Fluid Inclusions Research Articles

Preservation and alteration of inclusion-based calcite-water oxygen isotope and clumped isotope temperature signals in calcite veins

Knowledge of the formation temperatures of geological deposits is essential for investigating their genesis. Oxygen isotope thermometry (OIT), using the temperature dependence of oxygen isotope fractionation between host carbonate mineral and mineral-forming water trapped in fluid inclusions, and clumped isotope thermometry, based on the degree of 13C and 18O clumping, are receiving increasing interest. However, only a few studies have applied combinations of these methods, and their databases are limited. In this study, we compare OIT and clumped isotope temperatures obtained for 18 samples from Mesozoic to early Cenozoic calcite veins. Our analysis indicates that the formation temperatures were preserved in the clumped isotopic compositions (16–45 °C), whereas the OIT temperatures were shifted to lower temperatures (− 2 to 33 °C). An OIT temperature shift occurred, due to a retrograde oxygen isotope exchange between the fluid inclusion water and the host calcite. These results imply that the retrograde isotope exchange should be taken into consideration, even for low-temperature carbonate deposits, if a sufficiently long time is available.

Transient non-soluble noble metal transport in hydrothermal ore systems

The transport of noble metals (Au, Ag) by metal-rich melts in hydrothermal ore systems is now acknowledged as a complementary mechanism to complexing ligands in solution. However, it is unclear where/when both mechanisms coexist and whether metal-rich melts can be physically transported by hydrothermal fluids. Here we show evidence for a suspension-like transport of nano-to-micron-sized metal-rich sulfide-sulfosalt melts within epithermal fluids at <400 °C, forming irregular and bleb-like polymineral inclusions of Ag-Au-Cu-Pb(-Fe-Zn)-As-Sb-S-Se upon cooling. These polymineral inclusions, 5 nm to 40 µm in size, are cogenetic with fluid inclusions in quartz. Numerical modeling based on particle fluidization and settling theory shows hydrothermal fluids can mechanically transport metal-rich sulfide-sulfosalt nano-micromelts at fluid flow rates <10–1 m/s. The chemical similarity between nano- and micron-scale polymineral inclusions suggests the coalescence of nanomelt precursors during transient transport from their source(s) to deposition sites, playing a key role in noble metal mineralization.

Analyzing petrographic characteristics and trace element distribution of high-purity quartz deposits from the Peshawar Basin, Pakistan: insights into processing and purification techniques

Abstract. This study examined the potential of quartz vein ore from the Peshawar Basin, Pakistan, as a raw material for producing high-grade, high-purity quartz sand. These samples were purified using a combination of methods including crushing, magnetic separation, ultrasonic cleaning, flotation, high-temperature calcination, water quenching, and acid leaching. Impurities in the quartz vein samples were analyzed through optical microscopy, SEM-CL, Raman spectroscopy, XRD, ICP-OES, and ICP-MS. Petrographic analysis revealed that the main impurities in quartz consisted of fluid inclusions, most of which were concentrated along the microfractures. After purification, the refined quartz sand exhibited a smooth surface with an extremely low concentration of gas–liquid inclusions. The ICP-OES bulk solution analysis of the raw quartz samples showed that the NB-1 SiO2 content is 99.989 wt %, NB-2 99.989 wt %, and NB-3 99.990 wt %. The total impurity content in raw quartz ore was 104.73 µg g−1 for NB-1, 102.25 µg g−1 for NB-2, and 95.01 µg g−1 for NB-3. After purification, the ICP-MS analysis indicates the SiO2 content in processed quartz was 99.999 wt % for NB-1, 99.997 wt % for NB-2, and 99.998 wt % for NB-3, and the total for the 13 impurity elements' content of refined quartz sand was 12.08 µg g−1 for NB-1, 34.57 µg g−1 for NB-2, and 16.79 µg g−1 for NB-3. The main impurity elements, Li and Al, were found in the following concentrations: NB-1 contained 2.06 µg g−1 of Li and 9.16 µg g−1 of Al, NB-2 had 3.23 µg g−1 of Li and 30.15 µg g−1 of Al, and NB-3 showed 2.09 µg g−1 of Li and 13.68 µg g−1 of Al. These impurities can be further reduced using more advanced techniques. Based on these results, these purified quartz sands are suitable for producing high-purity quartz products (4N7 to 4N9) that meet the standard requirements for crucible preparation for industrial applications. Therefore, these quartz vein ores are considered potential resources for high-purity quartz (HPQ).

