Characteristics of high sulphidation epithermal gold deposits. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. The association of gold mineralization with volcanic and geothermal hot spring activity has long been recognized by prospectors and geologists. Most of the samples from veins in the oatman area analyzed by smith. Hydrothermal alteration and fluid ph in alkalinehosted epithermal. The geochemical behavior of gold in hydrothermal systems. High sulphidationepithermal deposits explorationalliance. Sulfur could hold key to next generation of mining deposits, research says. Hydrothermal deposits are never formed from pure water, because pure water is a poor solvent of most ore minerals. Epithermal gold deposits of the southwest pacific, journal. Precious metals accompany all types of epithermal deposits. Island arc metallogenesis, geothermal systems and geology on free shipping on qualified orders. Epithermal mineral deposits are the products of largescale hydrothermal convective systems driven by magmatic heat in the upper 510 km of the earths crust. Although they are a product of the same igneous system, low sulfidation epithermals gold deposits are very different from high sulfidation.
Although, geologically recent porphyryepithermal mineral systems are mostly thought to form in magmatic arcs both continental and oceanic associated with convergent plate margins seedorff et al. This photo is pamukkale, low sulfidation hot springs in turkey, with a beautiful white centre terraces. Crystal laflamme and phd candidate stefano caruso were joined by adjunct professor and cet board member dr. How metalliferous brines line mexican epithermal veins with. Mag3dinv software was undertaken campagne, 20 on the.
When digging, mining an epithermal deposit, the surrounding rock formations are usually permeated with associated minerals and gold. A fascinating group and characteristic of epithermal gold deposits is that you can virtually see them forming today, simply by visiting hot springs. Controls to low sulphidation epithermal auag mineralisation presentation to the sydney mineral exploration discussion group. Fluids migrate upwards along faults and permeable horizons. Alkalic porphyry and epithermal deposits a view from. Gold systems innovation, and of course, technology. Hydrothermal mineral deposits are those in which hot water serves as a concentrating, transporting, and depositing agent. Epithermal gold deposits form at shallow depths and are nearsurface portions of fossil geothermal systems, which contrasts them to porphyry deposits which are formed at greater depth williams, 1997. Epithermal gold deposits are often appealing to mining companies because they are typically highgrade, smallsize deposits. The auas and ausb associations are common in gold deposit. 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. The nizi hosts gold bearing epithermaltype veins associated with felsic volcanic rocks cavey and chapman, 1992.
Jon hronsky from western mining services and featured in an abc news clipping and article entitled. This photo is pamukkale, low sulfidation hot springs. The mineral products of boiling in the golden cross epithermal deposit. Papua new guinea is endowed with spectacular porphyry coppergold and epithermal gold. Remnants of most of these products are preserved in some of their lesseroded, extinct equivalents. Fluids leach gold from low abundance crustal rocks big systems source gold from large volumes of crust. These deposits are best regarded as components of large hydrothermal systems centered on highlevel, generally oxidized, intermediate to felsic porphyry stocks figure 1. As the name suggestions they from part way between the high sulfidation and the low sulfidation environments, with a degree of dilution by groundwater but not as the same extent as in low sulfidation systems. Not only about delivering exceptional software, but also about the communities our technical solutions serve. The following aspects of the epithermal precious metal deposits in volcanic environments are of particular interest to exploration geologists. Porphyry coppergold and epithermal goldsilver systems. E pithermal gold deposits form in the shallow parts of magmarelated hydrothermal systems, commonly in subaerial volcanic arcs fig. Clarke epithermal mineralisation research unit, geology department, universityof auckland, privatebag, auckland, new zealand abstract vein samplesfrom the exploration for epithermal mineralisation are commonly subjectedtomultielement. Descriptive models for epithermal goldsilver deposits usgs.
Hydrothermal alteration and fluid ph in alkalinehosted epithermal systems. Ag tend to be most elevated deeper ni hte systems, with au, ag. Other articles where epithermal deposit is discussed. The formation of the axi epithermal gold deposit involved two major. Hse precious metal systems are associated with large systemically zoned advanced argillic to argillic alteration systems. However, many known alkalicrelated deposits contain. Like those with yellowstone in wyoming or rotorua in new zealand. Controls to low sulphidation epithermal auag mineralisation. Thermal springs and epithermal ore deposits journal.
Partington2 1 institute of geological and nuclear sciences, po box 30368, lower hutt, new zealand. Zaf corrections were made with proprietary joel software. Published examples of vtem surveys over hs epithermal gold deposits include cerro quema in panama kwan et al. Prospectivity models and gis data for the exploration of epithermal gold mineralisation in new zealand m. Hydrothermal circulation in the oceans is the passage of the water through midoceanic ridge systems the term includes both the circulation of the wellknown, hightemperature vent waters near the ridge crests, and the muchlowertemperature, diffuse flow of water through sediments and buried basalts further from the ridge crests. Characteristics of high sulphidation epithermal gold.
