Widespread orogenic gold deposits are hosted by practically all rock types over the range of metamorphic grades in the archaean yilgarn craton, western australia. Crowe fluid chemistry of orogenic lode gold deposits and j. Epithermal gold deposits many of the worlds most famous gold deposits are related to subaerial volcanic activity, these are known as epithermal gold deposits. Research on the characteristics, distribution and timing of these gold deposits tests these classifications and supports an alternative interpretation. Fluid inclusion and h o s pb isotope geochemistry of the. Richard goldfarb, discusses orogenic gold deposits from the 3 aces project camp in the yukon. Atypical gold mineralization in an orogenic settingthe bohaun.
Pdf comparison between orogenic or mesothermal gold. Phillips, 20, continues largely because it is difficult to reliably identify the source of gold. Victoria hosts one of the worlds largest orogenic gold provinces. They are all referred to pretty much the same sort of deposit. Geological characteristics and oreforming process of the. Most ores are postorogenic with respect to tectonism of their immediate host rocks, but are simultaneously synorogenic with respect to ongoing deepcrustal, subductionrelated thermal processes and the prefix orogenic satisfies both these conditions. Lithospheric controls on the formation of provinces. Mineralogical, fluid inclusion and stable isotope characteristics of birimian orogenic gold mineralization at the morila mine, mali, west africa. This remarkable association is clearest in circumpacific mesozoic to cenozoic deposits but is also apparent innorth american, australian and soviet paleozoic deposits within the orogenic belts. In the early 1990s, the crustal continuum model groves, 1993 was developed to explain the occurrence of orogenic gold deposits in metamorphic rocks of granulite to subgreenschist facies. Basing on geological characteristics of the ore deposit as well as new data from the oreforming. A similar deep carbonic source has also been suggested to explain the formation of cm, gold, auriferous pyrite in the sedimenthosted chinese carlintype gold deposits gu et al. 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. Cline characteristics and genesis of epithermal gold deposits d.
They commonly occur in island arcs and continental arcs associated with subduction. To constrain the timing of gold mineralization in the other major gold province of california, white mica was separated from samples from eight deposits. Smith2 abstract mines in the oatman mineralized district, near oatman in northwestern arizona, have produced more than 1. Geological and geochemical characteristics of the sawaya. Debate on the genesis of socalled orogenic gold deposits 75% of gold recovered through history. In combination, lode gold deposits irrespective of their host rocks and host terrane, formed over a. Aug 01, 2001 widespread orogenic gold deposits are hosted by practically all rock types over the range of metamorphic grades in the archaean yilgarn craton, western australia. Latearchean granitoidhosted lodegold deposits, yilgarn. The term orogenic has been originally introduced by groves et al. The table below provides a summary of some major irgs classified deposits, their metal. Also termed as greenstone hosted gold deposits, orogenic gold deposits, shear gold deposits, goldonly deposits intrusion related 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. Orogenic gold deposits were emplaced throughout much of saudi arabia, especially along the numerous strands of the major najd fault system, during ca.
Lithotectonic classification of gold deposits lode gold deposits epigenetic vein deposits of gold in metamorphic terranes kerrich, 1993. The deposits display many similarities to welldescribed turbiditehosted orogenic gold deposits. Cooke, xunrong longd, jun denga, yusheng zhaia a state key laboratory of geological processes and mineral resources, china university of geosciences, beijing 83, peoples republic of china. 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. In contrast to typical orogenic gold deposits displaying textures indicating brittle ductile deformation and recrystallization, those of grass valley only display minor brittle fracturing of quartz and pyrite. Orogenic gold deposits such as huachanggou, liziyuan, and baguamiao lie between the shangdan and mianlue sutures and are confined to wnwtrending brittleductile shear zones in devonian and carboniferous greenschist. Fluid inclusions of orogenic gold deposits in the zhongchuan. Dr richard goldfarb is a world expert on orogenic gold deposits. Generally, orogenic belts consist of long parallel strips of rock exhibiting similar characteristics along the length of the belt. Orogenic gold deposits are the main source of gold for humanity. Timing, nature and characteristics of orogenic gold. It is critical to note that this terminology has been defined solely as a subdivision for orogenic gold deposits based on many modern geothermobarometric studies. Typomorphic characteristics of pyrites from the shuangwang. Structural geometry of gold deposits inherited from earlier tectonic features.
