Pdf exploration for epithermal gold deposits researchgate. 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. This photo is pamukkale, low sulfidation hot springs in turkey, with a beautiful white centre terraces. Structural, textural and supergene controls on grade and. As you go deeper the hotter deposits are found and the gold bearing lode narrows to cracks filled with quartz and the easiest of metals to reduce. Alteration vectoring in epithermal high sulfidation auag. 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. Porphyryrelatld low sulfidation gold systems 195 society of ecoiomc geologists special publication no. Characteristics of high sulphidation epithermal gold deposits.
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. Most of the epithermal systems have mineral assemblages and textural features which suggest formation at shallow depth. Characteristics of highsulfidation epithermal deposits, and their relation to magmatic fluid antonio arribas jr. 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. The oreforming fluids of ls epithermal deposits have been fully investigated. Quality low sulphidation epithermal auag mineralisation is best developed in settings.
Pdf epithermal gold for explorationists researchgate. E pithermal gold deposits form in the shallow parts of magmarelated hydrothermal systems, commonly in subaerial volcanic arcs fig. 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. We have extensive experience designing, developing, deploying, and maintaining enterpriselevel it solutions. Duration of hydrothermal systems that form epithermal goldsilver deposits. Papua new guinea is endowed with spectacular porphyry copper gold and epithermal gold. Characteristics of high sulphidation epithermal gold. Hydrothermal fluids forming epithermal gold deposits are ausaturated in most cases, whereas deposits of carlintype are auundersaturated. Hydrothermal deposits are never formed from pure water, because pure water is a poor solvent of most ore minerals. Notable exceptions are those gold deposits hosted in alkaline host rocks. Metallis expands goldrich mineralization at cole porphyry. Scribd is the worlds largest social reading and publishing site.
Competent host rocks fracture to aid vein formation. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. Sulfur could hold key to next generation of mining deposits, research says. Gold ore in lowsulfidation deposits is commonly associated with quartz and adularia, plus. Epithermal vein systems mostly low sulphidation are controlled by the interaction of. Prospectivity models and gis data for the exploration of epithermal gold mineralisation in new zealand m. 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. Epithermal gold deposits are often appealing to mining companies because they are typically highgrade, smallsize deposits. 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. How metalliferous brines line mexican epithermal veins. Zaf corrections were made with proprietary joel software.
In this post, i would like to share some key points for conceptual mapping of hydrothermal alteration in high sulfidation hs epithermal systems. Models and exploration methods for major gold deposit types robert, f. Precious metals accompany all types of epithermal deposits. Controls to low sulphidation epithermal auag mineralisation. Mineral deposit mineral deposit hydrothermal solution. They contain economic concentrations of gold, silver and in some cases base metals such as copper, lead and zinc. 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. Characteristics and genesis of epithermal gold deposits. 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. 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. It is obviously good practise,when exploring for epithermal gold mineralisation at any scale,to sample any vein material. A new programme to explore these favourable epithermal systems, it will be successful in locating new gold deposits. Island arc metallogenesis, geothermal systems and geology on free shipping on qualified orders.
In the case of exploration for epithermal gold deposits, this understanding can be augmented. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. The following aspects of the epithermal precious metal deposits in volcanic environments are of particular interest to exploration geologists. Gold grade distribution within an epithermal quartz vein system.
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. 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. 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 deposits in volcanic terranes springerlink. Pdf the mineral products of boiling in the golden cross. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p.
Mag3dinv software was undertaken campagne, 20 on the. Fluids migrate upwards along faults and permeable horizons. Summary of geophysical responses over epithermal systems modified after hoschke, 2011. 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. Descriptive models for epithermal goldsilver deposits usgs. The occurrence of gold mainly depends on temperature, pressure, ph values, cl. The nizi hosts gold bearing epithermaltype veins associated with felsic volcanic rocks cavey and chapman, 1992. Ag tend to be most elevated deeper ni hte systems, with au, ag. 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. Lowsulphidation epithermal systems silicon dioxide.
Remnants of most of these products are preserved in some of their lesseroded, extinct equivalents. How metalliferous brines line mexican epithermal veins with. Hydrothermal alteration and fluid ph in alkalinehosted epithermal systems. 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. Other articles where epithermal deposit is discussed. 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 mineralisation is found in a wide compositional range of host.
