DOCSLIB.ORG

Mineralogy and Geochemistry of the Heddleston Porphyry Cu-Mo Deposit, Montana Ben Schubert Montana Tech

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Mineralogy and Geochemistry of the Heddleston Porphyry Cu-Mo Deposit, Montana Ben Schubert Montana Tech Montana Tech Library Digital Commons @ Montana Tech Graduate Theses & Non-Theses Student Scholarship Spring 2017 Mineralogy and Geochemistry of the Heddleston Porphyry Cu-Mo Deposit, Montana Ben Schubert Montana Tech Follow this and additional works at: http://digitalcommons.mtech.edu/grad_rsch Part of the Geochemistry Commons, Geology Commons, and the Other Earth Sciences Commons Recommended Citation Schubert, Ben, "Mineralogy and Geochemistry of the Heddleston Porphyry Cu-Mo Deposit, Montana" (2017). Graduate Theses & Non-Theses. 114. http://digitalcommons.mtech.edu/grad_rsch/114 This Non-Thesis Project is brought to you for free and open access by the Student Scholarship at Digital Commons @ Montana Tech. It has been accepted for inclusion in Graduate Theses & Non-Theses by an authorized administrator of Digital Commons @ Montana Tech. For more information, please contact [email protected]. Mineralogy and Geochemistry of the Heddleston Porphyry Cu-Mo Deposit, Montana by Ben Schubert A non-thesis research paper submitted in partial fulfillment of the requirements for the degree of Master of Science in Geosciences: Geology Option Montana Tech April, 2017 ii Acknowledgements This research was made possible by the Society for Mining, Metallurgy & Exploration; the Montana Tobacco Root Geological Society; Anadarko; and Montana Tech’s Scholarships and financial assistance to help me cover the costs of attending Montana Tech and allowing me to avoid debt. I am grateful to the faculty and students who took time to accurately answer my questions and bring good suggestions for furthering my research. Many people were very busy with various projects, but generously helped me through problems and brought useful thoughts to this project. Among them include Kyle Eastman, Vincent Spinazola, Garrett Hill, Gary Wyss, Larry Smith, and my committee members Chris Gammons, Diane Wolfgram, and Stan Korzeb. iii Abstract The Heddleston porphyry Cu-Mo deposit is located in Lewis and Clark County, Montana, near the headwaters of the Blackfoot River. It is immediately west of the historic Mike Horse mine, an important producer of Pb-Zn from polymetallic veins and lodes. The Heddleston property was explored extensively by the Anaconda Company in the 1960s and 1970s, but was never mined. Specimens of polished drill core from the deposit are archived in the Anaconda Research Collection at Montana Tech campus. The purpose of this research project was to use the archived samples to examine the geochemistry and mineralogy of the Heddleston and Mike Horse deposits using modern methods of ore deposit research, including portable X-ray fluorescence (pXRF), short-wave infrared (SWIR) mineral analysis, fluid inclusions, scanning electron microscopy (SEM) and sulfur isotope analysis. The Heddleston deposit is centered on the Mike Horse stock, an Eocene (44.5 Ma) quartz monzonite porphyry, which has intruded into argillite of the mid-Proterozoic Spokane Formation and a thick diorite sill, also Precambrian in age. Drill core examined in this study was from DH 265-161, completed near the center of the district but just outside the mapped limit of the Number 3 Tunnel ore body. Several generations of quartz veins are present, including early quartz-chalcopyrite-pyrite veins with narrow potassic alteration envelopes, quartz-molybdenite veins with no alteration, and quartz-pyrite-chalcopyrite veins with phyllic alteration. Some of the late veins also contain galena, sphalerite, and Ag-bearing tetrahedrite-tennantite. Based on SWIR data, the most common alteration minerals in the altered porphyry host rock are muscovite (sericite), K-illite, kaolinite, and halloysite. Most of the kaolinite is well crystalline and is probably hypogene, while some is poorly crystalline and may have formed during weathering. Fluid inclusions from quartz-molybdenite and quartz-pyrite veins homogenized between 350 and 450˚C and have widely varying liquid/vapor ratios. Many inclusions contain halite daughter minerals, with sylvite and/or chalcopyrite daughter minerals also sometimes being present. This information suggests that boiling of a primary magmatic fluid occurred in the temperature range of 400 to 450˚C. Stable isotopes of S (δ34S) in pyrite from Heddleston range from 3.5 to 5.2‰, and overlap with δ34S values for pyrite, sphalerite, and galena in two samples from Mike Horse. These data also overlap with δ34S data for hypogene sulfides in the world-class Butte porphyry- lode deposit. This suggests that the two porphyry systems may have inherited their sulfur from a common source. However, the Heddleston deposit differs from Butte in many ways, including its smaller size, its younger age (Eocene vs. late Cretaceous), its host rocks (Precambrian metasediments vs. Butte Granite), a lack of copper-rich “Main Stage” veins in the center of the district, and a shallower depth of emplacement. iv Table of Contents Contents Acknowledgements ............................................................................................................. ii Abstract .............................................................................................................................. iii List of Figures .................................................................................................................... vi List of Tables ................................................................................................................... viii 1. Introduction ..................................................................................................................... 1 1.1. Purpose and History ................................................................................................. 