Porphyry copper deposits account for more than 80% of the worlds total cu resources. Porphyry copper deposits are large commonly hundreds to thousands of million tonnes and low to medium in grade 0. A different but closely related group of deposits to porphyry copper deposits are the skarn deposits. A surge of scientific interest has been marked by a compa areal and structural geology rable increase in the flux of papers treating different properties of porphyry copper systems. The porphyries occur as tertiary quartzmonzonite stocks and dikes, ranging in composition from microdiorite to diorite and granodiorite. Porphyry ore deposits are the source of much of the copper, molybdenum, gold and silver used by humans. Gold can be removed from porphyry copper systems by vapors that separate at high temperatures or by. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Porphyry copper assessment of western central asia. Porphyry copper deposit model, chapter b of mineral deposit. Except for ag grade, all grades from chitalin and others 2011, with 0. Crosssection of alteration zones characteristic of highsulphidation deposits 1. This approach attempts to capture the rapid and sometimes haphazard application of pxrf in mineral exploration.
The purpose of the study was to 1 delineate permissive areas tracts for undiscovered porphyry copper deposits. The link between reduced porphyry copper deposits and. Based on geophysical data, hydrothermal alteration and sulfide mineralization extend more than 1 km at depth. Coppercontaining rock, or copper ore, holds only a small percentage of copper. Why no porphyry copper deposits in japan and south korea.
Porphyry copper deposit is part of wikiproject geology, an attempt at creating a standardized, informative, comprehensive and easytouse geology resource. Although christmas is known for skarn deposits in paleozoic carbonate rocks, oregrade porphyrytype copper mineralization also occurs in a composite granodioritic intrusive complex and adjacent mafic volcanic country rocks. Copper skarn deposits occur near many porphyry copper host intru sions that intruded carbonatebearing units einaudi and others, 1981, and skarn mineral zoning patterns may be useful in the targeting of a potentially associated porphyry copper deposit meinert and others, 2005. An important feature of the porphyryepithermal mineral system is the telescoping of different deposit types, for instance porphyry cuaumo deposits and epithermal deposits of various types.
Distribution of porphyry copper deposits along the. In porphyry copper deposits, copper grades can range from 0. Gold abundances in porphyry copper deposits vary greatly, complicating efforts to define goldrich porphyry copper deposits. Porphyry copper deposits of the american cordillera.
The potential of goldrich porphyry deposits is underscored by the fact that onefifth of the worlds giant gold deposits, defined as those containing 600 all, are porphyry type. The formation of porphyry copper deposits springerlink. The predicted magnetic anomaly over a porphyry copper system 1. Economic filters for evaluating porphyry copper deposit. Copper is more easily extracted from the suifide and carbonate m i nerals. The original definition was based on the aumo ratios of porphyry copper deposits with no reference to their copper content, and resulted in the suggestion that goldrich deposits were found largely in island arc regions kesler, 1973. In later stages, circulating meteoric fluids may interact with the magmatic. The problem is that while most of the magmas at convergent margins are highly oxidized, porphyry cu. Some thoughts on goldrich porphyry copper deposits.
At the beginning of 2006 the remaining resources in asarel porphyry copper deposit were 186 mt ore with average grade 0. This increase began in the early porphyry deposits of the region lie above the north ameri 1 960s. This information is compiled by dr bruce rohrlach and is not to be copied or reproduced in any form without written consent. Copper mines in pennsylvania total prospects occurrences plants producers adams 16 15 1 berks 4 1 3 bradford 1 1 bucks 4 1 3 carbon 1 1 centre 1 1 chester 8 1 7 franklin 1 1 lancaster 3 1 2 lawrence 1 1 lebanon 4 4 lehigh 1 1 montgomery 9 9 northampton 3 1 1 1 perry 1 1.
Copper mines in pennsylvania total prospects occurrences plants producers adams 16 15 1 berks 4 1 3 bradford 1 1 bucks 4 1 3 carbon 1 1 centre 1 1 chester 8 1 7 franklin 1 1 lancaster 3 1 2 lawrence 1 1 lebanon 4 4 lehigh 1 1 montgomery 9. Collectively, these type of deposits are known as porphyry copper deposits. The mines on this list account for more than 99% of u. Although christmas is known for skarn deposits in paleozoic carbonate rocks, oregrade porphyry type copper mineralization also occurs in a composite granodioritic intrusive complex and adjacent mafic volcanic country rocks. More than 90% of the porphyry cu deposits in the world are distributed along convergent margins. Abstract this analysis concludes that there is little realistic likelihood of discovering large, high. Porphyry copper deposits commonly contain hundreds of millions of metric tons of ore that averages a fraction of 1 percent copper by weight. Porphyry cuaumo deposits are one of the most important economic mineral associations sillitoe, 1997, sillitoe, 2010, hedenquist et al. Porphyry copper deposits commonly contain hundreds of millions of metric tons of. So this gives us a start in deciding where to focus our exploration because of the extensive subduction during the tertiary i. Previous studies have revealed that porphyry copper deposits are usually associated with oxidized, calcalkalic, adakitic shallow intrusive rocks. This region is characterized by a series of fault bound blocks that have risen and fallen creating a distinctive valleymountain range topography. Pdf a description of the structural geology, mineralogy. The importance of porphyry deposits as a copper and gold resource.
