scholarly journals Method for Revealing Placer Gold Source

2020 ◽  
Vol 4 (4) ◽  
pp. 273-281
Author(s):  
O. V. Vladimirtseva
Keyword(s):  
Gold Mineralization ◽  
Spatial Association ◽  
Gold Deposits ◽  
High Order ◽  
Placer Gold ◽  
Location Determination ◽  
Python Programming ◽  
Logical Information ◽  
Geomorphological Features ◽  
Primary Gold

Material characteristics of placer gold and geological and geomorphological features of placercontaining watercourses allow revealing the type of source that formed the placer. The studied area (the middle reach of theAdychaRiver, Verkhoyansk District, Yakutia) is characterized by highly developed placer gold mineralization both in ancient terrace sediments and high-order watercourses. The significant placer gold mineralization in the high-order watercourses, at very limited number of known bedrock gold deposits suggests the presence of not yet discovered bedrock gold mineralization. Revealing the type of sources of placer gold in young high-order watercourses allows to create prognostic and prospecting models for both potential placer and primary (vein) ore occurrences. The purpose of the study is to compile a logical-information algorithm, which, based on the most significant material and geological-geomorphological factors, will enable revealing the type of placer gold source and the possibility of its location discovery and probability of gold transportation continuation from the source. The study result is presented by a program (the Python programming language) that characterizes the type of placer gold source based on gold grain rounding degree, the presence of gold intergrowths with other minerals and the presence of heavy fraction. Assessment of the possibility of placer gold source location determination is based on geological and geomorphological factors: watercourse order, the type of placer, and spatial association with terraces of ancient erosion levels. The study of well-known gold placers using the created program allowed revealing gold placers  with supposedly primary gold source and other ones with the source in the form of a natural intermediate gold concentrator. A map of exogenous gold mineralization with forecast elements was also created, presenting areas promising for revealing primary gold mineralization (areas of presence of high-order watercourses with gold mineralization source) and areas of high-order watercourses promising for discovering gold placers (identified by analogy (in geological and geomorphological position) with watercourses with the known source in the form of natural intermediate gold concentrator.

scholarly journals Placer gold occurrences along the major rivers of Nepal Himalaya and their possible primary sources

1996 ◽  
Vol 13 ◽  
Author(s):  
K. P. Kaphle ◽  
P. R. Joshi ◽  
H. R. Khan
Keyword(s):  
Gold Mineralization ◽  
Gold Deposits ◽  
Primary Sources ◽  
Gold Content ◽  
Lower Paleozoic ◽  
Nepal Himalaya ◽  
Placer Gold ◽  
Flood Plains ◽  
River Flood ◽  
Primary Gold

Recent exploration in Lungri Khola area, Rolpa district, midwestern Nepal helped to delineate a discontinuous 1.5 to 40 m thick and about 30 km long primary gold mineralization zone in the Precambrian greenschists and Lower Paleozoic micaceous marbles of the Lesser Himalaya. The gold content in these lodes vary from 0.01 to 6.7 ppm. In eastern Nepal occurrences of primary gold is recorded in quartz-biotiteschist, amphibolite and pegmatite bodies in Sunmai and Bering Khola of Ilam district. Fine flakes of gold also occur in the pyritiferous quartz beds/lenses in chlorite-sericite phyllite and quartzite of Bamangaon polymetallic prospect, Dadeldhura district, far western Nepal. In this prospect the gold content is from 0.2 to 0.8 ppm, and one sample showed up to 14 ppm. Primary gold occurrences are also detected in few irregular quartz-pyrite veins and iron-copper sulphide bearing quartzite lying close to the amphibolite bodies. Some pyrite bearing radioactive quartzite beds in Banku Quartzite of Purchauni Crystalline Complex exposed at Boregad, Bangabagar, Baggoth and Jamari Gad area in Darchula and Baitadi districts, far western Nepal also contain gold. The gold content in the radioactive quartzite varies from 0.2 to 1.2 ppm and in some pyritiferous radioactive quartzite floats it reaches up to 5.06 ppm. The primary gold appears to be of synsedimentary, hydrothermal and possibly volcanogenic in origin. Placer gold is derived from primary sources and deposited at favourable locations along the river flood plains. Further investigations in similar geological terrain may help to identify economically viable primary as well as placer gold deposits in the Nepal Himalaya.

scholarly journals Typomorphic Features of Placer Gold from the Billyakh Tectonic Melange Zone of the Anabar Shield and Its Potential Ore Sources (Northeastern Siberian Platform)

