COLLABORATIVE RESEARCH: Ocean Oxidation and the Biosphere During Neoproterozoic Glaciation

合作研究：新元古代冰川期海洋氧化与生物圈加州大学圣巴巴拉分校；西北大学yarra声明：“该提案将使用2009年美国复苏和再投资法案（公法111-5）提供的资金进行奖励。长期以来，地球表面氧含量的增加一直被认为是新元古代（1000至5.41亿年前）末期生物创新的驱动因素，当时包括动物在内的各种宏观生命首次繁荣起来。最近的研究表明，大约5.8亿年前海洋氧合的脉动可能允许了动物的进化，但几乎没有考虑到新元古代早期生物与波动的氧水平之间的关系，特别是跨越冰川纪（又名冰川纪）。大约在7.2亿到6.35亿年前，当时地球可能已经被冰所覆盖。该项目的目的有两个：(1)重建冰期间的氧气水平和生物；(2)验证在这段时间内观察到的生物群落多样性和组成变化与氧气水平波动有关的假设。为了实现这些目标，PIs将对挪威北部群岛斯瓦尔巴群岛和澳大利亚四个独立盆地的页岩进行微古生物学、地球化学和地质年代学分析。总的来说，这些单元跨越了整个冰川期。已经从斯瓦尔巴群岛收集了样本；来自澳大利亚的样本将在两个野外季节收集，一个在塔斯马尼亚，另一个在澳大利亚大陆。所有的分析都将在同一套地层定义明确的样品上进行，允许将生命和氧气可用性的记录明确地联系起来，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.