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Geophysical Signatures of Copper-gold Porphyry and Epithermal Gold Deposits, and Implications for Exploration

Geophysical Signatures of Copper-gold Porphyry and Epithermal Gold Deposits, and Implications for Exploration PDF Author: Terence Graham Hoschke
Publisher:
ISBN: 9781862956254
Category : Copper ores
Languages : en
Pages : 47

Book Description
Geophysical data are presented for a number of deposits including the Batu Jijau, Elang, Grasberg, and Alumbrera porphyry copper-gold deposits; the Martabe and Yanacocha high-sulphidation epithermal gold deposits; and the Pajingo and Waihi low-sulphidation epithermal gold deposits. The physical properties of the mineralisation and alteration are discussed with emphasis on those properties that can be measured with standard exploration techniques. Mineralisation in porphyry Cu-Au deposits is commonly associated with magnetite that can produce strong discrete magnetic anomalies. This is usually within a zone of magnetite-destructive alteration that can be identified with a high-resolution magnetic survey. Magnetic surveys are also useful in defining regional structure and geology in the porphyry environment. Strong chargeabilities due to sulphides are typically associated with porphyry systems. Mineralisation and clay-pyrite alteration can produce strong anomalies, and late-stage and post-mineral intrusions can be mapped as chargeability lows within the system. These systems may be more conductive than the host rocks because of clay-pyrite alteration and sulphide veining, and airborne EM can be useful in locating and defining their extent. Gravity, radiometrics, remote sensing and topography may also be useful in exploration for porphyry Cu-Au deposits. In high-sulphidation epithermal systems gold is commonly associated with massive silica alteration. This alteration results in resistivities in the order of thousands of ohm-metres compared with background resistivities of tens of ohm-metres in argillic and propylitic alteration. Both ground resistivity and airborne EM surveys have been successful in locating and defining these deposits. Alteration in high-sulphidation epithermal deposits is magnetite destructive over a large area, although it does not appear to have a large vertical extent as the subdued character of the underlying lithologies can be observed. Typically, gold in low-sulphidation epithermal deposits is in thin quartz veins that are associated with major structures. The alteration associated with the veins is magnetite destructive, and high-resolution magnetics can be very useful and cost-effective technique to map the structures and alteration. Some deposits are associated with broad zones of magnetite destruction which is apparent in the regional magnetics. The mineralised quartz veins are within broader zones of silicification, and resistivity surveying can be used to map these zones. Generally, the high resistivity zones due to silicification are coincident with the structures identified in the magnetics. High-resolution magnetics and electrical surveys are the most useful geophysical techniques in exploration for porphyry and epithermal deposits. Airborne magnetic and EM surveys are fast and cost effective, particularly in areas of rugged topography. Regional magnetics, gravity, remote-sensed data and topographic data can also be used to identify major structures, intrusive complexes and alteration. Radiometric surveys can be useful in mapping geology and alteration.

Geophysical Signatures of Copper-gold Porphyry and Epithermal Gold Deposits, and Implications for Exploration

Geophysical Signatures of Copper-gold Porphyry and Epithermal Gold Deposits, and Implications for Exploration PDF Author: Terence Graham Hoschke
Publisher:
ISBN: 9781862956254
Category : Copper ores
Languages : en
Pages : 47

