Papers by Keyword: Geochemistry

Abstract: Djerid Chott, in southwestern Tunisia, is one of the biggest salt lakes in the world. This work follows the specific precipitation of evaporites through progressive evaporation of Chott Djerid brines using geochemical, isotopic and mineralogical approaches, to explain the intricacy of the working of saline frameworks controlled basically by climatic driving and the underlying geochemical structure acquired from the geographical system. Toward the finish of every evaporation step, solid and liquid samples went through analyses. Djerid brine is remarkably saline (427.7 g/l) and it is supersaturated contrasted with halite. The outcomes indicated that the Chott Djerid brines shaped fundamentally Cl^--Na⁺-SO₄^- type geochemistry. Added to halite and gypsum as significant minerals, other minor minerals including carnallite, hexahydrite and sylvite were recognized in various phases of progressive evaporation of Djerid brine. Regardless of their low costs, significant minerals are of geo-economic interest because of their high amounts of production. Then, minor valuable minerals secure their geo-economic interest from their excessive costs. In this work, we find the window of precipitation of these valuable minerals' at the evaporation paces of 80% and 100%.

Abstract: The Samolazovskoye deposit (Central Aldan ore region, Russia) is confined to the porphyry syenite lopolith (J₃-K₁), localized between the granitic gneiss Archean basement and the series of the Vendian-Lower Cambrian carbonate cover rocks. Four hydrothermal-metasomatic parageneses have been identified within the deposit: skarn paragenesis, developed on the syenites and carbonate cover rocks contact; so called «gumbaite» paragenesis (kalifeldspar + fluorite + carbonate ± quartz), superimposed on the intrusive massif rocks; feldspatholitic paragenesis (quartz + feldspar), developed in the granitic gneisses of the crystalline basement; ore-bearing fluorite-roscoelite-carbonate-quartz paragenesis, superimposed on all of the above. The article compares ores evolved within gumbaitic syenites, basement feldspatholites and breccias, composed of all the above-mentioned rocks clasts. The geochemical study of given ores, resulted in two identified elements associations: gold-telluride (Au, Sb, As, V, Tl, Te, Hg, W) related to the fluorite-roscoelite-carbonate-quartz hydrothermal-metasomatic paragenesis and (uranium)-polymetallic (Bi, Cu, Pb, Zn, Mo, Se, Li, U), associated with the syenites gumbaitization (). There is only gold-telluride association within the basement ore bodies, while the ore bodies localized in the syenites intrusion hold both associations, along with the Au and Ag contents being an order of magnitude higher. Breccia ores are characterized by the maximum concentrations of the ore elements. Gold-telluride association of the Samoazovsky deposit ores is specific to epithermal Au-Te mineralization associated with alkaline (A-type) magmatism.

Abstract: The Central Aldan ore district is a geologically unique area, representing the conjunction zone of the ancient structures of the Archean–Proterozoic crystalline shield, overlain by the Vendian–Cambrian sedimentary cover. The latter was formed in the Mesozoic by intensive alkaline magmatism. Within the Central Aldan ore district, most of primary gold-ore deposits are confined to the sedimentary cover. Until recently it was considered that only ancient complexes in the crystalline basement contain commercial Au-U mineralization. As a result of the geological exploration works over the period of 2003–2006, the Podgolechnoe deposit was discovered. Gold mineralization in this deposit occurs both in rocks of sedimentary cover and crystalline basement. Ore bodies in rocks of the crystalline basement (A-type alkaline deposits) contain epithermal gold-telluride (Au-Te) mineralization, which is new for Central Aldan ore district. This work presents results of the study of geochemical composition of the Podgolechnoe deposit ores and their comparison with typical epithermal gold-ore deposits. In total, 15 samples were studied. The homogeneity of the sample collection, the correlation between Au and other elements, the enrichment coefficients of elements-admixtures, and the REE distribution were analyzed. It was established that gold ores of the Podgolechnoe deposit are geochemically heterogeneous, but, in general, they correspond to the geochemical spectrum characteristic of the gold ores of A-type epithermal deposits. In contrast to Au-U deposits, common in the studied area, ores of the Podgolechnoe deposit show no correlation between gold and uranium.

Abstract: H₂S gas would pose a threat to coal mine safety. This article from the biodegradation, microbial sulfate reduction, thermal decomposition chemistry, chemical sulfate reduction and magmatic 5 aspects to analyze the formation mechanism of hydrogen sulfide gas in coal mine, a coal mine combined with field data, analysis of hydrogen sulfide gas in the coal mining the transport mechanisms. Research for the comprehensive management of coal mine hydrogen sulfide gas has certain significance.