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 281
Author(s):  
Boris Gerasimov ◽  
Vasily Beryozkin ◽  
Alexander Kravchenko
Keyword(s):  
Native Gold ◽  
Gold Mineralization ◽  
Coarse Fraction ◽  
Gold Deposits ◽  
Primary Sources ◽  
The Arctic ◽  
Geochemical Data ◽  
Placer Gold ◽  
Anabar Shield ◽  
Tectonic Mélange

Precambrian shields and outcropped Precambrian rock complexes in the Arctic may serve as the most important sources of various types of mineral raw materials, including gold. The gold potential of the Anabar shield in the territory of Siberia has, thus far, been poorly studied. A number of primary and placer gold occurrences have been discovered there, but criteria for the prediction of and search for gold mineralization remain unclear. The main purpose of this paper was to study the typomorphic features of placer gold in the central part of the Billyakh tectonic mélange zone in the Anabar shield and to compare them to mineralization from primary sources. To achieve this, we utilized common methods for mineralogical, petrographic, and mineragraphic analyses. Additionally, geochemical data were used. As a result of this investigation, important prospecting guides were identified, and essential criteria for the prediction of and search for gold deposits were elucidated. The characteristics of the studied placer gold were specific for gold derived from a proximal provenance. These characteristics included the poor roundness of the native gold grains, a cloddy–angular and dendritic form, an uneven surface, and a high content of coarse-fraction native gold (0.5–2 mm), which was as high as 24% of the volume of analyzed native gold. In addition, we conducted a study on the mineralogical features of the gold-sulfide mineralization that was disseminated throughout a small exposure area of paleo-Proterozoic para- and orthogneisses in the Anabar shield basement. A comparison of mineral inclusions in the coarse-fraction native gold and mineral assemblages in the ore deposits showed that one of the possible primary sources for placer gold might be small bodies of metasomatically altered orthogneisses associated with large granitoid plutons.

scholarly journals Giant Placers of the Victorian Gold Province

SEG Discovery ◽  
2004 ◽  
pp. 1-18
Author(s):  
Martin J. Hughes ◽  
G. Neil Phillips ◽  
Stephen P. Carey
Keyword(s):  
Late Cretaceous ◽  
Quartz Vein ◽  
Late Eocene ◽  
Gold Deposits ◽  
Gold Production ◽  
Placer Gold ◽  
High Rainfall ◽  
Hydrothermal Quartz ◽  
Alluvial Gold ◽  
Primary Gold

ABSTRACT The Victorian gold province has yielded 2500 tonnes (t) Au, nearly 2 percent of cumulative world gold production, mostly mined between 1851 and 1910. Fifty-five percent (1375 t) was placer gold from modern and paleostream systems, and from eluvial deposits, and the remainder came from primary quartz vein-related deposits. Most of the alluvial gold placers are in unconsolidated or weakly cemented quartz pebble conglomerate and gravel, dominated by hydrothermal quartz, although a few paleoplacers are within duricrusted conglomerate that required crushing. Large and abundant gold nuggets were common. Placer gold deposits formed in three intervals following uplift in the Late Cretaceous, Late Eocene, and Pliocene. An important factor in the preservation of the paleoplacers has been their burial by younger sediments and basalt flows, with consequent protection from erosion and dispersal. Factors in the formation of the giant gold placers of Victoria include the following: (1) the existence of a major primary gold province with several multimillion-ounce gold deposits; (2) uplift and reactivation of older faults; and (3) high rainfall and deep Paleogene weathering.

Prospects of primary gold potential in southern Siberian platform based on study results for placer gold morphological and geochemical features

2021 ◽  
pp. 97-114
Author(s):  
Ivan Chetvertakov ◽  
Alexey Ivanov ◽  
Ekaterina Mikheeva ◽  
Tatyana Chikisheva ◽  
Tamara Yakich
Keyword(s):  
Siberian Platform ◽  
Geological Structure ◽  
Gold Deposits ◽  
Primary Sources ◽  
Placer Gold ◽  
Genetic Types ◽  
Study Results ◽  
Geochemical Property ◽  
Geochemical Studies ◽  
Primary Gold

Data on geological structure and minerals of the southern Siberian platform are presented. Placer and primary gold occurrences widespread in this region are briefly characterized. Based on placer gold morphological and geochemical property studies using electron microscopy, its four types are revealed. Conclusions are made about potential primary sources of various placer gold types. Using retrospective data and based on the authors’ placer gold morphological and geochemical studies, Ust-Ilimskaya, Chernorechinskaya and Buraevskaya gold areas are characterized, their prospects for discovering primary gold deposits of various genetic types are determined.

