scholarly journals MINERALOGICAL CONTRAINTS TO THE FORMATION OF VEIN-TYPE ZEOLITES FROM KIZARI AREA, THRACE NORTHERN GREECE

2017 ◽  
Vol 43 (5) ◽  
pp. 2786
Author(s):  
P. Voudouris ◽  
A. Magganas ◽  
M. Kati ◽  
N. Gerogianni ◽  
G. Kastanioti ◽  
...  
Keyword(s):  
Open Space ◽  
Volcanic Rocks ◽  
Space Filling ◽  
Northern Greece ◽  
Calcite Veins ◽  
Vein Type ◽  
Mineralogical Evidence

Vein-type zeolites in Kizari area, (western Thrace) are found within fresh to zeolitic altered volcanic rocks of andesitic to dacitic composition. The zeolites stilbite-Ca, Sr-bearing heulandite-Ca and laumontite occur in epithermal-style crustiform quartz/chalcedony-calcite veins crosscuting lavas and volcanic breccias. Open-space filling is common and well-shaped crystals (up to 3cm) were observed. Smectite, feldspar, magnetite, pyrite and rutile occur in minor amounts in the veins. Halite and barite grains are included in stilbite-Ca. SEM EDS data indicate high Sr (up to 4.4 wt. % SrO) and Ba (up to 2.9 wt. % BaO) contents for heulandite-Ca. It is suggested that the studied zeolites are intergral parts of the porphyry-epithermal mineralizing systems which operated in the area during the Oligocene. Their formation took place in the outmost transitional propylitic to fresh zones of the porphyry-epithermal systems and in a submarine environment as indicated by the geological and mineralogical evidence.

scholarly journals Fracture Fillings and Implication of Fluid Activities in Volcanic Rocks: Dixi Area in Kelameili Gas Field, Junggar Basin, Northwestern China

Minerals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 154 ◽  
Author(s):  
Mingyou Feng ◽  
Tian Liu ◽  
Tong Lin ◽  
Xiaohong Liu ◽  
Ningxin Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Volcanic Rocks ◽  
Junggar Basin ◽  
Hydrothermal Fluids ◽  
Northwestern China ◽  
Volatile Components ◽  
Gas Field ◽  
Weakly Alkaline ◽  
Quartz Veins ◽  
Calcite Veins

The Carboniferous Batamayineishan Formation of the Kelameili Gas Field is a specific weathered crust-related volcanic reservoir that has a significant production rate in the Junggar Basin, Northwestern China, attributed to debatable processes of fluid evolution. The results suggest that various types of fluids occurring in volcanic rocks lead to the filling of quartz and calcite in fractures and their associated alteration haloes. The silica that formed quartz veins was mainly derived from deep hydrothermal fluids, while the carbon dioxide that formed calcite veins originated from sources characterized by mixing and alteration of deep hydrothermal and hydrocarbon fluids. Siliceous hydrothermal fluids rich in sulphur dioxide and other volatile components were driven by a pressure gradient and buoyancy, and circulated both laterally and vertically along the fractures, forming quartz veins and tension fractures under different temperature conditions. Moreover, changes in salinity, pressure, and carbon dioxide of deep fluids, varying from acidic to weakly alkaline, resulted in earlier calcite precipitation in contraction fractures and weathered fractures. Tectonic uplift resulted in the long-term exposure of volcanic rocks, where fresh water mixed with the partially alkaline fluid escaping the basin to form calcite cements, thus retaining the characteristics of a seepage environment in the weathered fractures. Structural fractures occurred due to tectonic movements during the burial period. Filling and leakage of hydrocarbons caused pore fluids to convert from acidic to alkaline, precipitating late sparry calcite in dissolution fractures. Late hydrothermal fluid metasomatism, brought about by infiltration into the permeable zone, caused partial dissolution of local calcite along cleavage cracks.

scholarly journals Amethyst Occurrences in Tertiary Volcanic Rocks of Greece: Mineralogical, Fluid Inclusion and Oxygen Isotope Constraints on Their Genesis

Minerals ◽  
2018 ◽  
Vol 8 (8) ◽  
pp. 324 ◽  
Author(s):  
Panagiotis Voudouris ◽  
Vasilios Melfos ◽  
Constantinos Mavrogonatos ◽  
Alexandre Tarantola ◽  
Jens Gӧtze ◽  
...  
Keyword(s):  
Fluid Inclusion ◽  
Open System ◽  
Volcanic Rocks ◽  
Hydrothermal Fluids ◽  
Northern Greece ◽  
Quartz Veins ◽  
Low Salinity ◽  
Moderate Salinity ◽  
Host Rocks ◽  
Of Greece

