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次远征（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提供了一个独特的机会，可以探索晚白垩纪时期地球气候的演变，时间尺度从千年到数百万年。这一时期是众所周知的一个显着的过渡，从高峰温室气候在白垩纪中期到晚白垩世-早古近纪冷却。这一全球气候转变具有极大的潜力，可以提高我们对气候变化与碳固存过程之间的相互作用的理解，从短期到长期。成功应对这些总体气候-碳趋势的一个基本要求是建立一个强有力的地层框架。该项目将通过将现有的船上生物地层学和磁性地层学与来自392远征的三个地点的散装碳的新的高分辨率化学地层学数据相结合来完成这一任务，这些地点包括U1579地点（中央Agulhas高原），U1580地点（中央Agulhas高原南部）和U1581地点（特兰斯凯盆地的深平坦部分）。这些遗址涵盖了几乎完整的早期Cenomanian到Maastrichtian的沉积记录，从最初的沉积到中部和南部中部Agulhas高原的开阔和深海环境以及特兰斯凯盆地的永久深盆地环境。这种方法将提供深入了解如何沉积在阿古拉斯高原地壳就位后立即开始在~100马，以及如何不断变化的网关之间的南大西洋，南大洋，南印度洋盆地影响沉积和气候变量在不同的时间尺度。互补的D13 C（d13 Ccarb.和Cord 13 Corg.），有机（TOC）和无机（CaCO 3）的碳，氮，硫记录将产生提供一个关键的背景下讨论的历史pCO 2，碳丰富度和底层水氧化还原作为环境变化的证据。拟议的项目风险低，成本低，但可能会提供一个关键的基础，以进一步超越IODP 392巡航后研究。

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.