Controls to low sulphidation epithermal auag mineralisation greg corbett. Hydrothermal alteration and fluid ph in alkalinehosted. Burtner independent consultant, reno, nv mark hawksworth yamana gold, reno, nv jose carlos beltran encinas yamana gold, hermosillo, sonora, mexico tommy b. Skukum and the epithermal systems associated with the carmacks group in the yukon, that was not previously. Most of the epithermal systems have mineral assemblages and textural features which suggest formation at shallow depth. Many active volcanichydrothermal and geothermal systems are characterized by distinctive surface and nearsurface landforms and products, which are generated during discharge of a spectrum of fluid types under varied conditions. Epithermal gold mineralisation is found in a wide compositional range of host lithologies, but despite the diversity the alteration mineral assemblages are often similar between deposits. Epithermal gold deposits in volcanic terranes springerlink. I wont go through this again in detail, but one of the key ways was to break the gold sulfur bond by allowing the fluid to boil, this is the main way. Characteristics of highsulfidation epithermal deposits, and their relation to magmatic fluid antonio arribas jr.
Lowsulphidation epithermal systems silicon dioxide. Read epithermal gold deposits of the southwest pacific, journal of geochemical exploration on deepdyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. 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. Prospectivity models and gis data for the exploration of. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1.
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. Characteristics and genesis of epithermal gold deposits. I wont go through this again in detail, but one of the key ways was to break the gold sulfur bond by allowing the fluid to boil, this is the main way in which gold is deposited in low sulfidation epithermal. 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. Epithermal gold mineralisation is found in a wide compositional range of host.
In this post, i would like to share some key points for conceptual mapping of hydrothermal alteration in high sulfidation hs epithermal systems. It is commonly assumed that most epithermal gold deposits associated with alkaline igneous rocks deficient in silica with respect to alkalis are enriched in tellurium, and within colorado and new mexico, many deposits are indeed telluriumrich. Although, geologically recent porphyry epithermal mineral systems are mostly thought to form in magmatic arcs both continental and oceanic associated with convergent plate margins seedorff et al. Epithermal gold mineralization at apigania bay is one of several graniterelated goldsilver. Models and exploration methods for major gold deposit types robert, f. The occurrence of gold mainly depends on temperature, pressure, ph values, cl.
Summary of geophysical responses over epithermal systems modified after hoschke, 2011. Hydrothermal fluids forming epithermal gold deposits are ausaturated in most cases, whereas deposits of carlintype are auundersaturated. The deposits are host to both precious and base metals but are now mainly mined for their gold and silver contents, which can be substantial in total production and can achieve spectacular bonanza grades. 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. 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. 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. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. High sulphidation epithermal deposits form in continental and. Competent host rocks fracture to aid vein formation. A new programme to explore these favourable epithermal systems, it will be successful in locating new gold deposits. We now know that this association is a consequence of the hot magmas which not only produce volcanic eruptions and volcanic rocks but also are the source of the hot fluids that transport gold and other. Earlier on greenstone shear zone hosted gold, where we covered various ways to drop gold from a fire complex solution.
Goldsilver deposits, miopliocene belt, chileargentina 4 characteristics of large economic high sulphidation epithermal hse systems of the miopliocene age mineral belt of chile and argentina. Porphyryrelatld low sulfidation gold systems 195 society of ecoiomc geologists special publication no. A multiscalar perspective from the mercedes district, sonora, mexico geoffrey k. Notable exceptions are those gold deposits hosted in alkaline host rocks. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. Lowsulphidation epithermal systems free download as powerpoint presentation. The high and low sulphidation epithermal deposits associated with blue coloured belts are. Gold grade distribution within an epithermal quartz vein system. Pdf exploration for epithermal gold deposits researchgate. Scribd is the worlds largest social reading and publishing site. Epithermal deposits form in the ground at shallow depths. As with the calcalkalic systems, alkalic epithermal deposits are best preserved in younger volcanic arcs, although the alkalic systems occur in association with alkalic igneous rocks, implicating anomalous tectonic processes in their formation. It is obviously good practise,when exploring for epithermal gold mineralisation at any scale,to sample any vein material.
Airborne geophysical results over t he dolly varden high. Mineral deposit mineral deposit hydrothermal solution. Department of energys office of scientific and technical information. Papua new guinea is endowed with spectacular porphyry copper gold and epithermal gold. They are the most numerous of all classes of deposit. Quality low sulphidation epithermal auag mineralisation is best developed in settings. Alteration vectoring in epithermal high sulfidation auag. Models and exploration methods for major gold deposit types. Pdf epithermal gold for explorationists researchgate. Ore deposits 101 part 5 epithermal deposits youtube.
Metallis expands goldrich mineralization at cole porphyry. Duration of hydrothermal systems that form epithermal goldsilver deposits. Classification vs modeling each ore deposit is unique like a persons finger print this uniqueness arises out of. Epithermal vein systems mostly low sulphidation are controlled by the interaction of. Structural, textural and supergene controls on grade and zonation in epithermal vein systems. Now lets quickly cover the last of the broad groups, the intermediate sulfidation epithermal. They contain economic concentrations of gold, silver and in some cases base metals such as copper, lead and zinc. Epithermal gold and silver deposits icmjs prospecting. 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.
How metalliferous brines line mexican epithermal veins. Gold ore in lowsulfidation deposits is commonly associated with quartz and adularia, plus. Pdf the mineral products of boiling in the golden cross. Society of economic geologists special publication 6, 234 p. Tellurium in igneousrelated epithermal precious metal. We have extensive experience designing, developing, deploying, and maintaining enterpriselevel it solutions. Structural, textural and supergene controls on grade and. 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.
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