Ore Bearing Research Articles

Ilmenite Content of Different Genesis of Productive Sediments of the Trostyanytsky Deposit

The article presents information on the geological structure and ore content of the Trostyanytsky ilmenite deposit located in the northern part of the Volodarsk-Volynskyi massif of the Korostensky pluton bedrock. The deposit is localized in the weathering crust of the basement crystalline rocks and continental deluvial-alluvial and alluvial sediments of the Middle Jurassic-Lower Cretaceous, which were formed by erosion and redeposition of eluvium. Weathering crust together with deluvial-alluvial and alluvial sediments formed the productive deposits of the Trostyanytsky deposit. On the basis of the created target database containing conditional coordinates of wells, their description and testing results, mapping constructions (isohypses of the roof, sole, isopachites of the thickness of the weathering crust of crystalline rocks of the basement, alluvial sands and redeposited kaolins of the Middle Jurassic-Lower Cretaceous) were carried out; lateral distribution of the average ilmenite content in the weathering crust, in the Middle Jurassic-Lower Cretaceous fluvial deposits and in productive sediments, distribution of ilmenite content in the vertical section of wells). These mapping constructions were created based on the results of preliminary (1999) and detailed (2008) geological exploration. The direction and strength of correlations between the topography of the sole and the surface, topography of the sole and the thickness of ilmenite-bearing formations, sole relief and ilmenite content, sediment thickness and ilmenite content in the weathering crust, alluvial deposits of the Middle Jurassic-Lower Cretaceous and in productive deposits. The obtained results made it possible to clarify the structural and material parameters of the ore-bearing rocks, the lateral and vertical distribution of ore bearing in different genetic and different age's formations.

Polychronic-polygenic spatial-paragenetic ilmenite bearing of the Bukinska area of the Mezhyrichny deposit of titanium ores

Introduction. The primary task, aimed at meeting the needs of our own titanium raw materials, is to put into operation as soon as possible the deposits in which spatially and paragenetically different ore bearing capacity is combined in a spatial and paragenetic way and which have sufficient detail been studied. One of these deposits is Mezhyrichne, which is located within the Volyn megablock, in the central part of the Korosten pluton, Zhytomyr region. Within the deposit, several areas have been identified, including Bukinska. The purpose of the publication. To investigate the ilmenite ore-bearing of the polygenic-polychronic spatial-paragenetic ore-bearing system within the Bukinska area, which is composed of ore-bearing rocks of the foundation, their weathering crust, continental alluvial (Aptian-Lower Albian) deposits (formed due to erosion and redeposition of eluvium) and coastal-sea (Turonian) formations (formed due to erosion and redeposition of Lower Cretaceous alluvium and partially weathering crust). Materials and Methodology. The methodical and methodological basis of the research was the work of the autors on the structural and lithological modeling of placers of heavy minerals. The actual material for the studies were the production reports and scientific publications. A target database was created for cartographic modeling of the structure and quality indicators (distribution of ilmenite content along the lateral spread and vertical cross-sections of wells) of the rocks. The database contains the coordinates of 1635 wells, their description, test results. Cartographic constructions were made in Inkscape, Golden Software Strater, and Golden Software Surfer software. Correlations between certain parameters of ore-bearing sediments were studied in Microsoft Excell. Main Results. Information on the geological structure of the Bukinska area of the Mezhyrichne titanium ore deposit is given. It has been found that the ore-bearing potential of the area is determined by a polygenic-polychronic spatially-paragenetically connected ore system. This ore system is composed of titanium-bearing rocks of the crystalline basement of the Volodarsk-Volyn complex, their weathering crusts, Lower Cretaceous continental, Upper Cretaceous coastal – marine products of erosion and redeposition of eluvium and to a lesser extent and partially heterogeneous formations of the Quaternary system. Maps of the relief of the bottom, the top surface and thickness of the ore-bearing rocks have been constructed. The lateral distribution of the average ilmenite content in all rock types was studied. The directionality and strength of correlations were investigated. The peculiarities of the distribution of ilmenite in the vertical section of formations of different ages and different genesis have been clarified. Conclusions. A target database was created, on the basis of which a set of maps was built, which made it possible to study the structural and material parameters of ore-bearing deposits. The ore-bearing potential of the polygenic-polychronic spatial-paragenetic system of the Bukinska area was qualitatively and quantitatively assessed. It has been found that the Bukinska area, within which there is a spatially and paragenetically combined temporal and heterogeneous ore bearing, has a significant ore-bearing potential and is attractive for investment. The obtained results are an information base for supporting mining operations.

