Barite Mineralization Research Articles

Source of ore constituents for the hydrothermal barite mineralization in Vempalle Formation, Cuddapah Basin, India: Constraints from petrography, geochemistry and sulphur isotope composition

Source of ore constituents for the hydrothermal barite mineralization in Vempalle Formation, Cuddapah Basin, India: Constraints from petrography, geochemistry and sulphur isotope composition

Geochemical influences of hydrogen storage in depleted gas reservoirs with N2 cushion gas

Geochemical investigation of hydrogen (H2), brine, rock formations, and residual gases (nitrogen – N2, methane – CH4, and carbon dioxide – CO2) is crucial for understanding H2 storage processes in depleted gas reservoirs. This study examines the effects of injecting a gas mixture (60% H2 + 30% N2 + 5% CH4 + 5% CO2) into Bandera Grey sandstone with notable clay mineral content. The experiment lasted 50 days at 42 °C, 1350 psi, and 5 wt% NaCl brine, with detailed analytical characterization before and after aging. Results show minimal sample reactivity, causing slight alterations in petrophysical characteristics. Dissolution primarily affected dolomite and barite minerals, while illite and kaolinite caused pore blockage. Gas chromatography data indicate only 0.45% of injected H2 is lost (via dissolution in brine and reaction with CO2), CH4 increased by 6.22%, N2 remained stable, and CO2 decreased by 1%. These results provide valuable insights into the feasibility and safety of utilizing depleted gas reservoirs for H2 storage.

Fluid Inclusion, Rare Earth Element Geochemistry, and Isotopic (O and S) Characteristics of the Ardakan Barite Deposit, Yazd Province, Iran

The stratabound barite mineralization occurs in the Ardakan deposit as patches and veins in the dolomites and limestones of the Middle Triassic Shotori Formation. Rare-earth element (REE) geochemistry, O and S isotopes, and fluid inclusion data were used to identify the mode of barite formation. Barite is associated with subordinate fluorite and quartz and, to a lesser extent, with sphalerite, malachite, chrysocolla, and iron and manganese oxide-hydroxides. Barite contains a very low ∑REE concentration (14.80–19.59 ppm) and is enriched in light rare-earth elements (LREEs) relative to heavy rare-earth elements (HREEs). The low ∑REE content and the Ce/La ratio (4.0–6.5) indicate a hydrothermal (terrestrial) origin of the barite. Similar to barite, the ∑REE content in fluorite is low (0.14–6.52 ppm) and suggests a sedimentary setting. The Tb/Ca versus Tb/La diagram also indicates a hydrothermal origin of fluorite. The δ34S values in the barite (+27.9 to +32.4‰) indicate that the sulfur most likely originates from evaporites and/or connate waters from the Late Precambrian to the Lower Cambrian. The δ18O values (+15.9 to +18.1‰) in the barite show that the oxygen originated either from Late Precambrian–Lower Cambrian evaporites or from basinal brines with slightly higher δ18O values than the evaporites. The salinity and homogenization temperature ranges of the aqueous fluid inclusions in barite, fluorite, and quartz (0.88–16.89 wt% NaCl equivalent and 90–270 °C, respectively) reveal that the mineralizing fluids were formed from basinal brines with the participation of heated meteoric water. From this, it is concluded that the Ardakan barite deposit was formed by the meeting of heated, ascending sulfate-bearing meteoric water and cooler, Ba-bearing connate water trapped in the overlying Middle Triassic dolomites and limestones. The Ardakan deposit belongs to the structure-related class and the unconformity-related subclass of barite deposits.

Geology, Mineralogy and Analysis of Tectonic Fracturing of Barite Mineralization’s in Bateun Jeudari Paleozoic basement, Eastern High Atlas, Morocco

Bateun Jeudari barite and iron deposit located in the eastern High Atlas Shales; It occupied the Hercynian fault system trending N70 to N90. It corresponds to large hydrothermal vein associated with micro-fracturing rocks type in stockwork form, hosted in the Paleozoic schists and perlite. The petrographic, geochemical analysis and belayed scanning electron microscopy results shows the presence of the barite associated with iron minerals. The petrographic indicates the structures composed by ferruginous and white barite associate locally to quartz. The established model of the barite and iron deposit gives the presence intravenous sedimentary tissues formed from a low salinity solution. Moreover, the structures and morphology of the mineralization reflect the tectonic control responsible for the establishment of the mineralization by faulting movements. Thus, it corresponds to barium-rich occurrences related to a compression period ENE-WSW, probably of Visean- Namurian age.