Geophysical signatures of coppergold porphyry and epithermal. Codes the australian research councils centre for excellence in ore deposit research, university of tasmania, private bag 126, hobart, tasmania 7001, australia. The geological characteristics, geochemical signature and. These deposits provide over 60% of the worlds copper and include other important metals such as molybdenum, gold and silver. This report contains a revised descriptive model of porphyry copper deposits pcds, the worlds largest source about 60 percent and resource about 65 percent of copper and a major source of molybdenum, gold and silver.
Porphyry copper deposits are known for their low grades and very high tonnage. Porphyry ore typically forms in magmatic arcs above subduction zones. Kesler this book summarizes recent advances in information on the porphyry copper deposits of southwestern north america. Information on porphyry copper deposits from around the world with grade and tonnage models, a general classification based on geologic setting, mineralogy, with data allowing locations of these deposits to be plotted using gis.
Hydrothermal alteration and mineralization at darrehzar are centered on the stock and were broadly synchronous with its emplacement. The sombrero butte breccia pipe system is located at the southern end of the copper creek bunker hill mining district in the laramide porphyry copper province of southwestern north america titley, 1982. Pdf porphyry copper deposits of the american cordillera. Gold is normally present in potassium silicate alteration, which commonly carries an unusually high magnetite content. The christmas copper deposit, located in southern gila county, arizona, is part of the major porphyry copper province of southwestern north america. The composition of rhomb porphyry places it in the trachytelatite classification of the qapf diagram.
The general characteristics of porphyry systems include. Porphyry is a textural term for an igneous rock consisting of largegrained crystals such as feldspar or quartz dispersed in a finegrained silicate rich, generally aphanitic matrix or groundmass. Copper porphyry is a form of copper deposit that is often characterized as lowgrade, typically with 0. This paper presents a brief history of the technological evo lution of southwest porphyry copper deposits as bulk lowgrade deposits and the evolution of knowledge of their settings, habits. Pdf preliminary model of porphyry copper deposits researchgate. Porphyry copper gold deposit model porphyry deposits are the worlds most important source of cu and mo, and are major sources of au, ag, and sn. Most nonrecycled supplies come from porphyry copper deposits pcds, which form when hot, metalbearing fluids percolate up through earths crust. Porphyry cu au mo deposits are centered on the intrusions, whereas carbonate wall rocks commonly host proximal cuau skarns, less common distal znpb andor au skarns, and, beyond the skarn front, carbonatereplacement cu andor znpbag au deposits, andor sedimenthosted distaldisseminated au deposits.
The distal parts of porphyry cu systems, be yond the porphyry cu deposits, either lack porphyry intru sions or contain only relatively minor dikes e. As a mining interested learner, the geology of porphyry copper deposits is vital to your education now in the first exploration geology course i discussed how because our current mining technology all the metals that we use. May 28, 2014 porphyry copper deposits play an important role in the global economy. Porphyry copper deposits result from the complex interactions and. Gold resources copper resources a geological cross section through the batu hijau porphyry deposit, indonesia 920 million tons of ore grading 0. Porphyry deposits are the worlds principal resources of cu, mo, and re, and are major. Geology and porphyry coppertype alterationmineralization of. Observed relationship between resistivity and weight percent sulphide content from in situ measurements of porphyry copper deposits 1.
Porphyrycopper deposits were the first type of metallic mineral depositexploited by largescale, openpit mining methods in the early20th century, a lowcost mining technique since adapted toother largetonnage, lowgrade mineral deposits for example,gold and silver. Copper is a moderately incompatible chalcophile element. Copper containing rock, or copper ore, holds only a small percentage of copper. The updated cost models were used to perform an economic analysis of undiscovered resources estimated in porphyry copper deposits in six tracts located in north america. Porphyry copper deposits contain up to 100 t of gold and are among the largest reservoirs of gold in the upper crust kerrich et al. Advances in geology of the porphyry copper deposits. Pdf auagtese minerals in the elatsite porphyrycopper deposit. Porphyry, copper deposit density is inversely related to the exposed area of permissive rock.
