Other articles where epithermal deposit is discussed. Diversity of gold deposits, geodynamics and conditions of. Pdf epithermal gold deposits styles characteristics an. Internal vein texture and vein evolution of the epithermal. Epithermal veintype gold deposits with a brief look at the factors that affect the viability of a gold deposit conditions an epithermal gold deposit is one in which the gold mineralization occurs within 1 to 2 km of surface and is deposited from hot fluids. Hydrothermal deposits are never formed from pure water, because pure water is a poor solvent of most ore minerals. The ores and the volcanic rocks with which they are associated were generated at a noncollisional, oceancontinent convergent plate margin. Epithermal gold deposits have size, geometry, and grade variations that can be broadly organized around some genetic classes and, therefore, influence the exploration approach or philosophy.
Ls epithermal gold deposits in java show typical characteristics of quartz veins vein zones with crustiformcolloform textures, relatively high au agau jun 24, 20 epithermal precious metal deposits, regarded as the exhumed product of fossil geothermal systems 1, host 6% of the worlds gold resources and 17% of the silver 2. Ore deposit is a natural concentration of one or more minerals within the host rock. Thus, the gold period observed in the cenozoic is artificially amplified with respect to older periods which are minimized. Like those with yellowstone in wyoming or rotorua in new zealand. Epithermal gold deposits in chile are cretaceous to cenozoic in age. Symbols indicate deposits, prospects or showings associated with epithermal and intrusionrelated gold systems. Hedenquist 2 bhp minerals international exploration, 229 shepherds bush road, london w6 7an, u. Epithermal gold for explorationists paper 200201, april 2002 5 mineralogical differences used to categorise the styles of low sulphidation epithermal gold deposit styles corbett and leach, 1998.
Vein deposits of this nature are a type of hydrothermal deposit because the mineral species which compose the veins were precipitated by hot waters. Epithermal deposits form in the ground at shallow depths. Epithermal mineral deposits are the products of largescale hydrothermal convective systems driven by magmatic heat in the upper 510 km of the earths crust. Geological features of some epithermal gold systems. Low sulfidation deposits on the other hand from a geothermal system in which the magmatic fluid is cooled and diluted by groundwater and the ph is neutralized at depth. Distinctive features typically present include key alteration mineral assemblages low sulphidation. Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in earths crust through fractures. One of the most striking examples of gold sulfide selenide telluride mineralization is the kairagach high. Characteristics of high sulphidation epithermal gold. A fascinating group and characteristic of epithermal gold deposits is that you can virtually see them forming today, simply by visiting hot springs. On the source of orogenic gold geology geoscienceworld.
The ore deposits of the oatman area comprise gold bearing quartzcalcite veins which occupy fault fissures in. H2 geology and resources of gold in the united states the goldfield deposit is an epithermal bonanza of the enargitegold or quartzalunite type berger, 1986. Some properties are available for option or joint venture with junior mining companies. Hydrothermal mineral deposits are those in which hot water serves as a concentrating, transporting, and depositing agent. Smith geology and gold deposits of the marysville, mining district, montana by james w. Pdf geophysical exploration for epithermal gold deposits. Mineral deposit mineral deposit hydrothermal solution. Epigenetic vein deposits of gold in metamorphic terranes kerrich, 1993. Deposits having spatial and genetic relationship with igneous intrusions. By far the greatest number of publications in seg nevada publications report on epithermal and carlintype deposits. Portions of the host rock may either dissolve and be transported away or else react chemically with the circulating volatile fluids or.
The deposit occurs within the pajingo epithermal system pes, 72km south of charters towers in northeast queensland, australia porter 1990. View epithermal gold deposits research papers on academia. In the case of exploration for epithermal gold deposits, this understanding can be augmented by familiarity with active hydrothermal systems, their presentday ana. Ore mineralogy and formation condition of epithermal gold core. The study of the spatial distribution of known gold deposits has led to the as.
Diagnostic features of epithermal gold deposits geological, mineralogical, and geochemical features of epithermal au deposits are listed for each of three deposit subtypes in table 2. Magmatichydrothermal origin of mercury in carlinstyle and epithermal gold deposits in china. However, sometimes the preexisting rock wall which contains the vein undergoes alteration. Such deposits occur in calcalkalic volcanic rocks, are associated with the effects of intense acidsulfate hydro thermal alteration, and typically have significant byprod. The high and low sulphidation epithermal deposits associated with blue coloured belts are late mesozoic and cenozoic in age generally deposits located in the middle of plates grey coloured belts or metallogenic provinces are associated with paleozoic age ca. Mineral resources department, geological survey of japan, 1 higashi, tsukuba 305, japan introduction a consequence of the increased exploration for gold deposits during the late 1970s and early. Debate on the genesis of socalled orogenic gold deposits 75% of gold recovered through history. Notable exceptions are those gold deposits hosted in alkaline host rocks. This paper summarizes the characteristics of epithermal gold deposits and discusses potential ore deposition mechanisms. Magmatic vapor contraction and the transport of gold from. Aute deposit towards the central, northern, and eastern parts of the. Geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. The aim of this project was to define the geological and grade continuity of the vera south gold deposit, and to use this knowledge to apply geostatistical resource estimation techniques to the deposit. Although finding an attractive prospect in the first place is hard work, a majority of exploration budgets these days is spent on assessment.
