Gold can be described according to its natural size and nature of occurrence. Does gold in orogenic deposits come from pyrite in deeply. Using the world gold councils gt standard, many of the worlds highgrade gold mines are in the united states, russian, and peru. A syngenetic perspective is a comprehensive study of gold deposits, including field studies, geochemistry and structural overprinting with many examples of canadian lode gold deposits the book mentioned here is designed to provide geologists with the tools to develop comprehensive exploration and prospect evaluation. Gold deposits encyclopedia of life support systems. Many diverse ore systems are classified together as iron oxide copper gold locg deposits based on an empirical definition arising primarily from geochemical features that do not specify tectonic setting, geologic environment, or sources of oreforming fluid, metals, or other ore components. Pdf orogenic gold deposits are the main source of gold for humanity. The gold deposit type is the next stage in the transformation of the gold. Pdf documents opened from your browser may not display or print as intended.
Orogenic gold deposits, sources of fluids, sources of gold, sources of ligands, gold solubility, precipitating mechanisms, fluid channelling, gold exploration. Parameters for the formation of orogenic gold deposits. Orogenic gold deposits are the main source of gold for humanity. Gold mineralization in the eastern desert of egypt is confined, almost completely, to the basement rocks of the nubian shield that was cratonized during the panafrican orogeny. This type of deposit has long been exploited by gold panners, using small.
A rational geological classification of the commonly recognized lode gold deposits is feasible if it is based on the geological settings of the deposits, host rocks, nature of mineralization and geoche mical signature. Introduction ore deposits are crustal concentrations of useful elements that can be exploited at a pro. The books empirical model incorporates widely known and accepted principles of ore deposition and shows how it applies in the volcanicsedimentary greenstone belt environment. The purpose of this paper therefore is to present a. At the same time, gold bearing placer or alluvial deposits are being exhausted in other areas, forcing. This research has revealed a consistent pattern of geostructural and. Goldtelluride associations are typically regarded as characteristic of epithermal gold deposits as defined by hedenquist et al.
The gold mineralization, occurring in eastwest trending shear zone, shows a close spatial relationship to zones of intense alteration. Sixteen common types of bedrock gold deposits are distinguished from one another and their main geological attributes are. Although this classification is the first actual attempt at classifying gold deposits in egypt, it ignores the tectonic setting of host rocks, as well as the source of the. Thus, 14karat 14k gold indicates a composition of 14 parts of gold and 10 parts of other metals. The metallogenic relationship between birimian and tarkwaian. Archean orogenic lode gold deposits tend to occur in clusters within mining camps, defined as areas of about 100 km 2. Mcqueen crc leme, australian national university, canberra, act 0200 and school of rehs, university of canberra, act 2601.
This research has revealed a consistent pattern of geostructural and metallogenic evolution in. Metallogenetic provinces in the circumarcticre gion summary. There is a need to summarize such information and, more importantly, to attempt to synthesize it into a coherent classification of gold deposits. Mineralizing systems are defined to include all geologic factors that control the generation and preservation of mineral deposits and emphasize the processes responsible for deposit formation at a variety of scales. T he major gold deposits ar e located in the bir imian ar ea in upper guinea. Vein formation and deformation in greenstone gold deposits. Sulfur radical species form gold deposits on earth pnas. Archean orogenic lode gold deposits are the result of large, complex mineralizing systems that have developed within many archean terrains. Nov 03, 2015 the formation of gold deposits on earth requires aqueous fluids that extract gold from minerals and magmas and transport and precipitate the metal as economic concentrations in ores that are three to six orders of magnitude larger than the au mean content. Geologie et metallogenie des mineralisations a or et antimoine du jbel. Geochemistry, alteration, and genesis of gold mineralization. Gold deposit types gold prospecting equipment,tips. Classification of gold deposits is much more than a textbook exercise.
