OCE-PRF: Windows into Cretaceous diatom paleobiology: Seasonal responses in laminated sediments and survivability and response to the Cretaceous-Paleogene extinction event

OCE-PRF：白垩纪硅藻古生物学的窗口：层状沉积物的季节性响应以及生存能力和对白垩纪-古近纪灭绝事件的响应

• 批准号: 2205996
• 负责人: Jason Coenen
• 金额: $ 32.97万
• 依托单位: University of Nebraska-Lincoln
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2205996&HistoricalAwards=false
• 关键词: OCE; PRF; Windows; into; Cretaceous

Diatoms are photosynthetic algae that are an essential part of the biosphere and Earth’s climate system. While Cenozoic records indicate their impact on primary biological and chemical cycles, there is a lack of descriptive and applied research on Cretaceous diatoms. This lack of descriptive work limits their application for understanding ancient global ecosystems such as the Cretaceous greenhouse climates. Therefore, developing a better understanding of how diatoms responded to significant environmental perturbations during the end-Cretaceous mass extinction event and their response to seasonal changes in the early Cretaceous; is critical for understanding how Earth’s climate system has evolved through geologic time and helps constrain future climate variability. The unifying research theme is to better understand the controls on diatom responses to paleoenvironmental changes and improve their utility as tools for Cretaceous geological studies. PI Coenen will study modern and ancient laminated sediments to better understand Ocean Drilling Project Site 693 paleoenvironments and diatom taxonomy. This work will provide a critical understanding of early Cretaceous climate variability on a seasonal timescale, which will aid in the understanding of Earth’s climate system in a greenhouse world. Additionally, PI Coenen will study diatoms and silicoflagellates both before and after the Cretaceous-Paleogene (K/Pg) mass extinction to see how siliceous microfossils respond to environmental perturbations and understand what factors led to survivability in diatoms through this mass extinction event. As an NSF Postdoctoral Researcher, PI Coenen will mentor undergraduate student projects and learn how to mentor graduate level projects and run a research lab with Dr. Harwood. Additionally, PI Coenen will develop modules for an online Antarctic Geosciences course and a Paleogene and Cretaceous siliceous microfossil biostratigraphy workshop. PI Coenen will also host outreach activities at local libraries and k-12 schools and work closely with UNL to foster efforts to broaden participation in the geosciences.The proposed research seeks to develop new information on diatom paleobiology and paleoecology from two locations in the Southern Hemisphere, ranging in time from the early Cretaceous through the K/Pg mass extinction event. PI Coenen will evaluate whether modern ecological approaches can be applied to ancient paleontological records. The central hypothesis is that Cretaceous diatoms shared many life strategies with modern diatoms, allowing for the application of ‘biological uniformitarianism’ to interpret fossil diatom records. This research will be conducted at the University of Nebraska-Lincoln, where Dr. Harwood will mentor PI Coenen on Cretaceous diatom systematics, biostratigraphy, and paleoecology. Drs. Harwood and Coenen will collaborate with Dr. Leventer to provide Coenen training on modern diatom-bearing laminated sediments from the East Antarctic margin to build his skill set to interpret early Cretaceous diatom seasonal changes from ODP Site 693 laminations. This work will provide a rare opportunity to study high-resolution ocean-atmospheric forcing during early Cretaceous greenhouse climates. Additionally, siliceous microfossils from Seymour and Vega islands, Antarctic Peninsula, will be documented across a precursor extinction recognized in the macrofauna ~150 kyr prior to the K/Pg mass extinction event, as well as document the post-event recovery. The response of both silicoflagellates and diatoms to extreme environmental perturbations will be studied in detail to document silicoflagellate retrograde evolution and better understand how diatoms survived the K/Pg extinction that decimated other fossil phytoplankton. Study of diatom assemblages, with a focus on abundance and volume changes of diatom resting spores across a potential precursor extinction related to the Deccan Traps will provide data to resolve these questions. Additionally, this research on the newly forming Southern Ocean has important implications for understanding late Cretaceous paleoclimate and paleoceanography. Both proposed studies have the potential to constrain modeling efforts and provide a better sense of paleoenvironments in these respective intervals.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.

硅藻是光合作用的藻类，是生物圈和地球气候系统的重要组成部分。虽然新生代的记录表明它们对初级生物和化学循环的影响，但缺乏对白垩纪硅藻的描述性和应用性研究。这种缺乏描述性的工作限制了它们在了解古代全球生态系统(如白垩纪温室气候)方面的应用。因此，更好地了解硅藻如何对白垩纪末期大规模灭绝事件中的重大环境扰动做出反应，以及它们对早白垩世季节变化的反应，对于理解地球气候系统如何随着地质时间的推移而演变并有助于限制未来的气候变异性至关重要。统一的研究主题是更好地了解硅藻对古环境变化的控制作用，并提高它们作为白垩纪地质研究工具的实用性。PiCoenen将研究现代和古代的层状沉积物，以更好地了解海洋钻探项目693号遗址的古环境和硅藻分类。这项工作将在季节性时间尺度上提供对早白垩世气候变化的批判性理解，这将有助于理解温室世界中的地球气候系统。此外，Pi Coenen将研究白垩纪-古近纪(K/PG)大灭绝前后的硅藻和硅鞭毛虫，以了解硅质微化石如何对环境扰动做出反应，并了解是什么因素导致硅藻在这次大灭绝事件中存活下来。作为一名NSF博士后研究员，Pi Coenen将指导本科生项目，并学习如何指导研究生水平的项目，并与哈伍德博士一起运营一个研究实验室。此外，Pi Coenen将为南极地球科学在线课程和古近纪和白垩纪硅质微化石生物地层学讲习班开发模块。Pi Coenen还将在当地图书馆和K-12学校主持外联活动，并与联合国后勤基地密切合作，促进扩大对地球科学的参与。拟议的研究旨在从南半球的两个地点，从白垩纪早期到K/PG大灭绝事件，开发有关硅藻古生物学和古生态学的新信息。皮科宁将评估现代生态学方法是否可以应用于古代古生物记录。中心假设是，白垩纪硅藻与现代硅藻有许多共同的生活策略，允许应用生物统一论来解释硅藻化石记录。这项研究将在内布拉斯加-林肯大学进行，哈伍德博士将在那里指导Pi Coenen关于白垩纪硅藻系统学、生物地层学和古生态学的知识。Harwood博士和Coenen博士将与Leventer博士合作，为来自东南极边缘的现代含硅藻层状沉积物提供Coenen培训，以建立他的技能集，从ODP693点纹层解释早白垩世硅藻的季节变化。这项工作将为研究早白垩世温室气候期间的高分辨率海洋-大气强迫提供一个难得的机会。此外，来自南极半岛西摩尔岛和织女岛的硅质微体化石将被记录在K/PG大灭绝事件之前在~150KYR大型动物群中识别的前兆灭绝期间，以及事件后的恢复。将详细研究硅鞭毛藻和硅藻对极端环境扰动的反应，以记录硅鞭毛藻的逆行进化，并更好地了解硅藻是如何在导致其他浮游植物化石大量灭绝的K/PG灭绝中幸存下来的。对硅藻组合的研究，重点是与德干圈闭有关的潜在前体灭绝期间硅藻休眠孢子的丰度和体积变化，将为解决这些问题提供数据。此外，对新形成的南大洋的研究对认识晚白垩世古气候和古海洋学具有重要意义。这两项拟议的研究都有可能限制建模工作，并在这些各自的间隔时间内提供更好的古环境感觉。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。