ASSESSMENT OF THE EXTENT AND NATURE OF CLUSTERING OF ALLUVIAL GOLD DEPOSITS IN YAKUTIA

The article presents the results of a research study of anthropogenic affects of gold mining on forest landscapes in Northern Transbaikalia, Russia and processes of natural reclamation of vegetation cover of the disturbed areas. The study area is located northwest of the Maliy Amalat River, which flows along the Vitim Plateau; in the floodplains of its two tributaries the Aunik River and the Bagdarin River. It is an area where a large number of alluvial gold deposits have been discovered. Some of these deposits are currently being developed, some have already been explored, and some have been abandoned. The authors consider the current state of vegetation cover in a key area of the Amalat River basin, near villages of Malovsky and Bagdarin. The problem of natural resources development and conservation is becoming extremely important for the area under study because open-pit gold mining methods that are used here drastically change the environment and affect water, land and forest resources.

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GPR mapping of bedrock of alluvial gold deposits in permafrost

2016 16th International Conference on Ground Penetrating Radar (GPR) ◽

10.1109/icgpr.2016.7572638 ◽

2016 ◽

Cited By ~ 1

Author(s):

G. A. Kulyandin ◽

L. L. Fedorova ◽

D. V. Savvin ◽

N. D. Prudetskii

Keyword(s):

Gold Deposits ◽

Alluvial Gold

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Giant Placers of the Victorian Gold Province

SEG Discovery ◽

10.5382/segnews.2004-56.fea ◽

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.

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Main factors determining potential qualified appearance of pebble and effel dumps of depleted alluvial gold deposits

E3S Web of Conferences ◽

10.1051/e3sconf/20185601004 ◽

2018 ◽

Vol 56 ◽

pp. 01004

Author(s):

Gadzhi Mirzekhanov ◽

Zoya Mirzekhanova

Keyword(s):

Granulometric Composition ◽

Climatic Factors ◽

Gold Deposits ◽

Gold Content ◽

Alluvial Deposits ◽

Resource Potential ◽

Alluvial Gold ◽

Anthropogenic Deposits ◽

Main Factors ◽

Process Loss

The influence of two most important factors determining gold losses during mining of alluvial deposits is considered. They include the granulometric composition of sands and the initial gold content in them. It is shown that the underestimation of these indicators in the assessment of anthropogenic deposits significantly reduces the resource attractiveness of depleted objects. Specific examples give calculations that allow for a more accurate predictive estimate of the resource potential of the dredging tailing (effel) dumps. Based on the consideration of natural and climatic factors in determining the conditions, the placer content is plotted for the gold content in the sands of various economic areas of Khabarovsk Region. It has been established that at the same values of the designed process loss and given the comparability of the main placer parameters, a high average gold content in the initial sands makes it possible to predict within the dump some objects with standard contents.

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Quantitative texture analysis of alluvial gold: primary and secondary signatures

10.5194/egusphere-egu21-15930 ◽

2021 ◽

Author(s):

Juan Gómez-Barreiro ◽

Santos Barrios-Sánchez ◽

José Manuel Compaña Prieto ◽

Juan Morales Sánchez-Migallón ◽

Kelvin dos Santos Alves ◽

...

Keyword(s):

