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.
