Minerals free fulltext physicochemical parameters and. Mesothermal vein gold deposits investing news network june 2nd, 2016 mesothermal veins are known for their large size and continuation to depth, and therefore, are a major source of the world. Macraes orogenic gold deposit new zealand origin and. Deepdyve is the largest online rental service for scholarly research with thousands of academic publications available at your fingertips. Minerals free fulltext fluid inclusion study of the. Because gold is believed to be mostly transported as bisul. Feb 26, 2019 orogenic gold deposits are the main source of gold for humanity. The evidence further indicates involvement of magmatic fluids that is supported by the association of sandstone and carbonaceous black shales with magmatic rocks, such as rhyolite, rhyolitedacite, and trachyteandesite at the tersang and penjom orogenic gold deposits.
Minerals free fulltext invisible gold paragenesis and. White mica 40ar39ar geochronology from goldrich quartz veins by aldo izaguirre,1,2 michael j. Orogeny was used by amanz gressly 1840 and jules thurmann 1854 as orogenic in terms of the creation of mountain elevations, as the term mountain building was still used to describe the processes. Laicpms analysis of pyrite in ten gold deposits is used to determine the precise siting of invisible gold within pyrite, and thus the timing of gold introduction relative to the growth of pyrite and related orogenic events. Regional structures provide the main control on deposit distribution. Reduced intrusionrelated gold deposits have become a new, lowgrade, largetonnage exploration target during the last decade. One of the critical learning points you should walk away with from this talk. Dr richard goldfarb is a world expert on orogenic gold deposits. Utilization of preexisting competent and barren quartz veins as. The term mesothermal veins is really a sack term, referring simply to the depth formation. Gebremariam and stefan hagemann and francois robert.
Orogenic gold deposits are gold lodes within and associated with metamorphic belts 1,7,8,9. Whipple gold deposits of the boulder county gold district, colorado by james a. He explains how orogenic gold formed during plate tectonic collisions and especially during continental growth. 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. Mesothermal and greenstone gold deposits aka orogenic. An orogeny is an event that leads to both structural deformation and compositional differentiation of the earths lithosphere crust and uppermost mantle at convergent plate margins. Because such examples may have many features in common with orogenic gold deposits, such as anomalous bi, w and. These deposits formed from the archaean to phanerozoic at crustal depths of more than 4 km.
Orogenic article about orogenic by the free dictionary. Supergene gold mobility in orogenic gold deposits, otago schist, new zealand 5 ore, and a substantially greater proportion of that nearsurface gold was free particles fig. Neighbouring orogenic gold deposits may be the products of. Gold deposits in polydeformed metasedimentary rocks. Orogenic gold short course orogenic gold deposits in the superior province of manitoba orogenic gold deposits in the superior province of manitoba scott d. The model presented here challenges three current views related to orogenic gold deposits. The dominant sulphides in epizonal orogenic gold deposits are usually arsenopyrite, pyrite and stibnite. Parameters for the formation of orogenic gold deposits. Gold deposits encyclopedia of life support systems. 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. A spectrum of invisible gold relationships in pyrite has been observed which suggests that, relative to orogenic pyrite growth, gold introduction in some deposits is early.
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. Scientific underpinings of orogenic gold presentation. Mesothermal and greenstone gold deposits aka orogenic geology. On the source of orogenic gold geology geoscienceworld. Critical elements in carlin, epithermal, and orogenic gold. The laramide caborca orogenic gold belt of northwestern sonora, mexico. Primary au prospecting results in the logrosan area central iberian zone, spain the origin and assembly of the tethyside orogenic collage at the expense of gondwana land. Sulfur isotopes in sedimenthosted orogenic gold deposits.
Traceelement geochemistry of pyrite and arsenopyrite. The paleoplacer deposits occur as free gold hosted in conglomerates in the banket formation of the tarkwaian group with some hydrothermal. The macraes mine is the only modern mine in otago, and is therefore the only deposit to provide a window into the deeper parts of a mineralised system below the. At present, lodegold exploration in the cgd focuses on both the wellsbarkerville area and the structurally higher rock units of the quesnel terrane, located farther to the south and west where the span ish moun tain and frasergold deposits occur figure 1. New constraints on fluid sources in orogenic gold deposits. The mineralogy of ores changes according to the temperature of gold deposition.
This study of the fennoscandian shields orogenic gold deposits of archean age. Exploration targeting for orogenic gold deposits in the. Geology, fluid inclusion, and isotope constraints on ore. Controls on the distribution of invisible and visible gold in. Goldbearing veins and replacement deposits in the cgd are classed as orogenic systems. Orogenic gold deposits in the superior province of manitoba.
On the basis of their depth of formation, the orogenic deposits are best subdivided into. This book describes the nature and origin of the macraes gold deposit. Most fluids are co2rich and are interpreted to be of metamorphic origin. A carbonaceous sedimentary sourcerock model for carlintype. Vein, stockwork and disseminated gold deposits are very common within orogenic belts, providing a large percentage of total historical world and australian gold production. Orogeny, or mountain formation, is the result of intense upward. 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.
