Geology, geochemistry, and alteration of the Seligman and Monte Cristo stocks, White Pine mining district, White Pine County, Nevada

Abstract

The Seligman and Monte Crista stocks are small, Cretaceous, granodioritic to granitic plutons which produced calcic exoskarns and associated tungsten- molybdenum mineralization in the Cambrian carbonates they intruded. The stocks are the surface expression of a much larger granodioritic intrusive body. Age dates are inconclusive, but the Monte Cristo stock is inferred to be younger than the Seligman stock, based on the spatial distribution of plagioclase-pyroxene endoskarn in the Seligman stock. Rock types associated with the Seligman stock include granodiorite, granite, aplite, dacite porphyry, quartz monzodiorite and diorite. Intrusives associated with the Monte Cristo stock include granite porphyry, granodiorite porphyry, and rhyodacite porphyry. Variations in major and trace element chemistry, between the intrusive rock types, are related to the degree of magmatic differentiation and the effects of later hydrothermal alteration in the rocks. The Seligman stock exhibits characteristics, such as equigranular texture and endoskarn development, which are typical of plutons which are associated with tungsten skarn deposits, whereas the Monte Cristo stock exhibits porphyritic texture, intense stockwork quartz veining, and potassic alteration which are more typical of plutons associated with porphyry copper or molybdenum deposits.