Metallogeny and Genesis of Fault-Filling Barite-Sulfide Veins (Ougnat, Morocco): Petrography, Fluid Inclusion, and Sr-S Isotopic Constraints

The Ougnat Massif of the eastern Anti-Atlas (Morocco) hosts barite and sulfide vein-type deposits of vital economic importance. With over 150 mineralized structures reported in the Ougnat Massif, the ore-bearing ones are predominantly composed of barite, quartz, calcite, and minor portions of sulfides. The mineralized veins are driven by NW-SE and NE-SW to E-W oblique-slip opening faults that cross both the Precambrian basement and its Paleozoic cover. The mineralized structures occur as lenses and sigmoidal veins that follow stepped tension fracture sets oblique to the fault planes. These geometries and kinematic indicators of these structures point to a predominantly normal-sinistral opening in a brittle-ductile tectonic setting. The S isotopic compositions of barite from the Ougnat Massif (+10.8 to +19.5‰) fall mostly within the range of δ34S values of Late Triassic to Jurassic seawater, thus suggesting that some of the SO2− in barite comes from seawater sulfate. This range of δ34S values also corresponds approximately to the hydrothermal barite context. The 87Sr/86Sr ratios of barite, which range from 0.710772 to 0.710816, lie between the radiogenic strontium isotopic compositions of deposition by hydrothermal solutions, and also coincide with the non-radiogenic isotopic signature of Triassic to Jurassic seawater. Based on a fluid inclusions study, the ore-forming fluids were a mixture of two or more fluids. A deep hot fluid with an average temperature of 368 °C leached the granodiorites and volcanic-sedimentary complex of the Ouarzazate Group. This fluid provided the hydrothermal system with most of the Ba, radiogenic Sr, and some of the dissolved S. A second, shallow fluid with an average temperature of 242 °C was derived from Late Triassic to Jurassic seawater. The barite mineralization of the Ougnat Massif constitutes a typical example of vein-type mineralization that occurred along the northern margin of the West African Craton and regionally tied to the central Atlantic opening.

Nondestructive geochemical characterization of fossil hominin taphonomy and burial history

To date, only three Homo habilis specimens have been discovered that have associated craniodental and postcranial elements, providing a limited fossil record of the ontogeny and morphology of early members of the genus Homo. Recently, a nearly complete dentition, likely attributable to H. habilis, was discovered and excavated from early Pleistocene-age fluvial-lacustrine sediments of the upper Burgi Member of the Koobi Fora Formation at site F25787 in Area 13, near Ileret, Kenya. On the surface less than 15 m away, at site F25966, postcranial elements were found, which, if from the same individual as the nearby dentition, would represent the fourth associated craniodental and postcranial assemblage of this species. We developed a geochemical taphonomic history of these ca. 2 Ma hominin fossils using nondestructive X-ray based microanalytical tools (synchrotron and benchtop X-ray fluorescence chemical imaging and micro- and nano-computed tomography volumetric reconstruction), bulk analyses of sediments and paleosols at the excavation sites, and sedimentologic and stratigraphic observations. We integrate the chemical and physical taphonomic histories to test whether teeth (excavated in situ) and postcranial bones (eroded onto the outcrop surface) derive from a single individual. Minor differences in taphonomic history are attributable to the different biomineral properties of the dental and osseous components and to differences in physical damage during early post-mortem scavenging, dispersal, and burial in adjacent depositional settings. Microscale geochemical mapping enabled the temporal ordination of chemical and physical events in the specimens’ chemical taphonomic histories. Specifically, authigenic Fe- and K-bearing clays and Y, U, and Sr uptake occurred in post-burial fractures in bones and were also incorporated pervasively throughout dentin in teeth. Barite mineralization occurred along the latest fractures in both materials, and as a coating on tooth roots. The stratigraphic, taphonomic, and geochemical evidence supports the interpretation that the hominin fossils represent a single individual. Successful application of these nondestructive sample characterization methods demonstrates capabilities for thorough interrogation of the taphonomic histories of other potential hominin fossil associations, enabling more robust and accurate palaeontologic constraints using those relationships.

