Microfossils: a tool for dating and reconstructing paleoenvironmental changes and biological evolution

本研究计划的目的是利用微化石的独特潜力来重建地球系统在重大扰动期间过去的环境和进化变化。研究的重点是评估中生代大量海洋有机碳埋藏时期的原因和后果。这些层段被称为海洋缺氧事件（oae），代表了目前已开采的主要烃源岩。本研究的核心是对中生代四个最突出的OAE（陶拉纪OAE和白垩纪OAE1、2和3）的调查。这些事件与显著的碳同位素漂移（每英里1.5英里）和生物灭绝和物种形成的加速有关，表明对地球海洋、气候和生物系统的进化产生了广泛的影响。这些oae将在从加拿大西部内陆海道（CWIS）到大西洋的中高纬度样带进行研究。由于高纬度地区对控制全球海洋-大气环流系统非常重要，因此这些地区极有可能为oae的形成提供新的线索。建立高分辨率的生物和化学地层学，实现高低纬度剖面的精确地层对比，这对了解OAE形成的过程、时间和空间扩展具有重要意义。此外，还将利用已建立的新的环境变化指标（如生产力）来重建导致oae的古环境条件。为了开发新的环境指标，本文将分析全新世地中海富有机质沉积物的形成过程，即S1号藻推进体。该冲积物可以作为缺氧沉积物形成的理想范例，并为oae重建提供了开发新的古生物指标的潜力。此外，还将对选定的微化石类群进行研究，以评估和量化与中高纬样带oae形成相关的进化变化。这个样带将有助于区分微化石随时间的进化和生态趋势。

The objective of this research program is to exploit the unique potential of microfossils for reconstructing past environmental and evolutionary changes during major perturbations to the Earth system. The main focus is to assess the causes and consequences of periods of massive burial of marine organic carbon during the Mesozoic. These intervals, known as Oceanic Anoxic Events (OAEs), represent the main source rock of hydrocarbons that are exploited today. Central to the proposed research is the investigation of the four most prominent OAEs of the Mesozoic (Toarcian OAE and Cretaceous OAE1, 2, and 3). These events are associated with pronounced carbon isotope excursions of >1.5 per mille and elevated rates of biotic extinction and speciation indicating a broad impact on the evolution of Earth's ocean, climate, and biotic system. These OAEs will be studied in a mid- to high-latitude transect from the Canadian Western Interior Seaway (CWIS) to the Atlantic Ocean. These areas hold great potential to shed new light on the formation of OAEs because high latitude regions are so important for controlling the global ocean-atmospheric circulation system. A high resolution bio- and chemostratigraphy will be established, that allows the precise stratigraphic correlation between high and low latitudes sections, which are of utmost importance for the understanding of the processes, the timing, and the spatial extension of OAE formation. Furthermore, well established and new indicators for environmental changes (e.g., productivity) will be applied to reconstruct the paleoenvironmental conditions that led to OAEs. To develop new environmental indicators, the formation of organic rich sediments deposited in the Mediterranean Sea during the Holocene, the sapropel S1, will be analyzed. This sapropel may serve as an ideal example of how anoxic sediments have been formed and provides the potential to develop new paleontological indicators for the reconstruction of OAEs. Moreover, selected microfossil groups will be investigated to assess and quantify evolutionary changes connected with the formation of OAEs in a mid- to high latitudinal transect. This transect will allow to distinguish between evolutionary and ecological trends in microfossils through time.