Genesis of lode gold deposits of the Rock Creek area, Nome mining district, Seward Peninsula, Alaska.

摘要

The Nome mining district is located in northwest Alaska in the southwestern part of the Seward Peninsula. Lode gold deposits of the Rock Creek area, Nome mining district are located approximately 16 km north of Nome, Alaska and are hosted by greenschist-facies Paleozoic(?) metasedimentary rocks of the Nome Group. Gold-bearing veins, which occur predominantly in tensional fractures, are composed of quartz, carbonate (dolomite to ankerite), chlorite, feldspar (albite), gold, and minor sulfides (arsenopyrite, pyrite, galena, sphalerite, stibnite, chalcopyrite, and some jamesonite). The wall rock alteration is generally weak, and consists of silicification, carbonatization and sulfidation adjacent to the mineralized veins.;The study of fluid inclusions by microthermometry and mass spectrometry, along with stable isotope studies, has aided in constraining fluid sources and conditions of ore deposition. Fluids from the mineralized veins consist of H;The fluids that formed the gold-bearing quartz veins were emplaced post-kinematically, as indicated by the observation that undeformed veins crosscut the metamorphic foliation of their host rocks. Relative age relationships between the Rock Creek area, the tectonic history of the Seward Peninsula, and age constraints on mineralization from other gold-bearing deposits of the Seward Peninsula indicate that gold-bearing veins were emplaced during the Cretaceous. Ore solutions were derived from devolatilization reactions. The fluids migrated upward into tensional fractures during uplift of the peninsula, resulting in gold deposition by changes in the redox state, precipitation of sulfides, and possibly H