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 Gold and PGM bearing Conglomerate of the Valdez Creek Mining District Alaska written by Steven A. Fechner and published by . This book was released on 1990* with total page 53 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Mining and Minerals Policy written by United States. Dept. of the Interior and published by . This book was released on 1973 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Phanerozoic Tectonic Evolution of the Circum North Pacific written by Warren J. Nokleberg and published by . This book was released on 2001 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Environmental Risk Assessment written by Ian Lerche and published by Springer Science & Business Media. This book was released on 2007-04-03 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book explores environmental and human risk problems caused by contamination, from the perspective of real world applications with quantitative procedures. It includes risk methods for environmental problems where data are sparse or fuzzy, and incorporates political, social and economic considerations in determining directions of remediation solutions for environmental contaminant problems. It highlights the impact of contaminants on human health – sometimes fatal - and the anthropogenic exacerbation of natural processes.

Download or read book Into the Wild written by Jon Krakauer and published by Anchor. This book was released on 2009-09-22 with total page 241 pages. Available in PDF, EPUB and Kindle. Book excerpt: NATIONAL BESTSELLER • In April 1992 a young man from a well-to-do family hitchhiked to Alaska and walked alone into the wilderness north of Mt. McKinley. Four months later, his decomposed body was found by a moose hunter. This is the unforgettable story of how Christopher Johnson McCandless came to die. "It may be nonfiction, but Into the Wild is a mystery of the highest order." —Entertainment Weekly McCandess had given $25,000 in savings to charity, abandoned his car and most of his possessions, burned all the cash in his wallet, and invented a new life for himself. Not long after, he was dead. Into the Wild is the mesmerizing, heartbreaking tale of an enigmatic young man who goes missing in the wild and whose story captured the world’s attention. Immediately after graduating from college in 1991, McCandless had roamed through the West and Southwest on a vision quest like those made by his heroes Jack London and John Muir. In the Mojave Desert he abandoned his car, stripped it of its license plates, and burned all of his cash. He would give himself a new name, Alexander Supertramp, and, unencumbered by money and belongings, he would be free to wallow in the raw, unfiltered experiences that nature presented. Craving a blank spot on the map, McCandless simply threw the maps away. Leaving behind his desperate parents and sister, he vanished into the wild. Jon Krakauer constructs a clarifying prism through which he reassembles the disquieting facts of McCandless's short life. Admitting an interest that borders on obsession, he searches for the clues to the drives and desires that propelled McCandless. When McCandless's innocent mistakes turn out to be irreversible and fatal, he becomes the stuff of tabloid headlines and is dismissed for his naiveté, pretensions, and hubris. He is said to have had a death wish but wanting to die is a very different thing from being compelled to look over the edge. Krakauer brings McCandless's uncompromising pilgrimage out of the shadows, and the peril, adversity, and renunciation sought by this enigmatic young man are illuminated with a rare understanding—and not an ounce of sentimentality. Into the Wild is a tour de force. The power and luminosity of Jon Krakauer's stoytelling blaze through every page.

Download or read book Chemical Biomarkers in Aquatic Ecosystems written by Thomas S. Bianchi and published by Princeton University Press. This book was released on 2011-02-28 with total page 417 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook provides a unique and thorough look at the application of chemical biomarkers to aquatic ecosystems. Defining a chemical biomarker as a compound that can be linked to particular sources of organic matter identified in the sediment record, the book indicates that the application of these biomarkers for an understanding of aquatic ecosystems consists of a biogeochemical approach that has been quite successful but underused. This book offers a wide-ranging guide to the broad diversity of these chemical biomarkers, is the first to be structured around the compounds themselves, and examines them in a connected and comprehensive way. This timely book is appropriate for advanced undergraduate and graduate students seeking training in this area; researchers in biochemistry, organic geochemistry, and biogeochemistry; researchers working on aspects of organic cycling in aquatic ecosystems; and paleoceanographers, petroleum geologists, and ecologists. Provides a guide to the broad diversity of chemical biomarkers in aquatic environments The first textbook to be structured around the compounds themselves Describes the structure, biochemical synthesis, analysis, and reactivity of each class of biomarkers Offers a selection of relevant applications to aquatic systems, including lakes, rivers, estuaries, oceans, and paleoenvironments Demonstrates the utility of using organic molecules as tracers of processes occurring in aquatic ecosystems, both modern and ancient

Download or read book Economic Geology written by Jeffrey W. Hedenquist and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Risk Assessment Methods written by V.T. Covello and published by Springer Science & Business Media. This book was released on 2013-06-29 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: Much has already been written about risk assessment. Epidemiologists write books on how risk assessment is used to explore the factors that influence the distribution of disease in populations of people. Toxicologists write books on how risk assess ment involves exposing animals to risk agents and concluding from the results what risks people might experience if similarly exposed. Engineers write books on how risk assessment is utilized to estimate the risks of constructing a new facility such as a nuclear power plant. Statisticians write books on how risk assessment may be used to analyze mortality or accident data to determine risks. There are already many books on risk assessment-the trouble is that they all seem to be about different sUbjects! This book takes another approach. It brings together all the methods for assessing risk into a common framework, thus demonstrating how the various methods relate to one another. This produces four important benefits: • First, it provides a comprehensive reference for risk assessment. This one source offers readers concise explanations of the many methods currently available for describing and quantifying diverse types of risks. • Second, it consistently evaluates and compares available risk assessment methods and identifies their specific strengths and limitations. Understand ing the limitations of risk assessment methods is important. The field is still in its infancy, and the problems with available methods are disappoint ingly numerous. At the same time, risk assessment is being used.