Provenance analysis of rock crystal artefacts from Palaeolithic sites in Moravia (East Central Europe) – a comparative extended approach

The Bohemian Massif and the Alps are regions that are generally known for their rock crystal artefacts and the study thereof. The most important archaeological findspots in the Czech Republic are the Palaeolithic sites at Nová Dědina (East Moravia) and in Žitný Cave (Moravian Karst), which yielded numerous rock crystal artefacts. The study of fluid inclusions as sensitive objects reflecting the conditions of their formation was included in the research. Subsequently, natural sites with the occurrence of rock crystals were selected as potential extraction sites, and a comparative study was carried out. The methodological approach has been completed using microthermometry, Raman spectrometry, EPMA and stable isotopic studies of oxygen. The best match of the fluid inclusion assemblage resulted from samples from the Bory-Cyrilov area (West Moravia, the Moldanubicum geological unit) as the rock crystal source for the Nová Dědina Aurignacian site. Unfortunately, no natural sample that would match the artefacts from the Žitný Cave was discovered in terms of the investigated properties. Certain features of the artefacts suggest a possible origin in the Tauern Window region. The inaccessibility of the Alps during large parts of the Palaeolithic and the properties of fluids may point more to the source area of the Moldanubicum. The applied methodological approach clearly shows that the combination of the methods used and the interpretation of their data defines the formation conditions and provides essential information for a discussion of the provenance of the raw material used for rock crystal artefacts.

The Composition of Volatiles in Quartz and Pyrite from the Konduyak Gold Deposit (Yenisei Ridge, Russia)

The Konduyak gold–quartz–sulfide deposit is one of the most promising gold mines in the Ayakhta gold ore cluster on the Yenisei ridge. This article is devoted to the study of the composition of the volatile compounds in the ore-forming fluid, since this is one of the key aspects in understanding the conditions of deposit formation. The compositions of the fluids that formed quartz and pyrite in the deposit ore zone were determined using Raman spectroscopy and pyrolysis-free gas chromatography–mass spectrometry. The study of the fluid inclusions in the minerals showed that complex C-H-O-S-N multi-component fluids formed the quartz–sulfide ore zones. A range of 232 to 302 various volatile compounds were found in the fluids. The mineralizing fluids mainly consist of H2O (14.25–96.02 rel. %) and CO2 (2.07–54.44 rel. %). A high SO2 content (14.60–44.95 rel. %) is typical of fluids trapped by pyrites. Moreover, a wide range of hydrocarbons (oxygen-free aliphatic, cyclic, heterocyclic, and oxygenated) and nitrogenated and sulfur compounds were found among the volatiles in the fluid. The variable H/(H + O) ratios, from 0.51 to 0.81, and CO2/(CO2 + H2O) ratios, from 0.02 to 0.56, indicate changes in the redox conditions during ore formation.

Tracking CO2 migration and accumulation in the Subei Basin using geochronology and fluid inclusion quantitative analysis

