Geochronology of the Gold and Sulfide Mineralization of the Archean Witwatersrand Basin

太古宙威特沃特斯兰德盆地金矿和硫化物成矿年代学

• 批准号: 0308656
• 负责人: Joaquin Ruiz
• 金额: $ 10.43万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0308656&HistoricalAwards=false
• 关键词: Geochronology; Gold; Sulfide; Mineralization; Archean

EAR-0308656RuizThe Witwatersrand Archean basin has been at the center of Earth-system debates ranging from the oxygen content of the Archean atmosphere to the flux of gold from the mantle. At the heart of these debates is the question of whether sulfide, gold and uranium minerals were introduced into the basin as detrital grains of sedimentary origin or precipitates from hydrothermal fluids. Our recent Re-Os dating study produced convincing isochrons indicating a ca. 3.01 Ga old age. This age requires a detrital origin since the grains are older than the basin, and may support a very reduced--oxygen poor--atmosphere during the Archean. The work, however, is considered controversial due to the limited number of samples studied. This award will expand the set of analyses to more completely characterize gold and sulfide mineralization and answer questions such as the relationship of gold extraction to consolidation of the Kaapvaal craton and the mantle gold flux. Broader impacts include education of a graduate student and international collaboration with the private sector. Placer Dome and Anglogold corporations will provide access, logistic, and some scientific support.

威特沃特斯兰德太古宙盆地一直处于地球系统争论的中心，从太古宙大气的含氧量到地幔中的金通量。这些争论的核心是硫化物、金和铀矿物是作为沉积成因的碎屑颗粒还是作为热液沉淀引入盆地的问题。我们最近的Re-Os测年研究产生了令人信服的等时线，表明其年龄约为3.01Ga。这个时代需要碎屑起源，因为颗粒比盆地更古老，并可能支持太古宙期间非常稀少的氧气环境。然而，由于研究的样本数量有限，这项工作被认为是有争议的。这一奖项将扩大分析范围，以更全面地描述金和硫化物矿化的特征，并回答诸如黄金提取与Kaapvaal克拉通的固结和地幔金流的关系等问题。更广泛的影响包括研究生教育和与私营部门的国际合作。Placer Dome和盎格鲁黄金公司将提供通道、后勤和一些科学支持。