scholarly journals Epigenetic-Hydrothermal Fluorite Veins in a Phosphorite Deposit from Balaton Highland (Pannonian Basin, Hungary): Signatures of a Regional Fluid Flow System in an Alpine Triassic Platform

Minerals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 640
Author(s):  
Zsuzsa Molnár ◽  
Gabriella B. Kiss ◽  
Ferenc Molnár ◽  
Tamás Váczi ◽  
György Czuppon ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Carbonate Platform ◽  
Pannonian Basin ◽  
Fluorite Structure ◽  
Middle Part ◽  
Raman Spectroscopic ◽  
Primary Fluid ◽  
Phosphorite Deposit ◽  
Growth Zones ◽  
Platform Carbonates

The middle Anisian extensional tectonics of the Neotethyan realm developed a small, isolated carbonate platform in the middle part of the Balaton Highland (western Hungary), resulted in the deposition of uranium-bearing seamount phosphorite on the top of the drowned platform and produced some epigenetic fluorite veins in the Middle Triassic sequence. The stable C-O isotope data of carbonates are shifted from the typical Triassic carbonate ranges, confirming the epigenetic-hydrothermal origin of veining. Primary fluid inclusions in fluorite indicate that these veins were formed from low temperature (85–169 °C) and high salinity NaCl + CaCl2 + H2O type (apparent total salinity: 15.91–22.46 NaCl wt%) hydrothermal fluids, similar to parent fluids of the Alpine-type Pb-Zn deposits. These findings indicate that the Triassic regional fluid circulation systems in the Alpine platform carbonates also affected the area of the Balaton Highland. This is also in agreement with the previously established palinspatic tectonic reconstructions indicating that the Triassic carbonate and basement units in the Balaton Highland area were a part of the Southern Alpine. Similar fluorite veining in phosphorite deposits is also known in the Southern Alpine areas (e.g., Monte San Giorgi, Italy). Raman spectroscopic analyses detected H2 gas in the vapor phase of the fluid inclusions and a defect-rich fluorite structure in violet to black colored growth zones. This unique phenomenon is assumed to be the result of interaction between the uranium-rich phosphorite and the parent fluids of the epigenetic fluorite veins.

Paragenesis of an Orogenic Gold Deposit: New Insights on Mineralizing Processes at the Grass Valley District, California

2020 ◽  
Author(s):  
Ryan D. Taylor ◽  
Thomas Monecke ◽  
T. James Reynolds ◽  
Jochen Monecke
Keyword(s):  
Fluid Inclusion ◽  
Fluid Inclusions ◽  
Hydrothermal System ◽  
Pressure Fluctuations ◽  
Hydrothermal Fluids ◽  
Orogenic Gold ◽  
The North ◽  
Primary Fluid ◽  
Growth Zones ◽  
East West

Abstract The Grass Valley orogenic gold district in the Sierra Nevada foothills province, central California, is the largest historical gold producer of the North American Cordillera. Gold mineralization is associated with shallowly dipping north-south veins hosted by the 160 Ma Grass Valley granodiorite to the southwest of the Grass Valley fault and steeply dipping east-west veins in accreted oceanic rocks to the northeast of this major fault. Quartz veins from both vein types show well-preserved primary textural relationships. Using a combination of petrographic and microanalytical techniques, the paragenetic sequence of minerals within the veins and the compositions of ore minerals were determined to constrain the mechanisms of quartz vein formation and gold deposition. The veins are composed of early quartz that formed through cooling of hydrothermal fluids derived from a geopressured reservoir at depth. The early quartz shows growth zoning in optical cathodoluminescence and contains abundant growth bands of primary inclusions. The primary inclusion assemblages and myriads of crosscutting secondary fluid inclusions have been affected by postentrapment modification, suggesting that early quartz formation was postdated by pronounced pressure fluctuations. These pressure fluctuations, presumably involving changes from lithostatic to hydrostatic conditions, may be related to fault failure of the host structure as predicted by the fault-valve model. Fluid flow associated with pressure cycling took place along microfractures and grain boundaries resulting in extensive recrystallization of the early quartz. Deposition of pyrite, arsenopyrite, and first-generation gold from these hydrothermal fluids causing recrystallization of the early quartz occurred as a result of wall-rock sulfidation. The gold forms invisible gold in the compositionally zoned pyrite or micron-sized inclusions within pyrite growth zones. The latest growth zones in euhedral quartz crystals that formed in association with this stage of the paragenesis contain very rare primary fluid inclusions that have not been affected by postentrapment modification. The hydrothermal system transitioned entirely to hydrostatic conditions immediately after formation of the latest quartz, explaining the preservation of the primary fluid inclusions. The formation of minor quartz in open spaces was followed by the deposition of second-generation native gold and telluride minerals that are commonly associated with base metal sulfides. Ore formation at this stage of the paragenesis is attributed to the rapid decompression of hydrothermal fluids escaping from the geopressured part of the crust into the overlying hydrostatic realm. There is no fluid inclusion evidence that this pressure drop resulted in fluid immiscibility of the hydrothermal fluids. Fluid inclusion evidence suggests that the north-south veins formed at a paleodepth of ~8 km, whereas the east-west veins appear to have formed at ~10 to 11 km below surface, confirming previous inferences that the NE-dipping Grass Valley reverse fault accommodated a large displacement. The findings of the study at Grass Valley have significant implications for the model for orogenic gold deposits, as the reconstruction of the paragenetic relationships provides evidence for the occurrence of two discrete events of gold introduction that occurred at different conditions during the evolution of the hydrothermal system.

