Download or read book Multiple Glaciation and Gold placer Formation Valdez Creek Valley Western Clearwater Mountains Alaska written by Richard D. Reger and published by . This book was released on 1990 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Exploring Competing Gold System Models in the Valdez Creek Region Clearwater Mountains Alaska written by Jane Marguerite Suhey and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Gold deposits located within the accretionary and subduction-related tectonic environment of south-central Alaska are interpreted to have formed via devolatilization of hydrous assemblages through regional metamorphism (orogenic model) or by intrusion-related hydrothermal processes (intrusion-related gold system model). The Valdez Creek mining district is located in the southern Clearwater Mountains of south-central Alaska along the intermontane-insular belt suture of the North American Cordillera. The 67-56 Ma south-vergent Valdez Creek shear zone resulted in the thrusting of North American-derived Maclaren schist (intermontane) structurally above lower greenschist-facies rocks of the Clearwater metasediments (Insular). The ~ 5km thick ductile shear zone preserves a complete inverted Barrovian metamorphic gradient ranging from lower greenschist-facies conditions in the south to upper-amphibolite-facies in the north. This event records the terminal suturing of the Wrangellia composite terrane with the North American margin. Placer gold mining and lode gold exploration is currently focused within the footwall of the Valdez Creek shear zone. The region also contains previously undated Cretaceous intrusive rocks associated with gold-in-soil geochemical anomalies. Here, competing gold system models were investigated to identify the predominant mineralization process. This information is used to improve exploration strategies in the area and further develop our understanding of gold formation in the Clearwater Mountains, Alaska. Constraining mechanisms of gold mineralization through integrating structural analysis, geochemistry, and a multiphase geochronologic framework provides a robust tool to determine dominant ore-forming mechanisms. 40Ar/39Ar and 206Pb/238U geochronological methods were used to determine the timing of gold mineralization and constrain ages of igneous rocks associated with known lode sources. Detrital gold geochemistry methods were used to compare placer gold and lode gold compositions. Bulk rock major and trace element geochemical methods were also used to evaluate a primary gold-model by investigating compositional differences of gold-like elements across the Valdez Creek shear zone. Detailed mapping and structural analysis were completed to test if gold mineralization is compatible with shear zone activity (supporting an orogenic model) or if mineralization was unrelated to regional metamorphism and overprinted by the shear zone from 67-56 Ma (supporting an intrusion-related gold system model). The 206Pb/238U zircon data collected from the alkali pluton suite and the placer system indicates gold-hosting veins were localized within and adjacent to alkaline plutons in the region. These data also indicate that detritus in the placer system was locally derived. White mica 40Ar/39Ar geochronology integration ages from undeformed gold-bearing quartz veins proximal to intrusions supports a young mineralization age for gold between 62.11 Ma to 66.58 Ma. Similarities in gold chemistry were also identified within placer gold samples collected from current mining operations and a lode gold location within the catchment. Structural observations show gold-bearing mineralization in quartz veins is likely synchronous with the penetrative deformation associated with the Valdez Creek shear zone. Discrete and network vein orientations throughout the shear zone have geometries compatible with top-to-the-south shear sense of the Valdez Creek shear zone. These results are compatible with a local gold lode source for the Valdez Creek placer deposit that formed coeval with the Valdez Creek shear zone. Bulk rock major and trace element geochemistry results from across the Valdez Creek shear zone metamorphic gradient show a systematic decrease in As, Cu, Ni, Zn, Pb, and Au across the greenschist-amphibolite facies transition indicating that auriferous fluids may have been derived from the shear zone. We hypothesize that metamorphic fluids generated from the dehydroxylation of chlorite occurred simultaneously with shearing along the Valdez Creek shear zone. In this system, auriferous fluids were likely concentrated within or proximal to rigid intrusion(s) in the footwall of the shear zone, coinciding with vein development and fluid channelization, similar in process to the Juneau Gold Belt.

Download or read book The Weathering of Placer Gold and the Quaternary Geology of Valdez Creek Clearwater Mountains Alaska written by Steven D. Teller and published by . This book was released on 1995 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Executive Summary of the Bureau of Mines Investigations in the Valdez Creek Mining District Alaska written by Michael D. Balen and published by . This book was released on 1991 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Geological Survey Circular written by and published by . This book was released on 1984 with total page 552 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 1990 Annual Report on Alaska s Mineral Resources written by and published by . This book was released on 1990 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings of the 1989 Exclusive Economic Zone Symposium on Mapping and Research written by and published by . This book was released on 1990 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alaska Railroad Corporation Construction and Operation of a Rail Line Extension to Port MacKenzie written by and published by . This book was released on 2011 with total page 608 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Professional Report written by and published by . This book was released on 1982 with total page 102 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Alaska Geology Observer written by and published by . This book was released on 1997 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Innoko Gold placer District Alaska with Accounts of the Central Kuskokwim Valley and the Ruby Creek and Gold Hill Placers written by Alfred Geddes Maddren and published by . This book was released on 1910 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Significant Metalliferous and Selected Non metalliferous Lode Deposits and Placer Districts for the Russian Far East Alaska and the Canadian Cordillera written by and published by . This book was released on 1996 with total page 784 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Geology of the Clearwater Mountains South central Alaska written by Thomas Edward Smith and published by . This book was released on 1981 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Past Glacial Environments written by John Menzies and published by Butterworth-Heinemann. This book was released on 1996 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt: This undergraduate textbook provides a current and comprehensive survey of the sediments and forms generated within Pleistocene and pre-Pleistocene glacial environments. Techniques and methods used in the examination of these sediments and forms are extensively reviewed. This is the most comprehensive and wide-ranging book ever prepared on this topic, and will form the basis for future work in the area. In studying past glacial environments, links are made between understanding modern glaciodynamics, ice physics, and the processes of erosion, transport and deposition of glacial sediments and the generation of various glacial landforms. Past Glacial Environments presents physical geography, earth and environmental science students with an extensive review of the latest research on past glacial environments. The text encompasses Pleistocene subglacial, supraglacial and proglacial sediments and environments, pre-Pleistocene global glacial conditions and sediments, as well as past glacioaeolian, glaciolacustrine, and glaciomarine sediments. Subsequent chapters focus on stratigraphy, lithofacies associations, paleosols, glacio-eustasy and isostasy, micromorphology, SEM, drift prospecting and placer mining.

Download or read book 1991 Annual Report on Alaska s Mineral Resources written by and published by . This book was released on 1991 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiple Glaciation in Alaska written by Troy Lewis Péwé and published by . This book was released on 1953 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Special Report Alaska Division of Mines and Minerals written by and published by . This book was released on 1971 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: