Investigation of Ultra-18O Depleted "Slushball" Earth Rocks from Karelia, Russia and the Timing of Paleoproterozoic Glaciations and the Great Oxidation Event

对俄罗斯卡累利阿超 18O 贫化“泥球”地球岩石的调查以及古元古代冰川作用和大氧化事件的时间

• 批准号: 1447337
• 负责人: Ilya Bindeman
• 金额: $ 35.5万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-03-01 至 2019-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1447337&HistoricalAwards=false
• 关键词: Investigation; Ultra; 18O; Depleted; Slushball

Investigation of Ultra-18-O Depleted "Slushball" Earth Rocks from Karelia, Russia and the Timing of Paleoproterozoic Glaciations and the Great Oxidation EventThis proposal seeks support to investigate and interpret the Paleoproterozoic rocks from Karelia, Russia, which are extraordinarily depleted with respect to oxygen 18 (these rocks have the world's lowest known values). Rocks with such depleted 18O require derivation from interaction with glacial meltwaters during panglobal glaciation. These depletions now characterize 11 localities along a 450 km long belt and are spatially associated with the 2.45-2.2 Ga mafic intrusions formed in subglacial rifting environment zones. Since Karelia was located near equatorial latitudes throughout the Paleoproterizoic, these rocks provide isotopic evidence of ice at low latitudes, and a robust hydrologic cycle, in which low latitude oceans remained unfrozen (a "Slushball" climate state). As there were three panglobal glaciations between 2.45 and 2.2 Ga, precise determination of age of the mafic intrusions with the subglacial ultra-depleted meteoric hydrothermal features in Karelia will provide the most direct constraints on the timing of these global glaciations. Furthermore, this research may constrain which of the glaciations preceded the rise of atmospheric oxygen and disappearance of mass-independent fractionation of sulfur isotopes. The scope of this project will include mapping and sample collection in the field at the anomalously depleted areas, subsequent isotope analysis to identify the characteristic bulls-eyes meteoric hydrothermal features, dating the timing of such depletion by in situ and solution geochronology, geochemical modeling of these unique hydrothermal alteration trends, and investigation of the unmetamorphosed coeval early Paleoproterozoic Sariolian, and Sumian volcanic and sedimentary sequences of the Vetreny Belt in the context of the global oxidation event. The proposal will promote international collaboration, involve and support students including those traditionally underrepresented in geosciences, continue to involve large number of undergraduate and community college students into geochemical, geochronologic, and stable isotope research and expose them to science and international collaboration. The proposal will support the analytical infrastructure of the recently established stable isotope lab through work done by the PI and members of the research group and collaborators. PI will continue his outreach activities, public lectures and articles to popular journals.

俄罗斯卡累利阿地区超-18-O贫化的“Slushball”地球岩石的调查以及古元古代冰川和大氧化事件的时间这一提议寻求对调查和解释俄罗斯卡累利阿地区古元古代岩石的支持，这些岩石的氧18含量异常贫化（这些岩石具有世界上已知的最低值）。岩石与这种贫化18 O需要从与冰川融水的相互作用在pangtobalaciation推导。这些亏损现在表征11个地点沿着450公里长的带，并在空间上与2.45-2.2 Ga的镁铁质侵入体形成的冰下裂谷环境带。由于卡累利阿在整个古元古代都位于赤道附近，这些岩石提供了低纬度冰的同位素证据，以及一个强大的水文循环，其中低纬度海洋保持不冻结（“Slushball”气候状态）。由于在2.45和2.2 Ga之间有三次大冰期，精确测定卡累利阿冰下超贫化大气热液特征的镁铁质侵入体的年龄将为这些全球冰期的时间提供最直接的约束。此外，这项研究可能会限制的冰川之前，大气中的氧气和硫同位素的质量无关分馏的消失。该项目的范围将包括在严重贫化地区实地绘图和采集样品，随后进行同位素分析以确定特征性的靶心状大气热液特征，通过现场和溶液地质年代学确定这种贫化的时间，对这些独特的热液蚀变趋势进行地球化学建模，并调查未变质的同时代早古元古代Sariolian，在全球氧化事件背景下的维特雷尼带苏缅火山和沉积序列。该提案将促进国际合作，参与和支持学生，包括那些传统上在地球科学中代表性不足的学生，继续让大量本科生和社区学院的学生参与地球化学，地质年代学和稳定同位素研究，并使他们接触科学和国际合作。该提案将通过PI和研究小组成员以及合作者的工作支持最近建立的稳定同位素实验室的分析基础设施。PI将继续开展外联活动，公开讲座和在流行期刊上发表文章。