Collaborative Research: Examining the Evolution of Biospheric Oxygenation in Late Archean to Middle Proterozoic Oceans Through High-Resolution Trace Metal Chemostratigraphy

合作研究：通过高分辨率痕量金属化学地层学研究晚太古代到中元古代海洋生物圈氧化的演化

• 批准号: 0952216
• 负责人: Ariel Anbar
• 金额: $ 15.21万
• 依托单位: Arizona State University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0952216&HistoricalAwards=false
• 关键词: Collaborative; Research; Examining; Evolution; Biospheric

Intellectual merit: The PIs propose to obtain high-resolution trace metal geochemical profiles from organic-rich sedimentary rocks to examine the evolution of climate and biospheric oxygenation in the Late Archean to Middle Proterozoic. The connections between climate and oxygenation are manifold. Oxygen levels in the deep sea are affected by the rate at which organic carbon is exported from productive surface waters, and hence ultimately from atmospheric CO2. In turn, enhanced burial of organic carbon in marine sediments can increase the O2 content of the atmosphere, with climatic consequences on an Archean Earth dependent on CH4 as a greenhouse gas. Oxygen levels also affect the ocean concentrations of trace nutrients such as Fe and Mo, potentially altering the vigor of marine surface biota and the efficiency of surface-to-deep carbon pumping. Earlier work by the PIs discovered traces of oxygenic photosynthesis and surface ocean oxygenation at least 50-100 M.y. before the first major rise of atmospheric O2 (2.45-2.32 Ga Great Oxidation Event; GOE). Their chemostratigraphic approach revealed an otherwise unrecognized history of biospheric oxygenation that is more complex than previously realized. Therefore, detailed investigation of this history allows them to test fundamental concepts that relate O2, carbon, micronutrients and climate. For example, can the same basic concepts developed to explain Holocene climate and carbon cycling explain conditions in the Archean and Proterozoic? The PIs propose to refine the timeline of biospheric oxygenation by developing an extensive compilation of trace metal concentrations for Late Archean to Middle Proterozoic rocks emphasizing key intervals straddling the GOE: the 2.7 Ga Joy Lake Sequence (Minnesota, U.S.A.), the 2.3 Ga Rooihoogte and Timeball Hill Formations (South Africa), and the 1.8-1.7 Ga Chuanlinggou Formation (North China). Trace metal geochemical profiles, when combined with sedimentary Fe geochemistry, can constrain the nature of local sedimentary conditions (e.g., bottom water redox state and basin restriction). Bottom water Mo concentrations in ancient oceans can be estimated by comparing Mo/TOC of these rock samples with sediment Mo/TOC and seawater concentrations in modern anoxic basins. For other trace metals whose marine geochemistry is less well understood, broad differences in metal marine budgets between time intervals can be made by comparison with Mo. The Mo isotope paleoredox proxy will be used to procure independent constraints on the extent of regional/global water column euxinia and assess the impact on trace metal abundances in seawater. Re-Os geochronology may provide precise depositional ages. The PIs will address four main questions: 1. How long is the time lag between the development of pervasive surface ocean oxygenation (and by inference oxygenic photosynthesis) and the GOE? 2. What is the response of early Paleoproterozoic metal marine budgets to the GOE? 3. Do metal marine budgets show temporal trends in the Middle Proterozoic related to increasing biospheric O2 and/or expansion of ocean euxinia?4. What implications do such trends have for climate during the early Earth and how was microbial and eukaryotic ecology and evolution affected?Broader Impact: This proposal promotes the early career development of Co-PI Kendall. Additionally, as a component of their project activities, the PIs plan to establish a pilot project that will provide laboratory research experience for ASU undergraduates with physical disabilities (i.e., vision, hearing, speech, or motor impairments). The ultimate goal of the pilot is to increase access to science laboratories for postsecondary students with disabilities. It will also leverage the experiences of Kendall as a successful young laboratory scientist with severe hearing and mild speech impairments. Specific programs will be crafted for each student in collaboration with the ASU Disability Resource Center (DRC). The DRC will provide classroom aids and assistive technologies to facilitate direct student participation in laboratory research activities, including sample preparation, analysis, data reduction, and preparation of undergraduate theses.

智力优点：PIS提议从有机丰富的沉积岩中获得高分辨率的痕量金属地球化学曲线，以检查晚期天生生物学到中间古代的气候和生物圈氧合的演变。气候和氧合之间的连接是多种多样的。深海中的氧气水平受到有机碳从生产地表水域的出口速率的影响，因此最终从大气二氧化碳中。反过来，在海洋沉积物中增强了有机碳的埋葬可以增加大气的O2含量，气候对大将地球的气候依赖于CH4作为温室气体。氧气水平还会影响FE和MO等微量营养素的海洋浓度，可能会改变海面生物群的活力以及地表到深碳抽水的效率。 PIS的早期工作发现了至少50-100 M.Y.的氧合光合作用和表面海洋氧合的痕迹。在大气O2的第一个重大崛起之前（2.45-2.32 GA大氧化事件； GOE）。他们的化学地层学方法揭示了原本未识别的生物圈氧合史，比以前实现的更为复杂。 因此，对此历史的详细研究使他们能够测试与O2，碳，微量营养素和气候相关的基本概念。例如，可以开发出相同的基本概念来解释全新世气候和碳循环解释天使和proterorokoic中的条件吗？ The PIs propose to refine the timeline of biospheric oxygenation by developing an extensive compilation of trace metal concentrations for Late Archean to Middle Proterozoic rocks emphasizing key intervals straddling the GOE: the 2.7 Ga Joy Lake Sequence (Minnesota, U.S.A.), the 2.3 Ga Rooihoogte and Timeball Hill Formations (South Africa), and the 1.8-1.7 Ga Chuanlinggou Formation (North 中国）。痕量金属地球化学轮廓与沉积Fe地球化学结合使用，可以限制局部沉积条件的性质（例如，底水氧化还原状态和盆地限制）。可以通过将这些岩石样品的MO/TOC与现代缺氧盆地中的沉积物MO/TOC和海水浓度进行比较，可以估算古老海洋中的底部水Mo浓度。对于其他对海洋地球化学的痕量金属的了解，可以通过与MO相比，在时间间隔之间在金属海洋预算之间存在广泛的差异。MO同位素PaleoDox Paleodox Proxy将用于在区域/全球水柱Euxinia的范围内采取独立的约束，并评估对海水中痕量金属丰富的影响。 Re-OS年代学可以提供精确的沉积年龄。 PI将解决四个主要问题：1。普遍的表面海洋氧合（以及通过推断氧合光合作用）的发展与GOE之间的时间滞后？ 2。早期古元中金属海洋预算对GOE的反应是什么？ 3。金属海洋预算是否显示出与增加生物圈O2和/或大洋Euxinia？4相关的中部元古代的时间趋势？4。这种趋势对地球早期的气候有什么影响？微生物和真核生态学和进化如何影响？更广泛的影响：该提议促进了Co-Pi Kendall的早期职业发展。此外，作为其项目活动的一部分，PIS计划建立一个试点项目，该项目将为ASU本科生提供实验室研究经验（即视觉，听力，语音或运动障碍）。该试点的最终目标是增加上学后残疾学生获得科学实验室的机会。它还将利用肯德尔（Kendall）作为成功的年轻实验室科学家的经历，并有严重的听力和轻度的言语障碍。将与ASU残疾资源中心（DRC）合作为每个学生制定特定的计划。刚果民主共和国将提供课堂辅助工具和辅助技术，以促进学生直接参与实验室研究活动，包括样本准备，分析，减少数据和本科论文的准备。