Models and exploration methods for major gold deposit types. Porphyry copper, gold, and molybdenum deposits society of. Pdf magmaticrelated porphyry copper and highsulphidation epithermal coppergold ore deposits are spatially and temporally clustered in. Department of mining geology, royal school of mines, imperial college of science and. In approximate order of decreasing gold contents, these goldrich potassic porphyry.
Tonnage and grade represent weighted average for 43101 compliant indicated and inferred resources for bayugo at 0. Porphyry deposits are the worlds principal resources of cu, mo, and re, and are major resources of au and ag. About 60% of the gold that is contained in the 25 largest porphyry coppergold deposits in the world, as ranked by gold content, occurs in nine potassic magmarelated deposits garwin, 2019. Geological survey of new south wales, report gs 20190306, digs. For coppermolybdenum porphyry deposits, formation is broadly concentrated in three time periods. Tracking cobalt, ree and gold from a porphyrytype deposit. Pdf gold endowments of porphyry deposits controlled by.
The ore is temporally and genetically related to the. Gold endowments of porphyry deposits controlled by. Primary commodities copper is the primary commodity of economic interest in most porphyry copper deposits, although some deposits with low. Critical metals and gold are known to occur in porphyry copper deposits, with many estimates reporting traceelement concentrations in the order of a few parts per million ppm or less e. Gold abundances in porphyry copper deposits vary greatly, complicating efforts to define goldrich porphyry copper deposits. The formation of porphyry copper deposits springerlink. The geological characteristics, geochemical signature and. Porphyrystyle ore deposits constitute our main source of copper and molybdenum and they contribute significant resources of gold and other rare metals such. These patterns are best analysed in the light of the model for the overprinting stages of porphyry evolution figure 3. The problem is that while most of the magmas at convergent margins are highly. Preliminary model of porphyry copper deposits usgs.
Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. The potential of gold rich porphyry deposits is underscored by the fact that onefifth of the worlds giant gold deposits, defined as those containing 600 all, are porphyry type. Characteristics of porphyry aucu systems in the ordovician. Porphyry copper deposits are very large mineralized systems that are typically formed by relatively small intrusions stocks, which are several thousand. Porphyry and vein copper gold deposits in the ordovician macquarie volcanic province, lachlan orogen. Like those with yellowstone in wyoming or rotorua in new zealand. The major products from porphyry copper deposits are copper and molybdenum or copper and gold. Rich gold deposits in porphyry geology 101 ask jeff williams duration. The speciation of sulfur is controlled by oxygen fugacity. Gold deposits can still be seen today forming in some active geothermal areas.
Major miners look to copper porphyry deposits for largetonnage, lowcost operations. This porphyry deposit 8 ma is located in the miocene calcalkaline. The term porphyry copper now includes engineering as well as geological considerations. Stanley3 introduction the alkaline suite is a distinctive group of porphyry copper gold deposits that occur in the cordillera of british columbia barr et al. Till geochemical and mineralogical case studies and surveys carried out around porphyry deposits in glaciated terrain are described here in two sections.
Endeavour 26 north, endeavour 22 and endeavour 27 coppergold deposits. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1. 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 gold rich deposits were found largely in island arc regions kesler, 1973. Porphyry gold deposits of the refugio district, maricunga. Porphyry copper and gold deposits are the dominant natural suppliers of these metals to our society, yet the large variations in metal endowments of porphyry cuau. Between these end members is an economically important group containing significant amounts of. Alteration strong alteration zones develop in and around granitic rocks with related porphyry deposits. Porphyry introduction1achf seg10lombok free download as powerpoint presentation. The porphyry gold deposits of the refugio district and similar deposits in the maricunga belt contain the lowest known copper to gold ratios % cuppm au 0. Characteristics of porphyry aucu systems in the ordovician macquarie arc of nsw bruce mowat, goldminco, mitchell hwy, orange nsw 2800. Porphyry copper deposits commonly contain hundreds of millions of metric tons of. Gold abundances in porphyry copper deposits vary greatly, complicating efforts to define gold rich porphyry copper deposits.
The formation of economic porphyry copper gold deposits. Porphyry deposits account for most of the copper and molybdenum world production, 60 and 95 percent of its supply respectively porphyrytype ore deposits form in hydrothermal fluid circulation systems developed above and around highlevel, subvolcanic felsic to intermediate magma chambers andor cooling plutons. Oxidized intrusionrelated deposits, including porphyry, skarn, and highsulfidation epithermal deposits, are associated with highlevel, oxidized porphyry stocks in magmatic arcs. Copper is a moderately incompatible chalcophile element. Pdf analysis of 55 porphyry copper deposits demonstrates a continuum between porphyry coppergold deposits emplaced at a median depth of 1 km, with a. These are large scale magmatichydrothermal systems associated with a series of porphyritic intrusions, which result in extensive alteration footprints that we map and model to target high grade coppergold mineralization. Most byproduct gold has come from porphyry deposits, which are so large that even though they contain only a small amount of gold per ton of ore, so much rock is mined that a substantial amount of gold is. The porphyry gold deposits of the maricunga belt in northern chile contain the lowest. Palaeoceneeocene, eoceneoligocene, and middle miocenepliocene. In the past decade, significant research efforts have been devoted to mineral chemistry studies to assist porphyry exploration. In approximate order of decreasing gold contents, these gold rich potassic porphyry. The miocene wafigolpu goldrich porphyry cuau deposit, and associated epithermal au mineralisation is located in the morobe province of png, and has a currently published resource of 28.
