A multiple isotope and trace element approach to constrain the oxygenation and metal cycling of 3.5 to 3.2 Ga paleo-oceans

限制 3.5 至 3.2 Ga 古海洋氧化和金属循环的多同位素和微量元素方法

• 批准号: 204399623
• 负责人: Professor Dr. Gerhard Peter Brey, Ph.D.
• 金额: --
• 依托单位: Abteilung Petrologie und Geochemie
• 依托单位国家: 德国
• 项目类别: Infrastructure Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/204399623?language=en
• 关键词: multiple; isotope; trace; element; approach

Geochemical proxies for the oxygenation of and metal cycling in the hydrosphere, such as Mo, U, Re-Os, S and Fe isotopes can be used to establish the spatiotemporal distribution of these elements in Paleo-oceans, which is inextricably linked to the evolution of life on Earth, by using well-dated and well-preserved marine sediments. However, to date, only little appropriate material is available especially for the Archaean. The Paleo- to Meso-Archaean Barberton Greenstone Belt, South Africa, represents the rosetta stone of research into the earliest Earth processes and conditions because it consists of little metamorphosed volcano-sedimentary successions. However, the primary (bio)geochemical signatures, especially of redox-sensitive elements, of outcrop samples may be compromised. Therefore, it is imperative to obtain continuous sections of unaltered, fresh material through drilling. Using drill core material from the Barberton Drilling Project, we seek funding to constrain (1) the metal sources, redox conditions and potential participation of biota in the Paleo-ocean, using Re-Os-Fe isotopes and platinum-group element systematics of organic-rich stratigraphic layers, banded iron formations and cherts deposited in the shallow to deep marine environment and (2) PGE and Os isotope composition of felsic volcanic rocks, which represent the continental sources of erosion products subsequently deposited on the ocean floor. Application of state-of-the-art geochemical tools to prospective sample material, strategic collaborations with other institutes and integration of data using multiple proxies offer a promising approach to successfully address these questions.

水圈中氧合和金属循环的地球化学代理，例如钼、铀、铼锇、硫和铁同位素，可通过使用年代清楚且保存完好的海洋沉积物来确定这些元素在古海洋中的时空分布，这与地球生命的进化有着千丝万缕的联系。然而，迄今为止，专门针对太古宙的合适材料却很少。南非的古至中太古宙巴伯顿绿岩带代表了研究最早地球过程和条件的罗塞塔石碑，因为它由少量变质的火山沉积序列组成。然而，露头样品的主要（生物）地球化学特征，尤其是氧化还原敏感元素的特征可能会受到损害。因此，必须通过钻孔获得未改变的新鲜材料的连续部分。利用巴伯顿钻探项目的钻芯材料，我们寻求资金来限制（1）古海洋中生物群的金属来源、氧化还原条件和潜在参与，利用铼-锇-铁同位素和铂族元素系统学对浅至深海洋环境中沉积的富含有机物地层、带状铁地层和燧石进行分类，以及（2）长英质的铂族元素和锇同位素组成 火山岩，代表随后沉积在海底的侵蚀产物的大陆来源。将最先进的地球化学工具应用于预期样品材料、与其他机构的战略合作以及使用多个代理进行数据集成，为成功解决这些问题提供了一种有前途的方法。