Predicted concentrations of the gold sulfide and chloride species in such fluids are generally rather low pdf format, 65 kb. Oct 16, 2016 classification of mineral deposit in egypt 1. Samples and methods representative whole rock samples were collected from unaltered metagabbro and zones of different. Pdf hydrothermal gold deposits epithermal, carlintype, and. For best results viewing and printing pdf documents, it is recommended that you download the documents to your computer and open them with adobe reader. The southwestern alaska mercury belt and its relationship to. There are six worldclass settings for magmatichydrothermal gold deposits. Metallogeny of gold in relation to the evolution of the. Tectonics and metallogeny of gold deposits in china article pdf available in mineralium deposita 373. Introduction to geology and resources of gold, and geochemistry of gold the case for gold an introduction to geology and resources of gold in the united states by daniel r. The most common occurrence of te is the low sulfidation type that is spatially associated with alkaline. Based on available resource data, hodgson 1993 estimated that the 28 deposits. Secondary deposits lateritic deposits laterites produced by tropical weathering of a wide range of primary rock types, including micashist, gneiss with diffused gold, magnetite quartzite, amphibolite, pegmatite and quartz veins, are important sources of gold in madagascar.
Some geologists think these deposits were formed when streams deposited the gold into an. Quebec mines new gold targets in the chibougamau area. Introduction to geology and resources of gold, and. This will increase mercury demand for use in smallscale gold mining if the present, lavish hg practices continue. The pattern of hydrothermal alteration associated with a gold prospect located within a differentiated ironrich gabbro sill in the chibougamau region has been investigated in order to establish the alteration mechanism. Phillips and powell either as the erosion of primary gold deposits or from hydrothermal accumulation. Metallogeny of the east malartic gold deposits, quebec. The massive deposits of the witwatersrand mines in south africa have produced more than 40 percent of the worlds total production of gold.
The gold mineralizations in the adola belt, similar to gold deposits in the ans, are strongly associated with the sheared and hydrothermally altered volcanosedimentary rocks and hosted in quartz veins of variable composition. The southwestern alaska mercury belt and its relationship. Homestake mine, located in western south dakota, was created in 1876. Porphyry deposits are the worlds principal resources of cu, mo, and re, and are major. Jiang, department of geology, the university of newcastle, callaghan, new south. Distribution of orogenic gold deposits in relation to fault. Orogenic gold deposits account for an estimated 75% of the gold extracted by humans phillips 20, including the tonnage of witwatersrand, the worlds largest district. Once there it will settle itself into various bends, fissures and various other obstructions in the river system. Cur r ently, the country annually pr od uces about 810 tons of gold, divided between the miners and industr ial.
Gold deposits can still be seen today forming in some active geothermal areas. Among these, the bourlamaque batholith in the valdor area hosts several gold deposits along its margins. The chibougamau mining district is known for its gold and copper potential. Paleoproterozoic, mali, west african craton, greenstone belt, shear, orogenic.
Gold auriferous deposits can be classified into types for which here is a list of 10 types of gold deposits. A syngenetic perspective is a synthesis of lode gold vein forming processes, addressing the commonality in similar worldwide deposits. Many diverse ore systems are classified together as iron oxide coppergold locg deposits based on an empirical definition arising primarily from geochemical features that do not specify tectonic setting, geologic environment, or sources of oreforming fluid, metals, or other ore components. The metallogenic relationship between birimian and. Such deposits are thus the largest, single genetic. Incidentally, 14k gold is commonly used in jewelry manufacture. And yet, exploration in the western part of the chibougamau pluton pdf format, 64 kb was mainly focussed on the search for copper, between 1935 and 1965. Gold, platinum group metals, tin, diamonds, rare earth metals, thorium, titanium, and uranium what is black sand, what is it composed of. Iron oxide copper gold ore deposits iocg are important and highly valuable concentrations of copper, gold and uranium ores hosted within iron oxide dominant gangue assemblages which share a common genetic origin. At the same time, goldbearing placer or alluvial deposits are being exhausted in other areas, forcing.