POLYCHRONIC-POLYGENIC PARAGENETIC-SPATIAL TITANIUM ORE SYSTEM OF THE SEDIMENTARY COVER OF THE SOUTH-WESTERN PART OF THE KORSUN-NOVOMYRHOROD PLUTON

Information is provided on the titanium-zirconium ore content of the weathered crust and continental and coastal Mesozoic- Cenozoic deposits within the Byrzulivska, Valuivska, Likarivska, Andriivska, Novomyrgorodska, Vytiazivska areas, which are located in the southwestern part of the Korsun-Novomyrhorod pluton within the Novomyrgorod massif. On the basis of the coordinates, description and results of testing wells for the specified areas, a target database was created on the basis of which cartographic constructions were made. The results of studies of the spatial distribution of the thickness of the weathering crust, sands and redeposited kaolins of the Lower Cretaceous within the Byrzulivska, Valuivska, Likarivska, Andriivska areas are presented; sands and redeposited kaolins of the lower-middle Eocene within the boundaries of the Novomyrhorodska area; Quaternary sands within the Vytiazivska area. It was found that the lateral distribution of the thickness of the weathering crust is due to the relief of the surface of the crystalline rocks of the foundation and the partial erosion of the eluvium during the geological development of the territory. Instead, the uneven distribution of the thickness of Mesozoic-Cenozoic sediments is caused by the amount of terrigenous material entering the sedimentation basin, facies conditions of formation, and erosion and redeposition of sediments to higher stratigraphic levels. The lateral distribution of the average content of ilmenite, rutile, and zircon and the correlations between these minerals in the weathering crust, redeposited kaolins, and sands of the specified areas were studied. It was found that the ore bearing of the weathered crust and the Mesozoic-Cenozoic continental and coastal marine sediments is paragenetically and spatially related to each other and is determined by the ore bearing of the crystalline rocks of the foundation. The average content of ilmenite, rutile and zircon in the weathering crust is determined by their average content in the parent rocks of the crystalline basement, in the continental and coastal formations of the Mesozoic and Cenozoic — by the content of minerals in the weathering crust and intermediate reservoirs (for deposits that do not lie on the weathering crust), facial conditions of formation. As a rule, aureoles of increased mineral content do not coincide spatially, and correlations between their average content are mostly very weak or absent. The obtained results confirm and complement the results of previous studies on ore bearing capacity and prospects for increasing the mineral-raw material base of critical raw materials within the Novomyrhorod massif. Research results can serve as an information base for forecasting, prospecting and mining operations within the investigated areas.

Ore-bearing of the osynova area of the Mezhyrichne deposit of titanium ores

Information on the geological structure and ore bearing of the Osynova area of the Mezhyrich deposit of titanium ores, which is located in the northeastern part of the Volodar-Volyn massif of the Korosten pluton and is part of one of the most promising Volyn zirconium-titanium ore districts, is presented. It was found out that the ore-bearing potential of the Osynova area is determined by a spatially and paragenetically connected ore system, which is composed of titanium-bearing rocks of the crystalline basement of the Volodarsk-Volyn complex, their weathering crusts, continental (irshan suite, apt-albian) and marine (moshno-rudnyan suite, turon) by products of erosion and redeposition of eluvium. Based on the coordinates of the wells, their description, and test results, a target database was created, which became the basis for cartographic constructions. Maps of the relief of the top, bottom and the thickness of mesozoic-cennozoic eluvial kaolins were created; redeposited kaolins and apt-albian sands; sand-silica horizon of turon. It was found that in most cases there is a direct correlation between the relief of the bottom and the top of the ore-bearing deposits. As a rule, there is an inverse correlation between the thickness of deposits and the relief of their bottom and top. A set of maps was created showing the lateral distribution of average ilmenite contents in eluvial kaolins, continental and marine aptian-albian and turonian sediments. The lateral distribution of the average ilmenite contents in the sedimentary cover formations of different ages and genetics is uneven and characterized by significant contrasts (in eluvium — 0.4-57.2 kg/m3; in apt-albian sands — 1.0-162.58 kg/m3; in re-deposited apt-albian kaolins — 1.5-125.48 kg/m3; in sand-silica horizon of the turonian — 0.6-45.57 kg/m3). The best correlation exists between weathering crust formations and aptian-albian alluvial deposits. In the deposits lying above the geological section, the correlation with the eluvium is lost. The study of the distribution of the ilmenite content in the vertical cross-section of the wells showed that the ilmenite content in the sands is uneven with one or several levels of maximum enrichment. For example, in the vertical section of the sands (from bottom to top) there are layers with different contents (kg/m3) of ilmenite: 53.0-57.0; 27.0-37.0; 39.0-41.0; 10.0-23.0; 5.2-13.3; 27.0-68.2; 7.6-9.9; 49.0-56.0. On the other hand, in redeposited kaolins, the content of ilmenite in the vertical section is mostly uniform; sometimes one distinct level of maximal enrichment is present (rarely two such levels are present). For example, with a predominant ilmenite content of 27.0-32.0 kg/m3, in the lower and upper parts there are layers with a content of 48.0-63.0 kg/m3 and 42.0-68.0 kg/m3, and in the middle part of the formation, the content is 193.0-199.6 kg/m3.In Turonian sand-silica rocks, the maximum ilmenite content is located in the lower part of marine sediments.

