However, in the yilgarn craton lodes, the low temperature overprint is never pervasive through large volumes of rock, and in all deposits, gold is. The terranes were subjected to compressional or transpressional events involved folding, thrusting. Carlintype gold deposits in nevada, usa, although characterized by aqueouscarbonic. Phillips and powell either as the erosion of primary gold deposits or from hydrothermal accumulation. Mcqueen crc leme, australian national university, canberra, act 0200 and school of rehs, university of canberra, act 2601. The archean orogenic new celebration gold deposit, located in the kalgoorlie terrane of the eastern goldfields province, western australia, is hosted within the western segment of the firstorder boulder lefroy fault zone blfz. Hydrothermal alteration styles in ancient and modern orogenic. Mineral potential mapping for orogenic gold deposits in the rio. Dr richard goldfarb is a world expert on orogenic gold deposits. A rchean orogenic lode gold deposits are widespread in most archean granitoidgreenstone terrains fig.
General setting geological and structural setting the pilbara craton western australia is a wellexposed 3. Exploration targeting for orogenic gold deposits in the granitestanami orogen. Deposit scale structural controls on orogenic gold deposits. The structural controls of gold mineralisation within the. Orogenic gold deposits are the main source of gold for humanity. Jurassic mineralization in the ytt occurred during convergent orogenesis and stacking of previously. Gold occurs in a wide range of deposit types and settings, but this paper is concerned with deposits in which gold forms the main economic commodity or a coproduct. 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. The twoday course will focus on the geology of and exploration for orogenic gold deposits, the most widespread type of gold deposit globally. Feb 26, 2019 pdf orogenic gold deposits are the main source of gold for humanity. Mesothermal and greenstone gold deposits aka orogenic geology. Potential for new gold deposit discoveries in the palaeozoic miogeosynclinal sedimentary sequences of the tasman geosyncline on both sides of the tasman a province known for its orogenic style turbidite. Distribution of orogenic gold deposits in relation to. Whipple gold deposits of the boulder county gold district, colorado by james a.
These deposits formed from the archaean to phanerozoic at crustal depths of more. A peculiar feature of these deposits is the association of gold with a variety of copper sulfides and the rare copper arsenides domeykite and koutekite which is atypical for orogenic type gold deposits. A proposed classification in the context of their crustal distribution and relationship to other gold deposit types, authordavid i. The country rocks hosting the deposits are predominantly of devonian age with low. Gold deposits in jiaodong province have been mainly divided into the extensional massive quartzvein type and the fracture. A scaleintegrated exploration model for orogenic gold deposits. Aug, 2019 the application of depositscale structural targeting to orogenic gold deposits is primarily concerned with locating volumes of highergrade mineralisation ore shoots within a broader, host structural system.
Orogenic deposits are the source of much of the worlds gold. Orogenic gold deposits bohlke, 1982 dominantly form in metamorphic rocks in the mid to shallow crust 515 km depth, at or above the brittleductile transition, in compressional settings that facilitate transfer of hot goldbearing fluids from deeper levels goldfarb et al. These deposits formed from the archaean to phanerozoic at crustal depths of. 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. Controls on the distribution of invisible and visible gold in. This deposit is a classic example of a lowsulfide turbidityhosted orogenic gold quartz deposit sulfide less than 25% located in the folds of sandstoneshale rock as a saddle reef and as discordant veins and stockwork, predominantly in the anticlinal domes. The yukontanana terrane ytt of western yukon territory in nw canada and otago schist belt osb of south island, new zealand share similar geological evolutionary histories as convergent orogenic belts. There are six worldclass settings for magmatichydrothermal gold deposits. Orogenic gold deposits, or gold deposits in metamorphic rocks, are the spatially and temporally most widespread gold deposit type, defining important exploration targets in precambrian shields and in phanerozoic orogen ic belts. Scheelite from 25 representative orogenic gold deposits from various geological settings was investigated by epma electron probe microanalyzer and laicpms laser ablationinductively coupled plasmamass spectrometer to establish discriminant geochemical features to constrain indicator mineral surveys for gold exploration. Both belts host orogenic gold deposits of mainly jurassic to early cretaceous age. The changes in pressure and temperature caused by orogeny release fluids that extract valuable substances such as gold from other places and transport and precipitate them to new places.