The geological and grade continuity of the pajingo. A mineral deposit model is a systematically arranged body of information that describes the essential attributes of a mineral deposit type. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. Recognising sinters in epithermal gold deposits surficial deposits of siliceous sinter are a com mon feature of presentday hot springs in areas of active volcanism, but they are rarely recognised in older, eroded volcanic ter ranes because of their low preservation poten tial, and their limited vertical and lateral. They are related to long, slightly sinuous northnortheasttrending magmatic belts roughly parallel to the pacific coast. Here we highlight the general characteristics of the two principal styles of epithermal mineralization in which gold is the dominant economic. Lowsulfidation epithermal gold deposits in java, indonesia. Pdf exploration for epithermal gold deposits researchgate. Nearly 80 years ago, waldemar lindgren defined the epithermal environment. There are six worldclass settings for magmatichydrothermal gold deposits. They are the most numerous of all classes of deposit.
Epithermal gold mineralization, hot spring activity, and volcanism on fergusson and goodenough islands of papua new guinea have recently been recognised to. Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term bonanza. Epithermal gold deposits are highly variable in form, ranging from thin quartz veins to large disseminated deposits, and are located in a variety of geological environments. They contain economic concentrations from a precious metal such as gold and silver, and in some cases base. Mineral deposits of nevada society of economic geologists. Consequently, they exhibit a wide range of geophysical signatures. Bowden, christopher david 2007 epithermal systems of the seongsan district, south korea an investigation on the geological setting and spatial and temporal relationships between high and low sulfidation systems.
Pdf the successful exploration geologist uses knowledge of geologic relationships and oredeposit styles, tempered by experience, to interpret all. 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. The first is epithermal gold deposits associated with magmatic rocks, the second is epithermal gold deposits associated with sedimentary rocks carlintype and the third is epithermal gold. What are the characteristic textures of epithermal gold deposits. Petrological and mineralogical aspects of epithermal low. Although they are a product of the same igneous system, low sulfidation epithermals gold deposits are very different from high sulfidation. Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. Based on alteration, mineralization, vein texture, ore geochemistry and fluid inclusion data results, therefore the deposit type at the study area is an intermediate epithermal sulphidation is. In spite of the early silver dominance in mine production, the surge in gold production after 1965 led to the states preeminence in world gold production from carlintype deposits fig.
They are popular with prospectors because can yield very rich deposits and they are widespread in the western us. Characteristics of high sulphidation epithermal gold deposits of the miopliocene age volcanic belt, chile and argentina 2018. Scribd is the worlds largest social reading and publishing site. Gold deposits can still be seen today forming in some active geothermal areas. Geology and geochemistry of epithermal systems presents a synthesis of the current under standing of the processes responsible for the concentration of metals especially gold and silver in nearsurface environments, provides an overview of the systematics of the most important approaches to. Nearly 80 years ago, waldemar lindgren defined the epithermal environment as being shallow in depth. Characteristics and genesis of epithermal gold deposits gold in. Epithermal deposits typically form above the level of porphyry cuau deposits. The goldfield deposit is an epithermal bonanza of the enargitegold or quartzalunite type berger, 1986. Hydrothermal alteration and fluid ph in alkalinehosted.
Epithermal gold deposits styles characteristics an. Phillips, 20, continues largely because it is difficult to reliably identify the source of gold. Hydrothermal circulation, in particular in the deep crust, is a primary cause of mineral deposit formation and a cornerstone of most theories on ore genesis. Of these deposits, there is a notable association among epithermal gold mineralization. Epithermal deposits are responsible for 8% gold frimmel, 2008, 17% silver singer, 1995, and a certain amount of base metals production globally, being the important source of precious metals for mexico, the united states, canada, chile, peru, papua new guinea, and japan. High sulphidation epithermal gold deposits form in geothermal systems where hot acidic hydrothermal fluid directly from the intrusion, remains undiluted by ground water.
Gold has historically been a key strategic commodity, and the study of gold deposit formation has long been investigated. Regional geologic setting of epithermal gold deposits, chile. Examples of such gold deposits subset developed are, intrusionrelated gold deposits 7, bulk mineable gold deposit 8, the epithermal gold deposits, or 9 the epigenetic archean gold deposits 1110 stated that a rational geological classification of the commonly recognized lode gold deposits is not feasible if it. Porphyry cuaumo deposits epithermal cuagauznpb deposit shear zonehosted gold deposit mesozoic dexing area east china based on previous studies and detailed. Similarly, geochemical evidential themes include placer gold deposits and gold and silver analyses from stream sediment silt samples from national forest lands.
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. Nov 02, 2014 ore deposit is a natural concentration of one or more minerals within the host rock. Epithermal gold and silver deposits icmjs prospecting. They contain economic concentrations from a precious metal such as gold and silver, and in some cases base metals such as copper, lead, iron ore and. Magmatic vapor contraction and the transport of gold from the porphyry environment to epithermal ore deposits. Controls to low sulphidation epithermal auag mineralisation. Whipple gold deposits of the boulder county gold district, colorado by james a. They eventually create richmetallic fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. Keywords vein system texture epithermal gold breccia structural control peru introduction epithermal deposits often occur in a convergent tectonic setting and associated with volcanism e.
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