Such deposits have been referred to as goldplus deposits e. These deposits form in response to major orogenic events caused by accretion or changes in subduction direction or dip. A brief introduction to orogenic gold deposits gold fields. The country rocks hosting the deposits are predominantly of devonian age with low. Implications for exploration of worldclass and giant deposits david i.
Parameters for the formation of orogenic gold deposits. There are six worldclass settings for magmatichydrothermal gold deposits. Several recurrent and typical field characteristics include 1 at a regional scale, location of the mineralization in loworder structures. In the above orogens, isotopegeochronological estimates suggest that the ore deposits were formed late in the orogenic history or even after orogeny had demonstrably ended 3,4,10,11. Schematic representation of the range orogenic gold deposits. For orogenic gold deposits, integrated terrane to district scale tectonic, structural and geochronological studies worldwide have demonstrated a latekinematic timing of gold mineralization related to a change from compression normally annotated d1d2 to.
Distribution of orogenic gold deposits in relation to. Irgs gold deposits are commonly confused with orogenic gold deposits with which they share characteristics 1 to 4 above. In both types of orogen, hydrated marine sedimentary and volcanic rocks have been added to continental margins during tens to some 100. Structural geometry of gold deposits inherited from earlier tectonic features. Coffee is interpreted as an epizonal orogenic gold deposit, the result of a regionally significant gold. Aspects of the genesis of many gold deposits remain unanswered. Orogenic gold deposits are one of the worlds main groups of gold deposits that provide a source of gold 1, etc. This spatial association, the ore fluid characteristics, and the midcretaceous tectonic regime argues for ore fluids sourced from metamorphic devolatilization of likely siliciclastic rocks at depth. The characteristics, origins, and geodynamic settings of. Orogeny, or mountain formation, is the result of intense upward. Within the host volcanosedimentary sequences at the province scale, worldclass orogenic gold deposits are most commonly located in secondorder structures adjacent to crustal scale faults and. There is a need to summarize such information and, more importantly, to attempt to synthesize it into a coherent classification of gold deposits.
Main features of alteration zones identifiable in hand specimen in alteration sequences surrounding orogenic gold deposits hosted in metamorphosed. On the source of orogenic gold geology geoscienceworld. 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. Coffee is interpreted as an epizonal orogenic gold deposit, the result of a regionally significant gold mineralizing event. Mineral potential tracts for orogenic, carlinlike, and. Magnetic signatures related to orogenic gold mineralization, central lapland. Models and exploration methods for major gold deposit types. The origins of both carlintype and iron oxide coppergold systems are the subject of much debate.
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. Typomorphic characteristics of pyrites from the shuangwang. Fluid inclusions of orogenic gold deposits in the zhongchuan. 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. These deposits formed from the archaean to phanerozoic at crustal depths of.
Metallogenesis of mesozoic orogenic gold deposit in bangong. Parameters for the formation of orogenic gold deposits taylor. Although mostly small in volume, the gold deposits. What have we learnt about orogenic lode gold deposits over the. Metallogenesis of mesozoic orogenic gold deposit in. In general there is a strong structural control of the ore forming processes and potential deposition takes place near large scale compressional structures thrust faults.
Orogenic gold deposits are typified by quartzcarbonatedominant vein systems. One of the unifying characteristics of lode gold deposits through time and space are low to moderatesalinity generally pdf. As example, laicpms pyrite mapping shown that gold is associated with silver ratio of auag orogenic gold deposits. These deposits formed from the archaean to phanerozoic at crustal depths of more than 4 km. This concept of open reactor accounts well for the characteristics of the gold mineralisation at the depositscale.
Controls on gold mineralization at the coffee gold deposit. The key geological characteristics of the bohaun mineralization which have a. The socalled mesothermal gold deposits are associated with reginally metamorphosed terranes of all ages. The purpose of this paper therefore is to present a. Such an assumption is valid because this deposit type is, by far, the most dominant gold deposit type in the studied craton. There are six distinct classes of gold deposits, each represented by metallogenic provinces, having 100s to tonne gold production. 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. These gold deposits performance as same geological characteristics as that typical orogenic gold deposit, which confirm that an important orogenic gold mineralization event existed in the bangongnujiang suture belt. Known orogenic gold deposits bear similar characteristics as in other gold districts around the world. Orogenic gold, or gold deposits in metamorphic rocks, and associated placer deposits, comprise.
