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•Lateritic gold deposits offer low-cost production, driven by demand and rising prices.•Supergene gold forms through the accumulation and redistribution during weathering.•Ferruginous ...Gravels and Duricrust deposits are an additional source of gold resources.•Evaluating lateritic gold faces sample heterogeneity and complex distribution challenges.•Understanding metallogeny principles enhances discovery success.
Lateritic gold deposits are emerging as a substantial reservoir of precious metals. The growing demand and escalating gold price have focused on lateritic gold and other supergene deposits due to their potential for low-cost production. The occurrence of gold in economic concentrations has been described in supergene-enriched mineralization in many regions dominated by intensely weathered terrains of the humid tropics and sub-tropics, such as equatorial rainforests, savannas, and some Mediterranean regions. Lateritic gold deposits also occur in semi-arid belts with historically similar climates. These deposits form through the physical accumulation and biological and chemical redistribution of Au during the weathering of primary mineralization. This study focuses on the upper ferruginous part of a lateritic profile known as Ferruginous Gravels and Duricrust (FGD) deposits, which includes lateritic residuum and/or similar ferricrete, overlying the ferruginous saprolite or mottled zone. The FGD and saprolite are separate systems with different physical and chemical conditions for Au mobilization. Intense artisanal mining in areas considered barren by geochemical surveys reveals disparities in sampling and analytical methods, such as panning for coarse gold versus geochemical analysis of fine fractions. Coarse gold in FGD significantly contributes to total gold content. Still, small drill samples fail to represent gold distribution accurately—the friable nature of lateritic materials results in low sample recovery rates (55%-70%). This paper synthesizes information from diverse deposits in Africa, South America, and Australia, drawing on academic papers and technical reports from industry to provide a comprehensive global overview of the supergene gold metallogeny and exploration strategies leading to enhance the success of new discoveries or the re-assessment of known deposits.
The pre-Quaternary stratigraphic section in Agnew–Lawlers area consists of Permo-Carboniferous glacial sediments, unconformably overlain by Tertiary clastics of palaeochannel sequence and Quaternary ...alluvial and colluvial sediments. The unique Permo-Carboniferous glacial sedimentary succession in the Yilgarn Craton has not been studied in detail in terms of vertical chemostratigraphic variations, basin and landscape evolution, diagenesis and post-Permian weathering overprints. In Agnew–Lawlers district, continental facies of glacial diamictites, glaciofluvial sandstones and glaciolacustrine rhythmites vary in thickness from 28 m to 181 m and is preserved beneath Cenozoic sediments as relict landforms in highly irregular, asymmetrical and poorly drained basins. The Permo-Carboniferous sediments were mechanically weathered and eroded by glaciers from the surrounding Archaean basement palaeohighs under a cold arid climate. Textural relationships of diamictites indicate that they were derived from proximal and distal source rocks. The denuded palaeotopography of the basement palaeohighs (source rocks) and Permo-Carboniferous sediments were subjected simultaneously to an intensive, post-Permian chemical weathering. The exposed basement rocks were deeply weathered into residual saprolite, whereas the Permo-Carboniferous sediments were differentiated into three chemostratigraphic units. The diamictite and rhythmite of the lower unit are unweathered and preserves the signature of the glacial/interglacial weathering. Mineralogical and geochemical changes dominated in this unit are related mainly to diagenesis at shallow depth (eogenesis) with no significant compaction. The formation of a paragenetic diagenetic sequence of chlorite, ferroan dolomite and pyrite indicates diagenesis has occurred under reducing and alkaline conditions below the permafrost and modern water table. Mineralogical and geochemical changes dominated in the middle unit are linked mainly to eogenetic redox reactions. The formation of smectite and ferruginous cements in this unit is attributed to weathering of ferromagnesian and opaque heavy minerals under oxic and slightly alkaline conditions. Mineralogical and geochemical changes dominated in the upper unit is related mainly to Post-Permian chemical weathering, where almost all rock-forming minerals are altered to kaolinite and alkali and alkaline earth elements are leached forming bleached white saprolitic diamictites. A change in clay minerals from kaolinite in the weathered Permo-Carboniferous succession to smectite in the overlying Cenozoic succession demarcates the unconformity and probably reflects a change to an arid climatic condition. Chemically, the Cenozoic succession shows a sharp increase in Ti/Al and La/Ce ratios and a decrease in Ce anomaly that remain constant in the Permo-Carboniferous section. These mineralogical and chemical variations through the Phanerozoic stratigraphic section can be used to follow the landscape and climatic evolution since the late Palaeozoic glaciation.