Ore–Bearing Fluids of the Blagodatnoye Gold Deposit (Yenisei Ridge, Russia): Results of Fluid Inclusion and Isotopic Analyses

The Blagodatnoye deposit with 340 t gold reserves is one of the most productive mines in Russia. Modern methods of studying fluid inclusions were used to determine the properties of fluids that formed this deposit. A comprehensive study revealed that the Blagodatnoye gold deposit was formed between 120 and 350 °C and at 0.2–2.6 kbar, and from fluids with salinities ranging from 0.5 to 30 wt.% (NaCl–eq.). These fluids are: 1—water–carbon dioxide; 2—carbon dioxide–hydrocarbon; 3—highly saline aqueous. According to Raman spectroscopy and gas chromatography–mass spectrometry, ore–forming fluids contained H2O, CO2, hydrocarbons and oxygenated organic compounds, sulfonated, nitrogenated and halogenated compounds. Early oxidized water–carbon dioxide fluids formed barren associations of the deposit. Later reduced carbon dioxide–hydrocarbon fluids had a key role in the formation of gold-bearing quartz veins. The stable isotope data (δ34S = 0.8 to 21.3‰, δ13C = −2.8 to −20.9‰, 3He/4He = 0.14 ± 0.3 × 10–6) suggest the ore-forming fluids have a crustal source.

Early Neoproterozoic Metapicrite–Basalt Association of the Angara Region, Yenisei Ridge: Petrogeochemical Composition, Tectonic Settings, and Pb–Zn Mineralization

In the Angara part of the Yenisei Ridge, a sequential section of the metapicritic–basalt sequence and overlying carbonate rocks of the Gorevskaya Formation is established. This section is considered as a single volcanic–sedimentary complex formed at the Late Mesoproterozoic–Early Neoproterozoic boundary in the riftogenic marginal–continental paleobasin in the southwestern Siberian Craton. It is proposed to introduce the metapicrite–basaltic sequence into the stratigraphic legend of the Shirokaya Group of the western Yenisei Ridge under the name “Nizhnerechinskaya Sequence”. In the studied section, metamorphosed picrobasalts and picrites predominate in the lower part of the Nizhnerechinskaya Sequence, while the middle and upper parts consist mainly of basalts containing Pb–Zn mineralization (Stepanovsky ore occurrence). At the contact with carbonate deposits of the Gorevskaya Formation, an alternation of volcanogenic rocks and terrigenous–carbonate sediments and metabasaltic sills are observed. The petrochemical and trace-element composition of metavolcanic rocks has much in common, which indicates the paragenetic relationship of rocks of this high-Mg rock association. All these rocks are enriched in Fe and Ti, while metabasalts and metagabbros show elevated alkalinity and P2O5 content. In terms of total alkalinity, metabasalt–picrobasalts deviate from the normal petrochemical series towards the subalkaline series, which correlates with their elevated Ti content. Basites enriched in alkalis, especially, in potassium and corresponding to trachybasalts are observed among them. The contents of incompatible trace elements clearly increase from picrites to basalts and reach maximum in trachybasalts, which show 1.5–3 times enrichment in high-field strength elements compared to the basalts. The paragenetic nature of the considered association is supported by the similar REE distribution patterns: (La/Yb)n = 6–7 at Eu/Eu* = 0.9–1. The Late Mesoproterozoic–Early Neoproterozoic rifting of the Earth’s crust in the Angara region led to the opening of the marginal–continental sea basin, where basalt-picrite volcanism occurred simultaneously with accumulation of terrigenous–carbonate sediments, including ore–bearing (Pb–Zn) rocks of the Gorevskaya Formation, which host the Gorevskoye Pb–Zn deposit. The basin under consideration is interpreted as a relict rift-related paleobasin on the western margin of the Siberian craton, while the volcanic–sedimentary Nizhnerechinskaya Sequence is considered as the lower potential stratigraphic level of the base-metal mineralization in the Gorevsky ore field.