Rietveld Method ◽

Secondary Growth ◽

Primary Source ◽

Close Correlation ◽

Gold Deposits ◽

Pure Gold ◽

Transport Length ◽

Alluvial Gold ◽

Placer Deposits ◽

Non Destructive

The origin of gold nuggets (Au&#8208;Ag alloys) is not completely understood. They crop out in placer deposits, potentially derived from a primary source (hydrothermal/magmatic). Meteorization, erosion and transport of primary gold deposits result in the liberation of a variety of particle size. Recent investigations suggest that both primary and secondary microstructural features may be preserved and could be related to deformation during transport, recrystallization and primary formation. Besides, the contribution of biological mechanisms (biomineralization) may have played an important role during secondary growth in some nuggets. In many cases, there is no clear evidence to distinguish between supergenic and hypogenic gold, so texture information could be excellent information to constrain the origin. Besides, it has been demonstrated that crystallography controls the de&#8208;alloying processes in gold nuggets. This mechanism, that transforms the primary Au&#8211;Ag alloys into pure gold by preferential dissolution of Ag along crystal boundaries, could be determined by variations on texture, a factor never explored before, which may explain the dispersion in de&#8208;alloying values in the same deposit.&#160;In this case we have explored a selection of gold nuggets collected in the W sector of the Iberian Massif (Spain), representing the principal morphological types. As a non-destructive technique neutron diffraction appears as the technique of choice in this case. Beside, neutrons absorption is very low so that large samples could be investigated. Samples were analyzed in transmission at ILL (Grenoble) for texture. Quantitative texture and gold crystallinity was calculated using Rietveld method as implemented in Maud software (EWIMV). Mono- and polycrystalline nuggets and alloy composition were clearly identified in each particle with this technique.&#160;Our results show a close correlation between the morphology (i.e. transport length) of the particle and the crystallographic results, particularly for fibrous and discoid shapes (i.e. Zingg, Corey shape factor), what could be used to develop better transport models (distance-to-bedrock sources) and understand multisource gold placer assemblages.&#160;

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EARLY THEORIES AND PRACTICALITIES ON GOLD OCCURRENCE IN AUSTRALIA

Earth Sciences History ◽

10.17704/1944-6187-40.2.409 ◽

2021 ◽

Vol 40 (2) ◽

pp. 409-432

Author(s):

KENNETH G. McQUEEN

Keyword(s):

Government Regulation ◽

Gold Mining ◽

Mining Industry ◽

Great Depth ◽

Gold Rush ◽

Gold Deposits ◽

Rock Types ◽

Gold Occurrence ◽

Alluvial Gold ◽

Gold Bearing

The discovery of gold in Australia forced many changes to theory on the occurrence and origin of gold deposits. Initial discoveries appeared to confirm existing ideas on the global distribution of gold-bearing terrains. Later discoveries and research would show that this confirmation was largely coincidental, but nevertheless helpful in early prospecting. Prior to the first Australian gold rush, theoretical predictions of payable gold were made by Sir Roderick Murchison and Rev. W. B. Clarke based on knowledge of accidental gold finds and geological analogy with known areas of significant gold occurrence, particularly the Ural region in Russia. These predictions were overwhelmed when Edward Hargraves, realised he might be able to spark a gold rush that would prove the existence of payable gold. Hargraves travelled to the Bathurst region of New South Wales where numerous gold finds had already been made and with local guides, prospected Lewis Ponds Creek and the Macquarie River. He demonstrated the methods of alluvial mining, to John Lister and William and James Tom enabling them to find sufficient alluvial gold to initiate a gold rush. The crowd of attracted diggers demonstrated the existence of a payable goldfield. The unstoppable first rush resulted in the pragmatic introduction of government regulation and administration to allow alluvial gold mining. Other discoveries of payable goldfields quickly followed. As the local scientific expert on gold, W. B. Clarke was commissioned to conduct two extensive surveys of the goldfields between 1851 and 1853. Clarke also drew on his geological knowledge to provide practical advice to the thousands of prospecting gold diggers. Gold-bearing quartz reefs and lodes were discovered, but it was predicted that these could not be mined economically. Theory also predicted that the reef gold would not continue to depth. Practical observations and mining experience from the numerous discoveries led to revision of the widely held dicta on gold occurrence. Alluvial gold was found in a range of settings, including the recent drainage and ancient and buried leads. A wider variety of rock types was recognised as favourable for gold. Different styles of reef gold were identified and found to be economically mineable to great depth. Evolving ideas on the origin of gold deposits were widely discussed, tested, and refined. Of the many players involved in the early discovery of gold in Australia, Clarke, Hargraves and Murchison probably had the greatest overall influence in terms of theoretical predication and practical outcomes that initiated the Australian gold-mining industry.

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