1 1.2. Regional and local geology ..................................................................................... 2 1.3. Mineralization ......................................................................................................... 6 1.4. Objectives of This Study ......................................................................................... 7 2. Methods.......................................................................................................................... 9 2.1. Sample Collection ................................................................................................... 9 2.2. Portable X-ray Fluorescence Scanning .................................................................. 10 2.3. Terraspec Halo Mineral Identifier Scanning .......................................................... 10 2.4. Petrographic Examination ..................................................................................... 12 2.5. Scanning Electron Microscope Work .................................................................... 13 2.6. Fluid Inclusion Work ............................................................................................ 14 2.7. Sulfur Isotopes ...................................................................................................... 16 3. Results ........................................................................................................................... 17 v 3.1. Portable X-ray Fluorescence Scanning .................................................................. 17 3.2. Terraspec Halo Mineral Identifier Scanning .......................................................... 22 3.3. Petrography ........................................................................................................... 29 3.3.1. Vein types ....................................................................................................... 29 3.3.2. Wallrock alteration.......................................................................................... 31 3.3.3. Ore microscopy ............................................................................................... 32 3.3.4. Scanning Electron Microscope Work ............................................................. 34 3.4. Fluid Inclusion Work ............................................................................................. 37 3.5. Sulfur Isotopes ....................................................................................................... 43 4. Discussion ..................................................................................................................... 45 4.1. Comparison of Heddleston to traditional porphyry copper deposit models .......... 45 4.2. Comparison of Heddleston to Butte ....................................................................... 46 5. Conclusions and Recommendations ............................................................................. 51 5.1. Major Findings ....................................................................................................... 51 5.2. Recommendations for Future Work....................................................................... 53 6. References Cited ........................................................................................................... 54 vi List of Figures Figure 1: Location of the Heddleston District ................................................................................ 2 Figure 2: Regional geologic setting of the Heddleston District ...................................................... 3 Figure 3: Geology of the area surrounding the Heddleston District ............................................... 4 Figure 4: Map of the geology of the Heddleston District, showing the location of historic mines
Load more

Recommended publications
  • Supergene Mineralisation of the Boyongan Porphyry Copper-Gold Deposit, Surigao Del Norte, Philippines
    Supergene Mineralisation of the Boyongan Porphyry Copper-Gold Deposit, Surigao del Norte, Philippines by Allan Maglaya Ignacio B.Sc. Geology, National Institute of Geological Sciences University of the Philippines Thesis submitted in partial fulfilment of the requirements of the Masters of Economic Geology Degree Centre for Ore Deposit Research, University of Tasmania December, 2005 DECLARATION OF ORIGINALITY This thesis contains no material which has been accepted for a degree of diploma by the University of Tasmania or any other institution, except by way of background information and duly acknowledged in the thesis, and contains no previous material previously pub- lished or written by another person except where due acknowledgement is given. Allan Maglaya Ignacio 01 December 2005 _________________________ STATEMENT OF AUTHORITY OF ACCESS This thesis may not to be made available for loan or copying for 1.5 years following the date this statement was signed. Following that time, the thesis may be available for loan and lim- ited copying in accordance with Copyright Act 1968. Allan Maglaya Ignacio 01 December 2005 _________________________ TABLE OF CONTENTS Page (s) LIST OF FIGURES …………………………………………………….. i - iii LIST OF APPENDICES ………………………………………………… iv ACKNOWLEDGMENTS ………………………………………………. v ABSTRACT ……………………………………………………………... vi - vii 1.0 INTRODUCTION ………………………………………………………. 1 - 8 1.1 Introduction …………………………………………………………. 1 1.2 Aims and Objectives ……………………………………………….. 1 1.3 Methods Employed …………………………………………………. 2 1.4 Location and Accessibility …………………………………………. 3 1.5 Climate ……………………………………………………………... 5 1.6 Previous Work ……………………………………………………… 5 2.0 GEOLOGICAL SETTING ………………………………………………. 9 - 37 2.1 Introduction ………………………………………………………. 9 2.2 Regional Tectonics …………….…………………………………. 9 2.3 Regional and Local Stratigraphy ………………………………... 11 2.3.1 Basement (Cretaceous-Paleogene) ………………………. 11 2.3.2 Bacuag Formation (Oliogocene-Miocene) .……………..