As IoT has increasingly evolved in recent years, it has become more important to ensure security on IoT devices. Many of such devices are under the threat of attacks in the beyond black‐box model. To ...protect from the threat, the cryptographic implementation that can offer secure execution in the grey‐/white‐box model is important. However, such cryptographic implementations require a large number of clock cycles to execute and cannot fully cover resistance against various types of side‐channel attacks. In this paper, a new family of table‐based cipher dubbed Cubicle is proposed, which can offer efficient execution and sufficient security against side‐channel attacks on IoT devices powered by ARM Cortex‐M processors, which are widely deployed in IoT applications. To evaluate the security of Cubicle in the grey‐box model, the authors derive the bound of table leakage in the grey‐box model by applying space hardness, which is the notion to evaluate the security against code lifting attacks in the white‐box. The security of Cubicle in the grey‐box model is shown by using this bound. In addition, the security of Cubicle is also shown in the black‐box and white‐box models. Finally, the performance of Cubicle and other ciphers in some devices powered by ARM Cortex‐M3, ‐M4, and ‐M7 processors is evaluated. The authors show that Cubicle is significantly efficient compared to other grey‐/white‐box‐ model‐secure ciphers in target experiments for IoT applications.
Analysis of Atom against quantum attacks Anand, Ravi; Nandi, Rimpa; Isobe, Takanori
IET quantum communication,
March 2024, Letnik:
5, Številka:
1
Journal Article
Recenzirano
Odprti dostop
A significant amount of study is being done to review the security promises made for the various ciphers now in use as a result of the development of quantum computing technology. A general attack ...against symmetric key cryptography primitives that can reduce search costs to the square root is Grover's search algorithm. To implement Grover's algorithm, it is necessary that the target cipher be implemented as a quantum circuit. Despite being relatively new, this area of study has received significant attention from the research community. The authors have estimated the cost of Grover's key search attack against the stream cipher Atom, for the first time, under circuit depth restrictions defined in National Institute of Standards and Technology (NIST) PQC standardisation process. The authors implement the quantum circuit of Atom in QISKIT, (open‐source software development kit for working with quantum computers running on IBM Quantum Experience). The results are also compared with other existing literature on LFSR‐based stream ciphers, such as Grain‐v1, Grain‐128‐AEAD, and Lizard. The authors also find that, to the best of their knowledge, in the existing literature on estimating the cost of Grover's attack on symmetric ciphers, Atom is the only 128‐bit key cipher that meets the threshold of ≈2170 set by NIST for quantum security of 128‐bit key ciphers. The authors also analyse the security of Atom against quantum TMDTO attacks.
A cost estimation of Grover’s key search attack on the stream cipher Atom is provided, taking into account circuit depth restrictions specified by NIST’s PQC standardisation process. The quantum circuit of Atom is implemented using QISKIT, and the results are compared with other LFSR‐based stream ciphers, including Grain‐v1, Grain‐128‐AEAD, and Lizard. The authors also analyse the security of Atom against quantum TMDTO attacks.
Nature Communications 4: Article number: 2614 (2013); Published online 22 October 2013; Updated 25 May 2018 The original HTML version of this Article had an incorrect article number of 2274; it ...should have been 2614. This has now been corrected in the HTML; the PDF version of the Article was correctfrom the time of publication.