The role of porphyry-related skarns in the Chating porphyry copper and gold deposit, eastern China

The Chating deposit is a porphyry copper deposit in the Middle Lower Yangtze River Valley Metallogenic Belt, with skarns found in both the carbonate wall rock and in carbonate xenoliths in the intrusions. Detailed drill hole logging identified endoskarn and exoskarn in Chating, mainly distributed inside the ore–bearing quartz diorite porphyry instead of at the contact with the country rock. The skarns at Chating are unmineralized unless overprinted by porphyry related copper mineralization. Garnet in the Chating skarns can be divided into several types based on their occurrence and whether they were overprinted by porphyry mineralization. The garnets from the ore–bearing (G1a), barren endoskarn (G1b) and proximal ore–bearing exoskarn (G2a) are LREE-enriched, HREE–depleted with positive Eu anomalies whereas garnets from the barren massive exoskarn (G2b) are LREE-enriched with flat HREE and negative Eu anomalies. The G3 garnets are from marbleized skarn distal to the ore-bearing quartz diorite porphyry and consist of Al-rich and Fe-rich andradite; the Al–rich G3 garnets are LREE-depleted and HREE-enriched whereas the Fe-rich G3 garnets are LREE-enriched and HREE-depleted, both have negative Eu anomalies. The physicochemical conditions and composition of skarn-forming fluids controlled the REE, Eu, U and Y distribution in the garnets. The similarities of the REE patterns to those of magmatic–derived fluids suggests a dominantly magmatic fluid formed the endoskarn and proximal exoskarn. Fluid–rock interaction and addition of external fluids diluted the fluid that formed the exoskarn, decreasing the Cl and metal contents, resulting in lower REE contents and negative Eu anomalies in G2b and G3 garnets. The δ34S data for anhydrite from potassic alteration, sericite alteration, endoskarn and exoskarn range from 3.51‰ to 10.92‰, consistent with a dominantly magmatic fluid source. The δ34S for the anhydrite from the skarns ranges from 3.51‰ to 8.74‰, which combined with the absence of coeval sulfides, suggests a very high oxygen fugacity for the skarn-forming fluids. The small-scale skarns in Chating contain more anhydrite than garnet and consequently did not act as ground preparation as they do in typical skarn deposits. We propose that the anhydrite-rich exoskarn and the small scale of the endoskarn, combined with the high oxygen fugacity and low Cl content in the skarn-forming fluids resulted in the barren skarns of the Chating deposit.

Петрология и минералого-геохимическая оценка перспектив рудоносности ультрабазитов и базитов Тескудук-Ченгельдинского массива (Тамдытау, Западный Тянь-Шань)

Петрология и минералого-геохимическая оценка перспектив рудоносности ультрабазитов и базитов Тескудук-Ченгельдинского массива (Тамдытау, Западный Тянь-Шань)

Geology and structural controls of the Ag–Sn–Zn Pirquitas deposit, northwestern Argentina

