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

本研究的目的是建立~2.8 Ga ~ ~2.0 Ga砾岩层金铀矿床形成过程及其古环境的综合模型。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型，并更好地了解早期地球大气和生物圈的进化史。为实现研究目标，需要解决三个主要问题：(1)金、铀矿和黄铁矿的成因是碎屑、成岩还是热液？(2)金、铀、黄铁矿溶解/沉淀的流体来源是含氧地下水还是高温热液？(3)有机质的来源是什么：本地微生物席还是外来石油？解决这三个问题的方法将从对南非威特沃特斯兰德地区和加拿大埃利奥特湖区的矿石和乡村岩石中的各种矿物和有机物的详细和系统的调查中寻求。研究将集中在矿物特征（形态、结构、丰度、共生）、化学特征（主要、微量和稀土元素）和稳定同位素特征（氢、氧、碳和硫）的微观变化上。

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).