Minerageny of Jurassic deposits of the northeastern side of the Ulyanovsk-Saratov depression

The Jurassic terrigenous-clayey complex on the territory of the northeastern side of the Ulyanovsk-Saratov depression contains numerous groups of solid minerals. Some of them are at the stages of industrial development, some have not found application due to local distribution. Analysis of the composition and conditions of formation of solid mineral raw materials showed that the main factor influencing the formation of minerals was the marginal position of the territory in the Middle-Upper Jurassic time. The relatively high bioproductivity of the epicontinental Central Russian paleosea contributed to the accumulation of layers of calcareous marls, oil shale and phosphate raw materials. All these rocks were formed in the Mesozoic basin of sedimentation with the active participation of organic matter, the producers of which were zoo- and phytoplankton. The accumulation of coccolithophora in clayey silts led to the formation of calcareous marls, the accumulation of dying algae in bottom sediments led to the formation of oil shale. Nodular phosphorites are also biochemogenic raw materials. During periods of regressive development of the Central Russian paleosea along the coast, conditions were created for the accumulation of oolitic siderites together with leguminous goethite-hydrogethite aggregates of iron ores. Periodically, regional faults were activated on the northeastern edge of the Ulnovsko-Saratov depression. At this time, there was an upward migration of deep mineralized fluids through weakened zones. Unloading in the bottom part of the Central Russian paleosea, they contributed to the formation of fields of pyrite and barite mineralization in sedimentary rocks.

Structural Conditions for Localization of Barite Mineralization in Tectonic Evolution of the Southern Sanandaj Zone, Iran

Structural Conditions for Localization of Barite Mineralization in Tectonic Evolution of the Southern Sanandaj Zone, Iran

Origin of Hydrothermal Barite in Polymetallic Veins and Carbonate-Hosted Deposits of the Cyclades Continental Back Arc

Abstract Polymetallic veins and breccias and carbonate-replacement ore deposits in the Cyclades continental back arc, Greece, formed from a range of fluid and metal sources strongly influenced by the dynamics of the late Mesozoic-Cenozoic Hellenic subduction system. These complexities are recorded in the isotopic signatures of hydrothermal barite. We investigated 17 mineral occurrences on four Cycladic islands and from Lavrion on the mainland. Here, barite occurs in almost all deposit types of Miocene to Quaternary age. We used a multiple isotope and geochemical approach to characterize the barite in each deposit, including mineral separate analysis of δ34S and δ18O and laser ablation-inductively coupled plasma-mass spectrometry of 87Sr/86Sr and δ34S. Barite from carbonate-hosted vein and breccia Pb-Zn-Ag mineralization on Lavrion has a wide range of δ34S (2–20‰) and δ18O (10–15‰) values, reflecting a mix of magmatic and surface-derived fluids that have exchanged with isotopically heavy oxygen in the carbonate host rock. Sulfur (δ34S = 10–13‰) and oxygen (δ18O = 9–13‰) values of barite from the carbonate-hosted vein iron and barite mineralization on Serifos are permissive of a magmatic sulfate component. Barite from epithermal base and/or precious metal deposits on Milos has δ34S (17–28‰) and δ18O (9–11‰) values that are similar to modern seawater. In contrast, barite from vein-type deposits on Antiparos and Mykonos has a wide range of δ34S (16–37‰) and δ18O (4–12‰) values, indicating a seawater sulfate source modified by mixing or equilibration of the hydrothermal fluids with the host rocks. Strontium isotope ratios of barite vary regionally, with 87Sr/86Sr ≥ 0.711 in the central Cyclades and 87Sr/86Sr ≤ 0.711 in the west Cyclades, confirming the strong influence of upper crustal rocks on the sources of fluids, Sr, and Ba in the formation of ore.