Book Description
Geophysical data are presented for a number of deposits including the Batu Jijau, Elang, Grasberg, and Alumbrera porphyry copper-gold deposits; the Martabe and Yanacocha high-sulphidation epithermal gold deposits; and the Pajingo and Waihi low-sulphidation epithermal gold deposits. The physical properties of the mineralisation and alteration are discussed with emphasis on those properties that can be measured with standard exploration techniques. Mineralisation in porphyry Cu-Au deposits is commonly associated with magnetite that can produce strong discrete magnetic anomalies. This is usually within a zone of magnetite-destructive alteration that can be identified with a high-resolution magnetic survey. Magnetic surveys are also useful in defining regional structure and geology in the porphyry environment. Strong chargeabilities due to sulphides are typically associated with porphyry systems. Mineralisation and clay-pyrite alteration can produce strong anomalies, and late-stage and post-mineral intrusions can be mapped as chargeability lows within the system. These systems may be more conductive than the host rocks because of clay-pyrite alteration and sulphide veining, and airborne EM can be useful in locating and defining their extent. Gravity, radiometrics, remote sensing and topography may also be useful in exploration for porphyry Cu-Au deposits. In high-sulphidation epithermal systems gold is commonly associated with massive silica alteration. This alteration results in resistivities in the order of thousands of ohm-metres compared with background resistivities of tens of ohm-metres in argillic and propylitic alteration. Both ground resistivity and airborne EM surveys have been successful in locating and defining these deposits. Alteration in high-sulphidation epithermal deposits is magnetite destructive over a large area, although it does not appear to have a large vertical extent as the subdued character of the underlying lithologies can be observed. Typically, gold in low-sulphidation epithermal deposits is in thin quartz veins that are associated with major structures. The alteration associated with the veins is magnetite destructive, and high-resolution magnetics can be very useful and cost-effective technique to map the structures and alteration. Some deposits are associated with broad zones of magnetite destruction which is apparent in the regional magnetics. The mineralised quartz veins are within broader zones of silicification, and resistivity surveying can be used to map these zones. Generally, the high resistivity zones due to silicification are coincident with the structures identified in the magnetics. High-resolution magnetics and electrical surveys are the most useful geophysical techniques in exploration for porphyry and epithermal deposits. Airborne magnetic and EM surveys are fast and cost effective, particularly in areas of rugged topography. Regional magnetics, gravity, remote-sensed data and topographic data can also be used to identify major structures, intrusive complexes and alteration. Radiometric surveys can be useful in mapping geology and alteration.

Geophysics for the Mineral Exploration Geoscientist

Geophysics for the Mineral Exploration Geoscientist PDF Author:
Publisher: Cambridge University Press
ISBN: 0521809517
Category :
Languages : en
Pages : 457

Book Description


New Concepts and Discoveries

New Concepts and Discoveries PDF Author: William M. Pennell
Publisher: DEStech Publications, Inc
ISBN: 1605952265
Category : Science
Languages : en
Pages : 719

Book Description
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.

The Business of Mining

The Business of Mining PDF Author: Ifan Odwyn Jones
Publisher: CRC Press
ISBN: 0429614357
Category : Business & Economics
Languages : en
Pages : 155

Book Description
The Business of Mining complete set of three Focus books provides readers with a holistic all-embracing appraisal of the analytical tools available for assessing the economic viability of prospective mines. Each volume has a discrete focus. This third volume commences with "Our Earth, its Minerals and Ore Bodies", followed by a review of mineral exploration and sampling of mineral deposits. It continues with detailed sections covering the reporting of mineral resources and reserves in Australia, and concludes with the basic principles and application of the various methods of estimating the in-situ mineral resources and ore reserves. The books were written primarily for undergraduate applied geologists, mining engineers and extractive metallurgists and those pursuing course-based postgraduate programs in mineral economics. However, the complete series will also be an extremely useful reference text for practicing mining professionals as well as for consultant geologists, mining engineers or primary metallurgists.

Gold metallogeny and exploration

Gold metallogeny and exploration PDF Author: R. P. Foster
Publisher: Springer Science & Business Media
ISBN: 1461304970
Category : Science
Languages : en
Pages : 447