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. 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. Research on the characteristics, distribution and timing of these gold deposits tests these classifications and supports an alternative interpretation. 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 are an important part of the gold endowment of mexico. Geochemistry of hydrothermal gold deposits request pdf. The ore forming fluids of orogenic lode gold deposits are generally low saline 3 wt. Fluid inclusion and hospb isotope geochemistry of the yuka. The hypothesis is that there may be a multiphase, overlapping fluid evolution in the system which should be reflected in the detailed gold particle characteristics. Geological, petrographical and geochemical characteristics. Orogenic gold deposits are the main source of gold for humanity. Hydrothermal gold deposits epithermal, carlintype, and orogenic have accounted for 75% of lode gold production.
These deposits formed from the archaean to phanerozoic at crustal. 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. Orogenic gold deposits are present in various metamorphic terrains displaying variable types of mineralization. Timing, nature and characteristics of orogenic gold. This is reflected by the disagreement about genetic models. Orogenic gold deposits are associated with regionally metamorphosed terranes of middle archaeantertiary age goldfarb et al. Pdf with very few exceptions, orogenic gold deposits formed in subductionrelated tectonic settings in accretionary to collisional orogenic. Lithotectonic classification of gold deposits lode gold deposits epigenetic vein deposits of gold in metamorphic terranes kerrich, 1993. The key to a unified model for orogenic gold deposits. Summary characteristics of archean orogenic gold deposits.
Atypical gold mineralization in an orogenic settingthe bohaun. Diamond implications for genetic models characteristics and models for carlintype gold deposits a. Orogenic gold deposits were generated during a time span. The tasiast belt of deposits, which came into production in 2007, is located in the southwestern corner of the rgueibat shield and defines a worldclass paleoproterozoic. 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. Focus paper structural geometry of orogenic gold deposits. Importantly, the lodes may be located on one side of a cross fault, but not consistently displaced to the other side of the fault. The producing guelb moghrein deposit occurs along a shear zone in middle archean. It is located in terrigenous rocks of the top triassic, poorly contrast on petrophysical characteristics. Features of oreforming fluids for orogenic gold deposits. Ores were formed during compressional to transpressional deformation processes at convergent plate margins in accretionary and collisional orogens.
If a multiphase deposit evolution can be confirmed, it will be an important contribution to the global debate of gold deposit genetic models in orogenic systems. Either the og deposits in clgb follow completely different size distribution or the data reflects the low exploration history and hence the high amount of undiscovered orogenic gold deposits in the district. Point 2 implies a short fluid pathway from the site of liberation to the site of gold deposition, thus lessening the chance of. Boundaries between rigid granitoids and ductile greenstone are common sites for. The key feature of archean orogenic lode gold systems is a broadly uniform lowmoderate salinity, mixed aqueouscarbonic fluid that is capable of carrying au but has limited capacity to transport base metals. Orogenic gold deposits are present in metamorphic terranes of various. Within the host volcanosedimentary sequences at the province scale, worldclass orogenic gold deposits are most commonly located in secondorder structures adjacent to crustal scale faults and shear zones, representing the. Orogenic gold deposits are gold lodes within and associated with metamorphic belts 1,7,8,9. A brief introduction to orogenic gold deposits craig feebrey july 2104. Pdf parameters for the formation of orogenic gold deposits. Associated with regional scale deformation structures. The paper presents the analysis of characteristics of abnormal geophysical fields of the ore control of the malotarynskoe orogenic gold deposit in verkhoyanokolymsky folded area, the northeast of russia. Detailed material for this globally important deposit type will be provided on tectonic and structural controls, geological characteristics, geochemical and. Pdf orogenic gold deposits are the main source of gold for humanity.
Minor types of gold deposits are not discussed in this paper. The characteristics, origins, and geodynamic settings of supergiant. Crowe fluid chemistry of orogenic lode gold deposits and j. Orogenic gold mineralization in the qolqoleh deposit.