The effect of huntite and barite mineral-based polymer composite brake materials on friction and braking performance

Mineral materials are used in brake pad polymer composites at different rates, and positive results are obtained in tests conducted with the brake pads produced. This study produced brake pad polymer composites based on huntite and barite minerals. The materials forming the samples were mixed in a kinetic-type mixer, pressed using the hot molding method and prepared for the experiments with the curing process as the final process. Density, friction coefficient, wear rate and TG-DSC mass loss tests were performed on the samples. After the friction coefficient test, microscopic analyses of the brake pad samples were performed using a scanning electron microscope, and the surface roughness was measured using a three-dimensional profilometer. In the friction coefficient, hardness and mass loss analyses, values similar to those reported in the literature were obtained for all the samples. As a result, it was determined that the huntite and barite mineral-based polymer composite brake friction materials produced for automobiles exhibited performance following the brake pad characteristics.

Multiscale Structural Analysis of Ediacaran–Cambrian Rocks on the Northeastern Edge of the Saghro Inlier (Eastern Anti-Atlas): Relevance of Post-Cambrian Deformation

The Ediacaran–Cambrian rocks on the northeastern edge of the Saghro inlier experienced polycyclic tectono-thermal events, which are reported here based on a multiscale structural analysis, from field measurements to fluid inclusion planes. Three striking populations were identified, cutting across both the Ediacaran and Cambrian formations. These tectonic structures were generated during four tectonic events. (i) E-W-striking structures that host ore mineralized bodies (sulfide, oxide, quartz, and barite). They display a polyphase tectonic history, caused by a dextral movement in response to a NW–SE-oriented shortening, leading to the formation of quartz gashes and veins. This tectonic event took place during the Neovariscan. These E–W-striking structures were subsequently reactivated during the Mesozoic time under a sinistral strike-slip regime as a result of NE–SW shortening syn-kinematic with barite mineralization. (ii) NE–SW-striking strike-slip structures (dextral or sinistral) crosscut the E–W-striking veins. These faults are related to the NW–SE-oriented shortening that occurred during the Neogene. (iii) The last tectonic episode, related to the N–S shortening, took place during the late Neogene to the Quaternary period. It resulted in NW–SE to N–S-striking structures that were related to dextral and sinistral strike-slip movements, which crosscut the preexisting E–W structures.

Formation of barite in the Ab Torsh deposit, Kerman province, Iran: Insights from rare earth elements, O and S isotopes, and fluid inclusions

Barite can form in a variety of geological environments, as it occurs in a wide range of mineral deposits. To determine the origin and physicochemical conditions under which the Ab Torsh barite deposit formed, an extensive study was conducted using petrographic, Rare Earth Element (REE) geochemical, O and S isotopic, and fluid inclusion methods. Barite mineralization occurs at Ab Torsh as a stratabound vein in the Senonian carbonate rock units. Barite-quartz is accompanied by subordinate malachite, chrysocolla, Fe-Mn oxide-hydroxides, galena, azurite, fluorite, pyrite, and bornite. The ∑REE values are very low in barite (5.32–14.56 ppm), with chondrite-normalized patterns showing enrichment of Light Rare Earth Elements (LREE) relative to Heavy Rare Earth Elements (HREE). The low ∑REE content and REE element ratios (Ce/La, (La/La*)N, and (Gd/Gd*)N) indicate that seawater with a highly altered geochemical signature (connate water) acted as a Ba ore-forming fluid. The δ18O and δ34S values in barite (+10.4–+11.1 ‰ and +27.3–+27.8 ‰, respectively) and the δ34S values in galena (+6.3 and + 7.9 ‰) indicate that the sulfate (and thus sulfur) originated from sulfate-bearing connate waters and/or evaporites. Thermochemical Sulfate Reduction (TSR) was the most likely mechanism for the formation of the reduced sulfur in galena. The salinity and homogenization temperatures in the aqueous fluid inclusions of barite and quartz (2.7–19.3 wt% NaCl equivalent and 110–275 °C, respectively) indicate that basinal fluids containing a meteoric water component were the source of the mineralizing solutions. The fluid inclusion data demonstrate that two fluid mixing have occurred: one between the hot basinal brines and cold meteoric waters, and another between heated and cold meteoric waters. It is estimated that the hot fluids derived from a maximum depth of about 9 km. The Ab Torsh deposit is classified here as a structure (unconformity)-related barite deposit. It is concluded that intense faulting and brecciation of the host rocks caused by post-Cretaceous compressional tectonics probably provided the channels necessary for the upward migration of deep mineralizing fluids from a basinal brine source. Barite formed where these ascending hot, Ba-bearing hydrothermal fluids encountered cooler, sulfate-bearing connate waters trapped in the overlying Senonian strata and/or the descending cold meteoric waters that dissolved evaporite-bearing rock units.

