Structure and Origin of Gold Mineralization: From Primary to Placer Gold Deposits

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Deposits".

Deadline for manuscript submissions: 31 July 2024 | Viewed by 5153

Special Issue Editors

Prospecting and Mining Research Area, Higher Technical School of Mining Engineering, University of León, 24071 León, Spain
Interests: mineral prospecting; geology of ore deposits; mineral prospection; mining geomorphology; geoarchaeology; remote sensing; UAVs; LiDAR
Special Issues, Collections and Topics in MDPI journals
Department of Geological Sciences, California State University, San Bernardino, CA 92405, USA
Interests: economic geology; stable isotope geochemistry; geoarchaeology
Department of Mining Technology, Topography and Structures, Higher Technical School of Mining Engineering, University of León, 24071 León, Spain
Interests: petrology; geochemistry; mineralogy; ore deposits; economic geology

Special Issue Information

Dear Colleagues,

Gold has been coveted for thousands of years due to its rarity in nature, beauty and physical properties such as durability and ductility. From the early Egyptian civilization to the California gold rush, the prospection and exploitation of gold ores has aroused considerable interest. Gold represents a reserve asset material, as a safe haven for capital in time of crisis. Since the stock market crash in October 1987, gold has acquired a notable interest for economies worldwide. Recent advances in the study of gold mineralization requires a multidisciplinary approach based on geological, geochemical, and geophysical data. The implementation of remote sensing techniques and hyperspectral images in combination with soil, water, and biologic geochemistry has led to the recognition of potential economic deposits within a variety of tectonic settings. The development of aeromagnetic surveying has also allowed for large-scale prospecting tasks in remote or difficult to access areas of the planet, improving the geological characterization of near-to-surface deposits. Studies range from the analysis of macro- and micro-scales based on traditional geological prospection and metallogenetic relations observed in new and different types of gold deposits to the advanced analysis of isotope geochemistry and fluid inclusions using the latest techniques to gain insights into the genesis and evolution of mineralizations. This Special Issue aims to contribute to understanding the origin and structure of gold mineralization using different methods and techniques. The main goal is to provide readers with a comprehensive and updated overview via studying primary and secondary gold occurrences.

Dr. Javier Fernández Lozano
Prof. Dr. Erik Melchiorre
Dr. Pablo Caldevilla Domínguez
Guest Editors

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Keywords

  • gold prospecting
  • biogeochemistry of gold
  • geochemical analysis
  • gold deposits
  • geophysical survey
  • remote sensing

Published Papers (4 papers)

