U/Pb 测年方面取得的进展，珊瑚对气候变化和水团结构变化的反应可以精确测定。此外，通过全面的研究。珊瑚（IODP U1317 - Challenger Mound）和来自不同地点的北半球沉积物（ODP 982、IODP U1304 和 IODP U1388/1386）我们打算测试风化层风化增强、气候变冷以及 MOW 或 NAC 跨越分叉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）更精确。通过创新珊瑚测年和重新审视土丘演化来确定事件的时间；(2) 使用温度 (Li/Mg) 和放射性 Nd 的地球化学示踪剂重建热历史和水团来源和风化模式。结合有关东北大西洋冰盖动力和热力结构的所有新发现和先前评论，我们将建立一个新的阈值跨越及其可能的北半球源区的概念模型。该项目应由早期博士后研究员和以海德堡大学和法兰克福大学专家团队的联合力量为基础，提供独特的研究环境和基础设施结构。