Abstract: Yalong river basin is located in the southeast of the qinghai-tibetan plateau. This area is the important mineral resources region, where ecological environment problems caused by mineral resources development are uncertain and complicated. It is necessary to understand the influence of mineral resources development urgently and control human activities scientifically. In this paper, the eco-environment influence of mineral resource exploitation is studied on basis of geochemical data and remote science, and dividing into mining point distance, soil type, land cover, vegetation coverage and the soil erosion. The method of principal component analysis is adopted to sort the corresponding degree of various factors. Then the impact of mineral resources development on ecological environmental factors can be mastered overall, which providing decision basis for mining development measures.

Abstract: In the past forty years, the investigation on Hot Dry Rock (HDR) geothermal resource has been a hot topic. A great number of investigations confirm that electricity power generated from HDR is feasible and propose that a right HDR site is composed of basement rock and its overlying cover. In the present study, we explore the petrology, geochronology and geochemistry features of the HDR basement rocks with the aim to further optimize HDR siting conditions. Combined analyses show that young S-type or crustally-derived granites with high U, Th and K contents have great potential to develop HDR geothermal resources.

Abstract: Volcanic rocks of Yixian Formation were widely distributed in western Liaoning. The Yixian volcanic cycle of early Cretaceous in the Chaoyang basin can be divided into two subcycles. The first subcycle is composed of basalt, basalt andesite and andesite. The second subcycle is composed of trachyandensite and trachyte. The volcanic rocks are characterized by high SiO₂, Al₂O₃, K₂O and Na₂O, and comparatively low TiO₂ components. The volcanic rocks are obviously enriched in incompatible elements, and depleted in compatible elements. The ∑REE of volcanic rocks is high and rich in LREE. The spider patterns are the right-incline, there is a slight low Eu negative abnormality and low Ce negative abnormality. The characteristics show that volcanic rocks of Yixian Formation belong to the high-K calc-alkaline magmatic serious. Comprehensive study shows that the volcanic rocks of Yixian Formation were generated in response to lithosphere extension in the continent intraplate orogenic belt.

Abstract: Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the concentrations of rare earth elements and yttrium (REY) in coal and associated rock samples from the Guanbanwusu Mine, Jungar Coalfield, Northern China. The Guanbanwusu coals have a similar vitrinite reflectance and sulfur content, and a slightly higher ash yield. The concentration of REY (from La to Lu plus Y) in the 6 coal of the Guanbanwusu Mine varies from 72 μg/g to 396 μg/g and averages 186 μg/g, higher than that in normal Chinese coal (136 μg/g) and much higher than that in average world hard coals. The H-type distribution patterns in the No. 6 coal (W9-2 and W9-9) were probably caused by stronger water influences than those in the other coalfield. The coal bench (W2 and W9) with L-type is because terrigenous input influence.

Abstract: The Ordos basin Chang 7 hydrocarbon source rocks are the most important rock strata of premium oil source formed during the largest lake flood period of the terrestrial lacustrine. Our study found that the bottom of the rocks are rich in radioactive uranium. Element geochemical studies showed that the rocks are also rich in C, S, P, Cu, V, Mo and other pro-life elements but not rock-forming minerals-related lithophile elements Li, Zr, Sr, etc. Their uranium content has obvious positive correlation with phosphorus, sulfur, iron, organic carbon content, but not with major rock-forming elements. Petrography and scanning electron microscopy revealed the rocks are rich in pyrite, phosphate rock and striped organic matters. These features indicate that uranium enrichment and the presence of these minerals are closely related. The significantly positive correlation of the ratio of uranium to trace elements such as U/ (U+Ni) and U/Sc indicates that anoxic environment played an important role in uranium enrichment. Electron microprobe analysis found for the first time uranium ore and independent titanium-containing uranium minerals in phosphate rocks in the area. α radiation photography and sequential chemical extraction found that 50% of uranium present as independent uranium and its isomorphic minerals in the phosphate rocks, 20% is absorbed to pyrite and organic matter, and less than 10% is absorbed on clay minerals.

Abstract: Based on stream sediment geochemical anomalous features of molybdenum element in China, this paper studied the main zoning of geochemical anomalous features of molybdenum element. At the same time, geochemical anomalous features and genesis of molybdenum element in different types of uranium deposits in Uranium resources potential evaluation were analyzed. Research shows that, molybdenum is an important dedicator element in uranium geochemical exploration, though there is some difference of geochemical anomalous features in different types of uranium deposit. Molybdenum element played an important role in prediction of further ore-prospecting of carbonaceous-siliceous-argillaceous, volcanic and sandstone uranium deposit. By combining the analysis of geological factors such as rock formation, succession of strata, structure, molybdenum element geochemical anomaly helps to improving prediction accuracy of uranium resources potential evaluation.