Hydrothermal alteration and fluid ph in alkalinehosted epithermal. Most of the samples from veins in the oatman area analyzed by smith. When digging, mining an epithermal deposit, the surrounding rock formations are usually permeated with associated minerals and gold. The auas and ausb associations are common in gold deposit. Published examples of vtem surveys over hs epithermal gold deposits include cerro quema in panama kwan et al. Epithermal gold mineralization at apigania bay is one of several graniterelated goldsilver. They are the most numerous of all classes of deposit.
Hse precious metal systems are associated with large systemically zoned advanced argillic to argillic alteration systems. Papua new guinea is endowed with spectacular porphyry coppergold and epithermal gold. Jon hronsky from western mining services and featured in an abc news clipping and article entitled. 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. The mineral products of boiling in the golden cross epithermal deposit. Prospectivity models and gis data for the exploration of.
Models and exploration methods for major gold deposit types. The formation of the axi epithermal gold deposit involved two major. Airborne geophysical results over t he dolly varden high. A multiscalar perspective from the mercedes district, sonora, mexico geoffrey k. Burtner independent consultant, reno, nv mark hawksworth yamana gold, reno, nv jose carlos beltran encinas yamana gold, hermosillo, sonora, mexico tommy b. Lowsulphidation epithermal systems free download as powerpoint presentation. Epithermal gold and silver deposits icmjs prospecting.
Alkalic porphyry and epithermal deposits a view from. The geochemical behavior of gold in hydrothermal systems. Not only about delivering exceptional software, but also about the communities our technical solutions serve. A fascinating group and characteristic of epithermal gold deposits is that you can virtually see them forming today, simply by visiting hot springs.
Earlier on greenstone shear zone hosted gold, where we covered various ways to drop gold from a fire complex solution. High sulphidationepithermal deposits explorationalliance. Thermal springs and epithermal ore deposits journal. Porphyry coppergold and epithermal goldsilver systems. Controls to low sulphidation epithermal auag mineralisation presentation to the sydney mineral exploration discussion group. Like those with yellowstone in wyoming or rotorua in new zealand. They are popular with prospectors because can yield very rich deposits and they are widespread in the western us. 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. Partington2 1 institute of geological and nuclear sciences, po box 30368, lower hutt, new zealand. Campbell summary of relevant geologic, geoenvironmental, and geophysical information deposit geology manganese oxide concentrations are present as small veins, stringers, nodular masses, brecciafillings, and coatings. Although they are a product of the same igneous system, low sulfidation epithermals gold deposits are very different from high sulfidation.
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. Hydrothermal mineral deposits are those in which hot water serves as a concentrating, transporting, and depositing agent. Controls to low sulphidation epithermal auag mineralisation greg corbett. Department of energys office of scientific and technical information. Epithermal gold deposits of the southwest pacific, journal. Society of economic geologists special publication 6, 234 p. Tellurium in igneousrelated epithermal precious metal.
High sulphidation epithermal deposits form in continental and. Skukum and the epithermal systems associated with the carmacks group in the yukon, that was not previously. 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. This photo is pamukkale, low sulfidation hot springs. Crystal laflamme and phd candidate stefano caruso were joined by adjunct professor and cet board member dr. However, many known alkalicrelated deposits contain. 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. Ore deposits 101 part 5 epithermal deposits youtube. Clarke epithermal mineralisation research unit, geology department, universityof auckland, privatebag, auckland, new zealand abstract vein samplesfrom the exploration for epithermal mineralisation are commonly subjectedtomultielement. Now lets quickly cover the last of the broad groups, the intermediate sulfidation epithermal. Classification vs modeling each ore deposit is unique like a persons finger print this uniqueness arises out of.
Structural, textural and supergene controls on grade and zonation in epithermal vein systems. Gold systems innovation, and of course, technology. Epithermal mineral deposits are the products of largescale hydrothermal convective systems driven by magmatic heat in the upper 510 km of the earths crust. Hydrothermal alteration and fluid ph in alkalinehosted. The association of gold mineralization with volcanic and geothermal hot spring activity has long been recognized by prospectors and geologists. 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. Survey mineral resources program to update existing, and develop new. Epithermal deposits form in the ground at shallow depths. Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term bonanza. The high and low sulphidation epithermal deposits associated with blue coloured belts are. 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. These deposits are best regarded as components of large hydrothermal systems centered on highlevel, generally oxidized, intermediate to felsic porphyry stocks figure 1.
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