In petroliferous sedimentary basins, the interplay between CO2 and hydrocarbons exerts a notable influence on hydrocarbon generation and accumulation. This research focuses on the Huangqiao oil and gas reservoir, which is known for hosting the largest CO2 reserves in China. U–Pb isotopic dating of calcite veins in fractures, carbon and oxygen isotope analyses, along with rare earth element (REE) analysis were applied to elucidate the chronology and origin of inorganic and organic fluids in the studied area. Petrographic observations revealed the presence of various components of fluid inclusions, including gaseous CO2, gaseous CH4, CH4-CO2 mixtures, and hydrocarbon fluids. Besides, through Raman quantitative measurements and thermodynamic simulations, the density, composition, pressure, and temperature characteristics of CH4 and CO2 bearing fluid inclusions were calculated. Based on the entrapment conditions of fluid inclusions and U–Pb dating results, two stages of hydrocarbon charging were identified: an early-Jurassic stage (approximately 200–185 Ma) characterized by mid-maturity oil and CH4 and an early-Eocene stage (approximately 61–41 Ma) marked by high-maturity oil and CH4. CO2 accumulation events were divided into two stages: high-density CO2 fluid activity during the early Eocene (approximately 59–39 Ma) and low-density CO2 fluid activity during the Tertiary-Quaternary (approximately 23–4 Ma). Moreover, deep fluid influx into reservoirs led to hydrothermal alteration, as evidenced by anomalously high homogenization temperatures and vitrinite reflectance. CO2 has an extraction effect on crude oil, where its late entry primarily results in the removal of lighter components, especially CH4. When high-temperature hydrothermal CO2 fluid enters the oil reservoir, it accelerates the cracking of crude oil and alters the fluid’s composition. This thermal event also speeds up the source rock’s thermal evolution, leading to extraction, pyrolysis, and gas displacement throughout the reservoir’s development process. This study presents a comprehensive approach for quantitatively studying geological fluids in petroliferous basins of this nature.

Gold mineralization of the Huangjindong gold deposit in the Jiangnan Orogen, South China: Constraints from fluid inclusions and LA-ICP-MS analysis of pyrite and arsenopyrite

Gold mineralization of the Huangjindong gold deposit in the Jiangnan Orogen, South China: Constraints from fluid inclusions and LA-ICP-MS analysis of pyrite and arsenopyrite

Ore-forming fluid evolution and gold precipitation mechanism at Huangjindong gold deposit, southern China: Insights from fluid inclusions and trace elements in quartz

Ore-forming fluid evolution and gold precipitation mechanism at Huangjindong gold deposit, southern China: Insights from fluid inclusions and trace elements in quartz

Metamorphic magnesite deposits of Brumado (Bahia, Brazil): Evidence from highly saline H2O-CO2 fluid inclusions

Metamorphic magnesite deposits of Brumado (Bahia, Brazil): Evidence from highly saline H2O-CO2 fluid inclusions

Phase Relations in Co-Ni-Fe-(±Au ±Ag) Mineralizations of Bou Azzer-El Graara Inlier, Central Anti-Atlas, Morocco: Insights from Mineral Chemistry and Fluid Inclusions Analysis

Phase Relations in Co-Ni-Fe-(±Au ±Ag) Mineralizations of Bou Azzer-El Graara Inlier, Central Anti-Atlas, Morocco: Insights from Mineral Chemistry and Fluid Inclusions Analysis

Features of the Composition, Release, Localization, and Environmental Effects of Free Gases in the Khibiny Massif (Kola Peninsula, Northwest Russia): A Review

The article presents a comprehensive analysis of long-term studies on hydrogen-hydrocarbon free gases (FGs) in the rocks of the Khibiny massif, systematically organized and generalized for the first time. Gasometric observations were predominantly conducted within underground mine workings, with occasional measurements taken during the drilling of exploration boreholes at the surface or in subsurface air within loose sediments. Methane is the primary component of these gases, followed in descending order by hydrogen, ethane, helium, other methane homologs, and alkenes. Nitrogen is also presumed to be present, although its proportions remain undefined. The carbon and hydrogen in FGs exhibit relatively heavy isotopic compositions, which progressively lighten from methane to ethane. The intensity of gas emissions is characterized by a gas flow rate from shot holes and boreholes, reaching up to 0.5 L/min but generally decreasing significantly within an hour of reservoir exposure. Gas-bearing areas, ranging in size from a few meters to tens of meters, are distributed irregularly and without discernible patterns. The FG content in rocks and ores varies from trace amounts to approximately 1 m3 of gas per cubic meter of undisturbed rock. These gases are primarily residual, preserved within microfractures and cavities following the isolation of fluid inclusions. Their distribution and composition may fluctuate due to the dynamic geomechanical conditions of the rock mass. The release of flammable and explosive FGs presents a significant hazard during ore deposit exploration and development, necessitating the implementation of rigorous safety measures for mining and drilling operations. Additionally, the environmental implications and potential applications of gas emissions warrant attention. Future comprehensive studies of the Khibiny gases using advanced methodologies and equipment are expected to address various scientific and practical challenges.