Gold deposits of the tapajos and alta floresta domains. Distinguishing intrusionrelated from orogenic gold systems. A 4d geological model of the gto has previously been developed and constrained by integrated surface mapping, structural analysis, geochemistry and geophysical data detailed in joly et al. This knowledge is used herein to develop a targeting model for orogenic gold deposits in the framework of a mineral systems approach cf. Rapid dewatering of the crust deduced from ages of mesothermal gold deposits. Thus, these deposits most likely share a similar genesis with the jinshan gold deposits and belong to parts of the neoproterozoic orogenic gold belt along the east jiangnan orogen. Well greenstones shears hosted gold deposits are an important source of gold and there are lots of juniors out looking for them. Orogenic gold deposits have formed over more than 3 billion years of earths history, episodically during the middle. Deposits can range from single small quartz veins to large and commonly highgrade, faultshear controlled systems containing in excess of 25 million ounces of gold. Geology and gold deposits of the marysville mining district, montana by james w. Orogenic gold deposits are found in metamorphic belts throughout the world goldfarb et al. 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. The main objective of this report is to present the sample locations, 40ar39ar experimental methodology, and ar39ar isotopic data tables 14.
Orogenic definition of orogenic by the free dictionary. Rapid dewatering of the crust deduced from ages of. 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. The vargbacken orogenic gold deposit, skellefte district. Orogenic gold deposits have typically formed from reduced, near neutral, co2rich and h2sbearing fluids of low salinity. This worldclass gold deposit has been a spectacular geological and economic success story, as. Orogenic gold deposit model vein, stockwork and disseminated gold deposits are very common within orogenic belts, providing a large percentage of total historical world and australian gold production. 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. A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Orogenic gold short course manitoba mining and minerals convention 2008. Detailed material for this globally important deposit type will be provided on tectonic and structural controls. Orogenic gold deposits are the main source of gold for humanity. Timing, nature and characteristics of orogenic gold deposits in the broken river province, ne queensland, australia i.
Pdf parameters for the formation of orogenic gold deposits. It also documents the key features of this spectacular deposit for a wide range of professionals in the resource geology community. Orogenic gold mineralization in the qolqoleh deposit, northwestern. We invite contributions on all aspects of geochemistry applied to these intriguing deposits. The laramide caborca orogenic gold belt of northwestern. Distinguishing intrusionrelated from orogenic gold. Gold in the orogenic gold deposits of the yangshan. That then is a quick summary of greenstoneorogenic shear hosted gold deposits. Gold bearing veins and replacement deposits in the cgd are classed as orogenic systems. 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. Such deposits are thus the largest, single genetic type of deposit for. Orogenic deposits are the source of much of the worlds gold. In the manual analysis, exploration targets are manually identified based solely on the knowledge about the gold mineral systems in the gto that is acquired from the 4d geological modeling and syntheses of orogenic gold systems in general. Carlintype gold deposits in nevada, usa, although characterized by aqueouscarbonic.
More detailed work in this region will be conducted in the future to constrain the genesis of these gold deposits. In contrast to typical orogenic gold deposits displaying textures indicating brittle. Based on the mesoscopic nature of the orebodies, and, in some cases, on microthermometric and stable isotope data, the tapajos gold deposits are classified as 1 orogenic and 2 intrusionrelated, and may be grouped into four deposittype categories. Predictive targeting in australian orogenicgold systems at the. Studies of the geology, mineral paragenesis, fluid inclusions and oxygen geothermometry have been carried out to determine the mineralisation events and alternative. That then is a quick summary of greenstone orogenic shear hosted gold deposits. Nov 10, 20 dr richard goldfarb is a world expert on orogenic gold deposits. A carbonaceous sedimentary sourcerock model for carlin. Victorian gold deposits vary from large turbiditehosted orogenic lode and disseminatedstockwork goldonly deposits, formed close to the metamorphic peak, to smaller polymetallic gold deposits, temporally associated with later postorogenic granite intrusions. Latekinematic timing of orogenic gold deposits and. The process of mountain formation, especially by a folding and faulting of the earths crust. Phillips and powell either as the erosion of primary gold deposits or from hydrothermal accumulation. An orogen or orogenic belt develops when a continental plate crumples and is pushed upwards to form one or more mountain ranges.
There are six worldclass settings for magmatichydrothermal gold deposits. Free gold maps of the united states and other parts of the world, by county. Archean orogenic lode gold deposits are the result of large, complex mineralizing systems that have developed within many archean terrains. Many of these trace elements are commonly referred to as critical or nearcritical elements or metals and have been locally recovered. The best recognized examples of such deposits are recognized throughout the tintina gold province of the northern north american cordillera. A powerpoint from 1995 shows the main consequences of that discovery. Both deposits share the main characteristics of orogenic gold deposits.
Timing, nature and characteristics of orogenic gold deposits. A rchean orogenic lode gold deposits are widespread in most archean granitoidgreenstone terrains fig. Orogenicmesothermalgreenstone gold deposits exploration. Orogenic gold deposits are one of the worlds main groups of gold deposits that provide a source of gold 1, etc. Free gold is rarely found in unoxidised ores and gold may also be present as aurostibite ausb2. Abstract the qolqoleh gold deposit is located in the northwestern part of the. A proposed classification in the context of their crustal distribution and relationship to other gold deposit types, authordavid i. 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.
That is the primary reason orogenic gold deposits low fluid rock ratio are different to porphyry copper deposits where both fluid sources alter the rock high fluid rock ratio. Timing, nature and characteristics of orogenic gold. Deepdyve is the easiest way to get instant access to the academic journals you need. Deposits can range from single small quartz veins to large and commonly highgrade, faultshear controlled systems containing in excess of. Gold deposits can still be seen today forming in some active geothermal areas. Orogenictype coppergoldarsenicbismuth mineralization at. At present, lode gold exploration in the cgd focuses on both the wellsbarkerville area and the structurally higher rock units of the quesnel terrane, located farther to the south and west where the span ish moun tain and frasergold deposits occur figure 1. Here is a look at the components that make up orogenic deposits. Orogenic gold deposits are a widespread coherent group of epigenetic ore deposits that are sited in accretionary or collisional orogens.
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