The aim of this study was to determine specific distribution of metals in the termite Tumulitermes tumuli (Froggatt) and identify specific organs within the termite that host elevated metals and ...therefore play an important role in the regulation and transfer of these back into the environment. Like other insects, termites bio-accumulate essential metals to reinforce cuticular structures and utilize storage detoxification for other metals including Ca, P, Mg and K. Previously, Mn and Zn have been found concentrated in mandible tips and are associated with increased hardness whereas Ca, P, Mg and K are accumulated in Malpighian tubules. Using high resolution Particle Induced X-Ray Emission (PIXE) mapping of whole termites and Scanning Electron Microscope (SEM) Energy Dispersive X-ray (EDX) spot analysis, localised accumulations of metals in the termite T. tumuli were identified. Tumulitermes tumuli was found to have proportionally high Mn concentrations in mandible tips. Malpighian tubules had significant enrichment of Zn (1.6%), Mg (4.9%), P (6.8%), Ca (2.7%) and K (2.4%). Synchrotron scanning X-ray Fluorescence Microprobe (XFM) mapping demonstrated two different concretion types defined by the mutually exclusive presence of Ca and Zn. In-situ SEM EDX realisation of these concretions is problematic due to the excitation volume caused by operating conditions required to detect minor amounts of Zn in the presence of significant amounts of Na. For this reason, previous researchers have not demonstrated this surprising finding.
Areas under a thick Permian glacial cover in Western Australia formed as glaciers gouged fresh bedrock and deposited diamictites in disconnected valleys and basins. These areas now present the ...greatest challenge for mineral exploration in the northeast Yilgarn Craton. At the Lancefield North gold prospect, in the southern part of the Duketon Greenstone Belt, Permian diamictites on average 40 m thick cover unweathered basalt hosting gold mineralization. The basal Permian diamictites consist of fresh, very poorly sorted, angular to rounded, pebble- to boulder-sized, polymictic clasts supported by a matrix of coarse-grained sand and mud. The framework and matrix are cemented by calcite, dolomite, chlorite, and pyrite. These diamictites are stable under alkaline and reducing conditions below the water table. Detrital; fresh sulfides; gold; and opaque oxides, such as pyrite, pyrrhotite, chalcopyrite, sphalerite, arsenopyrite, gersdorffite, cobaltite, pentlandite, scheelite and galena, chromite, ilmenite, and magnetite, are identified in the framework and matrix of the fresh diamictites, and these are identical to those in the primary gold mineralization. Weathering of diamictites and oxidation of detrital and diagenetic sulfides above the water table produced several Fe- and Mn-rich redox fronts and secondary chalcocite and bornite. Interface sampling across the Archean–Permian unconformity shows Au, As, Zn, Ni, Co, and Cd anomalism over the mineralization compared to the background. However, these elements are low in concentration in the redox fronts, where Fe is correlated with As, Cu, Mo, and Sb and Mn is correlated with Co, Ni, and Ba. Gold shows elevated levels in the fresh basal diamictites and decreases in the weathered diamictites over the mineralization. A sampling at or near the Archean–Permian unconformity (interface sampling) only delineates gold mineralization, with no hydromorphic dispersion halo beyond the peripheries. At the Lancefield North prospect, the detrital indicator sulfides are mechanically dispersed up to 500 m to the east of the mineralization in the direction of ice flow. This dispersal distance is controlled by the rough topography of the Archean–Permian unconformity, and it may be greater, but the estimation of the actual distance of transport is limited by the distribution of drill hole locations.
Microbial contribution to gold biogeochemical cycling has been proposed. However, studies have focused primarily on the influence of prokaryotes on gold reduction and precipitation through a ...detoxification-oriented mechanism. Here we show, fungi, a major driver of mineral bioweathering, can initiate gold oxidation under Earth surface conditions, which is of significance for dissolved gold species formation and distribution. Presence of the gold-oxidizing fungus TA_pink1, an isolate of Fusarium oxysporum, suggests fungi have the potential to substantially impact gold biogeochemical cycling. Our data further reveal that indigenous fungal diversity positively correlates with in situ gold concentrations. Hypocreales, the order of the gold-oxidizing fungus, show the highest centrality in the fungal microbiome of the auriferous environment. Therefore, we argue that the redox interaction between fungi and gold is critical and should be considered in gold biogeochemical cycling.
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