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A New Approach to the Archean Sulfur Cycle from Marine Carbonates

从海洋碳酸盐中研究太古代硫循环的新方法

基本信息

批准号：
1349858
负责人：
Jess Adkins
金额：
$ 34.5万
依托单位：
California Institute of Technology
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2014
资助国家：
美国
起止时间：
2014-03-01 至 2017-02-28
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1349858&HistoricalAwards=false
关键词：
New Approach Archean Sulfur Cycle

项目摘要

A New approach to the Archean sulfur cycle from marine carbonatesBy Jess Adkins, Woodward FischerABSTRACTThe rise of atmospheric oxygen from an originally reduced planet surface is a central problem in Earth history. It is widely believed that the oxygenation of the Earth's oceans and atmosphere occurred in abrupt steps. The Great Oxygenation Event at the Archean-Proterozoic boundary is one of the better studied of these deep-time jumps, chiefly through the mass independent fractionation (MIF) of the stable sulfur isotopes. However, most of this evidence comes from the reduced forms of sulfur, chiefly pyrite being enriched in the MIF signal. The current understanding assumes that the complementary light MIF signal resides in oceanic sulfate at this time, a trace phase in carbonates that has been analytically inaccessible until now. PIs will use a new MC-ICP-MS method that lowers the current detection limit for sulfate in Archean carbonates by over three orders of magnitude. Micro-drilling of specific textures to unravel the simultaneous evolution of the sulfate and sulfide phases in Late Archean rocks will be used to better understand how it is that the early earth transitioned from an anoxic atmosphere to one with substantial amounts of molecular oxygen. PIs will collect new outcrop and drill core samples during a field campaign to the Campbellrand Platform in South Africa and make hundreds of new sulfur isotope measurements on these samples. Their goal is to create a history of seawater sulfate evolution during this key moment in earth history.

从海洋碳酸盐中研究太古代硫循环的新方法大气中氧气从最初减少的行星表面上升是地球历史上的一个中心问题。人们普遍认为，地球海洋和大气的氧化作用是突然发生的。太古宙-元古代边界的大氧化事件是这些深时跳跃中较好的研究之一，主要通过稳定硫同位素的质量无关分馏（MIF）。然而，大多数证据来自硫的还原形式，主要是黄铁矿富集在MIF信号中。目前的理解假设互补光MIF信号此时存在于海洋硫酸盐中，这是碳酸盐中的一种痕量相，迄今为止一直无法分析。 PI将使用新的MC-ICP-MS方法，将太古代碳酸盐中硫酸盐的当前检测限降低三个数量级以上。对特定纹理进行微钻，以揭示晚太古代岩石中硫酸盐和硫化物相的同时演化，将用于更好地了解早期地球如何从缺氧大气过渡到具有大量分子氧的大气。 PI将在南非Campbellrand平台的野外活动期间收集新的露头和钻探岩心样品，并对这些样品进行数百次新的硫同位素测量。他们的目标是在地球历史的这一关键时刻创造一个海水硫酸盐演变的历史。