Epithermally altered volcanic rocks in Greece host amethyst-bearing veins in association with various silicates, carbonates, oxides and sulfides. Host rocks are Oligocene to Pleistocene calc-alkaline to shoshonitic lavas and pyroclastics of intermediate to acidic composition. The veins are integral parts of high to intermediate sulfidation epithermal mineralized centers in northern Greece (e.g., Kassiteres–Sapes, Kirki, Kornofolia/Soufli, Lesvos Island) and on Milos Island. Colloform–crustiform banding with alternations of amethyst, chalcedony and/or carbonates is a common characteristic of the studied amethyst-bearing veins. Hydrothermal alteration around the quartz veins includes sericitic, K-feldspar (adularia), propylitic and zeolitic types. Precipitation of amethyst took place from near-neutral to alkaline fluids, as indicated by the presence of various amounts of gangue adularia, calcite, zeolites, chlorite and smectite. Fluid inclusion data suggest that the studied amethyst was formed by hydrothermal fluids with relatively low temperatures (~200–250 °C) and low to moderate salinity (1–8 wt % NaCl equiv). A fluid cooling gradually from the external to the inner parts of the veins, possibly with subsequent boiling in an open system, is considered for the amethysts of Silver Hill in Sapes and Kassiteres. Amethysts from Kornofolia, Megala Therma, Kalogries and Chondro Vouno were formed by mixing of moderately saline hydrothermal fluids with low-salinity fluids at relatively lower temperatures indicating the presence of dilution processes and probably boiling in an open system. Stable isotope data point to mixing between magmatic and marine (and/or meteoric) waters and are consistent with the oxidizing conditions required for amethyst formation.

scholarly journals Amethyst occurrences in Tertiary volcanic rocks of Greece: mineralogical and genetic implications

2013 ◽  
Vol 47 (1) ◽  
pp. 477 ◽  
Author(s):  
P. Voudouris ◽  
I. Psimis ◽  
C. Mavrogonatos ◽  
C. Kanellopoulos ◽  
M. Kati ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
Hydrothermal Activity ◽  
Hydrothermal Fluids ◽  
Calc Alkaline ◽  
Northern Greece ◽  
Volcanic Arc ◽  
Quartz Veins ◽  
High Sulfidation ◽  
Host Rocks ◽  
Of Greece

Epithermal-altered volcanic rocks in Greece host gem-quality amethyst veins in association with various silicates, carbonates, oxides, sulfides and halides. Host rocks are Oligocene to recent calc-alkaline to shoshonitic lavas and pyroclastics of intermediate- to acid composition. The amethyst-bearing veins occur in the periphery of porphyry-type and/or high-sulfidation epithermal mineralized centers in northern Greece (e.g. Sapes, Kirki, Kornofolia/Soufli, Lesvos island) and on Milos island in the active Aegean Volcanic Arc. Hydrothermal alteration around the quartz veins includes sericitic, K-feldspar (adularia), argillic, propylitic and zeolitic types. Precipitation of amethyst in the northern Greece occurrences, took place during the final stages of the magmatic-hydrothermal activity from near-neutral to alkaline fluids, as indicated by the presence of gangue adularia, calcite, smectite, chlorite, sericite, pyrite, zeolites (laumontite, heulandite, clinoptilolite), analcime and minor amounts of barite, halite, epidote and fluorite in the quartz veins. Amethyst at Milos Island (Chondro Vouno and Kalogries-Vani areas), is accompanied by barite, smectite and lepidocrocite. Colloform-crustiform banding with alternations of amethyst, chalcedony and/or carbonates is a common characteristic of the studied amethyst-bearing veins. Fluid inclusion- and mineralogical data suggest that the studied amethyst were formed at: 174-246 °C (Sapes area), 100-175 °C (Kirki and Kornofolia areas) and 223-234°C (Lesvos island). The amethyst formation requires oxidizing conditions and is probably the result of mixing between meteoric or seawater with upwelling hydrothermal fluids. The involvement of seawater in the studied mineralization is supported by the presence of halite and abundant barite in the veins. Finally, the studied amethyst deposits should be evaluated as potential gemstone sources in Greece.

