Climatic forcing and tectonic control on environments in evolving lake basins of Africa and North America

非洲和北美演化湖盆环境的气候强迫和构造控制

• 批准号: RGPIN-2020-06653
• 负责人: Scott, Jennifer
• 金额: $ 1.82万
• 依托单位: Mount Royal University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750952
• 关键词: Climatic; forcing; tectonic; control; environments

Orbital cycles, which affect the amount of solar energy on the surface of the Earth, and tectonic activity together controlled paleoenvironments during periods of climate change and evolution. Lake basins are particularly sensitive to changing inputs of precipitation and sediment as influenced by these controls, and preserve the best evidence to interpret changing environments and their impact on paleoecosystems. My research uses detailed studies of sediments and animal behaviour (i.e., trace fossils) to recognize cycles and changing environments in the rock record, used to reconstruct changing landscapes through time. Integrated with other lines of evidence (e.g., minerals, elemental composition, diatom assemblages), we can interpret how conditions in environments change within and between each of the cycles. My research program focuses on three long-term projects: 1) Pliocene lakes of the central Kenya Rift Valley; 2) Pliocene lakes of Afar, Ethiopia; and 3) Cretaceous lakes of Alberta. These projects focus on important periods for evolutionary change, namely the Pliocene-Pleistocene in East Africa, where early humans evolved (~5-1.5 million years ago) during the onset of "icehouse" conditions in the northern hemisphere, and the Cretaceous "greenhouse" of North America, where dinosaur fossils are especially abundant (~80-75 million years ago). Initial results indicate that, in the Baringo Basin of central Kenya where Austrolopithecus and Homo fossils are known after ~3.8 million years ago (Project 1), wide swings in lake level occurred due to orbital cycles and resulted in extremely different environments with periodicity of ~23,000 years (precession) modulated by ~100- and 400-thousand-year eccentricity. These short-term cycles are not the only controls; rifting events and hydrothermal input to the lake basin also influenced the lake system, as did longer term global change in climate, which led to the ice age in the northern hemisphere. Short-term climate cycles are also observed further north in Africa in the Afar region of Ethiopia, where "Lucy" lived during the late Pliocene (~3.5 million years ago; Project 2), but the sedimentary record of these cycles is also complicated by volcanism and faulting events. Once we are able to distinguish the more local geological controls, we can compare between central Kenya and northeast Ethiopia to better interpret the influence of global climate change and changing environments home to early humans. The approach taken for the Plio-Pleistocene will also be applied to a recently recognized lake basin with cyclical deposits in the Cretaceous of Alberta (Project 3) to provide an entirely new look at the potential for climate control on dinosaur evolution. By focusing on tectonically active lake basins during times of climate change and distinct turnover events in animal fossil assemblages, my research impacts our understanding of how Earth and atmospheric processes have repeatedly impacted life on Earth.

影响地球表面太阳能量的轨道循环，并在气候变化和进化期间共同控制了古环境。湖泊盆地对受这些控制的影响，对改变降水和沉积物的投入特别敏感，并保留解释不断变化的环境及其对古生系统的影响的最佳证据。我的研究使用对沉积物和动物行为（即痕量化石）的详细研究来识别岩石记录中的周期和不断变化的环境，用于随着时间的推移重建景观。与其他证据线（例如矿物质，元素组成，硅藻组合）集成在一起，我们可以解释环境中每个周期内和之间环境中的条件如何变化。 我的研究计划侧重于三个长期项目：1）肯尼亚裂谷中部的上新世湖； 2）埃塞俄比亚远处的上新世湖； 3）艾伯塔省的白垩纪湖泊。这些项目着重于进化变化的重要时期，即东非的上新世 - 普遍新世，早期人类在北半球的“冰屋”条件发作期间（〜5-150万年前）在这里进化（〜5-150万年前），以及北美的白垩纪“温室”，恐龙剂特别丰富了（北美的绿色温室”（尤其是80-75亿年前）。最初的结果表明，在肯尼亚中部的Baringo盆地中，在〜380万年前众所周知，澳大利亚和同性化石是在大约380万年前知道的（项目1），由于轨道周期，湖泊水平发生了广泛的摇摆，并导致〜23,000年（预求）的周期性造成的环境极为不同。这些短期周期不是唯一的对照。盆地湖湖的裂谷事件和热液投入也影响了湖泊系统，长期的全球气候变化也导致了北半球的冰河时代。在埃塞俄比亚远处地区，在非洲的北部还可以观察到短期的气候周期，“露西”在上新世晚期生活（约350万年前；项目2；项目2），但是这些周期的沉积记录也因火山主义和故障事件而复杂化。一旦我们能够区分更本地的地质控制，我们就可以比较肯尼亚中部和埃塞俄比亚东北部之间，以更好地解释全球气候变化和变化的环境的影响。 Plio-Pleisteene采用的方法还将应用于最近公认的湖泊盆地，并在艾伯塔省的白垩纪（项目3）中使用周期性沉积物，以提供全新的景象，以了解对恐龙进化的气候控制的潜力。通过在气候变化的时期关注构造活跃的湖泊盆地和动物化石组合中的不同周转事件，我的研究影响了我们对地球和大气过程如何反复影响地球生命的理解。