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

Mo、U、Re-Os、S和Fe同位素等水圈氧合和金属循环的地球化学代用物可用于确定古海洋中这些元素的时空分布，这些元素与地球生命的进化有着不可分割的联系。然而，到目前为止，只有很少的合适的材料，特别是对于太古宙。南非古太古代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，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，特别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剖面。利用Barberton钻探项目的岩心材料，我们寻求资金来约束(1)古海洋中金属来源、氧化还原条件和生物群的潜在参与，利用富有机质地层、浅海至深海环境中的带状铁地层和燧石沉积的Re-Os-Fe同位素和铂族元素系统；(2)长英质火山岩的PGE和Os同位素组成。它们代表了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潜在的样品材料，与其他研究所进行战略合作，以及使用多种代理进行数据整合，为成功解决这些问题提供了一种有希望的方法。

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.