Re-Os PYRITE GEOCHRONOLOGY OF THE YELLOWHEAD-TYPE MINERALIZATION, PEND OREILLE MINE, KOOTENAY ARC, METALINE DISTRICT, WASHINGTON

2020 ◽  
Vol 115 (7) ◽  
pp. 1373-1384
Author(s):  
Suzanne Paradis ◽  
Danny Hnatyshin ◽  
George J. Simandl ◽  
Robert A. Creaser
Keyword(s):  
Fossil Record ◽  
Open Space ◽  
The United States ◽  
Textural Analysis ◽  
Sulfide Deposit ◽  
Sulfide Mineralization ◽  
Space Filling ◽  
Middle Cambrian ◽  
Metal Mine ◽  
Igneous Activity

Abstract Pend Oreille, a carbonate-hosted Zn-Pb sulfide deposit, is the only base metal mine recently in production within the historically prolific Kootenay arc belt. The deposit consists of two spatially and lithologically distinct types of stratabound, carbonate-hosted Zn-Pb mineralization: Josephine and Yellowhead. The Yellowhead-type sulfide mineralization, the focus of this study, consists of en échelon tabular to lensoidal pyrite-sphalerite–rich orebodies hosted by the middle Cambrian to Early Ordovician Metaline Formation. The Yellowhead-type mineralization is characterized by carbonate replacement and open-space filling textures, indicating diagenetic and epigenetic origin. As with most low-temperature deposits not directly associated with igneous activity, the timing of sulfide mineralization has traditionally been difficult to constrain using radiometric methods. In this study, we present a new Re-Os age of 512 ± 17 Ma from the Yellowhead mineralization. Combining this age date with the Cambrian-Ordovician fossil record of the host Metaline Formation and detailed textural analysis of the mineralization, we conclude that the Yellowhead sulfide mineralization is largely diagenetic in origin. Such an origin for the Yellowhead mineralization is similar to that of Irish-type deposits worldwide. For explorationists, the presence of Irish-type deposits in the United States portion of the Kootenay arc opens the possibility of discovering similar mineralization in the Canadian extension of the Kootenay arc.

Palygorskite-bearing fracture fills in the Kinshasa area, DR Congo – an exceptional mode of palygorskite vein development

2019 ◽  
Vol 122 (2) ◽  
pp. 173-186
Author(s):  
F. Mees ◽  
R. Adriaens ◽  
A. Delgado-Huertas ◽  
D. Delvaux ◽  
P. Lahogue ◽  
...  
Keyword(s):  
Hydrothermal Activity ◽  
Upper Jurassic ◽  
Dr Congo ◽  
Quartz Content ◽  
Clay Particles ◽  
Fine Grained ◽  
Calcite Veins ◽  
Vein Type ◽  
Authigenic Mineral ◽  
Temperature Interaction

Abstract Tectonic fractures in Palaeozoic strata of the Kinshasa area, DR Congo, locally host palygorskite-bearing veins and associated calcite occurrences. The palygorskite deposits are typically massive, with a varying degree of alignment of clay particles, a higher quartz content than the arkose substrate, and a variable amount of smectite (montmorillonite). The associated calcite occurrences are macrocrystalline coatings and infillings, and more fine-grained calcite veins with cataclastic texture. The calcite coatings and infillings formed from solution in earth surface conditions, as recorded by their stable isotope signature. The palygorskite-dominated deposits in the fractures formed at a later stage, in a setting without indications of authigenic mineral formation related to hydrothermal activity or to low-temperature interaction of solutions with the local substrate. The veins most likely formed by vertical infiltration of suspended matter in fractures that extended to a post-Palaeozoic palaeosurface, during or after deposition of palygorskite-bearing Upper Jurassic to Early Cretaceous sediments. This represents an exceptional mode of palygorskite vein development, unrelated to any form of mineral authigenesis that is typically invoked to explain vein-type occurrences of palygorskite and related minerals.

Geochemistry of a fossil hydrothermal system at Barton Peninsula, King George Island

1995 ◽  
Vol 7 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Chil-Sup So ◽  
Seong-Taek Yun ◽  
Maeng-Eon Park
Keyword(s):  
Hydrothermal System ◽  
Meteoric Water ◽  
Volcanic Rocks ◽  
King George Island ◽  
Sulphur Isotope ◽  
Alteration Zones ◽  
Vein Formation ◽  
Calcite Veins ◽  
Lead Zinc ◽  
Barton Peninsula