Genesis of the Xiangluwanzi Gold Deposit, Northeastern China: Insights from Fluid Inclusions and C-H-O Isotopes

The Xiangluwanzi gold deposit, located in the southern Jilin Province of Northeast China, is hosted within the Jurassic Guosong Formation, and surrounded by Archean granitoids. The ore bodies are governed by near-EW and NE-trending faults. Four alteration/mineralization stages have been distinguished: I, pyrite–sericite–quartz; II, gold–pyrite–quartz; III, sphalerite–quartz–carbonate; and IV, quartz–carbonate. Four types of fluid inclusions (FIs) were identified: pure CO2, CO2-rich, CO2-bearing, and NaCl–H2O fluid inclusions. Stage-I quartz veins contain all FIs, whereas stage II quartz veins host CO2-rich, CO2-bearing, and NaCl-H2O FIs. Only NaCl–H2O FIs were present in stages-III and -IV quartz veins. The homogenization temperatures of the FIs range, respectively, from 233 to 279, 185–242, 171–217, and 148–170 °C in stages I–IV, having salinities of 2.62–8.54, 2.81–7.58, 4.32–6.58, and 3.37–5.25 wt% NaCl equivalents, respectively. The H (−93.5‰ to −75.9‰) and O (δ18OH2O = −5.8‰ to 4.6‰) isotopic compositions suggest magmatic water was gradually diluted by meteoric water. Carbon isotopic values (22.8‰ to −17.8‰) suggest the incorporation of organic carbon from surrounding strata via water–rock interactions. Fluid boiling, fluid mixing, and water–rock interactions are the primary mechanisms driving mineral precipitation.

Phase equilibria modelling, fluid inclusion study, and U-Pb zircon dating of ultra-high temperature mafic granulites from Rampur domain, Eastern Ghats province: implications for the Indo-Antarctic correlation

Phase equilibria modelling, fluid inclusion study, and U-Pb zircon dating of ultra-high temperature mafic granulites from Rampur domain, Eastern Ghats province: implications for the Indo-Antarctic correlation

Implementation of FEM and Taguchi analysis on blood flow for Casson fluid inclusion of di- and tri-Hamilton Crosser nanofluid through the cylinder with a rough surface

Implementation of FEM and Taguchi analysis on blood flow for Casson fluid inclusion of di- and tri-Hamilton Crosser nanofluid through the cylinder with a rough surface

Variscan Plutonism in the Geodynamic Evolution of the Central Iberian Zone of Portugal: Castelo Branco Pluton as Another Piece of the Puzzle