Timing of gold mineralization in the kalgoorlie gold field and its host. Archean orogenic lode gold in the superior province of manitoba. Orogenic gold deposits are typified by quartzcarbonatedominant vein systems. Lithospheric controls on the formation of provinces hosting. There are six worldclass settings for magmatichydrothermal gold deposits. Characteristics of giant orogenic gold systems orogenic gold deposits groves et al. A scaleintegrated exploration model for orogenic gold deposits. Also termed as greenstone hosted gold deposits, orogenic gold deposits, shear gold deposits, goldonly deposits intrusion related deposits deposits having spatial and genetic relationship with. The terrain is dominantly covered by colluvial deposits and post mineral cover rocks, thus indirect targeting. The deposits display many similarities to welldescribed turbiditehosted orogenic gold deposits described from several palaeozoic orogens. 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. Exploring the source of metals in archean orogenic gold. Structural geometry of orogenic gold deposits sga student. Golden predators director and technical committee chair, dr.
Orogenic gold deposits were generated during a time span. 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. Pdf distinguishing intrusionrelated from orogenic gold systems. These characteristics suggest that the granitoidhosted lode gold deposits represent a coherent genetic group that is equivalent to the more abundant greenstonehosted lode gold deposits of the craton. Primary alteration and geochemical dispersion haloes of. The producing guelb moghrein deposit occurs along a shear zone in middle archean rocks at the bend in the northern mauritanides and is most commonly stated to be an iron oxidecopper gold iocg type of deposit, although it also has some important characteristics of orogenic gold and skarn deposits. Gold has historically been a key strategic commodity, and the study of gold deposit formation has long been investigated. Archean orogenic lode gold deposits are the result of large, complex mineralizing systems that have developed within many archean terrains. Irgs gold deposits are commonly confused with orogenic gold deposits with which they share characteristics 1 to 4 above. Formed more than 3 billion years ago, orogenic gold deposits also known as mesothermal deposits are characteristically associated with deformed and metamorphosed midcrustal blocks. At the province to district scale, the association of the larger. The gold resources of mauritania presently include two important deposits and a series of poorly studied prospects.
The four deposits have a total identified mineral resource of. General characteristics of orogenic gold deposits orogenic gold deposits are a widespread coherent group of epigenetic mineral deposits controlled by a similar set of factors groves, 1993. These deposits form in response to major orogenic events caused by accretion or changes in subduction direction or dip. Models and exploration methods for major gold deposit types. Instead, the unique temporal and spatial association of this deposit type with orogeny means that the vein systems are best termed orogenic gold deposits.
Introduction pyrite is one of the most common gold bearing sulfides in a series of hydrothermal gold deposits, such as orogenic type, carlintype, and epithermaltype gold deposits 15. Recent results on structural controls, relative timing and orogenic context of mineralization archean orogenic lode gold in the superior province of manitoba. Orogenic gold deposits are generated at midcrustal 416 km levels proximal to terrane boundaries, in transpressional subductionaccretion complexes of cordilleran style orogenic belts. It has long been recognised that orogenic gold deposits of all. Knoxrobinson, 2000 and are sited in accretionary or collisional orogens of all ages. It was suggested that gold deposits can form at almost any depth in the crust, at temperatures from 750 c to 180 c. Teale2 1 pmdcrc, school of geosciences, monash university, vic 3800, australia. Pdf reduced intrusionrelated gold deposits have become a new, lowgrade, largetonnage exploration target during the last decade. Timing, nature and characteristics of orogenic gold deposits. Distribution of trace elements between carbonaceous matter. Summary characteristics of archean orogenic gold deposits.
On the source of orogenic gold geology geoscienceworld. The country rocks hosting the deposits are predominantly of devonian age with low. Prospectivity analysis of orogenic gold deposits in saqez. Though scarce, gold is concentrated by geologic processes to form commercial deposits of two principal types. Most ores are postorogenic with respect to tectonism of their immediate host rocks, but are simultaneously synorogenic with respect to ongoing deepcrustal, subductionrelated thermal processes and the prefix orogenic satisfies both these. Features of oreforming fluids for orogenic gold deposits. Comments on genesis although still regarded as controversial, intrusion related gold deposits irgd. Epithermal gold deposits part ii geology and gold deposits of the oatman district, northwestern arizona by ed dewitt, jon p. Deposits having spatial and genetic relationship with igneous intrusions. The deposit was included in the sample if its geological characteristics did not contradict to the attributes of orogenic gold deposits formulated in the classical work 4. The twoday course will focus on the geology of and exploration for orogenic gold deposits, the most widespread type of gold deposit globally. Mcqueen crc leme, australian national university, canberra, act 0200 and school of rehs, university of canberra, act 2601.
Gold is relatively scarce in the earth, but it occurs in many different kinds of rocks and in many different geological environments. Mackenzie geology department university of otago po box 56 dunedin 9054, new zealand dave. Epigenetic vein deposits of gold in metamorphic terranes kerrich, 1993. Hydrothermal alteration styles in ancient and modern orogenic gold deposits, new zealand d. Nov 10, 20 dr richard goldfarb is a world expert on orogenic gold deposits. Deposits of this class are formed in deformed and metamorphosed crustal blocks and terranes, typically in greenschist facies rocks adjacent to major crustal fault zones.