A fossil hydrothermal system on Barton Peninsula, King George Island, Antarctica, formed a series of lead-zinc- and pyrite + native sulphur-bearing epithermal quartz ± calcite veins, filling fault-related fractures in hydrothermally altered volcanic rocks of Eocene age. The lead-zinc veins occur within argillic hydrothermal alteration zones, whereas the pyrite + native sulphur veins are found within advanced argillic alteration zones. Fluid inclusion data indicate that the vein formation occurred at temperatures between about 125° and 370°C (sphalerite deposition formed at 123–211°C) from fluids with salinities of 0.5–4.6 wt.% eq. NaCl. Equilibrium thermodynamic interpretation of mineral assemblages indicates that the deposition of native sulphur in the upper and central portions of the hydrothermal system was a result of the mixing of condensates of ascending magmatic gases and meteoric water giving rise to fluids which had lower pH (<3.5) and higher fugacities of oxygen and sulphur than the lead-zinc-depositing fluids at depth. The δ34S values of sulphide minerals from the lead-zinc veins (δ34S = −4.6 to 0.7‰) are much higher than the values of pyrite and native sulphur from the pyrite + native sulphur veins (δ34S = −12.9 to −20.1‰). This indicates that the fluids depositing native sulphur had higher sulphate/H2S ratios under higher fo2 conditions. Sulphur isotope compositions indicate an igneous source of sulphur with a δ34SΣS value near 0‰, probably the Noel Hill Granodiorite. Measured and calculated δ18O and δD values of the epithermal fluids (δ18Owater = −6.0 to 2.7‰, δDwater = −87 to −75‰) indicate that local meteoric water played an important role for formation of lead-zinc and native sulphur-bearing quartz veins.

scholarly journals Characteristics of the Ahmadabad hematite/barite deposit, Iran – studies of mineralogy, geochemistry and fluid inclusions

Geologos ◽  
2018 ◽  
Vol 24 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Amir Haji Babaei ◽  
Alireza Ganji
Keyword(s):  
Low Temperature ◽  
Fluid Inclusions ◽  
Open Space ◽  
Volcanic Rocks ◽  
Major And Trace Elements ◽  
Hydrothermal Conditions ◽  
Hydrothermal Origin ◽  
Fe Oxyhydroxides ◽  
Host Rocks ◽  
Ree Patterns

Abstract The Ahmadabad hematite/barite deposit is located to the northeast of the city of Semnan, Iran. Geostructurally, this deposit lies between the Alborz and the Central Iran zones in the Semnan Subzone. Hematite-barite mineralisation occurs in the form of a vein along a local fault within Eocene volcanic host rocks. The Ahmadabad deposit has a simple mineralogy, of which hematite and barite are the main constituents, followed by pyrite and Fe-oxyhydroxides such as limonite and goethite. Based on textural relationships between the above-mentioned principal minerals, it could be deduced that there are three hydrothermal mineralisation stages in which pyrite, hematite and barite with primary open space filling textures formed under different hydrothermal conditions. Subsequently, in the supergene stage, goethite and limonite minerals with secondary replacement textures formed under oxidation surficial conditions. Microthermometric studies on barite samples show that homogenisation temperatures (TH) for primary fluid inclusions range from 142 to 256°C with a temperature peak between 200 and 220°C. Salinities vary from 3.62 to 16.70 NaCl wt% with two different peaks, including one of 6 to 8 NaCl wt% and another of 12 to 14 NaCl wt%. This indicates that two different hydrothermal waters, including basinal and sea waters, could have been involved in barite mineralisation. The geochemistry of the major and trace elements in the samples studied indicate a hydrothermal origin for hematite and barite mineralisation. Moreover, the Fe/Mn ratio (>10) and plots of hematite samples of Ahmadabad ores on Al-Fe-Mn, Fe-Mn-(Ni+Co+ Cu)×10, Fe-Mn-SiX2 and MnO/TiO2 – Fe2O3/TiO2 diagrams indicate that hematite mineralisation in the Ahmadabad deposit occurred under hydrothermal conditions. Furthermore, Ba and Sr enrichment, along with Pb, Zn, Hg, Cu and Sb depletion, in the barite samples of Ahmadabad ores are indicative of a low temperature hydrothermal origin for the deposit. A comparison of the ratios of LaN/YbN, CeN/YbN, TbN/LaN, SmN/NdN and parameters of Ce/Ce* and La/La* anomalies of the hematite, barite, host volcanic rocks and quartz latite samples to each other elucidate two important points: 1) the barite could have originated from volcanic host rocks, 2) the hematite could have originated from a quartz latite lithological unit. The chondrite normalised REE patterns of samples of hematite barite, volcanic host rocks and quartz latite imply that two different hydrothermal fluids could be proposed for hematite and barite mineralisation. The comparison between chondrite normalised REE patterns of Ahmadabad barite with oceanic origin barite and low temperature hydrothermal barite shows close similarities to the low temperature hydrothermal barite deposits.

scholarly journals Magmatic-Hydrothermal Processes of Vein-Type Haman-Gunbuk-Daejang Copper Deposits in the Gyeongnam Metallogenic Belt in South Korea