A multidisciplinary analysis of the Pennsylvanian Castelo Branco pluton of Central Iberian Zone (Iberian Variscan belt) was made, focusing on its magnetic behavior and fabric, microstructures, microfractures, and radiometric and gravimetric anomalies. The findings reveal that the Castelo Branco pluton is an ilmenite-type granite, characterized by low magnetic susceptibility values. The petrographic observations and high-temperature solid-state deformation indicate that pluton was emplaced during the latest compression phase (D3) of the Variscan tectonic regime. Magnetic fabric and gravimetric data show that the Castelo Brano pluton has a flat-shaped geometry with a depth of approximately 2–3 km, a feeding zone corresponding to NE-SW-trending regional faults, and that its fabric is oriented parallel to the NW-SE-trending regional foliation of the host rocks. The concentric magnetic foliation in the Alcains granite suggests an earlier ascent and emplacement compared to the Rio de Moinhos and S. Miguel da Acha granites, with Alcains demonstrating a laccolithic shape indicative of significant upward force. The ascent pathways of the different granites seem to have occurred along pre-existing NE-SW faults. The Castelo Branco pluton displays zoned nesting, with fluid inclusion planes indicating NNE-SSW to NE-SW and ENE-WSW trends in biotite-rich granites, and NNE-SSW to NE-SW and ESE-WNW trends in two-mica granites. Structural alignments in the study area show both NE-SW and NW-SE trends. The NE-SW faults and thrust faults are supported by residual gravimetric anomaly data, and NW-SE alignments are evident in magnetic fabric and regional folded structures. These findings enhance our understanding of the geodynamic processes influencing the Variscan plutonism in the Central Iberian Zone, positioning the Castelo Branco pluton as a key component in this geological puzzle.

Multidecadal hydroclimate responses to volcanic forcing in the Mid-Holocene

The impact of volcanic and solar forcings on multi-decadal climate change during the Holocene remains unclear. Here, we analysed the stable isotopes of fluid inclusions in a stalagmite to investigate hydroclimate responses to the forcings in the Northwest Pacific region. Our stalagmite data, covering the active volcanism period in the mid-Holocene, showed that the start of large volcanic eruption clusters tends to coincide with an onset or an ongoing cooling phase. The impact of one of the largest volcanic eruptions during the Holocene, likely at Kikai caldera, is recorded as an amplified multi-decadal scale variation, including a noticeable cold-wet climate anomaly. Excluding this anomalous period, the solar forcing record negatively correlated with stalagmite-derived precipitation but not with stalagmite-derived temperature. Our data suggest that clusters of volcanic activity during the mid-Holocene likely contribute to climate change at multi-decadal scale via a teleconnection between the Northwest Pacific and the North Atlantic regions.

Oil and gas charging dating in the Northern Slope of Bongor Basin, Chad

The oil discovery in the Pre-Cambrian fractured basement buried-hills of the Bongor Basin, Chad, is a milestone in the potential of new exploration play in the African onshore exploration. The dating of hydrocarbon accumulations in the buried-hills of the basin were studied in this paper using technologies of organic geochemistry, fluid inclusion, apatite fission track analysis (AFTA) and thermal modeling. The results indicate that (1) R-P zone and B zone have similar characteristics of crude oil, Bongor basin (2) there are two groups of fluorescence hydrocarbon inclusions well developed in the B zone and R-P zone of Bongor basin, i.e., yellow-green and green, indicating different episodes of oil charge stages; (3) the analysis of hydrocarbon-bearing brine inclusions and AFTA indicated that the different buried-hill zones experienced two successive episodes of primary hydrocarbon accumulations during the Mesozoic-Cenozoic; (4) hydrocarbon charging in B zone buried-hill reservoirs has the characteristics that there exist two stages of continuous petroleum accumulation started in the middle Late Cretaceous (about 85 Ma) lasting to 55 Ma; R-P zone also exist two stages of continuous petroleum accumulation events began in the middle Late Cretaceous (about 80 Ma) lasting to 55 Ma.

Relationship between hydrocarbon genration-expulsion and deformation in exhumated Lower Cretaceous kitchen of the Austral-Magallanes basin, Southern Patagonia