Gold Deposits of the ~15-Moz Ahafo South Camp, Sefwi Granite-Greenstone Belt, Ghana: Insights into the Anatomy of an Orogenic Gold Plumbing System

2021 ◽  
Author(s):  
Quentin Masurel ◽  
Paul Morley ◽  
Nicolas Thébaud ◽  
Helen McFarlane
Keyword(s):  
Rock Mass ◽  
Shear Zone ◽  
Gold Mineralization ◽  
Hanging Wall ◽  
Spatial Association ◽  
Sedimentary Rocks ◽  
Shear Zones ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Plutonic Rocks

Abstract The ~15-Moz Ahafo South gold camp is located in southwest Ghana, the world’s premier Paleoproterozoic gold subprovince. Major orogenic gold deposits in the camp include Subika, Apensu, Awonsu, and Amoma. These deposits occur along an ~15-km strike length of the Kenyase-Yamfo shear zone, a major tectonostratigraphic boundary juxtaposing metamorphosed volcano-plutonic rocks of the Sefwi belt against metamorphosed volcano-sedimentary rocks of the Sunyani-Comoé basin. In this study, we document the geologic setting, structural geometry, and rheological architecture of the Ahafo South gold deposits based on the integration of field mapping, diamond drill core logging, 3-D geologic modeling, and the geologic interpretation of aeromagnetic data. At the camp scale, the Awonsu, Apensu, and Amoma deposits lie along strike from one another and share similar hanging-wall plutonic rocks and footwall volcano-sedimentary rocks. In contrast, the Subika gold deposit is hosted entirely in hanging-wall plutonic rocks. Steeper-dipping segments (e.g., Apensu, Awonsu, Subika) and right-hand flexures (e.g., Amoma, Apensu) in the Kenyase-Yamfo shear zone and subsidiary structures appear to have represented sites of enhanced damage and fluid flux (i.e., restraining bends). All gold deposits occur within structural domains bounded by discontinuous, low-displacement, sinistral N-striking tear faults oblique to the orogen-parallel Kenyase-Yamfo shear zone. At the deposit scale, ore-related hydrothermal alteration is zoned, with distal chlorite-sericite grading into proximal silica-albite-Fe-carbonate mineral assemblages. Alteration halos are restricted to narrow selvages around quartz-carbonate vein arrays in multiple stacked ore shoots at Subika, whereas these halos extend 30 to 100 m away from the ore zones at Apensu and Awonsu. There is a clear spatial association between shallow-dipping mafic dikes, mafic chonoliths, shear zones, and economic gold mineralization. The abundance of mafic dikes and chonoliths within intermediate to felsic hanging-wall plutonic host rocks provided rheological heterogeneity that favored the formation of enhanced fracture permeability, promoting the tapping of ore fluid(s). Our interpretation is that these stacked shallow-dipping mafic dike arrays also acted as aquitards, impeding upward fluid flow within the wider intrusive rock mass until a failure threshold was episodically reached due to fluid overpressure, resulting in transient fracture-controlled upward propagation of the ore-fluid(s). Our results indicate that high-grade ore shoots at Ahafo South form part of vertically extensive fluid conduit systems that are primarily controlled by the rheological architecture of the rock mass.

scholarly journals MINERAL POTENTIAL MAPPING USING GEOGRAPHIC INFORMATION SYSTEMS (GIS) FOR GOLD MINERALIZATION IN WEST JAVA, INDONESIA

2015 ◽  
Vol 7 (1) ◽  
pp. 61
Author(s):  
Seang Sirisokha ◽  
Lucas Donny Setijadji ◽  
I Wayan Warmada
Keyword(s):  
Gold Mineralization ◽  
Spatial Association ◽  
Geographic Information ◽  
Gold Deposits ◽  
Weights Of Evidence ◽  
Rock Unit ◽  
West Java ◽  
Mineral Potential ◽  
Potential Mapping ◽  
Potential Area

Western Java is a part of the Sunda Banda magmatic belt. This belt is well known to be host for several gold deposits in Indonesia, the distribution of 107 Au occurrences in this area was examined in terms of spatial association with various geological phenomena. The goal of this project is to use GIS to conduct weights of evidence (WofE) model for gold mineralization in West Java, Indonesia. A Geographic Information System (GIS) is a computer system for capturing, storing, querying, analyzing, and displaying geospatial data and weight of evidence method is one of the most important datadriven methods for mapping in GIS. The method is a probability based on technique for mapping mineral potential using the spatial distribution of known mineral occurrences. Therefore this method is very useful for gold potential mapping. There are six evidences maps such as NE–SW lineaments NW–SE Lineament, host rocks, heat sources, clay alteration and limonitic alteration, have been combined using a weights of evidence model to predict gold potential in West Java. The best predictive map generated by this method defines 21.62% (9902 km) of study area as favourable zones for gold mineralization further exploration work. It predicts correctly 74 (92.5%) of the 80 model deposits and predicts correctly 26 (96.35%) of the 27 validation deposits, has 6 main 2 prospective target for future exploration are located in Bayah Dome, southern mountain, Honjie Igneous Complex and Bogor zone, Purwakarta. Bayah Dome is highest potential area for gold deposit like Gunung Pongor, Cikidang, Cirotan, Ciawitali, Cikotok destricts and other deposits. The potential area of Au occurrences in research area is associated with NE–SW and NW–SE structure/ lineaments, dominated surrounding the Tertiary intrusive rock unit and hosted in Miocene to Pleistocene lithology rock unit.

