Collaborative Research: The Rise and Fall of the Neoproterozoic Era in Siberia: Connections between Tectonics, Ocean Chemistry, and Biologic Innovation

生命和环境的共同进化是地球45亿年历史上最引人注目的故事之一。亿万年以来，简单的单细胞生物主宰着地球上的海洋，直到大约10亿年前，第一批带有细胞核的生物开始增殖。然后，在大约5.5亿年前的地质瞬间，复杂的动物突然出现了。这两个非同寻常的进化事件发生的时间一直是自然科学中最经久不衰的谜团之一。在这项提议中，主要研究人员测试了一个有趣的假设，即这两种进化转变都是由主要的造山活动催化的，这些造山活动向海洋输送了营养物质，并改变了海洋生物可利用的关键生物氧气的数量。为了验证这一假设，科学小组将测量西伯利亚古代石灰岩沉积物中保存的化学元素锂（Li）和铀(U)质量的微小差异。这些来自西伯利亚的岩石保存了这两个进化转变期间海洋生命的壮观记录，该项目产生的新数据旨在为推动地球进化变化的基本过程提供新的视角。研究人员还将领导一个广泛的推广项目，旨在为马里兰州和弗吉尼亚州的高中生提供野外地质学和大学实习机会。具体来说，在西弗吉尼亚州暴露的壮观的地质构造将以虚拟和亲自的方式呈现给学生，以培养下一代地球科学家的广泛目标。中元古代-新元古代过渡时期的“真核生物进化大爆炸”，以及随后埃迪卡拉纪-寒武纪过渡时期动物的大量繁殖，标志着地球历史上最关键的两个生物转变。有趣的是，这两个进化事件都与全球造山运动的剧烈时期有关，这可能传递了营养物质并改变了海洋-大气系统的氧化还原平衡。为了测试全球构造、海洋氧化作用和生物创新之间的联系，该项目将测量西伯利亚海相碳酸盐岩序列中锂（Li）和铀(U)的同位素组成，这些序列跨越了地球历史上的每一个关键转变。Li同位素是硅酸盐风化系统的敏感晴雨表，而U同位素是海洋氧化还原量化的有力新工具。将这些同位素与西伯利亚富含化石序列的沉积学和古生物学数据相结合，有望为地球上早期真核生物和动物进化的环境条件提供新的见解。该奖项反映了美国国家科学基金会的法定使命，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 co-evolution of life and environment is one of the most compelling stories in Earth's 4.5 billion year history. For eons, simple, single-celled organisms dominated the Earth's oceans, until the first organisms with a cell nucleus began to proliferate about a billion years ago. Then, in the geologic blink of an eye approximately 550 million years ago, complex animals burst onto the scene. The timing of these two extraordinary evolutionary events has been one of the most enduring mysteries in the natural sciences. In this proposal, the principal investigators test an intriguing hypothesis that both of these evolutionary transitions were catalyzed by major mountain-building events that delivered nutrients to the oceans, and changed the amount of biologically-critical oxygen available for use by marine organisms. To test this hypothesis, the science team will measure minute differences in the masses of the chemical elements lithium (Li) and uranium (U) preserved in ancient limestone deposits from Siberia. These rocks from Siberia preserve a spectacular record of life in the oceans across these two evolutionary transitions, and new data generated from this project aim to provide a fresh look at the fundamental processes that drive evolutionary change on Earth. The researchers will also lead a broad outreach program aimed at bringing field geology and university internships to high school students in Maryland and Virginia. Specifically, spectaculargeologic formations exposed in West Virginia will be presented to students both virtually and in person, with the broad goal of training the next generation of geoscientists.The 'big bang of eukaryotic evolution' across the Mesoproterozoic-Neoproterozoic transition, and the subsequent proliferation of animals across the Ediacaran-Cambrian transition, mark two of the most critical biological transformations in Earth history. Intriguingly, both of these evolutionary events are associated with intense periods of global mountain-building, which may have delivered nutrients and changed the redox balance of the ocean-atmosphere system. To test the linkages between global tectonics, ocean oxygenation, and biological innovation, this project will measure the isotopic composition of lithium (Li) and uranium (U) in marine carbonate successions from Siberia that span each of these critical transitions in Earth history. Li isotopes are a sensitive barometer for the silicate weathering system, and U isotopes are a powerful new tool for ocean redox quantification. Pairing these isotopes with sedimentological and paleontological data from fossil-rich successions in Siberia promises to provide new insights into the environmental conditions that accompanied early eukaryotic and animal evolution on Earth.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.