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Porphyry Copper Deposit Model

By David A. John, editor, with contributions by Robert A. Ayuso, Mark D. Barton, Richard J. Blakely, Robert J. Bodnar, John H. Dilles, Floyd Gray, Fred T. Graybeal, John C. Mars, Darcy K. McPhee, Robert R. Seal, Ryan D. Taylor, and Peter G. Vikre

Chapter B of Mineral Deposit Models for Resource Assessment

This report contains a revised descriptive model of porphyry copper deposits (PCDs), the world’s largest source (about 60 percent) and resource (about 65 percent) of copper and a major source of molybdenum, gold and silver. Despite relatively low grades (average 0.44 percent copper in 2008), PCDs have significant economic and societal impacts due to their large size (commonly hundreds of millions to billions of metric tons), long mine lives (decades), and high production rates (billions of kilograms of copper per year). The revised model describes the geotectonic setting of PCDs, and provides extensive regional- to deposit-scale descriptions and illustrations of geological, geochemical, geophysical, and geoenvironmental characteristics. Current genetic theories are reviewed and evaluated, knowledge gaps are identified, and a variety of exploration and assessment guides are presented. A summary is included for users seeking overviews of specific topics.

First posted September 2, 2010 Report PDF (26.3 MB) For additional information contact: USGS Central Mineral and Environmental Resources Science Center Box 25046, MS-973 Denver Federal Center Denver, CO 80225 http://minerals.cr.usgs.gov/ Part or all of this report is presented in Portable Document Format (PDF); the latest version of Adobe Reader or similar software is required to view it. Download the latest version of Adobe Reader, free of charge.

Suggested citation:

John, D.A., Ayuso, R.A., Barton, M.D., Blakely, R.J., Bodnar, R.J., Dilles, J.H., Gray, Floyd, Graybeal, F.T., Mars, J.C., McPhee, D.K., Seal, R.R., Taylor, R.D., and Vikre, P.G., 2010, Porphyry copper deposit model, chap. B of Mineral deposit models for resource assessment: U.S. Geological Survey Scientific Investigations Report 2010–5070–B, 169 p.

Contents

Abstract

Summary of Porphyry Copper Deposit Model

A. Introduction

B. Deposit Type and Associated Commodities

C. History of Porphyry Copper Deposits

D. Regional Environment

E. Physical Description of Deposits

F. Geophysical Characteristics

G. Hypogene Ore Characteristics

H and K. Hypogene and Supergene Gangue Characteristics

I. Hydrothermal Alteration

J. Supergene Ore Characteristics

L. Weathering/Supergene Processes

M. Geochemical Characteristics

N. Petrology of Associated Igneous Rocks

O. Petrology of Associated Sedimentary Rocks

P. Petrology of Associated Metamorphic Rocks

Q. Theory of Ore Deposit Formation

R. Porphyry Copper Exploration and Resource Assessment Guides

S. Geoenvironmental Features

T. Knowledge Gaps and Future Research Directions

U. Broader Implications and Societal Relevance of Porphyry Copper Systems

References Cited

Appendix 1. Grade and tonnage models

Appendix 2. Characteristics of Representative Porphyry Copper Deposits