The Tungsten Queen Deposit, Hamme District, Vance County, North Carolina; a stable isotope study of a metamorphosed quartz-huebnerite vein

Abstract

The Tungsten Queen mine, Vance County, North Carolina, is a large quartz-huebnerite vein deposit of late Precambrian or early Paleozoic age that has undergone middle Paleozoic regional metamorphism of amphibolite grade. The preservation of large banded huebnerite crystals and the low delta 18 O values in the vein minerals and wall rocks indicate a premetamorphic hydrothermal origin for the vein which involves meteoric waters. Quartz-sericite oxygen isotope distributions in the vein and wall rocks indicate metamorphic temperatures of 550 degrees + or - 50 degrees C. All other isotope distributions except possibly those for hydrogen appear to reflect primary hydrothermal distributions that were not significantly disturbed by the metamorphic event. The stable isotope systematics of the vein are remarkably similar to those of younger huebnerite/wolframite-quartz veins associated with shallow intrusions in erogenic belts. Sulfur isotope fractionations among coexisting sulfides in two mineral assemblages may indicate primary mineralization temperatures of about 260 degrees and 320 degrees C. The hydrothermal sulfur was derived from a deep-seated source. The carbon isotope data suggest that a sedimentary organic component was present in the fluids during carbonate deposition. Except for reequilibration between coexisting quartz and sericite, the 18 O systematics of the vein minerals appear to reflect primary hydrothermal distributions and indicate that the vein was largely a closed system during metamorphism. Hydrous minerals and waters in fluid inclusions in the vein minerals show nearly a 50 per mil range in delta D values which may also reflect primary variations in the hydrothermal vein system.