A total of 31 samples from porphyry copper deposits of the western cordillera were examined. This requires an economic evaluation of estimates of undiscovered resources generated by traditional resource assessments singer and menzie, 2010. Wholerock composition was estimated over three points of analysis by pxrf. Oct 17, 2019 the porphyry copper deposits of arizona are located in what is known as the basin and range physiographic province. These are somewhat the giants of the ore deposits world. Copper porphyry deposits are almost always mined in industrialscale open pit operations. Porphyry deposits economic geology chemistry free 30. Pdf elatsite is one of the largest operating porphyrycopper deposits in eastern europe, and is also enriched in.
Thomson resources porphyry copper gold deposit model. Geology and porphyry coppertype alterationmineralization. What investors need to know about porphyry copper deposits. Skarn deposits are also zoned in this mineral system, with curich skarns generally very close to the causative intrusion, but znpbrich skarns more distal. Based on geophysical data, hydrothermal alteration and. Every year, the world consumes about 20 million tons of copper primarily for construction materials like electrical wiring and water pipes. They account for about 50 to 60% of world cu production and more than 95% of world mo production. Copper oxides are defined as those copper minerals containing oxidized anions, especially copper oxides, sensu strictu, sulfates, phosphates, carbonates, and. A comparative study of porphyrytype copper deposit. Those in island arc settingshave primitive strontium isotopic ratios 87sr86sr of 0. List of copper mines in the united states wikipedia.
Most of the rock is unwanted material, typically referred to as gangue. Porphyry copper deposit exploration and resource assessment objectives. There are hundreds of inactive or defunct copper mines in. If you would like to participate, you can choose to edit this article, or visit the project page for more information. Porphyry copper deposits are copper orebodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Porphyry copper deposit, large body of rock, typically a porphyry of granitic to dioritic composition, that has been fractured on a fine scale and through which chalcopyrite and other copper minerals are disseminated. Part three resources and technology princeton university. May 31, 2015 development of a copper porphyry porphyry copper deposits are copper orebodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the. Later english and chilean companies try to win the ore. Significant quantities of byproduct molybdenum, silver, gold, and platinum are also produced.
Fluid evolution of the magmatic hydrothermal porphyry copper. Jan 11, 2014 copper deposits are the most important source for copper, accounting for more than 60 percent of the annual world copper production and approximately 65 percent of the known total copper resource. An analysis of the amount and location of undiscovered mineral resources that are likely to be economically recoverable is important for assessing the longterm adequacy and availability of mineral supplies. Copper is the primary commodity of economic interest in most porphyry copper deposits, although some deposits with low to very low copper grades are mined principally for their gold for example, copler, turkey andor molybdenum for example, sierrita, arizona. Introduction porphyry cu systems are defined as large volumes 10. Geology of the porphyry copper deposits of the western hemisphere 9780895200488. In its nongeologic, traditional use, the term porphyry refers to the purplered form of this stone, valued for its appearance. The assessment estimated undiscovered porphyry copper deposits within 1 kilometer of the land surface in three depth intervals. The ulan uzhur copper deposit, situated on the western margin of the qaidam basin is a porphyry copper deposit controlled by granite porphyry dikes. Rhomb porphyry is a volcanic rock with graywhite large porphyritic rhombusshaped phenocrysts embedded in a very finegrained redbrown matrix. Critical metal particles in copper sulfides from the. Start this article has been rated as startclass on the projects quality scale. They are commonly surrounded by deposits and country rock containing gold that is thought to have been derived from them jones, 1992. Predating or associated with those fluids are vertical dikes of porphyritic intrusive rocks from which this deposit type derives its name.
A porphyry is not a rock type, but rock with a particular texture. Geochemistry of hydrothermally altered rocks from the asarel. Intrusions associated with porphyrycopper deposits intrusions associated with, porphyry copper deposits arediverse but generally felsic and differentiated. Deposits copper deposits are found worldwide in a variety of geological environments. Sandstone copper assessment of the chusarysu basin, central. In 1915, openpit mining was initiated on disseminated oxide ore by chile exploration co. But while geologists have long recognized and exploited pcds, two new studies suggest they may need.
However, the formation mechanism and controlling factors of porphyry copper deposits remain obscure. In silicate mineral deposits, the copper is linked with silicon and oxygen. Classes of copper deposits copper deposits are classified by general geologic setting, including the type of rock in which the copper deposit. The copper creek district is located 65 km north of tucson, on the western side of the galiuro mountains in pinal county, arizona fig.
Associated commodities and deposit typesporphyry copper deposits are mined. The great porphyry copper deposits of arizona geology for. Small exotic copper deposit in older holocene gravel deposits that cover kelvin riverside porphyry. Therefore, porphyry cu deposits are usually oxidized with oxygen fugacities. Studies reexamine how major copper deposits form earth. The problem is that while most of the magmas at convergent margins are highly oxidized, porphyry.
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