    [Show full text]
  • PORPHYRY CU DEPOSITS (MODEL 17; Cox, 1986) by Leslie J. Cox
    PORPHYRY CU DEPOSITS (MODEL 17; Cox, 1986) by Leslie J. Cox, Maurice A. Chaffee, Dennis P. Cox, and Douglas P. Klein SUMMARY OF RELEVANT GEOLOGIC, GEOENVIRONMENTAL, AND GEOPHYSICAL INFORMATION Deposit geology Porphyry copper deposits contain copper, molybdenum, and gold minerals, disseminated or in a stockwork of small veinlets within a large mass of altered rock (Singer and Mosier, 1981). The host rock is commonly a pyrite-rich porphyry ranging in composition from granodiorite to tonalite, but alkalic porphyries are locally important. In the southwestern United States, where porphyry copper deposits are abundant, associated igneous rocks are mainly Mesozoic and Cenozoic. Older plutonic, volcanic, sedimentary, and metamorphic rocks intruded by these porphyries also host ore minerals; the highest grades are found in reactive rocks such as limestone, or rocks, such as diabase, which contain abundant iron-rich minerals prior to alteration. Porphyry deposits exhibit a characteristic pattern of hydrothermal alteration, which includes biotite and K-feldspar assemblages in the center and grades outward to chlorite, actinolite, and epidote assemblages. Most deposits have a late-stage alteration assemblage that contains abundant white mica, clay, and carbonate minerals. Examples Bingham, Utah (Lanier and others, 1978); San Manuel, Ariz. (Lowell and Guilbert, 1970); El Salvador, Chile (Gustafson and Hunt, 1975). Spatially and (or) genetically related deposit types Related deposit types (Cox and Singer, 1986) include porphyry copper, skarn-related (Model 18a), base-metal skarn (Model 18c), porphyry copper-gold (Model 20c), porphyry copper-molybdenum (Model 21a), polymetallic vein (Model 22c), polymetallic replacement (Model 19a), volcanic-hosted copper-arsenic-antimony (Model 22a), quartz- alunite gold (Model 25e), distal disseminated silver-gold (Model 19c; Cox, 1992), and gold-skarn deposits.
    [Show full text]
  • Porphyry Deposits
    PORPHYRY DEPOSITS W.D. SINCLAIR Geological Survey of Canada, 601 Booth St., Ottawa, Ontario, K1A 0E8 E-mail: [email protected] Definition Au (±Ag, Cu, Mo) Mo (±W, Sn) Porphyry deposits are large, low- to medium-grade W-Mo (±Bi, Sn) deposits in which primary (hypogene) ore minerals are dom- Sn (±W, Mo, Ag, Bi, Cu, Zn, In) inantly structurally controlled and which are spatially and Sn-Ag (±W, Cu, Zn, Mo, Bi) genetically related to felsic to intermediate porphyritic intru- Ag (±Au, Zn, Pb) sions (Kirkham, 1972). The large size and structural control (e.g., veins, vein sets, stockworks, fractures, 'crackled zones' For deposits with currently subeconomic grades and and breccia pipes) serve to distinguish porphyry deposits tonnages, subtypes are based on probable coproduct and from a variety of deposits that may be peripherally associat- byproduct metals, assuming that the deposits were econom- ed, including skarns, high-temperature mantos, breccia ic. pipes, peripheral mesothermal veins, and epithermal pre- Geographical Distribution cious-metal deposits. Secondary minerals may be developed in supergene-enriched zones in porphyry Cu deposits by weathering of primary sulphides. Such zones typically have Porphyry deposits occur throughout the world in a series significantly higher Cu grades, thereby enhancing the poten- of extensive, relatively narrow, linear metallogenic tial for economic exploitation. provinces (Fig. 1). They are predominantly associated with The following subtypes of porphyry deposits are Mesozoic to Cenozoic orogenic belts in western North and defined according to the metals that are essential to the eco- South America and around the western margin of the Pacific nomics of the deposit (metals that are byproducts or poten- Basin, particularly within the South East Asian Archipelago.