Pirquitas is a polymetallic silver, tin, and zinc deposit, located in the Altiplano–Puna plateau, northwestern Argentina. The mineralization occurs in veins and hydrothermal breccia hosted in Ordovician meta–sedimentary rocks, but there is a lack of data on the structural geology of the deposit. In this paper we use detailed field mapping accompanied by structural analysis and mineralogy (petrography and XRD) to infer: (i) the mineralization structural controls, (ii) the influence of regional structures on the deposit formation, and (iii) characteristics of the Pirquitas deposit as compared with those from the Bolivian Tin–Silver Belt.The main stage of deformation observed at Pirquitas is associated with the Late Ordovician–Early Silurian Oclóyic orogeny. However, the ore deposition occurs as recurrent hydrothermal pulses related to the reactivation of Ordovician structures during the upper Miocene Quechua orogeny, which was partially contemporaneous with volcanic activity. The NW–SE and WNW–ESE ore–bearing veins of the Pirquitas deposit represent, respectively, second–order R– and T–fractures associated with major regional–scale, sinistral, brittle shear zones such as the Lípez and the Olacapato–El Toro faults.Similarities in mineralogy, structural control and association with magmatic activity indicate that Pirquitas is the southernmost deposit of the Bolivian Tin–Silver Belt. As such, subvolcanic intrusions associated with the Granada Volcano and the Coranzuli Caldera that are aligned along regional structures should be investigated by future exploratory works looking for porphyry to epithermal mineralization in the region.

Formation analysis of Maglajci-Moštanica ophiolytic zones in the North of Kozara for the use of rocks in construction

Based on the field work and laboratory research, the basic geological characteristics of the ophiolitic melange of northern Kozara are presented, with an emphasis on the Maglajci ophiolitic block. Criteria for separations of formations were established and then applied in the analysis, especially those geologically directly recognizable in the field and outcrops, so one ore formation with two ore subformations was separated in the Maglajci block. In the central zone of block, the basalt outflows and diabase are dominant, while in the south of the block it is an outflow basaltic sequence of the ocean floor with the acidic differences of rhyolites and keratophyres. The second subformation also includes the Moštanica and Vojkova Bloc as a whole. The ore bearing formation is evaluated as a medium to low perspective formation, while parts of the Maglajci block with a massive to brecciated outflow are highly perspective terrain. There are rocks of good physical-mechanical characteristics and they meet the most requesting standards for road building. The results of formation analysis have denied a prior prognosis of ore bearing characteristics of this area, because it was thought that the ophiolitic blocks was built almost exclusively of diabase, and that the fields with those blocks are equally and good perspective for researching the deposits of construction stone.

NATURAL RADIATION EXPOSURE TO THE PUBLIC IN MINING AND ORE BEARING REGIONS OF CAMEROON.

Within the framework of a joint research project on natural radiation exposure and its health effects in Cameroon from 2014 to 2017, the Institute of Geological and Mining Research and the Hirosaki University worked together to carry out natural radiation survey in mining and ore bearing regions of Cameroon. Air kerma rates were measured using car-borne survey method. In-situ gamma spectrometry was used to determine activity concentrations of 238U, 232Th and 40K in soil. A total of 450 RADUET detectors and 350 thoron progeny monitors were deployed in dwellings of the study areas for 2-3 months, collected and analysed. Although natural radioactivity level seems to be normal in most of the surveyed areas, there are many points where activity concentrations of natural radionuclides are largely above the world average values. Indoor radon, thoron and thoron progeny results show the importance to put in place the national radon plan in Cameroon. It was also pointed out that thoron cannot be neglected when assessing inhalation dose.

Genetic Nature of Platinum Ore Deposit Pansky Tundra in Kola Peninsula, Fennoscandian Shield

The article examine petrologic-geochemical and isotope peculiarities of forming low sulfide PGE deposit in Palaeproterozoic layered intrusion Pansky Tundra at central part of Kola Peninsula. PGE mineralization concentrated within rhythmic layered horizons (RLH) lower and upper parts of intrusion’s rocks mostly gabbronorite composition. Main feature rich PGE mineralization is close association with anorthosites and leiconorites located in RLH and subject of later magmatic metasomatic transformations. Isotope U-Pb age of anorthosites 2449 ± 12 Ma, and age of gabbronorites from RLH by zircons - 2491±1.5 Ma. Sm-Nd isotope dating of metasomatic ore bearing rocks shows age corresponding 2427±90 Ma with sign of eNd from -0.7 up to -1.7 and TDM = 2.5 Ga. For detail examination geochemistry ore bearing and host rocks it is applied neutron-activation analysis. Method factor analysis and estimation disposition REE were arranged affinity ore bearing and host rocks with specific of geochemical composition of lower crust. More later anorthosites enriched by fluids with Cu, Ni, PGE in combination with Cl, F, Se, S made executive metasomatic transformation of anorthosites and create possibilities for a forming reef type PGE deposit.