The thermal evolution of the hydrocarbon exhumated kitchen of the Rio Mayer Formation (Lower Cretaceous) in the Austral-Magallanes basin, was characterized in two profiles outcropping in the Southern Patagonian Andes. This study presents an integration of fluid inclusions, organic petrology, geochemistry, and apatite fission-track data incorporated into a one-dimensional (1D) basin and petroleum system modeling, to evaluate the timing of hydrocarbon generation and expulsion processes. In Ea. La Federica (internal fold-thrust belt domain), the lower organic-rich interval of Rio Mayer Formation is at present-day conditions in oil window, with development of natural fractures filled with fibrous calcite crystals. In Ea. Cristina, the unit is in dry gas window (basement domain), with natural fractures filled with granular calcite and quartz. The kitchens began the generation and expulsion processes from the west (Lower Cretaceous) to east (Upper Cretaceous - Eocene), i.e., from basement to internal and external fold-thrust belt domains. The advance of the orogenic wedge deactivated and exhumated those kitchens from west to east as well. The western kitchen was deactivated during the Late Cretaceous, while eastern kitchen, during the Eocene. These successive compressional pulses conditioned the eastward migration of the hydrocarbon generation front and would have favored the charge of reservoirs located in the westward (foreland region). The results of this study emphasize the importance to consider the temporal source kitchens activation related to Andean deformation, in order to a better comprehension of basin-scale controls related to source rock evolution and petroleum system development.

Unconformity-related mineralization and fluid transfers in the northern Aquitaine Basin (France) revealed by fluid inclusions and S-Sr isotopes studies

Unconformity-related mineralization and fluid transfers in the northern Aquitaine Basin (France) revealed by fluid inclusions and S-Sr isotopes studies

Quartz textures, trace elements, fluid inclusions, and in situ oxygen isotopes from Aktogai porphyry Cu deposit, Kazakhstan

Abstract The Paleozoic Aktogai Group in Kazakhstan ranks among the 30 largest porphyry Cu deposits globally. The Aktogai deposit is the largest one in the Aktogai Group and is characterized by intensive potassic alteration where the dominant orebody occurred. However, its mineralization processes still need to be clarified. Our investigation focused on the texture, trace elements, fluid inclusions, and in situ oxygen isotopes of the quartz from the ore-related tonalite porphyry and associated potassic alteration at Aktogai to trace the deposit’s mineralization processes. Ti-in-quartz thermobarometry, fluid inclusion microthermometry, and geological characteristics indicate that the ore-related magma at Aktogai originated from a shallow magma chamber at ∼1.9 ± 0.5 kbar (∼7.2 ± 1.9 km) and intruded as the tonalite porphyry stock at ∼1.7–2.4 km. The potassic alteration and associated Cu mineralization comprise five types of veins (A1, A2, B1, B2, and C) and two types of altered rocks (biotite and K-feldspar). Among them, nine types of hydrothermal quartz were identified from early to late: (1) VQA1 in A1 veins and RQbt in biotite-altered rocks; (2) VQA2 in A2 veins and RQkfs in K-feldspar altered rocks; (3) VQB1 in B1 veins and VQB2E in B2 veins; and (4) quartz associated with Cu-Fe sulfides (VQB2L, VQBC, and VQC) in B and C veins. Titanium contents of the quartz decreased, while Al/Ti ratios increased from early to late. Fluid inclusion microthermometry and mineral thermometers reveal that VQA1, RQbt, and hydrothermal biotite formed under high-temperature (∼470–560 °C) and ductile conditions. VQA2, RQkfs, VQB1, and hydrothermal K-feldspar formed during the transition stage from ductile to brittle, with temperatures of ∼350–540 °C. The rapid decrease in pressure from lithostatic to hydrostatic pressure led to fluid boiling and minor involvement of meteoric water (∼11–14%) in the mineralizing fluid. Extensive recrystallization in VQA1 to VQB1 was associated with repeated cleavage and healing of the intrusion. With cooling, K-feldspar decomposition and hydrolysis increased. Fluid cooling and water-rock reactions resulted in the co-precipitation of Cu-Fe sulfides, white mica, chlorite, VQBC, and VQC at temperatures of ∼275–370 °C and brittle conditions. The Paleozoic Aktogai deposit exhibits formation depths and fluid evolution processes similar to Mesozoic and Cenozoic porphyry Cu deposits worldwide. The close association between Cu-Fe sulfides and later quartz formed under intermediate-temperature conditions at Aktogai implies that Cu-Fe sulfides are not precipitated under early high-temperature conditions in porphyry Cu deposits.