Study of Radarfacies in Auriferous Placers at Baixada Cuiabana, Mato Grosso (Brazil)

The state of Mato Grosso (MT) is the fifth largest gold producer in Brazil, with much of it coming from the Baixada Cuiabana region. In this region, gold occurs in primary deposit associated with quartz veins and their host metasedimentary rocks of the Cuiabá Group and secondary sedimentary deposits (such as colluviums, alluviums and eluviums), the latter being quite profitable and easy to exploit. The gold exploitation in these areas often results in deforestation of the Pantanal biome, as mining uses random subsoil scarification to locate the deposits. In this study, the Ground Penetrating Radar (GPR) geophysical method was applied to differentiate and locate alluvial, colluvial and eluvial deposits. This may help to mitigate the local deforestation process. Thus, the acquisition of GPR data took place in a gold mine located in the municipality of Nossa Senhora do Livramento. The GPR recordings were done with a 200 MHz shielded antenna, along with ditches and gravel exposures. The results show variability of the electromagnetic wave velocity between 0.085 to 0.146 m/ns, with normalized amplitudes of -1 to 1 ranging between maximum values of -0.8 and 0.8. The lowest velocity values were found for gravels of alluvial origin. The intermediate velocity of 0.090 m/ns is associated with eluviums and the highest velocity (0.146 m/ns) is associated with gravel of colluvial origin. GPR was efficient to distinguish secondary sedimentary deposits in the Baixada Cuibana, becoming a prospective alternative for the region.

A Taphonomic Interpretation of the Postmortem Fate of the Victims Following the Massacre at Sandby Borg, Sweden

In the ringfort Sandby borg (A.D. 400–550) on Öland, Sweden, remains of 26 unburied humans were excavated between 2010 and 2016. Several of the skeletons display traces of lethal interpersonal violence. This study pres¬ents taphonomic analyses of unburied bodies, a situation seldom encountered archaeologically. The depositional context allows us to investigate human taphonomy in interaction with natural agents both “indoors” and “out¬doors.” A set of various techniques, including documentation of preservation via zoning, weathering stages, frac¬ture analysis, and archaeothanatology, were applied to understand the perimortem and postmortem fate of the human remains. The results of the taphonomic analysis showed no indications of manipulation postmortem. Expected differences in preservation between in-and outdoor skeletons were not observed. Perimortem fire al¬terations were interpreted as the result of burning hearths and smoldering roofs. The analysis indicates that the bodies have decomposed in voids. New observations for “unconfined void” taphonomy are presented. The ab¬duction of limbs could be the result of bloating and, hence, indicate a primary deposit of bodies. Atypical lack of splaying of bones might be caused by decomposition in unconfined voids, possibly allowing quicker drainage of putrefaction liquids than in confined voids such as coffins. These observations suggest that processes behind decomposition in voids are not completely understood archaeologically, and might challenge interpretations of mortuary treatment from human remains. In der Wallburg Sandby borg (400-550 n. Chr.) auf Öland, Schweden, wurden die Überreste von 26 nicht bestat¬teten Menschen gefunden, die zu einem großen Teil Spuren von tödlicher Gewalteinwirkung aufwiesen. In dieser Studie werden die Ergebnisse taphonomischer Untersuchungen von nicht bestatteten menschlichen Überresten präsentiert, auf die man im archäologischen Kontext nur selten trifft. Diese Art der Niederlegung und Auffindung erlaubt es uns die Taphonomie von menschlichen Überresten unter natürlichen Einflüssen von sowohl ”drinnen—im Haus” als auch ”draußen—außer Haus” zu untersuchen. Mehrere unterschiedliche Methoden wurden angewendet um sowohl das perimortale als auch das postmortale Schicksal der menschli¬chen Überreste zu verstehen, darunter Dokumentation der bewahrten Knochenteile, Stadien der Verwitterung, Bruchanalysen und Archäothanatologie. Die Ergebnisse der taphonomischen Untersuchungen zeigten keine postmortalen Veränderungen. Die erwarteten Unterschiede im Zustand der drinnen und draußen bewahrten Skeletten ließen sich nicht bestätigen. Perimortale Veränderungen der verbrannten Knochen wurden als Resul¬tat von aktiven Feuerherden und brennenden Dächern gedeutet. Die Analyse spricht dafür, dass die Körper in Hohlräumen verwesten. Neue Beobachtungen von Taphonomie in ”unbegrenzten Hohlräumen” werden eben¬falls präsentiert. Die Abduktion von Körpergliedern kann auf Aufblähungen beruhen, und spricht damit für eine primäre Niederlegung von Körpern. Der atypische Mangel an verteilten Knochenmaterial kann durch die Verwesung in unbegrenzten Hohlräumen verursacht worden sein, und damit einen schnelleren Abfluss von Verwesungsflüssigkeit erlauben, als es in begrenzten Hohlräumen wie z. B. Särgen der Fall ist. Diese Ergebnisse sprechen dafür, dass Verwesungsprozesse in Hohlräumen archäologisch noch nicht vollständig zu verstehen sind, und daher die Deutung wie menschliche Überreste behandelt wurden in Frage stellen können.