Orogenic gold deposits are one of the worlds main groups of gold deposits that provide a source of gold 1, etc. The key geological characteristics of the bohaun mineralization which have a. Hydrothermal alteration styles in ancient and modern orogenic. The most prospective geologic terrain, the altar trend, coincides with a favorable logisticalsocialpolitical location. The study of orogenic au deposits has driven geological research the last 100 years regarding archean tectonics, metallogeny and ore exploration robert et al. Epithermal deposits are classified as products of hydrothermal fluids which have a specific depth range. Orogenic gold deposits archaean greenstonehosted deposits. Introduction ore deposits are crustal concentrations of useful elements that can be exploited at a pro. Gold deposits in polydeformed metasedimentary rocks.
The characteristics, origins, and geodynamic settings of. Host rock characteristics, such as the anomalous thickness resulting from regional deformation during d1, as well as compe. Orogeny usually produces long arcuate from the latin arcuare, to bend like a bow structures, known as orogenic belts. As example, laicpms pyrite mapping shown that gold is associated with silver ratio of auag orogenic gold deposits are one of the most important resources of gold. Fluid inclusions of orogenic gold deposits in the zhongchuan area, western qinling and their geological significance zhang zuoheng institute of mineral resources, chinese academy of geological sciences, beijing 37. Because of this, the depth zones for these orogenic subclasses do not correspond to those in lindgrens epithermal, mesothermal, and hypothermal regimes. Mesothermal and greenstone gold deposits aka orogenic geology. The term mesothermal veins is really a sack term, referring simply to the depth formation.
Geological and geochemical characteristics of the sawayaerdun gold deposit, southwestern chinese tianshan jiajun liua,b,c. They are normally located in second or thirdorder structures, most commonly near crustal to regionalscale deformation zones, in brittle, brittleductile and ductile deformational environments. Recent results on structural controls, relative timing and orogenic context of mineralization scott anderson. The wellknown skellefte ore district, northern sweden, hosts a large number of massive sulphide deposits, a few porphyrytype deposits and a number of gold deposits. He explains how orogenic gold formed during plate tectonic collisions and especially during continental growth.
Bierleinb, franco pirajnoc,d, caisheng zhaoe, huishou yea, feng liua a mrl key laboratory of metallogeny and mineral assessment, institute of mineral resources, chinese academy of geological sciences, 26. Parameters for the formation of orogenic gold deposits. Gold mineralisation stage fluids range from magmatic to dominantly magmatic with variable amounts of external or unexchanged waters, probably introduced into the hydrothermal system during cooling. 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. Hydrothermal evolution of two stages of gold mineralization. One of the unifying characteristics of lode gold deposits through time and space are low to moderatesalinity generally orogenic lode gold deposits worldwide, which are typically located in higher order splays, and as such, the new celebration deposit provides a unique opportunity to study the hydrothermal, structural, alteration and fluid characteristics of a firstorder crustal scale shear zone. General setting geological and structural setting the pilbara craton western australia is a wellexposed 3. Mesothermal and greenstone gold deposits aka orogenic. He explains how orogenic gold formed during plate tectonic collisions and. Short course on orogenic gold in africa and worldwide. In combination, lode gold deposits irrespective of their host rocks and host terrane, formed over a range of crustal. Distinguishing intrusionrelated from orogenic gold systems. Detailed material for this globally important deposit type will be provided on tectonic and structural controls. Of these, the deposits in southern china are remarkably simi.
Geological characteristics and ore forming fluids of orogenic. Although orogenic belts are associated with subduction zones, subduction tectonism may be. Mineral potential tracts for orogenic, carlinlike, and. If all orogenic gold deposits define a coherent mineral system, there are. Pdf mineralogical, fluid inclusion and stable isotope.
Rock magnetic investigations constraining relative timing. Porphyry deposits occur in two main settings within the orogenic belts. Diamond implications for genetic models characteristics and models for carlintype gold deposits a. Boundaries between rigid granitoids and ductile greenstone are common sites for. The jinshan gold deposit is located in the famous dexing copper gold polymetallic district in eastern china fig. The collisionrelated magmatism also provided heat source for regional oreforming fluids in the carlinlike gold deposits. Introduction orogenic gold deposits are an important type of deposit for. This polymetallic district consists of the neoproterozoic jinshan gold deposit 180 tons of au wei 1996, the middle jurassic dexing porphyry cuaumo deposits.
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