Author : Bruce S. Hall
Publisher :
ISBN 13 :
Total Pages : 188 pages
Book Rating : 4.:/5 (76 download)
Book Synopsis Petrography and Geochemistry of a Part of the Painted Rocks Pluton, Idaho County, Idaho by : Bruce S. Hall
Download or read book Petrography and Geochemistry of a Part of the Painted Rocks Pluton, Idaho County, Idaho written by Bruce S. Hall and published by . This book was released on 1980 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Recent reconnaissance mapping by the U.S. Geological Survey has demonstrated the presence of an Eocene epizonal pluton with an areal 2 extent of 2600 km2 southwest of Darby, Montana. This 'Painted Rocks pluton' was intruded into Precambrian Belt metasedimentary rocks, Cretaceous Idaho batholith and its own volcanic ejecta. Based on criteria of relative grain size, petrologic color index, texture and mineralogy, lithologic units of the pluton are divided as follows: 1) coarse grained facies consisting of biotite-hornblende quartz rnonzonite, hornblende granite, and biotite granite subfacies, 2) fine- to medium-grained facies consisting of biotite quattz monzonite, muscovite-biotite granite, and leucocratic muscovite-biotite granite subfacies, 3) granophyric facies, and 4) quartz porphyry facies. Major and trace element averages and ratios as well as ternary trace element relationships strongly suggest that rocks of the pluton are divided into two geochemical suites, "depleted" and "enriched". Rocks of the depleted suite are characteristically higher in Al, Ba, Ca, Fe, Mg, Ti, and Sr while significantly lower than the enriched suite in F, Li, Rb, Si, Sn, and U. Major and trace element geochemistry indicates that rocks of this study are similar to recently proposed models of source rocks associated with incompatible element ore deposits i.e. molybdenum and tin. It is here noted that although F, Sn, and U anomalies occur in the study area, no significant mineralization is observed in the field"--Document.