Goldfarbb, liang zhangb aorebusters pty ltd, gwelup 6018, western australia, australia. Primary alteration and geochemical dispersion haloes of. Many of these trace elements are commonly referred to as critical or nearcritical elements or metals and have been locally recovered. He explains how orogenic gold formed during plate tectonic collisions and especially during continental growth. Nov 10, 20 dr richard goldfarb is a world expert on orogenic gold deposits.
Six orogenic gold deposits constitute the yangshan gold belt in the west qinling orogen. It is acknowledged that magmatic or thermally driven. The socalled mesothermal gold deposits are associated with regionally metamorphosed terranes of all ages. Orefluid evolution of the sizhuang orogenic gold deposit. Widespread orogenic gold deposits are hosted by practically all rock types over the range of metamorphic grades in the archaean yilgarn craton, western australia. Implications for exploration of worldclass and giant deposits david i. Orogenic gold deposits in the superior province of manitoba. Structural control of the sizhuang worldclass epizonal. Short course on orogenic gold in africa and worldwide.
Ores were formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and. Porphyry deposits are the worlds leading source of copper and molybdenum. Optical microscopy and optical cathodoluminescence imaging. The distribution of au and associated trace elements in pyrite and arsenopyrite from late archean hutti and hirabuddini orogenic gold deposits, eastern dharwar craton, southern india was investigated by laser ablationinductively coupled plasmamass spectrometry. Archean orogenic lode gold deposits are the result of large, complex mineralizing systems that have developed within many archean terrains. Mesozonal orogenic gold was the main source of historical primary gold production and also the predominant original source of gold in alluvial deposits.
Mesothermal gold deposits form half way up through the rise of the melt from the deep crust to the surface usually at a depth of less than 10 km but greater than 1 km. Carlin, epithermal, and orogenic gold deposits, today mined almost exclusively for their gold content, have similar suites of anomalous trace elements that reflect similar lowsalinity ore fluids and thermal conditions of metal transport and deposition. Main deposit types and clans the term orogenic has been originally introduced by groves et al. Much attention has been focused on the source of auriferous fluids. Excluding the supergiant 2,500 tonne au witwatersrand deposits of south africa, archean cratons contain some of the worlds largest gold deposits, including the giant golden mile 2,000 t. Gold deposits can still be seen today forming in some active geothermal areas. The model presented here challenges three current views related to orogenic gold deposits. The term mesothermal veins is really a sack term, referring simply to the depth formation. Controls on the distribution of invisible and visible gold. These deposits form in response to major orogenic events caused by accretion or changes in subduction direction or dip. Introduction ore deposits are crustal concentrations of useful elements that can be exploited at a pro.
Timing, nature and characteristics of orogenic gold deposits. The exception is the kaapvaal craton where a number of orogenic gold deposits are scattered through the barberton greenstone belt. This deposit type also contains a great abundance of gold and silver. Orogenictype coppergoldarsenicbismuth mineralization. Geology and gold deposits of the marysville mining district, montana by james w. He explains how orogenic gold formed during plate tectonic collisions and. Focus paper structural geometry of orogenic gold deposits. Classic provinces in continental settings include the northern. The term orogenic gold deposits has been widely accepted, but there has been continuing debate on their genesis. Such deposits are thus the largest, single genetic type of deposit for.
Gold deposits encyclopedia of life support systems. Orogenic mesothermal gold deposits are known to have varying degrees of alteration associated with their emplacement, but that alteration can be subtle clark et al. Reserves and resources as at june 30, 2017, see news release dated july 26, 2017. Here is a look at the components that make up orogenic deposits.
Three types of inclusions from these deposits have been recognized. Sedimenthosted orogenic gold deposits are associated with largescale, terranebounding fault systems and broad areas of deformation that existed along many of the active margins of precambrian blocks. The saramacca gold deposit, a new orogenic gold discovery. Alteration has been detected around major orogenic gold systems on a scale of hundreds of metres where appro. We treat gold occurrences as a single orogenic type deposit for the purposes of this analysis while recognizing that there may be a range of deposit styles.