Geobotanical and Biogeochemical Prospecting Method of Complex Sulphide Ore of Pb-Zn-Cu-Ba in Abuni-Adudu areas of the Middle Benue Trough, Nigeria

This research work focused on two plant species namely, the Anogeissus leiocarpus (DC.) and Dichrostachys cinerea for mineral prospecting. The two plants were sampled based on their occurrence, abundance and outlook. Twelve samples (six each of Anogeissus leiocarpus (DC.) and Dichrostachys cinerea) were collected around Abuni-Adudu mining communities in the Middle Benue Trough, Nigeria. In addition, bulk ore and twelve soil samples were also collected and analysed for correlation. Geologically, the study area is made up compacted shale, baked shale (hornfels), and sandstones of sedimentary origin, which are intruded by tertiary basalts of igneous origin. Samples were analysed for elemental composition, using inductively coupled plasma mass spectrometry method. Analysis revealed that the geobotanical method of prospecting for Pb-Zn-Cu-Ba mineralization in the area is promising as biogeochemical data indicated that the Dichrostachys cinerea are good indicator of Pb-Zn-Cu mineralization while the Anogeissus leiocarpus were indicative of Barium. Given the relatively low concentration of Barium in the ore (3.8 ppm) as against concentration in the soil samples, which ranges from 83 ppm (sample YS6) to 552 ppm (sample YS12), Barium has its source from the shale and sandstone or nearby Barite mineralization and not the ore.

Geological Structures Controlling Au/Ba Mineralization from Aeromagnetic Data: Harrat ad Danun Area, Saudi Arabia

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.

Fault-controlled barite veins of the eastern Anti-Atlas (Ougnat, Morocco), a far-field effect of the Central Atlantic opening? Structural analysis and metallogenic implications

Tectonic and micro-tectonic studies at different scales are of primary importance in a modern metallogenic investigation. In the Ougnat massif of the eastern Anti-Atlas belt (Morocco), the barite ore deposit is hosted within mafic to felsic rocks of the Ediacaran Saghro and Ouarzazate groups together with their folded Paleozoic cover. Here, we provide for the first time new field-based data on the tectonic control of barite mineralization, and their relation with regional tectonic events. The mineralization occurs in brittle-ductile structures as a vein-type system, mainly hosted within NE-SW to E-W and NW-SE strike-slip-normal faults. Economic orebodies spread frequently along the Precambrian-Cambrian contact zone thus acting as open conduits for mineralized fluid flow. The geometry of hosted barite sigmoidal lenses corresponds to “pull-apart” or “tension gashes” openings, commonly arranged en echelon arrays along the bearing transcrustal faults. The occurrence of predominant massive and breccia internal texture implies a tectonic-mineralizing collapse process in an extensional tectonic context. Kinematic pattern, directional distribution and host-rock age relationship point to a syntectonic barite control probably occurred during the NW-SE Atlantic rifting, as already attributed to similar deposits in the neighboring Ougarta and Atlas-Meseta domains.The barite ore is quantitatively and qualitatively more preserved in competent host rocks than those with ductile behavior, thus offering a useful hint for further barite exploration in this part of the Anti-Atlas fold and thrust belt.