P–T–X conditions on the genesis of orogenic Au (As, Bi, Ag) deposit in metasedimentary rocks of the Buracão Area, Araí Group, Brasília Fold Belt, Brazil

The orogenic Au (As, Bi, Ag) mineralization (up to 31 g/t) of the Buracão area is hosted in the metasedimentary Paleo–Mesoproterozoic Traíras Formation, Araí Group, Brasília Fold Belt, Brazil. In order to discuss the P–T–X conditions that generated this mineralization, we present mineralogical, geochemical and fluid inclusion data of veins, gold and wall rocks. Coupled with previous structural data these additional data allow us to link metamorphism and deformation with fluid migration and ore genesis. The integration of fluid inclusion microthermometry with mineral geothermobarometers and structures show that rocks of the study area evolved from: (i) syn–D1a metamorphic peak (400–560 °C, <6 kbar), through to the (ii) development of syn–D1b type I barren veins from low salinity H2O–NaCl fluids during syn– to late–metamorphic peak; and to the (iii) development of syn–D2a type II veins with the pyritic ore precipitation from low to high salinity H2O–CO2–CH4–NaCl ± HCO3 fluids during post–metamorphic peak (345–285 °C, 2.7–1.6 kbar).The high fineness gold nuggets accompanied by As, Bi and Ag within pyrite–arsenopyrite–bismuthinite association in the pyritic ore allows the Buracão area to be classified as “a gold-only orogenic ore deposit”. Fluid inclusion compounds and the enrichment of As, Bi, Pb, Cu, Te, Se and Ag in pyrite from the pyritic ore point out to metamorphism of carbonaceous phyllites and carbonate rocks of the Traíras Formation as a source for ore–forming fluids. We suggest that sulfur and gold in these fluids were derived by metamorphism of sedimentary rocks and conversion of pyrite into pyrrhotite in a metamorphic–hydrothermal system. The Au(HS)2−–bearing fluids percolated along intrabasinal D2a regional shear zones through the Traíras Formation towards the Buracão area, where they precipitated type II ore–bearing veins within local structures. The ore precipitation was induced by contrasting fO2–fS2 related to the interaction between the sulfur-bearing fluid and host magnetite–graphite phyllites. The lithological control is represented by a series of reactions such as 2FeO(in silicates/magnetite) + 4Au(HS)2−(aq) + 4H+(aq) ↔ 2FeS2(s) + 4Au(s) + 4H2S(aq) + 2H2O(l).The deposits of the Buracão area and other orogenic gold deposits hosted in metasedimentary rocks in the Brasília Fold Belt and worldwide confirm the potential of ore genesis in zones that do not show any relation with (meta)igneous rocks, thus, expanding the exploration possibilities in metasedimentary successions.

Triggers for the generation of post–collisional porphyry Cu systems in the Kerman magmatic copper belt, Iran: New constraints from elemental and isotopic (Sr–Nd–Hf–O) data