scholarly journals The Metamorphic Rocks-Hosted Gold Mineralization At Rumbia Mountains Prospect Area In The Southeastern Arm of Sulawesi Island, Indonesia

2017 ◽  
Vol 2 (3) ◽  
pp. 217
Author(s):  
Hasria Hasria ◽  
Arifudin Idrus ◽  
I Wayan Warmada
Keyword(s):  
Gold Deposit ◽  
Gold Mineralization ◽  
Gold Deposits ◽  
Orogenic Gold ◽  
Metamorphic Rocks ◽  
Quartz Veins ◽  
Orogenic Gold Deposit ◽  
Ore Mineralization ◽  
Hematite Fe2o3 ◽  
Primary Gold

Recently, in Indonesia gold exploration activities  are not only focused along volcanic-magmatic belts, but also starting to shift along metamorphic and sedimentary terrains. The study area is located in Rumbia mountains, Bombana Regency, Southeast Sulawesi Province. This paper is aimed to describe characteristics of alteration and ore mineralization associated  with metamorphic rock-related gold deposits.  The study area is found the placer and  primary gold hosted by metamorphic rocks. The gold is evidently derived from gold-bearing quartz veins hosted by Pompangeo Metamorphic Complex (PMC). These quartz veins are currently recognized in metamorphic rocks at Rumbia Mountains. The quartz veins are mostly sheared/deformed, brecciated, irregular vein, segmented and  relatively massive and crystalline texture with thickness from 1 cm to 15.7 cm. The wallrock are generally weakly altered. Hydrothermal alteration types include sericitization, argillic, inner propylitic, propylitic, carbonization and carbonatization. There some precious metal identified consist of native gold and ore mineralization including pyrite (FeS2), chalcopyrite (CuFeS2), hematite (Fe2O3), cinnabar (HgS), stibnite (Sb2S3) and goethite (FeHO2). The veins contain erratic gold in various grades from below detection limit <0.0002 ppm to 18.4 ppm. Based on those characteristics, it obviously indicates that the primary gold deposit present in the study area is of orogenic gold deposit type. The orogenic gold deposit is one of the new targets for exploration in Indonesia

Studi Awal Geologi di Daerah Beruang Kanan Kabupaten Gunung Mas Propinsi Kalimantan Tengah

PROMINE ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 1-11
Author(s):  
Retno Anjarwati ◽  
Arifudin Idrus ◽  
Lucas Donny Setijadji
Keyword(s):  
Gold Mineralization ◽  
Volcanic Rocks ◽  
Gold Deposits ◽  
Central Kalimantan ◽  
Magmatic Arc ◽  
Tertiary Sediment ◽  
Copper Gold ◽  
Regional Tectonic ◽  
Mineralization Processes ◽  
High Yields

The regional tectonic conditions of the KSK Contract of Work are located in the mid-Tertiary magmatic arc (Carlile and Mitchell, 1994) which host a number of epithermal gold deposits (eg, Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa Ria, Gunung Mas and Mirah. Copper-gold mineralization in the KSK Contract of Work is associated with a number of intrusions that have occupied the shallow-scale crust at the Mesozoic metamorphic intercellular junction to the south and continuously into the Lower Tertiary sediment toward the water. This intrusion is interpreted to be part of the Oligocene arc of Central Kalimantan (in Carlile and Mitchell 1994) Volcanic rocks and associated volcanoes are older than intrusions, possibly aged Cretaceous and exposed together with all three contacts (Carlile and Mitchell, 1994) some researchers contribute details about the geological and mineralogical background, and some papers for that are published for the Beruang Kanan region and beyond but no one can confirm the genesis type of the Beruang Kanan region The mineralization of the Beruang Kanan area is generally composed by high yields of epithermal sulphide mineralization. with Cu-Au mineralization This high epithermal sulphide deposition coats the upper part of the Cu-Au porphyry precipitate associated with mineralization processes that are generally controlled by the structure

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