Epithermal gold deposits styles characteristics an. Geology, geochemistry and mineralogy of epithermal gold ores. Hydrothermal fluids forming epithermal gold deposits are ausaturated in most cases, whereas deposits of carlintype are auundersaturated. Classification vs modeling each ore deposit is unique like a persons finger print this uniqueness arises out of. Geological features of some epithermal gold systems. 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. More information about viewing, downloading, and printing report files can be found here. 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. Each hydrothermal mineral deposit has different distinct structures, ages, sizes, grades, geological formation, characteristics and. The first is epithermal gold deposits associated with magmatic rocks, the second is epithermal gold.
Distinctive features typically present include key alteration mineral assemblages low sulphidation. Internal vein texture and vein evolution of the epithermal. Hydrothermal circulation occurs most often in the vicinity of sources of heat within the earths crust. Minerals free fulltext formation and aggregation of. Such controls occur commonly in ls epithermal deposits worldwide, but unfortunately, these have not been quantitatively analyzed to determine their spatial relationships with gold distribution and further guide mineral prospecting. 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. Minerals free fulltext formation and aggregation of gold. Since all major quartzillite systems in the philippines are mineralized, epithermal ore bodies are unlikely to be dependent on the presence of either specific goldrich source rocks or preexisting gold deposits e. In general, this occurs near volcanic activity, but can occur in the deep crust related to the intrusion of granite, or as the result of orogeny or. For best results viewing and printing pdf documents. The ore deposits of the oatman area comprise gold bearing quartzcalcite veins which occupy fault fissures in. 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.
Interestingly, while all free au observed in this study has been in the form of electrum, au and ag. 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. Hydrothermal mineral deposits are divided into six main subcategories. Epithermal gold and silver deposits, silver citydelamar.
Among the numerous classifications that followed, one group of deposits clearly showed a common set of. Gold deposits encyclopedia of life support systems. On the basis of the distribution of these veins and their mineralogy, the veins are divided into three groups. Other articles where epithermal deposit is discussed. Characteristics and genesis of epithermal gold deposits. Epithermal veins tend not to have great vertical continuity, but many are exceedingly rich and deserving of the term bonanza. Hydrothermal fluids forming epithermal gold deposits are ausaturated in most cases, whereas deposits of. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. Chemistry and occurrences of native tellurium from epithermal.
There are six worldclass settings for magmatichydrothermal gold deposits. Unfortunately, the tonnage of ore in epithermal veins is typically small compared with other types of lower grade gold deposits. In the case of exploration for epithermal gold deposits, this understanding can be augmented by familiarity with. Epithermal gold deposits dlc 90003011 ocolc21293922. What are the characteristic textures of epithermal gold deposits. They eventually create richmetallic fluids concentrated in a selected volume of rock, which become supersaturated and then precipitate ore minerals. Pdf epithermal gold deposits styles characteristics an. As epithermal quartz goldsilver mineralisation is characterised by coarse free.
Pdf documents opened from your browser may not display or print as intended. Correct identification of continental and oceanic arc settings is a pre. University of idaho morrill hall, 3rd floor 875 perimeter dr. Gold from lebong tandai drillcore, 2007 epithermal gold deposits a very important style of gold deposit can be very big.
If we group the deposits according to their characteristics, we get a. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1. Although they are a product of the same igneous system, low sulfidation epithermals gold deposits are very different from high sulfidation. 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. Controls to low sulphidation epithermal auag mineralisation. Hoover summary of relevant geologic, geoenvironmental, and geophysical information deposit geology central advanced argillic zone has iron, copper, and arsenicrich sulfide and sulfosalt minerals with. Lindgren, 1922, lindgren, 1933 first defined epithermal deposits as precious metal. Types, characteristics, and geodynamic settings of. 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. Jun 23, 2011 the epithermal gold deposits with telluriferous minerals are distributed widely in cretaceous to the present volcanic terranes in the japanese islands. Characteristics and behavior of hydrothermal fluids for gold. This below is an image of a simple low sulfidation vein system, with all its components preserved. Hoover summary of relevant geologic, geoenvironmental, and geophysical information deposit geology central advanced argillic zone has iron, copper, and arsenicrich sulfide and sulfosalt minerals with high acid.
