EAR-PF: A new archive of Paleoarchean ocean chemistry: the 3.24 Ga Panorama volcanogenic massive sulfide district, Western Australia

Benjamin Johnson博士获得美国国家科学基金会EAR博士后奖学金，在科罗拉多大学开展研究和教育计划。此次调查将重点研究古太古代（距今3400万至32亿年前）变质海洋地壳的生物地球化学，古太古代是地球进化的关键时期。约翰逊博士将破译行星地球化学和地质过程在生物进化和营养循环中的作用。教育计划将侧重于通过科罗拉多大学的课程与广泛的受众互动，分享早期地球和天体生物学的知识。PI将通过科罗拉多大学博尔德分校的暑期多元文化研究培训计划（SMART）吸引不同群体的学生，通过本科生研究机会计划（UROP）为本科生研究提供建议，并利用科学教育计划（SEI）、SAGANet和环境科学研究合作研究所（CIRES）的资源促进科学教育。本研究的总体目标是解决古太古代生物地球化学中的四个突出问题：是什么控制了古太古代海水的三角洲- 18o值？热液循环是否增加或减少了古太古代海洋中的氮？古太古代海洋中的硫酸盐含量是高还是低？古太古代洋中脊的深度是多少？虽然以前的工作是利用沉积岩档案来阐明古太古代矿物化学和表面条件，但在这个项目中，PI将使用古太古代矿物化学的新档案：热液矿床。其中，西澳大利亚3.24 Ga的Panorama volcanic - ogenic massive sulfide （VMS）区代表了一段非常完整的热液蚀变洋壳，包括热源、7 km厚的火山壳露头和沉积盖层，是古太古代生物地球化学的档案。经济地质界已对该地区进行了调查，但尚未用来回答地球历史的问题。

Dr. Benjamin Johnson has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education plans at the University of Colorado. The investigation will focus on examining the biogeochemistry of altered oceanic crust from the Paleoarchean (3,400 to 3,200 million years ago), a crucial time in Earth evolution. Dr. Johnson will be deciphering the role of planetary geochemical and geologic processes on biological evolution and nutrient cycling. The education plan will focus on interacting with a wide range of audiences through programs at the University of Colorado sharing knowledge on early Earth and astrobiology. The PI will engage a diverse group of students through CU-Boulder's Summer Multicultural Access to Research Training (SMART) initiative, advise undergraduate research through the Undergraduate Research Opportunities Program (UROP), and promote science education by utilizing resources of the Science Education Initiative (SEI), SAGANet, and the Cooperative Institute for Research in Environmental Sciences (CIRES).The overall goal of this research is to address four outstanding questions in biogeochemistry during the Paleoarchean: what controls the delta-18O value of Paleoarchean seawater? does hydrothermal circulation add or remove N from the Paleoarchean ocean? was sulfate in the Paleoarchean ocean high or low? and what is the depth of Paleoarchean mid-ocean ridges? While previous work has utilized sedimentary rock archives to elucidate Paleoarchean mineral chemistry and surface conditions, in this project, the PI will use a new archive of Paleoarchean mineral chemistry: hydrothermal deposits. Specifically, the 3.24 Ga Panorama volcanogenic massive sulfide (VMS) district in Western Australia, which represents a remarkably complete section of hydrothermally altered oceanic crust, including heat source, a 7 km thick outcrop of volcanic crust, and sedimentary cover serves as an archive of Paleoarchean biogeochemistry. The area has been investigated by the economic geology community, but has of yet not been utilized to answer questions of Earth history.