Petrologic, Geochemical, and Isotopic Investigation of Gulf Coast Salt Dome Cap Rocks

点击翻译按钮获取中文摘要

Salt dome hosted Zn-Pb-Ba-Ag deposits in the Gulf Coast Region of the United States offer unique information about the origin and evolution of metal-bearing brines and ore deposits in sedimentary terranes. The salt dome mineral deposits have genetic affinities with Mississippi Valley Type Zn-Pb-Ba deposits and sedimentary exhalative Zn-Pb-Ag-Ba deposits. Our previous studies, most of which have focused on the petrology and geochemistry of ore minerals, indicate that these deposits were apparently emplaced during and after the formation of cap rocks from relatively hot fluids leaking upward along the salt stock margins. We propose to continue our study, concentrating more on the processes of cap rock formation than ore mineral formation (1) to better establish the links between basin brines, cap rocks, and sulfide/sulfate mineral deposits, and (2) to determine what constituents in the sedimentary section or beneath the salt stock provided metals and sulfur. Detailed petrographic studies will be integrated with C, O, Sr, Pb, and S isotope, REE, and fluid inclusion studies cap rocks and associated minerals. We propose to determine the relative sequence of events that must take place in a sedimentary basin to produce salt dome mineral deposits, to characterize the nature of sulfur- and metal-bearing fluids, to investigate the isotopic relationships between anhydrite cap rocks and salt- hosted anhydrite to see what reactions involving anhydrite take place during cap rock formation, and to investigate how fluids in different salt basins may give rise to distinct isotopic signatures of salt dome cap rocks within that basin.