Petrologic and geochemical characterization of the Red Dog and other base-metal sulfide and barite deposits in the De Long Mountains, Western Brooks Range, Alaska

Abstract

Low Cu content, lead isotope ratios, mineralogy, stratigraphy, geochemistry, and morphology of the stratiform Red Dog and Drenchwater Zn-Pb-Ba deposits are consistent with a syngenetic, submarineexhalative origin in a Carboniferous back-arc or epicontinental rift basin. Red Dog apparently formed without vulcanism from ocean-floor hot springs like those active in the Guaymas Basin today. while submarine eruptions accompanied or followed Drenchwater sulfide emplacement. Story Creek and Ginny Creek epigenetic Zn-Pb mineralization is hosted in older sediments of the same basinal sequence. Lead isotope ratios from all four deposits are virtually identical. averaging Pb206/Pb204 = 18.408, Pb207/Pb204 = 15.598, Pb208/Pb204 = 38.250. These values fit the plumbotectonics lead growth curves for the orogene. This lead similarity also implies that the Ginny Creek and Story Creek occurrences are genetically related to Red Dog and Drenchwater, by remobilization or as parts of a regional 'plumbing system ' that fed the exhalative deposits.