NSFGEO-NERC: Collaborative Research: Developing a new Lower Cretaceous time scale: Foundation for the next generation of paleoceanographic and biogeochemical studies

白垩纪是全球变暖的时期，大气中的二氧化碳含量超过800 ppm，与“一切照旧”排放情景预测的2100年相似。白垩纪岩石记录了高海平面、高生物生产力、大规模火山活动以及几次海洋缺氧事件（OAE）期间碳循环的重大扰动。了解这些现象可以为未来的温室效应情景提供深时间模拟。记录这些危机的海洋沉积物遍布全球，但如果要揭示原因，将这些记录编织到一个共同的时间框架中至关重要。 该项目旨在产生一个新的时间框架，跨越1.25亿至9300万年前，在此期间发生了几次主要的OAE。这将有助于研究太平洋、大西洋和地中海海洋生态系统的反复恶化。该团队将参与新的外展，国际合作和未来地球科学领导者的培训。他们将通过参加斯特吉斯摩托车拉力赛为公众带来深度时间科学。 海洋缺氧事件的有利假设涉及火山爆发，导致一系列放大全球海洋生产的过程;关键因素是火山活动的性质和营养物质增加的来源。然而，代用记录（碳和锇同位素）的地理差异表明了额外的复杂性，例如海平面和海洋环流。该项目的目标是建立：（1）全球地球化学和古生物数据集的新时标;（2）使用同位素地层学将新时标与欧洲剖面进行化学地层对比;（3）提高对主要地球化学扰动的认识的新全球时标。该小组将：（i）确定日本沉积物中流纹岩凝灰岩的放射性同位素年龄，（ii）将这些新年龄与欧洲新的锇和碳同位素化学地层学相结合，（iii）在共同的时间和地层框架内汇编OAE 1a的全球地球化学代用数据，并分析从太平洋到欧洲的趋势和模式，（iv）评价火山与气候/轨道假说对OAE起源的影响，及（v）探索地理在地球化学信号的时间和幅度方面的重要性-这是一个由国家科学基金会地球科学理事会和联合王国国家环境研究理事会通过国家科学基金会/地球科学理事会-联合王国国家环境研究理事会牵头机构协议共同资助的项目。该协议允许美国/英国提交一份联合提案，并由研究者拥有最大预算比例的机构进行同行评审。一旦成功地共同确定了一个奖项，每个机构都会为预算的一部分和与自己的调查人员和工作组成部分相关的调查人员提供资金。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The Cretaceous was a time of global warming during which atmospheric carbon dioxide levels surpassed 800 ppm, similar to those predicted for 2100 by “business-as-usual” emission scenarios. Cretaceous rocks record high sea levels, high biological productivity, massive volcanism, and major perturbations of the carbon cycle during several ocean anoxic events (OAEs). Understanding these phenomena can provide deep-time analogs for future greenhouse scenarios. Marine sediments that record these crises are globally widespread but weaving these records into a common temporal framework is essential if they are to reveal the causes. This project aims to generate a new temporal framework spanning 125 to 93 million years ago during which several major OAEs occurred. This will permit examination of repeated deteriorations of marine ecosystems across the Pacific, Atlantic, and Mediterranean oceans. The team will be involved in novel outreach, international collaboration, and training of future earth science leaders. They will bring deep-time science to the public via presence at the Sturgis Motorcycle Rally. The favored hypothesis for ocean anoxic events involves volcanic initiation leading to a cascade of processes amplifying global marine production; key factors are the nature of volcanism and the source of increased nutrients. Yet geographic differences in proxy records (Carbon and Osmium isotopes) indicate additional complexities, such as sea level and ocean circulation. The goals for the project are to establish: (1) A new time scale for global geochemical and paleobiologic datasets; (2) Chemostratigraphic correlation of the new time scale to European sections using isotope stratigraphy, and (3) A new global time scale for improved understanding of major biogeochemical perturbations. The team will: (i) Determine radioisotopic ages of rhyolitic tuffs in sediments of Japan, (ii) Integrate these new ages with new Osmium and Carbon isotope chemostratigraphy in Europe, (iii) Compile global geochemical proxy data for OAE 1a within a common temporal and stratigraphic framework, and analyze trends and patterns from the Pacific to Europe, (iv) Evaluate the volcanic versus climatic/orbital hypotheses for OAE initiation, and (v) Explore the significance of geography in the timing and magnitude of geochemical signals.This is a project that is jointly funded by the National Science Foundation’s Directorate of Geosciences (NSF/GEO) and the National Environment Research Council (UKRI/NERC) of the United Kingdom (UK) via the NSF/GEO-NERC Lead Agency Agreement. This Agreement allows a single joint US/UK proposal to be submitted and peer-reviewed by the Agency whose investigator has the largest proportion of the budget. Upon successful joint determination of an award, each Agency funds the proportion of the budget and the investigators associated with its own investigators and component of the work.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.