Origins of Gold, Uraninite, Pyrite, and Organic Matter in Conglomerates of Archean and Early Proterozoic Age

9706279 Ohmoto这项研究的目的是建立一个关于~2.8Ga~~2.0Ga砾岩层中金-铀矿床形成过程及其古环境的综合模式。这项研究的结果将为这类最重要的矿床提供更好的勘探模式，并更好地了解早期地球大气和生物圈的演化史。研究目标将通过寻求三个主要问题的解决方案来实现：(1)金、铀矿和黄铁矿的来源是什么：碎屑岩、成岩作用或热液？(2)金、铀矿和黄铁矿的溶解/沉淀所涉及的流体的来源是含氧地下水还是高温热液？(3)有机质的来源是本地微生物垫还是外来石油？这三个问题的解决方案将通过对南非威特沃特斯兰德地区和加拿大埃利奥特湖地区矿石和围岩中各种矿物和有机物的详细和系统调查来寻求。研究将集中在矿物学特征(形态、结构、丰度、共生)、化学特征(常量、微量和稀土元素)和稳定同位素特征(H、O、C和S)的微观尺度变化。

9706279 Ohmoto The goal of this research is to develop a comprehensive model for the formation processes of gold-uranium deposits occurring in conglomerate beds of ~2.8 Ga to ~2.0 Ga and their paleoenvironments. The results of this study will lead to a better exploration model for this most important class of mineral deposits, and to a better understanding of the evolutionary history of the early EarthOs atmosphere and biosphere. The research goal will be achieved by seeking solutions to three major problems: (1) what are the origins of gold, uraninite, and pyrite: detrital, diagenetic, or hydrothermal?; (2) what are the origins of the fluids involved in dissolution/precipitation of gold, uraninite, and pyrite: oxygen-bearing ground water or high temperature hydrothermal fluid?; and (3) what are the origins of organic matter: indigenous microbial mats or extraneous petroleum? Solutions to these three problems will be sought from detailed and systematic investigations of a variety of minerals and organic matter in ore and country rocks in the Witwatersrand district, South Africa, and the Elliot Lake district, Canada. The investigations will focus on micro-scale variations in mineralogical characteristics (morphology, texture, abundance, paragenesis), chemical characteristics (major, trace, and rare earth elements), and stable isotopic characteristics (H, O, C, and S).