2021 ◽  
Vol 9 ◽  
Author(s):  
Tong Ha Lee ◽  
Jung Hun Seo ◽  
Bong Chul Yoo ◽  
Bum Han Lee ◽  
Seung Hee Han ◽  
...  
Keyword(s):  
Fluid Inclusions ◽  
Hydrothermal Activity ◽  
Hydrothermal Conditions ◽  
Copper Deposits ◽  
Quartz Veins ◽  
Calcite Veins ◽  
Vein Type ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Shale Formation

Haman, Gunbuk, and Daejang deposits are neighboring vein-type hydrothermal Cu deposits located in the SE part of the Korean Peninsula. These three deposits are formed by magmatic-hydrothermal activity associated with a series of Cretaceous granodioritic intrusions of the Jindong Granitoids, which have created a series of veins and alterations in a hornfelsed shale formation. The copper deposits have common veining and alteration features: 1) a pervasive chlorite-epidote alteration, cut by 2) Cu-Pb-Zn-bearing quartz veins with a tourmaline-biotite alteration, and 3) the latest barren calcite veins. Chalcopyrite, pyrite, and pyrrhotite are common ore minerals in the three deposits. Whereas magnetite is a dominant mineral in the Haman and Gunbuk deposits, no magnetite is present, but sphalerite and galena are abundant in the Daejang deposit. Ore-bearing quartz veins have three types of fluid inclusions: 1) liquid-rich, 2) vapor-rich, and 3) brine inclusions. Hydrothermal temperatures obtained from the brine inclusion assemblages are about 340–600, 250–500, and 320–460°C in the Haman, Gunbuk, and Daejang deposits, respectively. The maximum temperatures (from 460 to 600°C) recorded in the fluid inclusions of the three deposits are higher than those of the Cu ore precipitating temperature of typical porphyry-like deposits (from 300 to 400°C). Raman spectroscopy of vapor inclusions showed the presence of CO2 and CH4 in the three deposits, which indicates relatively reduced hydrothermal conditions as compared with typical porphyry deposits. The Rb/Sr ratios and Cs concentrations of brine inclusions suggest that the Daejang deposit was formed by a later and more fractionated magma than the Haman and Gunbuk deposits, and the Daejang deposit has lower Fe/Mn ratios in brine inclusions than the Haman and Gunbuk deposits, which indicates contrasting redox conditions in hydrothermal fluids possibly caused by an interaction with a hosting shale formation. In brines, concentrations of base metals do not change significantly with temperature, which suggests that significant ore mineralization precipitation is unlikely below current exposure levels, especially at the Haman deposit. Ore and alteration mineral petrography and fluid inclusions suggest that the Haman deposit was formed near the top of the deep intrusion center, whereas the Gunbuk deposit was formed at a shallower intrusion periphery. The Daejang deposit was formed later at a shallow depth by relatively fractionated magma.

scholarly journals Magma–sediment interaction during the emplacement of syn-sedimentary silicic and mafic intrusions and lavas into and onto Triassic strata (Circum-Rhodope Belt, northern Greece)

2013 ◽  
Vol 64 (3) ◽  
pp. 181-194 ◽  
Author(s):  
Argyro Asvesta ◽  
Sarantis Dimitriadis
Keyword(s):  
Middle Triassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Mafic Magma ◽  
Upper Triassic ◽  
Low Grade ◽  
Carbonate Sediments ◽  
Northern Greece ◽  
Mafic Intrusions ◽  
Silicic Volcanic

Abstract Within the Circum-Rhodope Belt in northern Greece, Middle Triassic neritic carbonate metasediments are locally intercalated with quartz-feldspar-phyric metarhyolites. In the same belt, Upper Triassic pelagic lime-marl-layered metasediments are similarly intercalated with low-grade metamorphosed basalt, dolerite and minor andesite and trachydacite. We interpret these sequences as due to magmatism active during the rifting event that eventually led to the opening of the Vardar Ocean. Despite the overprint of Late Jurassic deformation and low greenschist metamorphism, peperitic textures produced by magma-wet sediment interaction are well preserved at the contacts between the silicic volcanic rocks and the originally wet unconsolidated neritic carbonate sediments, suggesting contemporaneous magmatism and sedimentation. The mafic and intermediate volcanic rocks lack peperitic textures at their contacts with the pelagic sedimentary rocks. Thin margin parallel banding in the sedimentary members of the sequence indicates thermally affected original contacts with the mafic volcanic rocks only locally and at a microscopic scale. The absence of peperite in this case is attributed to the consolidated state of the sediments at the time of the mafic magma emplacement.

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