Porphyry deposits are important sources of copper and molybdenum, as well as gold, silver, and tin sinclair, 2007. Porphyry cu deposits are largetonnage, low grade mineral occurrences that are amenable to bulkmining techniques. This ignores the fact that sillitoe 1979 had earlier introduced the concept of. Australian ore deposits the australasian institute of mining and metallurgy. Jan 14, 2020 porphyry deposits are natural suppliers of most copper and significant gold to our society. Between these end members is an economically important group containing significant amounts of both gold and. Other articles where porphyry molybdenum deposit is discussed.
Codes the australian research councils centre for excellence in ore deposit research, university of tasmania, private bag 126, hobart, tasmania 7001, australia. Porphyry type mineral deposits result when large amounts of hot water that carry small amounts of metals pass through permeable rocks and deposit the metals. Porphyry and vein coppergold deposits in the ordovician macquarie volcanic province, lachlan orogen. Sixteen common types of bedrock gold deposits are distinguished from one another and their main geological attributes are. Pdf distribution of gold in porphyry copper deposits researchgate.
Copper resources a geological cross section through the batu hijau porphyry deposit, indonesia 920 million tons of ore grading 0. These activities can be divided into two major fields of research. We take a look at what makes for a copper porphyry takeover target. 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. Reduced porphyry coppergold deposits geoscienceworld. This photo is pamukkale, low sulfidation hot springs in turkey, with a beautiful white centre terraces. Epithermal gold deposits are among the richest gold deposits in the world with some bonanza grade ore shoots containing more than gt gold, or in other words, a kilogram of gold for every tonne of rock mined. It refers to large, relatively low grade, epigenetic, intrusionrelated deposits that can be mined using mass mining techniques. Porphyry indicator minerals pims from alkalic porphyry copper gold deposits in southcentral british columbia nts 092, 093. Porphyry deposits are natural suppliers of most copper and significant gold to our society. Jul 12, 20 epithermal gold deposits are among the richest gold deposits in the world with some bonanza grade ore shoots containing more than gt gold, or in other words, a kilogram of gold for every tonne of rock mined. This ignores the fact that sillitoe 1979 had earlier introduced the concept of a porphyry gold deposit style. Characteristics of porphyry aucu systems in the ordovician macquarie arc of nsw bruce mowat, goldminco, mitchell hwy, orange nsw 2800 stuart smith, oxiana ltd, 9th floor, 31 queen st, melbourne, vic 3000 key words.
The next variation in the classification was used in 1995 by bakker. Briggs over the last several years, many of you have probably heard the term porphyry copper and wondered what everyone is talking about. This study focuses on the spatial and temporal relationships between the porphyry and epithermal styles of mineralization in three districts. Map showing detailed geology and location of mines, oatman district 122. Showing a little bit of gold ore ive collected from one of my claims from three different offshoots of a main intrusive quart vein. Porphyry deposits are the worlds principal resources of cu, mo, and re, and are major. Thomson resources porphyry copper gold deposit model. Porphyry cu systems host some of the most widely distributed mineralization types at convergent plate boundaries, including porphyry deposits centered on intrusions. Some metallogenic features of gold and copper deposits related to. Copper porphyry deposits are almost always mined in industrialscale open pit operations. Magmatichydrothermal processes within an evolving earth.
About 60% of the gold that is contained in the 25 largest porphyry copper gold deposits in the world, as ranked by gold content, occurs in nine potassic magmarelated deposits garwin, 2019. They account for about 50 to 60% of world cu production and more than 95% of world mo production. The miocene wafigolpu gold rich porphyry cuau deposit, and associated epithermal au mineralisation is located in the morobe province of png, and has a currently published resource of 28. Therefore, porphyry cu deposits are usually oxidized with oxygen fugacities. Deposits of this type are mined for the predominant metals, but the gold is also recovered as a byproduct during processing of the ore.
Since 1905, more than 700 articles concerning porphyry deposits have been published by the society of economic geologists in its various publications economic geology. Porphyry deposits account for most of the copper and molybdenum world production, 60 and 95 percent of its supply respectively porphyry type ore deposits form in hydrothermal fluid circulation systems developed above and around highlevel, subvolcanic felsic to intermediate magma chambers andor cooling plutons. A rational geological classification of the commonly recognized lode gold deposits is feasible if it is based on the geological settings of the deposits, host rocks, nature of mineralization and geoche mical signature. 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. Tracking cobalt, ree and gold from a porphyrytype deposit by. Pdf distribution of gold in porphyry copper deposits. For both porphyry and epithermal gold deposits, they are generally from the time period ranging from the middle miocene to the recent period. Porphyry indicator minerals pims from alkalic porphyry coppergold deposits in southcentral british columbia nts 092, 093. Whereas the curichest aupoor porphyries are related to andeantype subduction and typical calc. Mhiocg deposits predominantly occur in precambrian rocks, are fe oxide rich, and have volumetrically extensive hightemperature alteration zones, whereas porphyry deposits occur almost. Gold is an important byproduct in many porphyry copper deposits, but the details. Porphyry cuau deposits display complex patterns of zonation in alteration and mineralisation which result from the overprinting of many prograde and retrograde events. Copper porphyry is a form of copper deposit that is often characterized as lowgrade, typically with 0. Models and exploration methods for major gold deposit types robert, f.
There are six worldclass settings for magmatichydrothermal gold deposits. Mhiocg deposits predominantly occur in precambrian rocks, are fe oxide rich, and have volumetrically extensive hightemperature alteration zones, whereas porphyry. Since this recognition, exploration projects have been undertaken by anaconda, newmont, and kennecott, the last of which began a deep drilling program on the property in 2006. Platinum groupelements in alkaline porphyry deposits, british columbia by john f.
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