E pithermal gold deposits form in the shallow parts of magmarelated hydrothermal systems, commonly in subaerial volcanic arcs fig. High sulphidation epithermal deposits form in continental and oceanic arc settings as subducting oceanic plates melt and generate large intrusive complexes and associated hydrothermal circ ulation cells. Ore deposits 101 part 5 epithermal deposits youtube. They contain economic concentrations from a precious metal such as gold and silver, and in some cases base. The occurrences of native tellurium are limited in the following six deposits.
Pdf geophysical exploration for epithermal gold deposits. The teine deposits are epithermal telluriferous gold. Pdf exploration for epithermal gold deposits researchgate. A large portion of the worlds economic deposits 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. Characteristics of high sulphidation epithermal gold. In some occurrences, minerals can be extracted at a profit by mining. Epithermal gold and silver deposits icmjs prospecting. View epithermal gold deposits research papers on academia. This concept was first proposed almost a century ago but the development of new analytical technologies, lab experiments, and the discovery of new epithermal deposits where nanoparticles are evident have added credence to. Chris ralph, professional prospector 8,114 views 34. The auas and ausb associations are common in gold deposit. Chris ralph, professional prospector 7,673 views 34. Minerals free fulltext 3d mineral prospectivity modeling.
Epithermal gold deposits free download as pdf file. Gold deposits can still be seen today forming in some active geothermal areas. Epithermal deposits include a broad range of precious metal, base metal, mercury. Cripple creek, usa 630 t au in veins grading 15 to 30 gt hishikari. Nov 26, 2018 epithermal comparative more epithermal, superlative most epithermal describing deposits of minerals formed from warm water at shallow depth describing neutrons of kinetic energy greater than that of thermal motion. Epithermal deposits form in the ground at shallow depths. This below is an image of a simple low sulfidation vein system, with all its. Hydrothermal circulation in its most general sense is the circulation of hot water ancient greek. The axi lowsulfidation ls epithermal deposit in northwestern china is the result of geological controls on hydrothermal fluid flow through strikeslip faults. According to sugimoto 1952, they occur in altered andesite and greenish tuffs of the teine formation in the zenibako group of the middle miocene in age. Part or all of this report is presented in portable document format pdf. Lindgren 1922 defined epithermal deposits as forming at shallow depths epithermal ore deposits form at shallow depth.
The epithermal deposits of the yanacocha district are classified as highsulfidation or acidsulfate epithermal deposits e. Geophysical exploration for epithermal gold deposits. Teine and kobetsuzawa in the western hokkaido, mutsu in the shimokita peninsula of the northern honshu, kawazu 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.
Pdf the successful exploration geologist uses knowledge of geologic relationships and oredeposit styles. Hydrothermal mineral deposits are accumulations of valuable minerals which formed from hot waters circulating in earths crust through fractures. Characteristics of high sulphidation epithermal gold deposits. 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.
Chemistry and occurrences of native tellurium from. Document, government publication, national government publication, internet resource. This concept was first proposed almost a century ago but the development of new analytical technologies, lab experiments, and the discovery of new epithermal deposits where nanoparticles are evident. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. The gold fields salares norte and barrick gold alturas projects represent examples of a new wave of. Like those with yellowstone in wyoming or rotorua in new zealand. Download the latest version of adobe reader, free of charge. 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. A fascinating group and characteristic of epithermal gold deposits is that you can virtually see them forming today, simply by visiting hot springs. They are popular with prospectors because can yield very rich deposits and they are widespread in the western us. The discovery and geology of the salares norte epithermal gold silver deposit, northern chile, ame roundup january 2017 funnel shaped ore body initial inferred resource. This conclusion was initially based on geologic reconstructions, ore mineralogy and related textures lindgren, 1933. Hydrothermal ore deposits edit during the early 1900s, various geologists worked to classify hydrothermal ore deposits that they assumed formed from upwardflowing aqueous solutions.