scholarly journals The Temperature of Halite Crystallization in the Badenian Saline Basins, in the Context of Paleoclimate Reconstruction of the Carpathian Area

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 831
Author(s):  
Anatoliy R. Galamay ◽  
Krzysztof Bukowski ◽  
Igor M. Zinczuk ◽  
Fanwei Meng
Keyword(s):  
Temperature Distribution ◽  
Air Temperature ◽  
Fluid Inclusions ◽  
Middle Miocene ◽  
Single Phase ◽  
Dead Sea ◽  
Paleoclimate Reconstruction ◽  
Near Surface ◽  
Carpathian Region ◽  
Primary Fluid

Currently, fluid inclusions in halite have been frequently studied for the purpose of paleoclimate reconstruction. For example, to determine the air temperature in the Middle Miocene (Badenian), we examine single-phase primary fluid inclusions of the bottom halites (chevron and full-faceted) and near-surface (cumulate) halites collected from the salt-bearing deposits of the Carpathian region. Our analyses showed that the temperatures of near-bottom brines varied in ranges from 19.5 to 22.0 °C and 24.0 to 26.0 °C, while the temperatures of the surface brines ranged from 34.0 to 36.0 °C. Based on these data, such as an earlier study of lithology and sedimentary structures of the Badenian rock salts, the crystallization of bottom halite developed in the basin from concentrated and cooled near-surface brines of about 30 m depth. Our results comply with the data on the temperature distribution in the modern Dead Sea.

Oxygen fugacity during tin ore deposition from primary fluid inclusions in cassiterite

2021 ◽  
pp. 104451
Author(s):  
Christian Schmidt ◽  
Matthias Gottschalk ◽  
Rongqing Zhang ◽  
Jianjun Lu
Keyword(s):  
Oxygen Fugacity ◽  
Fluid Inclusions ◽  
Primary Fluid ◽  
Ore Deposition

Microanalysis of primary fluid inclusions in halite: constraints for an evaporitic sedimentation modeling. Application to the Mulhouse Basin (France)

1993 ◽  
Vol 20 (8) ◽  
pp. 1139-1151 ◽  
Author(s):  
A. Canals ◽  
B. Carpenter ◽  
A.Y. Huc ◽  
N. Guilhaumou ◽  
M.H. Ramsey
Keyword(s):  
Fluid Inclusions ◽  
Primary Fluid

scholarly journals Tectono-stratigraphic correlations between Northern Evvoia, Skopelos and Alonnisos, and the postulated collision of the Pelagonian carbonate platform with the Paikon forearc basin (Pelagonian–Vardar zones, Internal Hellenides, Greece)

2020 ◽  
Vol 2 (1) ◽  
Author(s):  
Rudolph Scherreiks ◽  
Marcelle Boudagher-Fadel
Keyword(s):  
Shear Zone ◽  
Early Cretaceous ◽  
Carbonate Platform ◽  
Leading Edge ◽  
Island Arc ◽  
Ductile Shear Zone ◽  
Forearc Basin ◽  
Platform Carbonates ◽  
Geochemical Analyses ◽  
Uplift And Erosion

