Download or read book Petrology and Geochemistry of the Emigrant Pass Volcanics Nevada written by Curtis Lawrence Johnson and published by . This book was released on 2015 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Emigrant Pass volcanics (EPV) are a 38.3 to 36.4 Ma calc-alkaline volcanic center that erupted andesite and dacite, and a late series of felsic dikes along the south flank of the Carlin gold district in north-central Nevada. The EPV includes dacite and rhyolite porphyry dikes indistinguishable from porphyry dikes associated with mineralization within the district. The volcanic rocks likely represent eruptive equivalents of deeper, unexposed Eocene plutons that may be the source of heat, fluids, and metals of Carlin-type gold deposits. New petrologic and geochemical data of the EPV are presented to test this hypothesis. The EPV are exposed over a 30 x 15 km area, have an estimated volume of 100 to>200 km3 and are divided into the early Primeaux lavas (38.1-38.3 Ma), the Mack Creek lavas and related intrusions (37.1-38.4 Ma), and late eruptive and hypabyssal rocks (Henry and Faulds, 1999). The Primeaux lavas are a>500 m thick sequence of pyroxene and hornblende andesite to dacite lavas and intrusions; minor pyroxene, hornblende and biotite dikes; and volcanic conglomerates. The Mack Creek lavas are a 180 m thick succession of porphyritic dacite lava flows, domes, and intrusions. Late small-volume units include the Bob Creek basaltic andesite to andesite lava (37.7 Ma) and rhyolitic to dacitic dikes (36.4-36.7 Ma). Primeaux andesite crystallized early clinopyroxene, orthopyroxene, plagioclase, and late hornblende, which suggests moderate water contents (~3 wt.%). Mack Creek dacite and late rhyolite-dacite dikes crystallized hornblende and biotite early, attesting to high water contents (>4 wt.%). Early Primeaux andesites contain abundant magnetite and sparse ilmenite, whereas Mack Creek dacites and late rhyolite-dacite dikes contain magnetite and local titanite. This mineralogy is consistent with the evolution of magmas from early moderately oxidized conditions to late strongly oxidized conditions (fO2 e"NNO+2) similar to porphyry copper magmas (Dilles, 1987). Carlin plagioclase-biotite-hornblende dacite porphyry dikes associated with gold ores yielded four new LA-ICP-MS U/Pb zircon ages (36.7±1.8, 38.8±1.7, 39.2±1.6, 39.4±1.5 Ma), overlapping in age with the earliest EPV eruptions. Two additional U/Pb zircon ages were obtained on a coarsely porphyritic dacite lava of the Mack Creek sequence (37.10±0.54 Ma), and a porphyritic dacite lava (148.2±2.3 Ma) likely of the Frenchie Creek Volcanics at the southern terminus of the EPV. All analyzed Carlin porphyries contain zircons with EuN/EuN* versus Hf arrays and EuN/EuN*> 0.4 similar to porphyry copper plutons (Dilles et al., 2015) and the 36 Ma Battle Mountain granodiorite porphyry associated with Cu(Au) ores (Farmer, 2013). Abundant partially melted granite xenoliths in EPV rocks indicate assimilation of crust during magma generation, whereas incompletely mixed magmas with differing mineralogy along with abundantly sieved plagioclase and resorbed amphibole indicate magma mixing processes. The andesites and dacites have high-K to shoshonitic compositions similar to subduction-related arc magmas. Whereas most major elements display simple linear correlations with silica, interpreted to indicate mixing, the MgO and Cr of most samples abruptly decrease with increased silica consistent with crystal fractionation. Dacites of the Mack Creek have elevated MgO and Cr compared to Primeaux andesites and Bob Creek basaltic-andesites, consistent with mixing of primitive basaltic andesite or andesite with rhyolite. Enrichment in Rb, Ba, and Cs indicate crustal additions compared to average arc magmas, whereas elevated V/Sc (1.4-17.3; Mean: 8.9) and Sr/Y (16.6-49.6; Mean: 36.1) ratios are similar to mineralizing porphyry Cu (Au) magmas (Loucks, 2014). Hornblende compositions from four samples are bimodal and include both low-Al and high-Al amphiboles now commonly recognized in arc suites (Aucanquilcha, Chile: Walker et al., 2013; Yanacocha, Peru: Chambefort et al., 2013). Using the Ridolfi et al. (2010) formulation, the low-Al hornblende crystallized at 820-890°C and 100-250 MPa (4-10 km depth), whereas high-Al amphibole crystallized at about 900-980°C and possibly greater depths. Electron microprobe studies of magmatic sulfide inclusions indicate monosulfide solid solution (MSS, pyrrhotite at low temperatures) was the dominant magmatic sulfide species with minor (n=4 of 119 analyses) intermediate solid solution (ISS, chalcopyrite at low temperatures). Sulfide contents decrease systematically as the magmas evolved from andesite-dacite-rhyolite, supporting the observation of increasing oxidation state and magmatic sulfate/sulfide ratio. Additionally, all phases of the EPV are highly depleted in whole rock Cu (
Download or read book New Concepts and Discoveries written by William M. Pennell and published by DEStech Publications, Inc. This book was released on 2015-06-12 with total page 719 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific analyses of the geology, metallogeny, and mineralization of gold, silver and other high-value elements in the western USATechnical details on working mines, exploration results, new depositsPresentations produced with the United States Geological Survey, Society of Economic GeologistsTwo-volume book set printed in full color with full-text searchable CD-ROM Produced under the auspices of the Geological Society of Nevada and published every five years, this two-volume book of peer-reviewed papers focuses on the geological analysis of ore-rich deposits in the western United States, especially ones containing gold and other high-value elements. Hundreds of stratigraphic, lithographic, remote-sensing and core sample examples are presented, particularly of areas likely to host Carlin-type gold deposits. The two volumes contain a wealth of data on specifically named mines, as well as technical information on high-potential areas for exploration. The book is profusely illustrated with full-color maps, photographs and charts for geology and mining engineering. A