Department of energys office of scientific and technical information. Zaf corrections were made with proprietary joel software. Hydrothermal alteration and fluid ph in alkalinehosted epithermal. Epithermal vein systems mostly low sulphidation are controlled by the interaction of. Characteristics of highsulfidation epithermal deposits, and their relation to magmatic fluid antonio arribas jr. Partington2 1 institute of geological and nuclear sciences, po box 30368, lower hutt, new zealand. Models and exploration methods for major gold deposit types. 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 and silver deposits icmjs prospecting.
Porphyry coppergold and epithermal goldsilver systems. Hydrothermal alteration and fluid ph in alkalinehosted. Alkalic porphyry and epithermal deposits a view from. Quality low sulphidation epithermal auag mineralisation is best developed in settings. A multiscalar perspective from the mercedes district, sonora, mexico geoffrey k. Thermal springs and epithermal ore deposits journal. Island arc metallogenesis, geothermal systems and geology on free shipping on qualified orders. Prospectivity models and gis data for the exploration of epithermal gold mineralisation in new zealand m. 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. Airborne geophysical results over t he dolly varden high. Burtner independent consultant, reno, nv mark hawksworth yamana gold, reno, nv jose carlos beltran encinas yamana gold, hermosillo, sonora, mexico tommy b. Characteristics of high sulphidation epithermal gold deposits. Controls to low sulphidation epithermal auag mineralisation presentation to the sydney mineral exploration discussion group. 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.
Classification vs modeling each ore deposit is unique like a persons finger print this uniqueness arises out of. 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. Gold grade distribution within an epithermal quartz vein system. Lowsulphidation epithermal systems free download as powerpoint presentation. 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. Lowsulphidation epithermal systems silicon dioxide. Remnants of most of these products are preserved in some of their lesseroded, extinct equivalents. However, many known alkalicrelated deposits contain. Earlier on greenstone shear zone hosted gold, where we covered various ways to drop gold from a fire complex solution. Summary of geophysical responses over epithermal systems modified after hoschke, 2011. Epithermal gold deposits of the southwest pacific, journal.
A new programme to explore these favourable epithermal systems, it will be successful in locating new gold deposits. 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. Controls to low sulphidation epithermal auag mineralisation. 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. 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. Mag3dinv software was undertaken campagne, 20 on the. Fluids leach gold from low abundance crustal rocks big systems source gold from large volumes of crust. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. 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. Published examples of vtem surveys over hs epithermal gold deposits include cerro quema in panama kwan et al. When digging, mining an epithermal deposit, the surrounding rock formations are usually permeated with associated minerals and gold.
Ag tend to be most elevated deeper ni hte systems, with au, ag. Ore deposits 101 part 5 epithermal deposits youtube. 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. The occurrence of gold mainly depends on temperature, pressure, ph values, cl. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. Competent host rocks fracture to aid vein formation. Hse precious metal systems are associated with large systemically zoned advanced argillic to argillic alteration systems. Hydrothermal mineral deposits are those in which hot water serves as a concentrating, transporting, and depositing agent. They are the most numerous of all classes of deposit. 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. Descriptive models for epithermal goldsilver deposits usgs. Jon hronsky from western mining services and featured in an abc news clipping and article entitled. Although they are a product of the same igneous system, low sulfidation epithermals gold deposits are very different from high sulfidation. Pdf the mineral products of boiling in the golden cross.
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. Structural, textural and supergene controls on grade and. In low sulfidation the main control for gold deposition, is fluid boiling caused by a drop in the confining pressures the fluid approaches the surface. This photo is pamukkale, low sulfidation hot springs. In this post, i would like to share some key points for conceptual mapping of hydrothermal alteration in high sulfidation hs epithermal systems. 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. A number of studies richards, 1995, jensen and barton, 2000, muller, 2002, sillitoe, 2002 have recognised that epithermal deposits developed in alkaline host rocks tend to have anomalous features relative to calcalkaline hosted systems they are commonly gold and telluriderich, have less hydrothermal quartz, and limited development of. Characteristics of high sulphidation epithermal gold. Epithermal gold mineralisation is found in a wide compositional range of host.
