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Orbock, E.J.C., Jr., 1992

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Bibliographic Reference

Orbock, E.J.C., Jr., 1992, Paragenesis, alteration and geothermometry of the cassiterite veins of Coal Creek, Alaska: University of Nevada, Reno, M.S. thesis, 125 p., illust., maps.


Greisen bordered, quartz-cassiterite veins have formed within 52-m.y.-old multiple-phase granitic intrusives. Four intrusives have been identified. The intrusives are hosted by hornfelsed argillites of the West Fork miniterrane. The mineralized zones comprise numerous steeply dipping sheeted-parallel quartz-cassiterite veins, ranging from hairline to 3-cm-wide fractures. Greisen borders range from 3 to 50 cm. From the vein, alteration grades from silicification to quartz-sericite to sericite to chlorite. Vein mineralization consists of topaz, wolframite, quartz, cassiterite, tourmaline, arsenopyrite, pyrrhotite, sphalerite, chalcopyrite, stannite, fluorite, bismuth, galena and proustite. The initial hydrothermal solution was boiling and exceeded 500 degrees C with a salinity as high as 46.3 volumetric percent NaCl. At the waning stages of quartz deposition, the solutions had cooled to 3,295 degrees C with a salinity of 4.2 equivalent weight percent NaCl.

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