Author : D. Scott Stevens
Publisher :
ISBN 13 :
Total Pages : 132 pages
Book Rating : 4.:/5 (111 download)
Book Synopsis Precious Metal Deposits Associated with Alkaline Rocks, North American Cordillera South of 41 Degrees N. by : D. Scott Stevens
Download or read book Precious Metal Deposits Associated with Alkaline Rocks, North American Cordillera South of 41 Degrees N. written by D. Scott Stevens and published by . This book was released on 1984 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Alkaline igneous rocks are the source, and host, of variety of mineral deposits in the North American Cordillera. These include: (1) epithermal Au deposits, (2) porphyry Cu deposits with significant concentrations of Ag, Pt, and Au metals, and (3) exhalative precious-metal deposits. I have used a computer data-base, ALKY, of published and unpublished major oxide and trace element analyses of alkaline rocks in the Cordillera. These data were used to evaluate and propose classification schemes, genetic models, and geochemical fingerprints for precious metal deposits associated with alkaline rocks. Alkaline rocks were emplaced in continental rift, extensional, and back arc spreading settings of the Cordillera. Gold deposits associated with alkaline rocks occur in exhalative, stock, caldera, high level intrusive, and vent environments. Mineralized hosts include: felsic syenites, altered mafic syenites, and carbonatitic rocks. Chemical attributes of alkaline rock-related gold deposits include: SiO2>45 wt% (unless CO2>5 wt%), Na2OK2O, high total alkalis (Na2O+K2O10 wt%), Fe2O3>FeO, MgO