COLLABORATIVE RESEARCH: Ocean Oxidation and the Biosphere During Neoproterozoic Glaciation

合作研究：新元古代冰川期间的海洋氧化与生物圈Susannah Porter(Pi牵头)；EAR-0922305加州大学圣巴巴拉分校Matthew Hurtgen；EAR-0921913西北大学ARRA声明：“这项建议将使用2009年美国复苏和再投资法案(公法111-5)提供的资金授予。最近的研究表明，5.8亿年前海洋氧合作用的脉动可能允许动物进化，但几乎没有考虑到生物与新元古代早期氧水平波动之间的关系，特别是跨越低温纪(又名。？雪球地球？)大约7.2亿到6.35亿年前的冰川，那时地球可能已经被埋在冰层中。该项目的目的有两个：(1)重建低温冰期期间的氧水平和生物学；(2)检验氧水平的波动与在此期间观察到的生物群落多样性和组成的变化有关的假设。为了实现这些目标，私人投资研究所将对挪威北部斯瓦尔巴群岛和澳大利亚四个不同盆地的页岩进行微古生物、地球化学和地质年代学分析。总体而言，这些单位跨越了整个低温冰期。来自斯瓦尔巴群岛的样本已经采集；来自澳大利亚的样本将在两个野外季节采集，一个在塔斯马尼亚，另一个在澳大利亚大陆。所有分析将在同一套地层定义明确的样品上进行，从而使生命和氧气可获得性的记录明确地联系在一起，并置于新元古代气候变化的背景下。

Collaborative Research: Ocean Oxidation and the Biosphere during Neoproterozoic GlaciationSusannah Porter (Lead PI); EAR-0922305University of California Santa BarbaraMatthew Hurtgen; EAR-0921913Northwestern UniversityARRA Statement: "This proposal will be awarded using funds made available by the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).ABSTRACTAn increase in Earth surface oxygen levels has long been invoked as a driver of biological innovation at the end of the Neoproterozoic Era (1000 to ~541 million years ago), when diverse macroscopic life, including animals, first flourished. Recent work suggests that a pulse in ocean oxygenation ~580 million years ago may have permitted the evolution of animals, but almost no consideration has been paid to the relationship between biology and fluctuating oxygen levels earlier in the Neoproterozoic, in particular spanning the Cryogenian (a.k.a. ?snowball Earth?) glaciations ~720 to 635 million years ago, when Earth may have been entombed in ice. The aim of this project is two-fold: (1) reconstruct oxygen levels and biology during the Cryogenian glacial interval; and (2) test the hypothesis that fluctuating oxygen levels are linked to changes in the diversity and composition of biological communities observed during this time. To address these goals, the PIs will undertake micropaleontological, geochemical, and geochronologic analyses of shales collected from successions in Svalbard, an archipelago north of Norway, and in four separate basins in Australia. Collectively, these units span the entire interval of Cryogenian glaciation. Samples from Svalbard have already been collected; samples from Australia will be collected during two field seasons, one in Tasmania, the other on the Australian mainland. All analyses will be performed on the same suite of stratigraphically well-defined samples, allowing records of life and oxygen availability to be unambiguously linked and placed within the context of Neoproterozoic climate change.