    [Show full text]
  • Sediment-Hosted Copper Deposits of the World: Deposit Models and Database
    Sediment-Hosted Copper Deposits of the World: Deposit Models and Database By Dennis P. Cox1, David A. Lindsey2 Donald A. Singer1, Barry C. Moring1, and Michael F. Diggles1 Including: Descriptive Model of Sediment-Hosted Cu 30b.1 by Dennis P. Cox1 Grade and Tonnage Model of Sediment-Hosted Cu by Dennis P. Cox1 and Donald A. Singer1 Descriptive Model of Reduced-Facies Cu 30b.2 By Dennis P. Cox1 Grade and Tonnage Model of Reduced Facies Cu by Dennis P. Cox1 and Donald A. Singer1 Descriptive Model of Redbed Cu 30b.3, by David A. Lindsey2 and Dennis P. Cox1 Grade and Tonnage Model of Redbed Cu by Dennis P. Cox1 and Donald A. Singer1 Descriptive Model of Revett Cu 30b.4, by Dennis P. Cox1 Grade and Tonnage Model of Revett Cu by Dennis P. Cox1 and Donald A. Singer1 Open-File Report 03-107 Version 1.3 2003, revised 2007 Available online at http://pubs.usgs.gov/of/2003/of03-107/ Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government. U.S. DEPARTMENT OF THE INTERIOR U.S. GEOLOGICAL SURVEY 1 345 Middlefield Road, Menlo Park, CA 94025 2 Box 25046, Denver Federal Center, Denver, CO 80225 Introduction This publication contains four descriptive models and four grade-tonnage models for sediment hosted copper deposits. Descriptive models are useful in exploration planning and resource assessment because they enable the user to identify deposits in the field and to identify areas on geologic and geophysical maps where deposits could occur.
    [Show full text]
  • Heinrich&Candela TOG2 For
    Research Collection Book Chapter Fluids and Ore Formation in the Earth's Crust Author(s): Heinrich, Christoph A.; Candela, Philip A. Publication Date: 2014 Permanent Link: https://doi.org/10.3929/ethz-b-000095425 Originally published in: 13, http://doi.org/10.1016/B978-0-08-095975-7.01101-3 Rights / License: Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International This page was generated automatically upon download from the ETH Zurich Research Collection. For more information please consult the Terms of use. ETH Library This is the Green Open Access version of: Heinrich C.A., and Candela P.A. (2014) Fluids and Ore Formation in the Earth's Crust. In: Holland H.D. & Turekian K.K. (eds.) Treatise on Geochemistry, 2nd Edition, vol. 13 (Geochemistry of Mineral Deposits, S. D. Scott, ed.), p. 1-28. Original publication see http://dx.doi.org/10.1016/B978-0-08-095975-7.01101-3 Fluids and Ore Formation in the Earth’s Crust Christoph A. Heinrich1 and Philip A. Candela2 1 ETH Zurich, Department of Earth Sciences, and University of Zurich, Faculty of Mathematics and Natural Sciences, Clausiusstr. 25, 8092 Zurich, Switzerland 2 Laboratory for Mineral Deposits Research, Department of Geology, University of Maryland, College Park, MD,20742, USA Synopsis Ore deposits are rock volumes containing selected elements in sufficient concentration and quantity that they can Be extracted economically. Except for Fe and Al, all technically important metals and other elements are scarce, in total constituting less that 1% of the Earth’s crust. Depending on the element and its mineralogy, a 10- to 10,000-fold enrichment is required for economic extraction today.