Barium isotope signatures of barite–fluid ion exchange in Equatorial Pacific sediments

The isotope composition of barium (Ba) in the mineral barite (BaSO4) is emerging as a powerful tracer of the pelagic Ba, carbon, and sulfur cycles. However, it is critical to identify and constrain processes that may alter the primary isotope composition of Ba, δ138Ba, in BaSO4, particularly during early diagenesis. To this end, we analyzed the Ba isotope composition of porewaters and co-located BaSO4 in sediments from the Equatorial Pacific and performed a series of laboratory experiments with these same BaSO4 to assess rates of Ba isotope alteration. We find that sedimentary BaSO4 exhibit Ba isotope compositions ≈+0.1‰ and are offset by ≈−0.16‰ relative to ambient porewaters. Experiments using isotope-labeled seawater show extensive and rapid transfer of Ba ions between the solid and fluid phase through coupled BaSO4 dissolution-precipitation, even at chemical equilibrium. Using published values for Ba isotope fractionation during BaSO4 precipitation and dissolution, we calculate that co-located BaSO4 and porewaters should exhibit Ba isotope offset of −0.17‰ at isotopic equilibrium, similar to the offsets observed in Equatorial Pacific sediments. Altogether, the field data, laboratory experiments, and calculations indicate that ion exchange occurs in Equatorial Pacific sediments and that this process also drives the observed Ba isotope offsets between pelagic BaSO4 and porewaters. This finding implies that ion exchange may alter the isotope composition of Ba in sedimentary BaSO4, though the degree of alteration will depend on the proportion of Ba held in the solid phase. More broadly, this study provides an example of how ion-exchange-mediated processes are widespread in marine geochemistry and that these processes likely affect other metals and minerals beyond Ba and BaSO4.

Geology, mineralogy and geochemistry of the Morro Preto Alkaline-carbonatite complex, Goiás, Brazil

The Morro Preto Complex, located in the northern portion of the Cretaceous Goiás Alkaline Province, is unique in the region due to the large predominance of carbonatites and phosphate mineralization. It comprises two circular intrusions (Morro Preto North and Morro Preto South) of apatite-rich magnesiocarbonatites gradually transitioning to ferrocarbonatites. The complex also hosts fenites produced by carbonatite metasomatism at the contacts with the Neoproterozoic country rocks. Kamafugite dykes with carbonate globules suggest an immiscibility link between silicate and carbonatite magma.The magnetite-apatite-dolomite carbonatites vary in texture and modal composition from cumulates to magnesiocarbonatites with variable apatite and magnetite, with minor barite and traces of pyrochlore, phlogopite, baddeleyite and zircon. In the ferrocarbonatites, magnetite and apatite are rare or absent, and the dominant carbonate varies from Fe-dolomite to ankerite and siderite, with traces of bastnaesite, monazite, thorium-rich monazite and sulfides. SiO2, Fe2O3, MnO, BaO:SrO and the sum of rare earth elements (REEs) increase from magnesiocarbonatites to ferrocarbonatites, whereas the CaO, MgO and P2O5 contents decrease.Four main apatite types are recognized in the complex: (i) high P-REE primary magmatic sub-euhedral apatites (type 1), (ii) fluorapatite associated with ferrodolomite-rich zones (type 2), (iii) fine-grained, Na-rich metasomatic apatite (type 3) and (iv) secondary fluorapatite filling veinlets and cavities (tuupe 4). In general, the apatite morphological and compositional variations correlate with carbonate evolution and with stable isotope data. Dolomite and type 1 apatite represent the primary group (+9.49 to +11.88‰ δ18O and −5.1 o −4.66‰ δ13C). Ferrodolomite, iron-rich carbonates, along with types 2 and 4 fluorapatite have heavier isotope compositions (up to +21.59‰ δ18O and −3.33‰ δ13C), indicating metasomatic reworking related to late-stage carbonatite-derived fluids.Geological, geochemical and mineral chemistry data are consistent with the evolution of the complex by crystal fractionation, liquid immiscibility, metasomatic overprinting and late hydrothermal events. The K fenitization and late-stage carbohydrothermal events suggest that the Morro Preto Alkaline-Carbonatite Complex represents the uppermost parts of a carbonatite magmatic system.