searchable CD accompanies the book and includes the full text of papers from the printed book, as well as abstracts and information from poster sessions not found in the printed book. Chapters in the text are fully refereed versions of presentations originally delivered at a symposium supported by the Geological Society of Nevada, along with the United States Geological Survey, Society of Economic Geologists and the Nevada Bureau of Mines. Sample key words: metallogeny, gold, epithermal ore, magmatism, Carlin trend, square array void mapping (SAVM), porphyry copper, tungsten, orogeny, lithogeochemistry, 3-D resistivity and modeling, fault-surface mapping, airborne electromagnetics and more. *The CD-ROM displays figures and illustrations in articles in full color along with a title screen and main menu screen. Each user can link to all papers from the Table of Contents and Author Index and also link to papers and front matter by using the global bookmarks which allow navigation of the entire CD-ROM from every article. Search features on the CD-ROM can be by full text including all key words, article title, author name, and session title. The CD-ROM has Autorun feature for Windows 2000 or higher products and can also be used with Macintosh computers. The CD includes the program for Adobe Acrobat Reader with Search 11.0. One year of technical support is included with your purchase of this product.
Download or read book R019 Guidebook to the geology of four Tertiary volcanic centers in central Nevada written by John W. Erwin and published by NV Bureau of Mines & Geology. This book was released on with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book University of Nevada Bulletin written by Nevada Bureau of Mines and published by . This book was released on 1904 with total page 992 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Potassic Igneous Rocks and Associated Gold Copper Mineralization written by Daniel Müller and published by Springer. This book was released on 2018-06-11 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book reviews the geochemical and petrological characteristics of potassic igneous rock complexes, and investigates the various tectonic settings in which these rocks occur. The authors provide an overview and classification of these rocks and elucidate the geochemical differences between barren and mineralized potassic igneous complexes. High-K rocks are genetically associated with a number of epithermal gold and porphyry copper-gold deposits. In recent years, there has also been growing recognition of an association of such rocks with iron-oxide copper-gold (IOCG) deposits, intrusion-related gold deposits (IRGDs) and Carlin-type gold deposits. This fifth updated and expanded edition incorporates new data and references from world-class copper and gold deposits worldwide. It also includes the latest publications on the petrogenesis of high-K magmatism and related mineral deposits. Numerous new representative ore photographs of the mineral deposits described are also included in the new edition. As such, the book offers a valuable guide not only for academic petrologists working on alkaline rocks, but also for exploration geologists prospecting for epithermal gold and/or porphyry copper-gold deposits in modern and ancient terrains.
Download or read book Further Contributions to the Geology of the Sierra Nevada written by Henry Ward Turner and published by . This book was released on 1896 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book GUIDEBOOK TO THE GEOLOGY OF FOUR TERTIARY VOLCANIC CENTERS IN CENTRAL NEVADA written by Nevada Bureau of Mines and Geology and published by . This book was released on 1974 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Formation of the Sierra Nevada Batholith written by Vali Memeti and published by Geological Society of America. This book was released on 2014-03-13 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This comprehensive field guide takes you on a six-day, west-to-east geologic journey across the Mesozoic magmatic arc of the central Sierra Nevada in California. It summarizes field, structural, geochemistry, and geochronology data collected on individual intrusions, basement terranes intruded by these intrusions, Mesozoic volcanic-sedimentary sections, and from several Sierra Nevada-wide datasets"--Provided by publisher.
Download or read book OF1999 09 Preliminary Geologic Map of the Emigrant Pass Quadrangle Eureka County Nevada written by and published by NV Bureau of Mines & Geology. This book was released on with total page 1 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology of Northern Nye County Nevada written by Frank Joseph Kleinhampl and published by . This book was released on 1985 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology of Nevada written by and published by NV Bureau of Mines & Geology. This book was released on with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology of Nevada a Discussion to Accompany the Geologic Map of Nevada written by Nevada Bureau of Mines and Geology and published by . This book was released on 1980 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Great Basin and Sierra Nevada written by David R. Lageson and published by Geological Society of America. This book was released on 2000-01-01 with total page 462 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geology of Pioche Nevada and Vicinity written by Frederick James Pack and published by . This book was released on 1906 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book SP035 A Geologic and Natural History Tour Through Nevada and Arizona Along U S Highway 93 written by Joseph V. Tingley and published by NV Bureau of Mines & Geology. This book was released on 2010 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Stratigraphy of Tertiary Volcanic Rocks in Eastern Nevada written by Earl Ferguson Cook and published by . This book was released on 1965 with total page 61 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Geochemical database for intrusive rocks of northcentral and northeast Nevada written by and published by DIANE Publishing. This book was released on with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