The geological characteristics, geochemical signature and. The objectives of this paper are to provide an update on gold deposit models, and what new approaches and techniques can now be used to find gold deposits. Geological survey, box 25046, ms 964, denver federal center, denver, co 802250046, usa b state key laboratory of geological processes and mineral resources, school of earth sciences and resources, china university of geosciences, beijing 83, china. Goldfarbb, liang zhangb aorebusters pty ltd, gwelup 6018, western australia, australia b state key laboratory of geological processes and mineral resources, china university of geosciences, beijing 83, china. Orogenic gold deposits have been separated into mesozonal and epizonal mineralisation on the basis of the depth and temperature of gold deposition. Pdf exploration targeting for orogenic gold deposits in. The genesis of veintype to disseminated gold deposits, broadly classified as orogenic gold deposits groves et al. Contrasting geochemistry of orogenic gold deposits in yukon. Gold is mostly invisible in solid solution or in the sulfide lattice, with minor visible gold associated with stibnite and in quartzcalcite veins. The orogenic gold deposits are confined to this jog and are sited in a number of d2 shear zones at, or close to, their intersection with the crossfault arrays. Fluid inclusions of orogenic gold deposits in the zhongchuan.
Trace element composition of scheelite in orogenic gold deposits. Although empirical correlations between structural heterogeneities and ore shoots have long been noted and certain key physical processes elucidated, no integrated, systembased. Fluids in orogenic gold deposits orogenic gold deposits are, as their name indicates, orogeny related. Distribution of orogenic gold deposits in relation to fault. A holistic model for the origin of orogenic gold deposits and its. Timing, nature and characteristics of orogenic gold. Gebremariam and stefan hagemann and francois robert. Hydrothermal evolution of two stages of gold mineralization. Parameters for the formation of orogenic gold deposits. This setting contrasts with the majority of orogenic lode gold deposits worldwide, which are. Jurassic mineralization in the ytt occurred during convergent orogenesis and stacking of. Orogenic gold deposits bohlke, 1982 dominantly form in metamorphic rocks in the mid to shallow crust 515 km depth, at or above the brittleductile transition, in compressional settings that facilitate transfer of hot gold bearing fluids from deeper levels goldfarb et al.
A carbonaceous sedimentary sourcerock model for carlin. Mineral system analysis, targeting model and prospectivity analysis. Such an assumption is valid because this deposit type is, by far, the most dominant gold deposit type in the studied craton. Critical elements in carlin, epithermal, and orogenic gold. A carbonaceous sedimentary sourcerock model for carlintype. Gold rich porphyry deposits occur in both continental and islandarc orogenic settings. On the source of orogenic gold geology geoscienceworld. Orogenic definition of orogenic by the free dictionary. Contrasting geochemistry of orogenic gold deposits in. Gold deposits in polydeformed metasedimentary rocks. Most genetic hypotheses for orogenic gold deposits that involve nearsurface or magmatichydrothermal fluids are now negated in terms of a global mineral. Depositscale structural controls on orogenic gold deposits. Predictive targeting in australian orogenicgold systems.
Orogeny, or mountain formation, is the result of intense upward. Models and exploration methods for major gold deposit types. The first approach considers orogenic gold deposits hosted at the contact between mafic and felsic rocks. Importantly, the lodes may be located on one side of a cross fault, but not consistently displaced to the other side of the fault. A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. As the tectonic setting and origin of gold mineralization are di erent from typical conventional orogenic gold, some studies term these deposits jiaodong type 2628. Detailed material for this globally important deposit type will be provided on tectonic and structural controls. In contrast to typical orogenic gold deposits displaying textures indicating brittleductile deformation and recrystallization, those of grass valley only display minor brittle fracturing of quartz and pyrite. Pdf orogenic gold deposits are the main source of gold for humanity. This workshop on orogenic gold will be held at the university of cape town from february 2 to 3, 2019, the weekend prior to the mining indaba meeting. This study presents data on the geological setting and ore mineralogy of these deposits. Pdf with very few exceptions, orogenic gold deposits formed in subduction related tectonic settings in accretionary to collisional orogenic.
Pdf parameters for the formation of orogenic gold deposits. The application of deposit scale structural targeting to orogenic gold deposits is primarily concerned with locating volumes of highergrade mineralisation ore shoots within a broader, host structural system. Timing, nature and characteristics of orogenic gold deposits in the broken river province, ne queensland, australia i. The process of mountain formation, especially by a folding and faulting of the earths crust. Mesothermal and greenstone gold deposits aka orogenic. They are normally located in second or thirdorder structures, most commonly near crustal to regionalscale deformation zones, in brittle, brittleductile and ductile deformational environments.