Regional scale prospectivity modelling of NW India for REE deposits associated with carbonatites and alkaline complexes

<p>The rare earth elements (REEs) are a group of seventeen metals including 15 lanthanides, scandium and yttrium.  These metals have been projected to be critical for future industrial development. However, India currently does not have any economic grade primary deposit of REEs; all of India’s production comes from monazite-bearing beach sands along the eastern and western coasts that have been derived from REEs-enriched continental rocks such as pegmatites or carbonatites. This contribution documents a GIS-based prospectivity model for exploration targeting of REE associated with carbonatites and alkaline-complexes in the geologically permissive tracts of NW India comprising parts of western Rajasthan and northern Gujarat. A mineral systems approach is applied to model the key ingredients of an REE system including geodynamic setting; fertile mantle/crustal sources of REEs; deep to shallow crustal architecture; and REE deposition.  This conceptual genetic model of REE mineral systems is, in turn, used to identify the key regional-scale REE-deposit targeting criteria in NW India. Regional-scale multi-parametric exploration datasets are processed to represent the targeting criteria in form of predictor GIS layers. Finally, an expert-driven fuzzy inference system is designed for delineating and raking prospective REE targets. Simultaneously, the stochastic and systemic uncertainties in the prospectivity modeling are modelled to delineated (a) high priority REE exploration targets areas with low uncertainty and high prospectivity for immediate ground follow up and (b) areas with high uncertainty and high prospectivity for further data acquisition in order to reduce uncertainty.</p>

Roman Gold from Tresminas (Portugal)

The reconstruction of Roman mining activities in a primary deposit during the 1st and 2nd centuries AD has been made possible thanks to the excellent preservation of ancient mining and the prerequisite accompanying industries in the territorium metallorum Tresminas / Jales. Decades of on-site research and careful documentation of the monuments and traces of mining have faciliated the understanding of the work processes presented in this volume: prospection, excavation and processing. Within this framework, prospecting not only served the discovery of deposits as reported by ancient sources, but it accompanied the miners’ daily work and was an essential element of the mining process. The mining itself has left traces that enable us to both follow and understand the progress of mining over time. The planning and execution that become visible as a result of this allow us to infer a central organisation. The fantastic extensive high galleries of Tresminas, whose dimensions and state of preservation still impress visitors and researchers today are a further example of this. Finds that were abandoned, never completed or destroyed in ancient times are particularly helpful in understanding the mining process. The complex processing of the gold-bearing ores has left behind in Tresminas around 1 000 stamp mills, countless rock-grinding mills and enormous ore washing structures. In addition, the water management system associated with mining and settlement is discussed. An important part of the industrial complex was also the local stone quarrying for the production of stamp mills, rock-grinding and grain mills. A summary of the historical context of the territorium metallorum Tresminas / Jales is presented in the introduction.

Revolution of Malaysia’s Kaolin to Metakaolin towards various application: A Mini Review

The transformation of kaolin to metakaolin was studied in various state in Malaysia which is Segamat, Nitar, Lenggor, Ipoh, Bidor, Mersing, Sabah, and Sarawak. In Segamat, the kaolin has a light colour due to the high silicate composition and also contain high mineral such as kaolinite and quartz existed as impurities. Aluminum rich kaolin is bright in color with elevated plasticity and is commonly used in the ceramic, plastic, dye, fabric, pesticide, pharmaceutical and beauty industry. For Nitar and Lenggor, production of metakaolin occurs at 510°C and formation of mullite occur at 900°C. Both clays show good crystallization of pseudohexagonal to hexagonal kaolinite particles. Moreover, the classification of clay and the sizing are the significant characteristic to be determined using the method of the beneficiations. The method of beneficiations is crucially important to increase the quality of clay to meet the requirement for industry application. In Ipoh and Sarawak, the primary deposit is dominated by kaolin and the mixture of granites and diorites produced from weathering. On the other hand, in Bidor, the primary deposit is a mixture of kaolinite, muscovite and smectite also formed by weathering. The increasing amount of illite in secondary kaolin deposits in the Mersing area due to the marine deposition of those deposits where illite formed by the absorption of clay minerals from the seawater by pottasium. Kaolin in Kg Gading, Bongawan Sabah were treated with sodium hexametaphosphate to remove impurities in natural kaolin. The transformation of kaolin to metakaolin was conducted at 800°C for 5 hours.

Kimberlite exploration at Serra da Canastra province, Brazil

Kimberlite and lamproite pipes are the only economically significant source rocks forming primary diamond deposits. Brazil, the world’s seventh largest diamond producer, has all of its production from alluvial deposits. The quest for a primary deposit has continued over several decades with very few positive results. To that end, airborne magnetic data from the Serra da Canastra diamondiferous province was used to identify kimberlite signatures. Serra da Canastra is located in the central portion of the Brazilian province in a low-magnetic-latitude region. The main tectonic feature of the area is a northwest-southeast major crustal fracture zone that extends for more than [Formula: see text] within the territory. The interpretation strategy was based on joint analysis of analytic signal and Euler deconvolution. A selected kimberlite target should typically have a roughly circular analytic signal anomaly coincident with a depth [Formula: see text] and structural [Formula: see text] constrained Euler solution. The proposed approach led to recognition of previously known pipes and generation of new targets. Ground geologic, geophysical, and geochemical follow-up surveys are necessary to test these selected targets.

Discovery of a Tin-tungsten Mineralization in Northern Khartoum Province, Sudan

A primary deposit of tin and tungsten has been discovered in association with granites of the Cambrian (?) sub-volcanic igneous complex at Sabaloka, on the Nile north of Khartoum. Wolfram and cassiterite occur in a stockwork of quartz veins which also contain minor amounts of sulphide minerals. The stockwork centres around a small intrusion of primary greisen lying on the contact of a porphyritic microgranite ring-dyke but the greisen and mineralizing solutions are believed to have originated from a nearby mass of biotite-muscovite granite. The deposit has many features in common with the primary tin veins associated with the Younger Granites of northern Nigeria and other parts of northern Africa.