    [Show full text]
  • Paleozoic–Mesozoic Porphyry Cu(Mo) and Mo(Cu) Deposits Within the Southern Margin of the Siberian Craton: Geochemistry, Geochronology, and Petrogenesis (A Review)
    minerals Review Paleozoic–Mesozoic Porphyry Cu(Mo) and Mo(Cu) Deposits within the Southern Margin of the Siberian Craton: Geochemistry, Geochronology, and Petrogenesis (a Review) Anita N. Berzina *, Adel P. Berzina and Victor O. Gimon V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the RAS, Koptyug Ave. 3, Novosibirsk 630090, Russia; [email protected] (A.P.B.); [email protected] (V.O.G.) * Correspondence: [email protected]; Tel.: +7-383-333-2304 Academic Editor: Maria Economou-Eliopoulos Received: 31 July 2016; Accepted: 21 November 2016; Published: 29 November 2016 Abstract: The southern margin of the Siberian craton hosts numerous Cu(Mo) and Mo(Cu) porphyry deposits. This review provides the first comprehensive set of geological characteristics, geochronological data, petrochemistry, and Sr–Nd isotopic data of representative porphyry Cu(Mo) and Mo(Cu) deposits within the southern margin of the Siberian craton and discusses the igneous processes that controlled the evolution of these magmatic systems related to mineralization. Geochronological data show that these porphyry deposits have an eastward-younging trend evolving from the Early Paleozoic to Middle Mesozoic. The western part of the area (Altay-Sayan segment) hosts porphyry Cu and Mo–Cu deposits that generally formed in the Early Paleozoic time, whereas porphyry Cu–Mo deposits in the central part (Northern Mongolia) formed in the Late Paleozoic–Early Mesozoic. The geodynamic setting of the region during these mineralizing events is consistent with Early Paleozoic subduction of Paleo-Asian Ocean plate with the continuous accretion of oceanic components to the Siberian continent and Late Paleozoic–Early Mesozoic subduction of the west gulf of the Mongol–Okhotsk Ocean under the Siberian continent.
    [Show full text]
  • Trace-Element Geochemistry of Molybdenite from Porphyry Cu Deposits of the Birgilda-Tomino Ore Cluster (South Urals, Russia)
    Mineralogical Magazine, May 2018, Vol. 82(S1), pp. S281–S306 Trace-element geochemistry of molybdenite from porphyry Cu deposits of the Birgilda-Tomino ore cluster (South Urals, Russia) 1,* 1 1,2 3 OLGA Y. P LOTINSKAYA ,VERA D. ABRAMOVA ,ELENA O. GROZNOVA ,SVETLANA G. TESSALINA , 4 4 REIMAR SELTMANN AND JOHN SPRATT 1 Institute of Geology of Ore Deposits, Petrography, Mineralogy, and Geochemistry Russian Academy of Sciences (IGEM RAS), Staromonetny per. 35, Moscow 119017, Russia 2 Institute of Experimental Mineralogy Russian Academy of Sciences (IEM RAS), Chernogolovka, Moscow region 142432, Russia 3 John de Laeter Centre for Isotope Research & The Institute for Geoscience Research (TIGeR), Curtin University, Kent St, Bentley, WA 6102, Australia 4 Natural History Museum, London SW7 5BD, UK [Received 16 January 2017; Accepted 23 December 2017; Associate Editor: Krister Sundblad] ABSTRACT Mineralogical, electron microprobe analysis and laser ablation-inductively coupled plasma-mass spectrometry data from molybdenite within two porphyry copper deposits (Kalinovskoe and Birgilda) of the Birgilda-Tomino ore cluster (South Urals) are presented.† The results provide evidence that molybdenites from these two sites have similar trace-element chemistry. Most trace elements (Si, Fe, Co, Cu, Zn, Ag, Sb, Te, Pb, Bi, Au, As and Se) form mineral inclusions within molybdenite. The Re contents in molybdenite vary from 8.7 ppm to 1.13 wt.%. The Re distribution within single molybdenite flakes is always extremely heterogeneous. It is argued that a temperature decrease favours the formation of Re-rich molybdenite. The high Re content of molybdenite observed points to a mantle-derived source. K EYWORDS: molybdenite, LA-ICP-MS, porphyry copper deposits, Urals.
