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Interaction between tectonics, plutonism and mineralization of the Duna Pb-Ba ore deposit regarding fluid inclusion study (Central Alborz, Iran)

Sadeghi Alireza, Asiabar Saeid Hakimi, Nezafati Nima, Ganji Alireza, Mukherjee Soumyajit

Acta Geologica Polonica

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2023

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Vol. 73, no. 2

201--222

EN

This article discusses the impacts of overprinting of tectonic and plutonic events on the mineralization of the Duna Pb-Ba ore deposit, according to geologic settings and fluid inclusion studies. The Duna carbonate-hosted deposit contains a significant amount of Ag (18.9–264.3 ppm ), Cu (77–41600 ppm), Sb (32.7–11000 ppm), Sr (63.5–15100 ppm), and Fluid inclusions with 7.34–23.65 wt.% NaCl equivalent. The homogenization temperature of about 110–285°C, as well as the paragenesis of the minerals shows a difference compared with other Pb-Zn deposits such as the Irish-type and MVT. The ore mineralization in the Duna mine occurred as stratabound, open space-filling, and along the brecciated fault zones. The concordant (stratabound) type of mineralization, with salinity and homogenization temperature of 18.54 to 23.65 wt.% NaCl equivalent, and 113°C to 165°C respectively, is usually typical of MVT-ore deposits, which in this area evolved during the Early Cimmerian orogeny and was later interrupted by mineralization along younger brecciated fault zones with salinity and homogenization temperature of 7.34 to 23.65 wt.% NaCl equivalent, and 113°C to 285°C respectively. This discordant mineralization, which occurred along the faults, formed by the end of the Late Cretaceous and during the Cenozoic as a result of the intrusion of a plutonic mass, and is comparable to the Irish-type ore deposits.

2

Geological and geochemical implications of the genesis of the Qolqoleh orogenic gold mineralisation, Kurdistan Province (Iran)

Taghipour B., Ahmadnejad F.

Geologos

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2015

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Vol. 21, No. 1

31--57

EN

The Qolqoleh gold deposit is located in the northwestern part of the Sanandaj–Sirjan Zone (SSZ), within the NE–SW trending Qolqoleh shear zone. Oligocene granitoids, Cretaceous meta-limestones, schists and metavolcanics are the main lithological units. Chondrite-normalised REE patterns of the ore-hosting metavolcanics indicate REE enrichment relative to hanging wall (chlorite-sericite schist) and footwall (meta-limestone) rocks. The pattern also reflects an enrichment in LREE relative to HREE. It seems that the LREE enrichment is related to the circulation of SO42- and CO2-bearing fluids and regional metamorphism in the Qolqoleh shear zone. Both positive and negative Eu anomalies are observed in shear-zone metavolcanics. These anomalies are related to the degree of plagioclase alteration during gold mineralisation and hydrothermal alteration. In progressing from a metavolcanic protomylonite to an ultramylonite, significant changes occurred in the major/trace element and REE concentration. Utilising an Al-Fe-Ti isocon for the ore-hosting metavolcanics shows that Sc, Y, K, U, P, and M-HREE (except Eu) are relatively unchanged; S, As, Ag, Au, Ca, LOI, Rb and LREE are enriched, and Sr, Ba, Eu, Cr, Co and Ni decrease with an increasing degree of deformation. Based on geochemical features and comparison with other well-known shear zones in the world, the study area is best classified as an Isovolume-Gain (IVG) type shear zone and orogenic type gold mineralisation. Based on the number of phases observed at room temperature and their microthermometric behaviour, three fluid inclusion types have been recognised in quartz-sulphide and quartz-calcite veins: Type I monophase aqueous inclusions, Type II two-phase liquid-vapour (L-V) inclusions which are subdivided into two groups based on the homogenisation temperature (Th): a) L-V inclusions with Th from 205 to 255°C and melting temperature of last ice (Tm) from –3 to –9°C. b) L-V inclusions with higher Th from 335 to 385°C and Tm from –11 to –16°C. Type III three-phase carbonic-liquid inclusions (liquid water-liquid CO2-vapour CO2) with Th of 345–385°C. The mean values of the density of ore-forming fluids, pressure and depth of mineralisation have been calculated to be 0.79–0.96 gr/cm3, 2 kbar and 7 km, respectively. The δ18Owater and δD values of the gold-bearing quartz-sulphide veins vary from 7.2‰ to 8‰ and –40.24‰ to –35.28‰, respectively, which are indicative of an isotopically heavy crustal fluid and likely little involvement of meteoric fluid. The δ18Owater values of the quartz-calcite veins have a range of –5.31‰ to –3.35‰, and the δD values of –95.65‰ to –75.31‰, which are clearly lower than those of early-stage quartz-sulphide-gold veins, and are close to the meteoric water line. Based on comparisons of the D–O isotopic systematics, the Qolqoleh ore-mineralising fluids originated from metamorphic devolatilisation of Cretaceous volcano-sedimentary piles. Devolatilisation of these units occurred either synchronously with, or postdates, the development of penetrative (ductile) structures such as shear zones and during overprinting brittle deformation.

3

The comparison of alteration zones in the Sungun porphyry copper deposit, Iran (based on fluid inclusion studies)

Asghari O., Hezarkhani A., Soltani F.