Geology, Petrography, and Mineralization of Sedimentary Hosted Strata-Bounded Barite Deposit at Gunga, Khuzdar District Balochistan, Pakistan

Gunga deposit is a type of sedimentary exhalative (SEDEX) deposit located in the northwest of Khuzdar Knot within the Kirthar Fold Belt (KFB) in the south-west of Khuzdar city. This deposit is formed during the late Triassic-Jurassic period due to rifting of the Gondwana supercontinent. being hosted with the Anjira Member of Jurassic Shirinab Formation, hosted the Strata bounded barite mineralization in these deposits contact with the siliceous and iron-rich gossan zones. The Baritic zone indicates the complex replacement of silica with the continuous silicification which is followed by massive to brecciated type Barite. Petrographically, barite has a very fine to coarse grain texture, anhedral to euhedral crystal shape, and forms dendritic crystal structure In the Back Scattered Electron (BSE) images, the crystal morphology of Barite exhibits well-developed elongated crystal structures with medium to coarse grain texture. Energy Dispersive X-rays (EDX) graphs indicates the high peaks of Ba, S, and O elements associated with sub-peaks rock-forming mineral elements (Si, Al, Na, K, and Ca) along with sub-peaks of ore-forming mineral elements (Pb, Zn, Fe, P, and Ni).

Žune Ba-F epithermal deposit Part 2: Geophysical characterization and exploration perspective

The Žune barite-fluorite ore body in northwestern Bosnia and Herzegovina has been explored in order to determine spatial distribution of the ore body. At the Žune site, barite mineralization occurs in the form of veins and is hosted by dolostone. A geophysical survey was carried out with the aim to detect anomalies associated with the barite-fluorite deposit and to characterize the abandoned old deposit. Therefore, 2D electrical resistivity tomography (ERT) was measured along four profiles. Prior to surface geophysical measurements, detailed geological field mapping of the ore body and host rocks was undertaken. The geometry of the abandoned mining cut with steep walls and complex structural setting with barite that incorporates coarse fragments of host rock and fluorite makes interpretation of the results challenging. The collected geological data were used to calibrate the geophysical models. Forward modelling in addition to inversion of the ERT data helped to reduce the ambiguity of geophysical data interpretation. The results revealed that the barite vein in the area of mining cut is limited to a depth of about 10 m and length is about 40 m. There is no indication for barite mineralization in the area south of the mining cut, while anomalies that may be associated with ore bodies are present in the northern and northeastern part.

Mineralogy, Geochemistry and Fluid Inclusion Study of the Stibnite Vein-Type Mineralization at Rizana, Northern Greece

The stibnite mineralization at Rizana (Kilkis ore district; Serbo-Macedonian metallogenic province; northern Greece) occurs along a NE–SW-trending brittle shear-zone, which transects a two-mica and an augen-gneiss of the Vertiskos Unit. Barren Triassic A-type granites and satellite pegmatites and aplites, as well as Oligocene-Miocene plutonic, subvolcanic and volcanic rocks that are variably hydrothermally altered and mineralized, outcrop in the broader region. The mineralization appears as veins, discordant lodes and disseminations. Veins and discordant lodes exhibit massive and brecciated textures. Historic underground mining (1930s–1950s) produced 9000 t of stibnite ore, grading 40% Sb on average. The main ore mineral assemblage includes stibnite + berthierite + sphalerite + pyrite + chalcopyrite + native antimony and traces of wolframite, galena, tetrahedrite, marcasite, pyrrhotite, arsenopyrite, realgar, native arsenic and native gold. Quartz, minor barite and ankerite are the gangue minerals. Sericitization and silicification developed along the shear-zone, forming hydrothermal halos of moderate intensity in the two-mica gneiss. Locally, valentinite, goethite and claudetite are present due to the supergene oxidation of the stibnite mineralization. Bulk ore geochemistry shows enrichments in specific elements including As, Au, Cd, Se, Tl and W. Fluid inclusion microthermometry showed that the mineralization was formed under a limited range of temperatures and salinities. The fluids had low to slightly moderate salinities (6.6–8.1 wt% equiv. NaCl) with low homogenization temperatures (217–254 °C, with a maximum at 220 °C).