Download or read book List of Cartographic Records of the Bureau of Indian Affairs written by United States. National Archives and Records Service and published by . This book was released on 1954 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Companion to the Anthropology of American Indians written by Thomas Biolsi and published by John Wiley & Sons. This book was released on 2008-03-10 with total page 594 pages. Available in PDF, EPUB and Kindle. Book excerpt: This Companion is comprised of 27 original contributions by leading scholars in the field and summarizes the state of anthropological knowledge of Indian peoples, as well as the history that got us to this point. Surveys the full range of American Indian anthropology: from ecological and political-economic questions to topics concerning religion, language, and expressive culture Each chapter provides definitive coverage of its topic, as well as situating ethnographic and ethnohistorical data into larger frameworks Explores anthropology’s contribution to knowledge, its historic and ongoing complicities with colonialism, and its political and ethical obligations toward the people 'studied'

Download or read book Science and Technology in Historic Preservation written by Ray A. Williamson and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: Technology transfer has played an increasingly important role in historic preservation during the latter half of the twentieth century, a situation attested to by the undertaking of an important congressional study in 1986 that assessed the role of federal agencies in the field. In this book leading researchers update the earlier findings and contribute state-of-the-art reviews and evaluations of technological progress in their areas of expertise.

Download or read book The Marine Mammals of the Gulf of Mexico written by Bernd G. Würsig and published by W. L. Moody JR. Natural Histor. This book was released on 2000 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given in honor of District Governor Hugh Summers and Mrs. Ahnise Summers by the Rotary Club of Aggieland with matching support from the Sara and John H. Lindsey '44 Fund, Texas A & M University Press, 2004.

Download or read book Seismic Hazards and Risk written by T. G. Sitharam and published by Springer Nature. This book was released on 2021-03-22 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume presents select papers presented at the 7th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics. The papers discuss advances in the fields of soil dynamics and geotechnical earthquake engineering. Some of the themes include seismic risk assessment, engineering seismology, wave propagation, remote sensing applications for geohazards,engineering vibrations, etc. A strong emphasis is placed on connecting academic research and field practice, with many examples, case studies, best practices, and discussions on performance based design. This volume will be of interest to researchers and practicing engineers alike.

Download or read book Safe Drinking Water written by Steve E. Hrudey and published by IWA Publishing. This book was released on 2004-05-31 with total page 501 pages. Available in PDF, EPUB and Kindle. Book excerpt: Drinking water provides an efficient source for the spread of gastrointestinal microbial pathogens capable of causing serious human disease. The massive death toll and burden of disease worldwide caused by unsafe drinking water is a compelling reason to value the privilege of having safe drinking water delivered to individual homes. On rare occasions, that privilege has been undermined in affluent nations by waterborne disease outbreaks traced to the water supply. Using the rich and detailed perspectives offered by the evidence and reports from the Canadian public inquiries into the Walkerton (2000) and North Battleford (2001) outbreaks to develop templates for understanding their key dimensions, over 60 waterborne outbreaks from 15 affluent countries over the past 30 years are explored as individual case studies. Recurring themes and patterns are revealed and the critical human dimensions are highlighted suggesting insights for more effective and more individualized preventive strategies, personnel training, management, and regulatory control. Safe Drinking Water aims to raise understanding and awareness of those factors that have most commonly contributed to or caused drinking-water-transmitted disease outbreaks - essentially a case-history analysis within the multi-barrier framework. It contains detailed analysis of the failures underlying drinking-water-transmitted disease epidemics that have been documented in the open literature, by public inquiry, in investigation reports, in surveillance databases and other reliable information sources. The book adopts a theme of 'converting hindsight into foresight', to inform drinking-water and health professionals including operators, managers, engineers, chemists and microbiologists, regulators, as well as undergraduates and graduates at specialty level. Key Features: Contains details and perspectives of major outbreaks not widely known or understood beyond those directly involved in the investigations. Technical and scientific background associated with case studies is offered in an accessible summary form. Does not require specialist training or experience to comprehend the details of the numerous outbreaks reviewed. By providing a broad-spectrum review using a consistent approach, several key recurring themes are revealed that offer insights for developing localized, tailor-made prevention strategies.

Download or read book Journal of Research of the U S Geological Survey written by Geological Survey (U.S.) and published by . This book was released on 1975 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: Scientific notes and summaries of investigations in geology, hydrology, and related fields.