Book Description
Within the last decade, the high and continuing demand for gold has prompted a global gold rush on a scale never before seen, not even in the heady days of Ballarat, California and the Yukon. Gold is being sought on every continent and, with very few exceptions, in every country around the world. Such interest and fierce competition has demanded considerable innovation and improvement in exploration techniques paralleled by a rapid expansion of the geological database and consequent genetic modelling for the many different types of gold deposits now recognized. This proliferation of data has swamped the literature and left explorationist and academic alike unable to sift more than a small proportion of the accumulating information. This new book represents an attempt to address this major problem by providing succinct syntheses ofall major aspects ofgold metallogeny and exploration, ranging from the chemical distribution of gold in the Earth's crust, and the hydrothermal chemistry of gold, to Archaean and Phanerozoic lode deposits, epithermal environments, chemical sediments, and placer deposits, and culminates in chapters devoted to geochemical and geophysical exploration, and the economics of gold deposits. Each chapter is written by geoscientists who are acknowledged internationally in their respective fields, thus guaranteeing a broad yet up-to-date coverage. In addition, each chapter is accompanied by reference lists which provide readers with access to the most pertinent and useful publications.

Geomagnetic Observations and Models

Geomagnetic Observations and Models PDF Author: M. Mandea
Publisher: Springer Science & Business Media
ISBN: 9048198585
Category : Science
Languages : en
Pages : 344

Book Description
This volume provides comprehensive and authoritative coverage of all the main areas linked to geomagnetic field observation, from instrumentation to methodology, on ground or near-Earth. Efforts are also focused on a 21st century e-Science approach to open access to all geomagnetic data, but also to the data preservation, data discovery, data rescue, and capacity building. Finally, modeling magnetic fields with different internal origins, with their variation in space and time, is an attempt to draw together into one place the traditional work in producing models as IGRF or describing the magnetic anomalies.

Assessment of Ore Deposit Settings, Structures and Proximity Indicator Minerals in Geological Exploration

Assessment of Ore Deposit Settings, Structures and Proximity Indicator Minerals in Geological Exploration PDF Author: Prakash R. Golani
Publisher: Springer Nature
ISBN: 3030651258
Category : Science
Languages : en
Pages : 398

Book Description
This well-illustrated book aims to enhance observations and understanding of structural features and proximity-indicator minerals, critical in exploration. The book provides a unique blending of different content on observational and critical aspects of data acquisition, geological, structural, tectonic set-up, mineral deposit types, geophysical framework, and proximity indicator minerals. Combining these topics led to a comprehensive understanding to facilitate mineral targeting and exploration in green- and brown-field terrains. Besides field photographs, the write-up is lavishly supplemented with relevant geological and geophysical maps, tables, and case stories in field geology, making it useful for a much larger section of the geoscientific community professional geologists and geophysicists, students, teachers, and also decision-makers in geo-surveys and exploration.

Potassic Igneous Rocks and Associated Gold-Copper Mineralization

Potassic Igneous Rocks and Associated Gold-Copper Mineralization PDF Author: Daniel Müller
Publisher: Springer
ISBN: 3319929798
Category : Science
Languages : en
Pages : 398

Book Description
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.

Exploration and Discovery of Base and Precious-metal Deposits in the Circum-Pacific Region During the Last 25 Years

Exploration and Discovery of Base and Precious-metal Deposits in the Circum-Pacific Region During the Last 25 Years PDF Author: Richard H. Sillitoe
Publisher:
ISBN:
Category : Mines and mineral resources
Languages : en
Pages : 142

Book Description
This report describes the exploration and discovery histories of 54 major base- and precious-metal deposits around the Pacific rim over the last 25 years (1970-95). The discoveries are considered to be representative and to include all those of world-class deposits. Each case history places the discovery in a historical context and summarizes the geological, geochemical and geophysical work undertaken prior to discovery, followed by that completed through to production. The time frames and organizational aspects of the exploration programmes are emphiasized along with any special "twists". Each case history is prefaced by the background geology, including tonnage and grade data, and concludes with a brief summary.

Epithermal Gold Mineralization of the Circum-Pacific

Epithermal Gold Mineralization of the Circum-Pacific PDF Author: J. W. Hedenquist
Publisher: Elsevier Publishing Company
ISBN:
Category : Science
Languages : en
Pages : 447

Book Description