Cenozoic tectono–magmatic activities and metallogenic processes in the Kerman magmatic copper belt (KMCB) led to the formation of two contrasting porphyry copper systems in a post–collisional setting: (1) early to late Oligocene (i.e., 33.9–23.03 Ma) Jebal Barez–type intrusive rocks comprising small porphyry copper deposits (PCDs) of normal calc–alkaline and locally tholeiitic affinity, and (2) early Miocene to early Pliocene (i.e., 17–3.6 Ma) Kuh Panj–type granitoids hosting moderate to giant PCDs, such as the world–class Sarcheshmeh deposit with potassic and adakite–like calc–alkaline features. Here I present new Sr–Nd–Hf–O isotopic data from the both economic and sub–economic porphyries. The Kuh Panj ore–bearing granitoids exhibit low ISr (<0.706), high εNd(t) (>−4.6), positive zircon εHf(t) (>+6.1), low δ18O (<6.76‰), and TDMC (Hf model ages) values of 425 to 705 Ma (mean TDMC = 571 Ma). These isotopic data imply that the KMCB economic porphyry systems originated mainly from dehydration melting of a composite juvenile underplated thick lower crust derived from a depleted mantle source.In contrast, the sub–economic porphyries at Jebal Barez show comparatively older Hf model ages (mean TDMC = 1274 Ma), low εNd(t) (<−4.1), and higher ISr (>0.706) values suggesting a source dominated by lower crust. A wide range of εHf(t) values (+2.8 to −10.6) and high zircon δ18O values (>7.31‰) for the Jebal Barez granitoids, are higher than pristine mantle values indicating involvement of the supracrustal recycling materials during zircon growth. These isotopic data, coupled with geochemical characteristics of the Kuh Panj granitoids, such as high SiO2 (>69.5%), K2O (>2.8%) contents, low MgO contents (<1.4), high Sr/Y (>60.9), and La/Yb (>20) ratios, relatively low Mg# (<42.6), and compatible element contents (e.g., Cr ≤ 21.6 ppm) reported in this study, indicate a magma mixing model for the generation of high–K adakite–like porphyries within the garnet amphibolite stability field in the sub–continental lithospheric mantle (SCLM). In new magma mixing model, ore–forming high Sr/Y magmas first involved partial melting of highly metasomatized SCLM that was triggered by post–collisional lithospheric thinning and asthenospheric mantle counterflow, which produced potassic magmas. Underplating of these mantle–derived magmas beneath the lower part of the thickened juvenile lower crust (~45–55 km) would have led to dehydration melting of the lower crust with excess water (>10 wt%).

Cross-hole reflection seismic to delineate a relatively thin volcanogenic massive sulphide deposit in shale hosted environment

SUMMARY The seismic reflection method is a high resolution technique that can be used in many exploration environments including mineral exploration. However, mountainous terrain, depth of burial and the steepness of ore bearing structures pose a challenge to the application of surface seismic in mineral exploration. The cross-hole seismic method may present an alternative approach under such conditions. Presented here is a synthetic study examining the capability of the cross-hole seismic method to delineate a volcanogenic massive sulphide ore body in a shale hosted environment. A simple model typical for volcanogenic massive deposits in Tasmania has been considered. There, an elongated steeply dipping volcanogenic massive sulphide deposit with an average thickness of 10 m is seated within a shale rock. The primary aim of the modelling is to test the capability of the technique to delineate relatively medium sized, steeply dipping volcanogenic massive sulphide lens in shale hosted environment. A second objective is to use the technique to prospect for extensions to mineralization along steeply dipping reflectors. Synthetic cross-hole seismic records were generated using a 120 Hz energy source. Kirchhoff VSP migration was applied to wavefield separated shot records and Pre- stacked Depth Migrated images created. The resulting migrated images correlate well with the position and dip of the ore body demonstrating the potential of the cross- hole reflection technique to delineate steeply dipping ore structures in challenging environments.

Evolution and economic significance of listwaenites associated with Neoproterozoic ophiolites in south Eastern Desert, Egypt

Most South Eastern Desert ophiolites are found along the Allaqi-Heiani-Gerf suture along the Egypt-Sudan border. Serpentinites, altered slices of upper mantle, are the main components of this suture and other sutures in the Arabian-Nubian Shield. Listwaenites are a distinctive alteration of serpentinized peridotite and are commonly found in shear zones that concentrate hydrothermal fluids involved in the formation of this type of rock. Along Wadi Allaqi area, listwaenites are distinguished into two main types: i) silica-rich, and ii) carbonate-rich. The presence of fuchsite in the former indicates that it is typical listwaenite, while the absence of fuchsite in the latter indicates listwaenite-like rock. These two types of listwaenites represent different stages of hydrothermal alteration. The large variations in their mineralogical and geochemical compositions are due to the different influence of reactions between protoliths and hydrothermal solutions, leading to different stages of metasomatic replacement. Ore minerals accompanying the listwaenites vary greatly both among and within separate occurrences. These variations depend on lots of factors, including the presence of shearing, P-T conditions, reactions with host rocks, and the composition of the hydrothermal fluids. Silica-rich listwaenite is well sheared and is more commonly ore bearing, while carbonate-rich listwaenite is less obviously sheared and shows less metal enrichment. The listwaenites of Wadi Allaqi area have a potential for gold mineralization (4-12ppm; 400-1100x enriched in comparison with serpentinites) since native gold occurs as inclusions in pyrite or as small disseminated specks along fractures. Base metals, mostly copper, lead and zinc, are also associated with listwaenites, but are more erratically distributed. Gold content increases with increasing SiO2 content of listwaenite. Carbonatization and silicification of ophiolitic peridotites can concentrate gold in the alteration products more than the parent rocks.