Pdf mineralogical, fluid inclusion and stable isotope. The table below provides a summary of some major irgs classified deposits, their metal. Apr 01, 2001 the orogenic gold deposits normally consist of abundant quartzcarbonate veins and show evidence for formation from fluids at supralithostatic pressures. Geological, petrographical and geochemical characteristics of. The shangxu gold deposit is a medium size deposit with average grade of 6. The deposit contains a reserve of gold mineralization at the morila mine in mali, which is the subject approximately 7 million ounces of au, at an average grade of 3.
Although these deposits form in distinctly different geologic settings and by. Primary alteration and geochemical dispersion haloes of. Although mostly small in volume, the gold deposits include also a large one. The characteristics, origins, and geodynamic settings of supergiant gold metallogenic provinces. Also termed as greenstone hosted gold deposits, orogenic gold deposits, shear gold deposits, gold only deposits intrusion related deposits deposits having spatial and genetic relationship with. As a structurally controlled gold deposit, c1santaluz. Distribution of orogenic gold deposits in relation to fault. The abundance of orogenic gold deposits reflects paleozoic to triassic closure of paleotethyan ocean basins between precambrian blocks derived from rodinia and gondwana as well as late. China produces about 500 t au per year and has stated reserves of approximately 10, 000 t au. Magnetic signatures related to orogenic gold mineralization. Their defining characteristics and spatial and temporal distributions are now relatively well documented, such that other gold.
Characteristics of orogenicgold deposits in the northcote. Cline characteristics and genesis of epithermal gold deposits d. The mineralized lodes formed over a uniquely broad range of upper to midcrustal pressures and temperatures, between about 200650c and 15 kbar groves, 1993. They are normally located in second or thirdorder structures, most commonly near crustal to regionalscale deformation zones, in brittle, brittleductile and ductile deformational environments.
Prospectivity analysis of orogenic gold deposits in saqez. As example, laicpms pyrite mapping shown that gold is associated with silver ratio of auag characteristics of orogenic gold deposits in the broken river province, ne queensland, australia i. Gold deposits can still be seen today forming in some active geothermal areas. The gold resources of mauritania presently include two important deposits and a series of poorly studied prospects.
Richard goldfarb, kunfeng qiu china univeristy of geosciences, beijing, china, email. 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 brittle. A unified model for gold mineralisation in accretionary orogens and. Jul 01, 2018 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. 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 controlling structures are mainly related to major faults. Here is a look at the components that make up orogenic deposits. Orogenic deposits are the source of much of the worlds gold. Orogenic lode gold deposits of middle archean to tertiary age are arguably the predominant gold deposit type in metamorphic belts, and include several giant 250 t au and numerous worldclass 100 t au examples.
Classification vs modeling each ore deposit is unique like a persons finger print this uniqueness arises out of. The origins of both carlintype and iron oxide copper gold systems are the subject of much debate. Geophysical methods of identification of ore control. Orogenic gold deposits of china society of economic. Archean orogenic lode gold in the superior province of manitoba. These are characterized by elevated s and as, and have only minor enrichments in the other elements. Other elements that are elevated in the gold zone at ar are silver up to 6 ppm, gallium up to 20 ppm, tungsten up to 22 ppm and barium up. Gold ore deposits are found in rocks throughout the earths geological history, from the earliest precambrianmore than 3. The deposits display many similarities to welldescribed turbiditehosted orogenic gold deposits described from several palaeozoic orogens. It is well known that low salinities and co 2rich fluids are one of the most important characteristics of the orogenic gold deposits e. Lowsulfide quartz gold gold only deposits quartzcarbonate lode gold synorogenic gold turbidite hosted gold structurally hosted vein systems in metamorphic terranes recent work by groves and others 1998 suggested that orogenic ought to be the central focus in the title describing these deposits. General setting geological and structural setting the pilbara craton western australia is a wellexposed 3. Photograph illustrating the parallel drainage pattern characteristic of. Knoxrobinson, 2000 and are sited in accretionary or collisional orogens of all ages.
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