    [Show full text]
  • Magmatic Arc and Associated Gold, Copper, Silver, and Barite Deposits in the State of Goiás, Central Brazil: Characteristics and Speculations
    Revista Brasileira de Geociências 30(2):285-288, junho de 2000 MAGMATIC ARC AND ASSOCIATED GOLD, COPPER, SILVER, AND BARITE DEPOSITS IN THE STATE OF GOIÁS, CENTRAL BRAZIL: CHARACTERISTICS AND SPECULATIONS RAUL MINAS KUYUMJIAN1 ABSTRACT In the western portion of the State of Goiás, Central Brazil, base-metal deposits typical of volcanic-plutonic arcs occur. Up- to-date studies suggest that porphyry Cu-Au, (volcanogenic ?) hydrothermal exhalative Cu-Au and stratiform, submarine exhalative Au-Ag-Ba are present. Although restricted, the present state of knowledge on the geology and mineralizations of the magmatic arc indicates potential resources for metallic mineral deposits in the Brasília Belt. Keywords: mineral deposits, magmatic arc, Goiás, Central Brazil. INTRODUCTION The Magmatic Arc of western Goiás is located during the Brasiliano orogeny, and is associated with recumbent within the Brasilia Belt, a complex fold-and thrust belt of more than isoclinal, open and normal folds. Younger crosscutting foliations one episode of deformation during the Brasiliano orogeny, in the cen- generate crenulations. Shear zones display NS, N100-200W and N200- tral part of the Tocantins Province. The Tocantins Province is a large 400Ed trends. Brasiliano deformation places the Mara Rosa volcanic- Neoproterozoic orogen in Central Brazil (Richardson et al. 1988, sedimentary sequence in the hangingwall of the Rio dos Bois thrust Pimentel et al. 1997, 1998). The magmatic arc is prevalently formed fault, whose footwall consists of Paleoproterozoic Santa Terezinha by Neoproterozoic island-arc terranes consisting of tonalitic to volcanic-sedimentary sequence that occurs to the east (Kuyumjian granodioritic orthogneisses, volcanic-sedimentary associations and 1995). This fault has a dextral oblique and reverse sense of shear late- to post-orogenic intrusions of granites and gabbros.
    [Show full text]
  • Porphyry Copper Deposits of the American Cordillera
    Porphyry Copper Deposits of the American Cordillera Frances Wahl Pierce and John G. Bolm, Editors Arizona Geological Society Digest 20 1995 Geological Summary and Perspective of Porphyry Copper Deposits in Southwestern North America SPENCER R. TITLEY Un iversity of Arizona, Tu cson, Arizona ABSTRACT enci, and Bisbee. Under the impetus of material requirements fo r prosecution of the war, the search for copper ores by 1942 had Porphyry copper deposits in the American southwest focused almost solely on discovery of new disseminated orebodies comprise a distinctive and important metal resource. Their and resulted in identification of 25 porphyry copper deposits by exploration and exploitation during the past hundred years 1980. Among the first recognized as having porphyry copper was accompanied by significant advances in geological knowl­ potential by mid-century were the disseminated ores at Silver Bell, edge and development of increasingly efficient mining and described by Richard and Courtright (1954). Much of the early his­ extraction methods. Cause and effect are indistinguishable be­ tory of these deposits has been recorded from economic and engi­ cause the necessity for increasing mining efficiency resulted in neering perspectives by Parsons (1933, 1957). enhancement of extractive methods and because geological In the early I 990s mining was proceeding at a dozen depos­ study of the ores resulted in recognition of broadly applicable its in Arizona that had survived the economic downturn of the geological and exploration concepts. The early view of linear 1980s: Twin Buttes, Sierrita-Esperanza, San Xavier-Mission, tectonic-based regional controls was supplanted by integra­ San Manuel-Kalamazoo, Ray, Morenci, Pinto Valley and Inspi­ tion of concepts of plate movements.
    [Show full text]
  • Is the EU's Resource Base of Copper Ore Deposits Large? a Fuzzy Set Theory Approach
    resources Article Is the EU’s Resource Base of Copper Ore Deposits Large? A Fuzzy Set Theory Approach Mariusz Krzak Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow, Poland; [email protected] Abstract: Copper raw materials have not been identified as a critical raw material for the economy of the European Union (EU). Demand for metal for use within the EU is satisfied mainly by imports of raw materials in various processing stages and from recycling. Imports include not only copper concentrates, but also refined metals, alloys, and intermediate and finished products. In terms of EU imports, mining supplies represent a minor share of demand. It is likely that copper demand will grow in the coming decades and that global as well as European reserves of copper will be depleted more rapidly. For Europe, no complete and harmonised dataset presenting estimates of total EU copper resources and reserves exists, with the exception of the attempted Minerals4EU project. In colloquial language, many imprecise concepts aim at describing reality. Classic probability tools cannot be used to describe imperfect information. There are no sharp thresholds between the boundaries of many measurements; instead, smooth transitions are observed. This gradation between full and partial membership and non-membership is not included in classical set theory; thus, the capacity for describing such effects is provided by fuzzy set theory. An attempt is made in the present paper at a fuzzy description of the copper reserve base in the EU countries. The basic terminology of fuzzy sets is presented and useful logical operators are indicated.
