A bio- and carbon isotope stratigraphy for dating late Cretaceous paleoceanographic changes of southern high latitudinal sedimentary successions (Expedition 392 Agulhas Plateau)

在第392次考察(2022年初)期间从南部高纬度地区获得的几乎完整的沉积记录为探索从千年到数百万年的时间尺度上晚白垩世时期地球气候的演变提供了一个独特的机会。这一时期以白垩纪中期温室气候的高峰期向晚白垩世-古近纪早期降温的显著过渡而闻名。这一全球气候过渡具有极大的潜力，可以增进我们对气候变化和碳封存过程之间在短时间和长时间尺度上的相互作用的理解。成功应对这些主要的气候-碳趋势的一个基本要求是建立一个强有力的地层框架。该项目将承担这项任务，将现有的船上生物地层学和磁性地层学与新的高分辨率化学地层学数据相结合，这些数据来自392次探险的三个地点，包括U1579地点(阿古勒哈高原中部)、U1580地点(中南部阿古拉哈斯高原)和U1581地点(特兰斯凯盆地的深水平坦部分)。这些遗址涵盖了从最初的沉积到中南部阿古拉斯高原的开阔和深海海洋环境以及特兰斯凯盆地的永久深水盆地环境的几乎完整的早期塞诺马期到马斯特里赫期的沉积记录。这一方法将深入了解约100 Ma地壳侵位后阿古拉斯高原的沉积是如何立即开始的，以及南大西洋、南大洋和南印度洋盆地之间不断演变的门户如何影响不同时间尺度的沉积和气候变量。互补D13C(d13Ccarb之间的偏移量。和d13 Corg)、有机(TOC)和无机(CaCO_3)碳、氮和硫的记录将被生成，这将为讨论二氧化碳、碳丰度和底水氧化还原作为环境变化证据的历史提供关键背景。拟议的项目是低风险和低成本的，但可能为进一步超越IODP 392巡航后研究奠定关键基础。

The nearly complete sedimentary records obtained from the southern high-latitudes during Expedition 392 (early 2022) offer a unique opportunity to explore the evolution of Earth's climate during the Late Cretaceous period at timescales from millennial to millions of years. The period is well known for a marked transition from peak hothouse climate in the mid Cretaceous to late Cretaceous-early Paleogene cooling. This global climate transition holds great potential for enhancing our understanding of the interplay between climatic change and carbon sequestration processes on short to long times scales. A fundamental requirement to successfully address these overarching climate-carbon trends is the development of a robust stratigraphic framework. This project will take this task by combining existing shipboard biostratigraphy and magnetostratigraphy with new high resolution chemostratigraphic data from bulk carbon for three sites from Expedition 392 including Site U1579 (Central Agulhas Plateau), Site U1580 (Southern Central Agulhas Plateau), and Site U1581 (deep flat part of the Transkei Basin). These sites cover a nearly complete early Cenomanian to Maastrichtian sedimentary record from initial sedimentation to open and deep marine settings for the Central and Southern Central Agulhas Plateau and the permanently deep basin setting of the Transkei Basin. This approach will provide insights into how sedimentation on the Agulhas Plateau started immediately after crustal emplacement at ~100 Ma and how the evolving gateways between the South Atlantic, Southern Ocean, and southern Indian Ocean basins impacted on sedimentation and climate variables at different timescales. Complementary D13C (offset between d13Ccarb. and d13Corg.), organic (TOC) and inorganic (CaCO3) carbon, nitrogen, and sulfur records will be generated which provide a critical context to discuss the history of pCO2, carbon richness and bottom water redox as evidence of environmental change. The proposed project is low risk and low cost but likely to deliver a critical foundation to further excel the IODP 392 post-cruise research.