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Research

22 pages, 12690 KiB  
Article
Geochemical Overprinting and Secondary Placer Crystal Formation in the La Cholla District, Quartzsite, Arizona, USA: Evidence from Copper Isotopes, Morphology, and Trace Elements
Minerals 2023, 13(11), 1444; https://doi.org/10.3390/min13111444 - 15 Nov 2023
Viewed by 709
Abstract
Geochemical overprinting on placer gold deposits produces complex deposits with apparently paradoxical geochemical and morphological attributes. The La Cholla placer gold deposits near Quartzsite, Arizona, USA, contain sharp and often undamaged gold crystals within high-energy gravels as a result of postdepositional recrystallization by [...] Read more.
Geochemical overprinting on placer gold deposits produces complex deposits with apparently paradoxical geochemical and morphological attributes. The La Cholla placer gold deposits near Quartzsite, Arizona, USA, contain sharp and often undamaged gold crystals within high-energy gravels as a result of postdepositional recrystallization by localized hot springs. Geothermal fluids emanated from a basin-bounding fault and left a distinct signature that includes recrystallized gold with low Pb and δ65Cu > 1.14‰, secondary uraninite and carnotite, travertine deposits, and mounds of highly silicified placer gravels. Surrounding these deposits are placer gravels with angular gold morphology and geochemistry indicative of flash-flood pulse placers with a lode gold source < 5 km and gold particles with low Pb and δ65Cu < 0.77‰. The multitude of small local lode gold source veins is likely related to specialized fluid migration along mid-Tertiary detachment faults. The unroofing of these veins at 5 to 17 Ma by high-angle Basin and Range faulting led to extensive placer development, with subsequent localized modification by geothermal fluid migration along the same faults. This study documents geochemical overprinting and modification of placer deposits and bears upon the study of other placers containing crystalline gold and uranium mineralization. Similar deposits may document past geothermal activity and identify structural fluid conduits and steep paleo-topographic gradients. Full article
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21 pages, 12650 KiB  
Article
Utilizing Remote Sensing and Satellite-Based Bouguer Gravity data to Predict Potential Sites of Hydrothermal Minerals and Gold Deposits in Central Saudi Arabia
Minerals 2023, 13(8), 1092; https://doi.org/10.3390/min13081092 - 15 Aug 2023
Cited by 1 | Viewed by 1285
Abstract
This article aims to aid in exploring and forecasting hydrothermal minerals and gold deposits in Central Saudi Arabia (SA), with a focus on structural contexts. Remote sensing (RS) and satellite-based Bouguer gravity (SBG) data were integrated in order to create a mineral prediction [...] Read more.
This article aims to aid in exploring and forecasting hydrothermal minerals and gold deposits in Central Saudi Arabia (SA), with a focus on structural contexts. Remote sensing (RS) and satellite-based Bouguer gravity (SBG) data were integrated in order to create a mineral prediction map for the researched location. Data from the Landsat Operational Land Imager (OLI) and Shuttle Radar Topography Mission (SRTM) were transformed and enhanced using a variety of approaches. The delineation of hydrothermal alteration zones (HAZs) and highlighting of structural discontinuities in the OLI data were made possible using band ratios and oriented principal component analysis (PCA). Additionally, the underlying structural features were successfully exposed by processing the SBG using a variety of edge detection techniques, like the analytical signal (AS), total horizontal derivative (THD), tilt angle (TA), horizontal tilt angle (TDX), theta map (TM), horizontal derivative of the tilt derivative (HD_TDR), horizontal gradient of the tilt angle (HGTA), tilt angle of the analytical signal (TAAS), and soft sign function (SF). As a result, more prominent lineaments were found in the NW–SE, NNW–SSE, NE–SW, and NNE–SSW directions than in the N–S and E–W directions. The GIS incorporated surface/subsurface geological structure density maps with zones of hydrothermal alteration. It was found that the lineaments derived from the analysis of the RS and SBG data were more in line with the HAZs, which demonstrated the common connection between alteration zones and deep lineaments. The findings revealed a mineral prediction map with extremely low to extremely high probabilities. Overall, combining RS and SBG data effectively identified probable mineralization sites associated with hydrothermal processes and made it easier to create this study’s final predictive mineralization map. Full article
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31 pages, 7477 KiB  
Article
Unconformities and Gold in New Zealand: Potential Analogues for the Archean Witwatersrand of South Africa
Minerals 2023, 13(8), 1041; https://doi.org/10.3390/min13081041 - 04 Aug 2023
Cited by 1 | Viewed by 1205
Abstract
Possible young analogues for regionally extensive unconformities (100 to 400 km2) in the gold-bearing Witwatersrand Supergroup (Archean, South Africa) occur in the South Island of New Zealand. Extensive marine unconformities in New Zealand show progression from an unconformity surface to conglomerate [...] Read more.
Possible young analogues for regionally extensive unconformities (100 to 400 km2) in the gold-bearing Witwatersrand Supergroup (Archean, South Africa) occur in the South Island of New Zealand. Extensive marine unconformities in New Zealand show progression from an unconformity surface to conglomerate to clean well-sorted sandstone to marine mudstone, as is also found in the major Witwatersrand auriferous reef horizons. The hosting young sedimentary basins of the South Island rest on thin or thick crust on inboard and outboard foreland settings, with variable alluvial gold budgets. They expose the Cretaceous–Oligocene Waipounamu Erosion Surface unconformity that formed when most of New Zealand was subsiding, and Pleistocene–Holocene unconformities related to global sea level changes. The Witwatersrand gold-bearing reef sediments are a good match for such marine transgressions, but not alluvial fans or braided streams. Most Witwatersrand gold is immediately above planar unconformity surfaces and not restricted to, or concentrated in, erosion channels that are incised through the reefs. However, in modern alluvial fans or braided streams, gold is almost entirely in erosion channels on a smaller scale than the Witwatersrand gold reef packages and not spread across the planar unconformities. Alluvial fans and braid plains in New Zealand dilute gold with large volumes of gravel. Full article
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13 pages, 9906 KiB  
Article
Geological Structures Controlling Au/Ba Mineralization from Aeromagnetic Data: Harrat ad Danun Area, Saudi Arabia
Minerals 2023, 13(7), 866; https://doi.org/10.3390/min13070866 - 26 Jun 2023
Cited by 3 | Viewed by 1287
Abstract
Positive and negative magnetic anomalies occupied the total aeromagnetic (TM) map of the Harrat ad Danun area, Saudi Arabia. Reduction to the pole (RTP) maps display the range of magnetic values (−312.4 to 209.4 nT) that vary in shape, size, and magnitude. These [...] Read more.
Positive and negative magnetic anomalies occupied the total aeromagnetic (TM) map of the Harrat ad Danun area, Saudi Arabia. Reduction to the pole (RTP) maps display the range of magnetic values (−312.4 to 209.4 nT) that vary in shape, size, and magnitude. These anomalies generally follow the NNW–SSE (Red Sea axis trend), NE–SW, and NNE–SSW trends. The NNW-SSE linear negative and positive magnetic anomalies could be brought on by buried faults, shear zones, or subsurface dikes. In the central part, the position of Au and Ba mineralization was connected to this trend. It is concluded that the principal structures are represented by the NNW–SSE, NE–SW, and NNE–SSW tendencies. Based on gridded RTP magnetic data, the 2-D power spectrum was computed and revealed the frequency of the near-surface and deep magnetic components. It is believed that the depths of the shallow and deep magnetic sources are typically 80 m and 570 m, respectively. Additional negative and positive magnetic anomalies with varied amplitudes and frequencies, trending in the NNW–SSE, ENE–WSW, and NE–SW directions, are seen when the high-pass and low-pass maps are closely examined. Many faults in various directions cut into these anomalies. The occurrence of negative linear magnetic anomalies (−36.6 nT to −137.3 nT) at this depth (80 m) is also confirmed by this map. The TDR filter and the Euler deconvolution method were used to identify the horizontal variations in magnetic susceptibility as well as the source position and depth of magnetic sources. The linear clustering rings are thought to be caused by contacts or faults with depths between 1 m to 474 m that are oriented WNW–ESE, NNE–SSW, and NNW–SSE. These faults or contacts are thought to be particularly prominent in the western, eastern, southern, northern, and central zones. The majority of felsic and mafic dikes are found to be connected to subsurface structures, showing that three structural trends—WNW–ESE, NNE–SSW, and NNW–SSE—affect the studied area. This demonstrates that important features and shear zones control the majority of Saudi Arabia’s gold deposits. A negative magnetic anomaly that is centered in the area, trending NNW–SSE and crossing the NNE–SSW fault, is connected to the plotted gold and barite mineralization in the study area. This may imply that these two tendencies are responsible for mineralization. This result raises the possibility of mineralization in the NNW negative magnetic feature located in the western part of the area. The occurrence of gold and barite was significantly impacted by the NNW–SSE and NNE–SSW structural lineaments. Full article
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