Gold is relatively scarce in the earth, but it occurs in many different kinds of rocks and in many different geological environments. Camps show a characteristic variation in size hodgson, 1993 with most of the production coming from worldclass 100 t au and a few giant 500 t au deposits. Goldbearing gravels are shoveled into the upper end of the sluiceway. Since the first production in 1878, almost 28 million troy ounces of gold have been extracted, worth 987 million dollars at present price causing the mine to be the most valuable in the united states. Gold bearing gravels are shoveled into the upper end of the sluiceway. The c 2 h 6 content is recorded in fluids from mesoarchean to cretaceous gold deposits, providing support for a general model where fluids and gold were sourced from deeply buried, carbonrich, and pyritegoldbearing sedimentary rocks. Similarly, there are many other examples of gold deposits associated with granitoid intrusions in the abitibi geological subprovince. Nov 27, 2012 further west in victoria there is very little gold in granite eg a bit around mafeking in the grampians, and north of lancefield, and only mafeking had any significant production from deposits in granites different in the northeast of the state, eg glen wills was important. Further west in victoria there is very little gold in granite eg a bit around mafeking in the grampians, and north of lancefield, and only mafeking had any significant production from deposits in granites different in the northeast of the state, eg glen wills was important. High gold prices lure miners into the ssgm sector in regions where suitable gold deposits are still available.
An iron deposit appears thus as the combination of favourable elementary geological phenomena with the specific properties of iron. The origin of these ancient oresseveral billion years oldis controversial. Such deposits have 1 cu, with or without au, as economic metals. Shawe geochemistry of gold in hydrothermal deposits by samuel b. Islandarc, orogenic and postorogenic stages are indicated for the tectonicmagmatic evolution of the nubian shield in late proterozoic times. The detrital sedimentary units described in these regions have been attributed to the tarkwaian system. Although the exact method of how lode gold is formed is the subject of dispute among some geologists, many scientists belie that lode gold is deposited underground due to the. These deposits formed from the archaean to phanerozoic at crustal depths of more than 4 km.
Codes the australian research councils centre for excellence in ore deposit research, university of tasmania, private bag 126, hobart, tasmania 7001, australia. New gold targets in the chibougamau area patrick houle geologie quebec. Though scarce, gold is concentrated by geologic processes to form commercial deposits of two principal types. This has been taken away from the immediate vicinity of the source rock and eventually found its way into a river system. A belt of small but 1111i11erous mereury deposits extends for about 500 km in the kuskokwim river region of southwestern alaska. Pdf tectonics and metallogeny of gold deposits in china. Pdf parameters for the formation of orogenic gold deposits. Definition of gold rich volcanogenic massive sulphide deposits simplified definition a lens of iron, copper, zinc and leadsulphides, with significant amounts of silver and gold, formed on or below the sea floor by hot springs on and around submarine volcanoes. Pdf metallogeny of the east malartic gold deposits. Pdf geochemistry of hydrothermal gold deposits researchgate. Goldauriferous deposits can be classified into types for which here is a list of 10 types of gold deposits. The traditional concept of the early proterozoic gold deposits in ghana i. The metallogeny of lode gold deposits queens university. Gr gold in madagascar andriamampianina roger rambeloson ddpflrtenicrit clcs scieiiccs cle in terrc, uizivcvsitd dantaiminrivo, macllrgflscnr mnliscrpt r.
These ore bodies range from around 10 million tonnes of contained ore, to 4,000 million tonnes or more, and have a grade of between 0. Gold telluride associations are typically regarded as characteristic of epithermal gold deposits as defined by hedenquist et al. The key parameters accounting for their formation remain under discussion. The books empirical model incorporates widely known and accepted principles of ore deposition and shows how it applies in the volcanicsedimentary greenstone belt. Input data for the present study are existing gold deposits, mapped and interpreted faults, and multiscale.
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