    [Show full text]
  • Porphyry Copper Mineralisation of Western Usa
    The Ishihara Symposium: Granites and Associated Metallogenesis PORPHYRY COPPER MINERALISATION OF WESTERN USA Allan J.R.White VIEPS, The University of Melbourne, Victoria 3010, Australia Porphyry copper deposits of western USA are very large low grade deposits dominated by disseminated Cu mineralisation but commonly with appreciable Mo and Au. Many deposits began as gold camps. Mineralisation is centred on, and mostly within, near surface quartz monzonite intrusions in which there is inner and deeper concentric Mo-rich shells. Mo shells are followed by Cu-rich shells, then pyrite and there may be an outermost Pb-Zn-Ag zone as in the country rock skarns of the Bingham deposit (John 1978). Cu-Mo mineralisation occurs within a “potassic” alteration zone characterised by secondary biotite (e.g. Moore 1978). Extensive outer sericitic (phyllic), argillic and propylitic alteration zones do not necessarily conform to the concentric pattern. Large scale bulk mining of a porphyry deposit was first carried out at Bingham. There is a belt of economic deposits extending from Butte Montana, through Bingham Utah, to Arizona where deposits are most abundant, and New Mexico. This review is based on visits to many deposits along the whole length of the belt and various petrological observations at Butte, Bingham, Bagdad, Miami-Globe and Sierrita. Most deposits are Laramide (approx. 70 Ma), a notable exception being Bingham (40 Ma). The Laramide belt is inboard up to 1200 km from the Pacific coast of the US where there are Recent to Mesozoic subduction related rocks. It is suggested that the Laramide igneous rocks were not formed as a result of subduction but as a result of rifting within the Precambrian basement.
    [Show full text]
  • Resolving the Timescales of Magmatic and Hydrothermal Processes Associated with Porphyry Deposit Formation Using Zircon U-Pb Petrochronology Simon J.E
    https://doi.org/10.5194/gchron-2020-5 Preprint. Discussion started: 25 February 2020 c Author(s) 2020. CC BY 4.0 License. Resolving the timescales of magmatic and hydrothermal processes associated with porphyry deposit formation using zircon U-Pb petrochronology Simon J.E. Large1*,†, Jörn F. Wotzlaw1, Marcel Guillong1, Albrecht von Quadt1, Christoph A. 5 Heinrich1,2 1Department of Earth Sciences, Eidgenössische Technische Hochschule (ETH) Zurich, 8092 Zürich, Switzerland. 2Faculty of Mathematics and Natural Sciences, University of Zurich, 8006 Zürich, Switzerland. †Current address: Department of Earth Sciences, Natural History Museum, Cromwell Road, London, SW7 5BD, UK 10 Correspondence to: Simon J.E. Large ([email protected]) Abstract. Understanding the formation of economically important porphyry-Cu-Au deposits requires the knowledge of the magmatic- to-hydrothermal processes that act within the much larger underlying magmatic system and the timescales on which they occur. We apply high-precision zircon geochronology (CA-ID-TIMS) and spatially resolved zircon geochemistry (LA-ICP- 15 MS) to constrain the magmatic evolution of the magma reservoir at the Pliocene Batu Hijau porphyry-Cu-Au deposit. We then use this extensive dataset to assess the accuracy and precision of different U-Pb dating methods of the same zircon crystals. Emplacement of the oldest pre- to syn-ore tonalite (3.736 ± 0.023 Ma) and the youngest tonalite porphyry cutting economic Cu-Au mineralisation (3.646 ± 0.022 Ma) is determined by the youngest zircon grain from each sample, which constrains the 20 duration of metal precipitation to less than 90 ± 32 kyr. Overlapping spectra of single zircon crystallisation ages and their trace element distributions from the pre-, syn and post-ore tonalite porphyries reveal protracted zircon crystallisation together with apatite and plagioclase within the same magma reservoir over >300 kyr.
    [Show full text]