The Proterozoic Strata Division and the Research of Ore Bearing Horizon in Mid-Inner Mongolia

This article introduces the contrast of the Proterozoic strata division and the ore-bearing horizon of the polymetallic deposits like iron and copper by taking advantage of the field geological investigation and the geological characteristic of mineralization to further analyze the ore-prospecting prospects in the area.

Dephosphorization of Iron Ore Bearing High Phosphorous by Carbothermic Reduction Assisted with Microwave and Magnetic Separation

Dephosphorization of Iron Ore Bearing High Phosphorous by Carbothermic Reduction Assisted with Microwave and Magnetic Separation

A Kind of Land Form Detector for Loose and Soft Sandy Soil Milling-Planing and Collecting Device Machinery

In a Certain Mining Engineering, it’s Needed to Collect the Ore Bearing Sandy Soil with Certain Thickness from the Ground Surface. in Order to Realize Accurate Collection, it’s Needed to Control the Collecting Thickness Strictly. the Application of Contacting Type Landform Detecting Method in the Engineering Machinery Was Discussed, and a Kind of Mechanical Contacting Landform Detector Was Developed for the Alluvium Landform of Mining Area in Gobi with Loose, Rough and Uneven Ground Surface. the Landform of Soft Sandy Soil Can Be Detected by Controlling the Contact Pressure between the Depth Wheel of the Detector and the Ground Surface. with the Use of PID Control Technology with Wave Filtering, the Real-Time Detection Accuracy of the Detector for Mixed Sandy Soil Ground Surface Reaches ± 3mm. this Detector Is Specially Used for Milling, Planing and Collecting Device, Achieving Uniform Thickness Collection of Ore Bearing Sandy Soil in Rolling Topography Condition.

U-Pb Zircon Geochronology of Granitic Rocks from the Chuquicamata-El Abra Porphyry Copper Belt of Northern Chile: Excimer Laser Ablation ICP-MS Analysis

This study reports the results of a comprehensive geochronological study of Tertiary plutonic rocks in the Chuquicamata-El Abra porphyry copper belt of northern Chile. Zircon U-Pb isotope ages of 22 intrusions from the composite Los Picos-Fortuna–Pajonal-El Abra igneous complex, Radomiro Tomic mine, and Opache prospect were determined by excimer laser ablation-inductively coupled plasma-mass spectrometry (ELAICP- MS). The dated samples from the Pajonal-El Abra complex show a continuous age range from 42.7 to 37.2 Ma, indicating that the intrusions were emplaced over a period of at least 5.5 m.y. Only the youngest of these, the El Abra mine porphyry, is ore bearing. The five units that were dated from the Los Picos-Fortuna complex range in age from 42.3 to 38.0 Ma and none host significant economic mineralization. An increase in the abundance of inherited zircons with decreasing age in the intrusive rocks is interpreted to indicate that magmatic activity in the source region of the Los Picos-Fortuna–Pajonal-El Abra igneous complex increased steadily from about 55 Ma. The five dated units from the Los Picos-Fortuna igneous complex have the same age, within analytical uncertainty, as petrologically equivalent units in the Pajonal-El Abra complex to the north, supporting the correlation suggested by previous workers. Because these complexes are now on opposite sides of the West fissure and separated by 35 km, the correlation constrains the net sinistral displacement on the fault subsequent to ca. 33 Ma. Ore-bearing porphyries at Chuquicamata, El Abra, Radomiro Tomic, and Opache span an age range of almost 5 m.y. from 37.9 to 33.3 Ma. The ore-bearing intrusions of the Chuquicamata Igneous Complex are 3.5 m.y. younger than the youngest intrusions of the Los Picos-Fortuna–Pajonal-El Abra igneous complex, which makes it unlikely that they are genetically related. The Opache porphyry, on the other hand, which is on the same side of the West fissure as the Los Picos-Fortuna complex and has the same age as the El Abra mine porphyry, could have formed during the final stages of crystallization of that complex.