Now lets quickly cover the last of the broad groups, the intermediate sulfidation epithermal. We have extensive experience designing, developing, deploying, and maintaining enterpriselevel it solutions. Survey mineral resources program to update existing, and develop new. A fascinating group and characteristic of epithermal gold deposits is that you can virtually see them forming today, simply by visiting hot springs. Pdf exploration for epithermal gold deposits researchgate. Controls to low sulphidation epithermal auag mineralisation greg corbett. The oreforming fluids of ls epithermal deposits have been fully investigated. Like those with yellowstone in wyoming or rotorua in new zealand. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1. The auas and ausb associations are common in gold deposit. 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. Sulfur could hold key to next generation of mining deposits, research says. The mineral products of boiling in the golden cross epithermal deposit.
Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term bonanza. They contain economic concentrations of gold, silver and in some cases base metals such as copper, lead and zinc. Tellurium in igneousrelated epithermal precious metal. Scribd is the worlds largest social reading and publishing site.
Epithermal mineral deposits are the products of largescale hydrothermal convective systems driven by magmatic heat in the upper 510 km of the earths crust. Alteration vectoring in epithermal high sulfidation auag. They are popular with prospectors because can yield very rich deposits and they are widespread in the western us. 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. Not only about delivering exceptional software, but also about the communities our technical solutions serve. Pdf epithermal gold for explorationists researchgate. 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. High sulphidationepithermal deposits explorationalliance. E pithermal gold deposits form in the shallow parts of magmarelated hydrothermal systems, commonly in subaerial volcanic arcs fig. 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. Structural, textural and supergene controls on grade and zonation in epithermal vein systems. Society of economic geologists special publication 6, 234 p.
The high and low sulphidation epithermal deposits associated with blue coloured belts are. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. Duration of hydrothermal systems that form epithermal goldsilver deposits. 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. Metallis expands goldrich mineralization at cole porphyry. 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. The geochemical behavior of gold in hydrothermal systems. The nizi hosts gold bearing epithermaltype veins associated with felsic volcanic rocks cavey and chapman, 1992. 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. Gold ore in lowsulfidation deposits is commonly associated with quartz and adularia, plus.
Notable exceptions are those gold deposits hosted in alkaline host rocks. Prospectivity models and gis data for the exploration of. Models and exploration methods for major gold deposit types robert, f. Precious metals accompany all types of epithermal deposits. Hydrothermal deposits are never formed from pure water, because pure water is a poor solvent of most ore minerals. How metalliferous brines line mexican epithermal veins. Most of the epithermal systems have mineral assemblages and textural features which suggest formation at shallow depth.
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 mineralization at apigania bay is one of several graniterelated goldsilver. Mineral deposit mineral deposit hydrothermal solution. 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. In the case of exploration for epithermal gold deposits, this understanding can be augmented. Epithermal gold deposits are often appealing to mining companies because they are typically highgrade, smallsize deposits. 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.
Skukum and the epithermal systems associated with the carmacks group in the yukon, that was not previously. 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 deposits form in the ground at shallow depths. The following aspects of the epithermal precious metal deposits in volcanic environments are of particular interest to exploration geologists. It is obviously good practise,when exploring for epithermal gold mineralisation at any scale,to sample any vein material. Clarke epithermal mineralisation research unit, geology department, universityof auckland, privatebag, auckland, new zealand abstract vein samplesfrom the exploration for epithermal mineralisation are commonly subjectedtomultielement. High sulphidation epithermal deposits form in continental and. How metalliferous brines line mexican epithermal veins with. 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. Crystal laflamme and phd candidate stefano caruso were joined by adjunct professor and cet board member dr.
The formation of the axi epithermal gold deposit involved two major. These deposits are best regarded as components of large hydrothermal systems centered on highlevel, generally oxidized, intermediate to felsic porphyry stocks figure 1. Porphyryrelatld low sulfidation gold systems 195 society of ecoiomc geologists special publication no. Other articles where epithermal deposit is discussed. Hydrothermal alteration and fluid ph in alkalinehosted epithermal systems. 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 gold deposits in volcanic terranes springerlink. Most of the samples from veins in the oatman area analyzed by smith. Papua new guinea is endowed with spectacular porphyry copper gold and epithermal gold. The association of gold mineralization with volcanic and geothermal hot spring activity has long been recognized by prospectors and geologists. Gold systems innovation, and of course, technology. Fluids migrate upwards along faults and permeable horizons.
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