The Pelagonian stratigraphy of the Internal Hellenides consists of a Permo-Triassic basement and an Upper Triassic and Jurassic carbonate platform formation that has been overthrust by the Eohellenic ophiolite sheet during the Early Cretaceous. Intensive erosion, during the Cretaceous, removed most of the ophiolite and parts of the Jurassic formation. It is hypothesised that uplift and erosion of eastern Pelagonia was triggered by the break-off of the subducted oceanic leading edge of the Pelagonian plate. An investigation of the rocks that succeed the erosional unconformity shows that they constitute a shear-zone that is tectonically overlain by Cretaceous platform carbonates. Geochemical analyses of the shear-zone rocks substantiate that they are of mid-oceanic ridge and island arc provenience. Eastern Pelagonia collided with a Cretaceous carbonate platform, probably the Paikon forearc basin, as the Almopias ocean crust subducted beneath that island–arc complex. The Cretaceous platform, together with a substrate of sheared-off ocean floor mélange, overthrust eastern Pelagonia as subduction continued, and the substrate was dynamically metamorphosed into cataclastic rocks, mylonite, phyllonite and interpreted pseudotachylite. This complex of Cretaceous platform rocks and a brittle-ductile shear-zone-substrate constitute the here named Paikon–Palouki nappe, which was emplaced during Early Palaeocene. The Paikon–Palouki nappe did not reach Evvoia. Seismic tomographic models of the Aegean region apparently depict images of two broken-off ocean-plate-slabs, interpreted as Almopias-lithosphere-slabs. It is concluded that the western Almopias slab began to sink during the Early Cretaceous, while the eastern Almopias slab broke off and sank after the Paikon–Palouki nappe was emplaced in the Early Palaeocene.

scholarly journals Cryogenic Raman Spectroscopic Studies on Common Ore-forming Fluid Systems

Minerals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 363
Author(s):  
Dan Yang ◽  
Xin Xiong ◽  
Weishi Chen
Keyword(s):  
Raman Spectroscopy ◽  
Quantitative Analysis ◽  
Correlation Coefficient ◽  
Fluid Inclusions ◽  
Intensity Ratio ◽  
Spectroscopic Studies ◽  
Ore Deposits ◽  
Raman Spectroscopic ◽  
Freezing Method ◽  
Fluid Systems

The composition and properties of ore-forming fluids are key to understanding the mechanisms of mineralization in ore deposits. These characteristics can be understood by studying fluid inclusions. Hydrates in fluid inclusions containing NaCl–H2O and MgCl2–H2O were studied using cryogenic Raman spectroscopy. The intensity ratio of peaks at 3401, 3464, 3514, and 3090 cm−1 shows a positive correlation with the concentration of hydrates in the inclusions, as does the ratio of the total integrated area of the MgCl2 hydrate peak (3514 cm−1) to the 3090 cm−1 peak with the concentration of MgCl2 (correlation coefficient >0.90). These correlations are important in the quantitative analysis of MgCl2 in synthetic and natural NaCl–MgCl2–CaCl2–H2O-bearing fluid inclusions. Semi-quantitative analysis of NaCl–MgCl2–H2O solutions indicates that peaks at 3437 and 3537 cm−1 reflect the presence of NaCl in the solution. Further, a peak at 3514 cm−1 is indicative of the presence of MgCl2. The relative intensities of these peaks may be related to the relative abundances of NaCl and MgCl2. A quantitative attempt was made on NaCl–MgCl2–CaCl2–H2O system, but it was found that quantifying NaCl, MgCl2 and CaCl2 separately in NaCl–MgCl2–CaCl2–H2O system by the secondary freezing method is difficult.

scholarly journals The Ultramicrochemical Analyses (UMCA) of Fluid Inclusions in Halite and Experimental Research to Improve the Accuracy of Measurement

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 823 ◽  
Author(s):  
Anatoliy R. Galamay ◽  
Krzysztof Bukowski ◽  
Daria V. Sydor ◽  
Fanwei Meng
Keyword(s):  
Chemical Composition ◽  
Fluid Inclusions ◽  
Error Rates ◽  
Analytical Error ◽  
Genetic Types ◽  
Primary Fluid ◽  
Accuracy Of Measurement ◽  
Distinguishing Features ◽  
Geological Period

Fluid inclusions in halite are widely used in research to determine the conditions of sedimentation in salt basins and reconstruct the chemical composition of seawater during a specific geological period. However, previous preliminary studies of the genetic types of inclusions, considered in the present research project, have not received due attention. Consequently, we decided to take into account the main distinguishing features of fluid inclusions in halite, belonging to various genetic types. The ultramicrochemical analysis (UMCA) method is one of the several methods that are used for the quantitative determination of the chemical composition of the primary fluid inclusions in halite. We have upgraded that technique, and that allowed us to reduce the analytical error rates of each component determination. The error rates were calculated in the study of Ca-rich and SO4-rich types of natural sedimentary brines.

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