Acta Geologica Polonica

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2009

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Vol. 59, no. 1

93-109

EN

The Sungun porphyry copper deposit (PCD) is located in East Azarbaijan, in northwestern Iran. The felsic rocks occur as stocks and dykes ranging in composition from quartz monzodiorite through quartz monzonite. The stocks are classified into porphyry stocks I and II. Porphyry stock II, hosting the copper ore, experienced an intense hydro-fracturing leading to the formation of stockwork-type veinlets and micro-veinlets of quartz, sulphides, carbonates and sulphates. Three distinct types of hydrothermal alteration and sulphide mineralization are recognized at Sungun (1) hypogene, (2) contact metasomatic (skarn), and (3) supergene. Hypogene alteration is developed in four kinds: potassic, phyllic, propylitic and argillic. Three types of fluid inclusions are typically observed at Sungun: (1) vapour-rich, two-phase, (2) liquid-rich two-phase and (3)multi-phase. Halite is the principal solid phase in multiphase inclusions. Primary multiphase inclusions (LVH type fluid inclusions) within the quartz crystals in quartz-sulphide and quartz-molybdenite veinlets (quartz associated with sulphide minerals) were selected for micro-thermometric analyses and considered to be suitable for pressure calculations and estimation of hydrothermal fluid density. Homogenization temperature, salinity, pressure and density were measured and calculated in forty-seven selected samples. None of the variables could distinguish the potassic from phyllic alteration zones clearly. In the potassic alteration zone, the average of homogenization temperature is about 413[degrees]C, while in the phyllic alteration zone its average is about 375[degrees]C. It was expected that the temperature in the potassic alteration zone would be higher than that in the phyllic zone, but the difference found was not very significant The fluid inclusion salinity within both alteration zones obviously relates to their homogenization temperature: the average salinity in the samples from the potassic zone is 46.3 (wt%NaCl equiv.), which is higher than that in the samples from the phyllic zone. Based on the estimated depth of the potassic alteration domain, it is expected that the lithostatic pressure was higher than in the phyllic alteration zone. According to the fluid inclusion studies and pressure calculation, it is estimated that the average pressure for the potassic alteration zone was about 512 (bars) while the average pressure for phyllic zone was about 310 (bars). The average density of fluids in the samples from the potassic alteration zone is 1.124 (g/cm[^3]), which is higher than that in the phyllic alteration zone (1.083 g/cm[^3]).

4

Integrated studies of Late Jurassic neptunian dykes from central Poland

Barski M., Ostrowski S.

Volumina Jurassica

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2006

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Vol. 4, no. 1

78-79

EN

Steeply dipping clastic dykes cutting through the Middle Jurassic clays with ironestone nodules have been exposed in three localities at Wieluń, Częstochowa and Zawiercie in central Poland. The dykes are grey calcareous, structureless sandstones, 5 to 10 cm wide running roughly along the NE-SW direction which corresponds approximately to system of faults in the area. Palynological analysis of the internal sediment from the dykes revealed mixed assemblages of the Middle (Bajocian-Bathonian), and the Upper Jurassic (Oxfordian – Lower Kimmeridgian) Dinoflagellate cyst taxa. The latter consist of Systematophora areolata, Ctenidodinium ornatum, Gonyaulacysta jurassica jurassica, Endoscrinium luridum, Endoscrinium galeritum, Leptodinium subtile and Scriniodinium crystallinum. Rich hydrothermal calcite mineralization occurs mainly where dykes cut ironestone nodules. Hydrotermal mineralization is composed of coarse palisadic crystals ranging form 2.5 to 6 mm in lenght. Cement of sandstones is also composed of hydrotermal calcite. Fluid inclusion analysis of palisadic crystals (performed by Prof. Andrzej Koz.owski) yielded homogenisation temperatures in range of 53 up to 72°C. Gradual decreasing of homogenisation point and change in composition of fluids from hydrotermal to more marine fluids is observed from dyke walls, toward the centre of the dyke. Fluid inclusion analysis confirms mixed, hydrotermal-neptunian genesis of dykes with stages postulated on the basis of thin section observations. Presented work demonstrates necessity of integrated geological studies to improve sedimentological and tectonic reconstructions.The origin of the dykes was related with synsedimentary tectonics during Late Jurassic (Oxfordian - Early Kimmeridgian) which controlled the facies distribution within the sponge megafacies of the Polish Jura Chain area.

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Reconstruction of crystallisation temperature of artificially grown H-analcimes by means of the IR and fluid inclusion studies

Słaby E., Kozłowski A.

Acta Geologica Polonica

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2002

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Vol. 52, nr 4

385-394

EN

A method of reconstruction of the crystallisation temperature (Tc) of analcime has been proposed. The method is based on the compilation of two data sets: the IR absorption spectra and fluid inclusion study results. The water position in the analcime structure depends on the crystallisation temperature. Certain bands in the IR absorption spectrum are sensitive to the change in the temperature conditions of the analcime formation. Moreover, the IR absorption band positions are also influenced by the composition of the crystallisation system as well as by the crystallisation time. For more precise information about Tc, fluid inclusion studies were performed. They provide additional data about salt concentrations in the crystallisation system, water behaviour in the analcime structure and crystallisation temperature.

6

Joints and mineral veins during structural evolution: case study from the Outer Carpathians (Poland)

Świerczewska A., Tokarski A.K., Hurai V.

Geological Quarterly

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2000

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Vol. 44, Nr 3

333-339

EN

This paper focuses on mineral veins hosted in small-scale fractures within the Tertiary sandstones of the Magura nappe (Outer Carpathians). Joints, faults and tension gashes record three successive stages of the nappe structural evolution: (1) synsedimentary folding and thrusting, (2) regional rotation and (3) late-orogenic collapse. The flow of mineral-bearing fluids was channelized by small-scale fractures resulting in calcite and quartz-calcite veins. Folding: columnar calcite formed the most common filling of early joints and the joints-related tension gashes and strike-slip faults. The mineralisation was restricted to sandstones containing primary carbonates. Rotation: precipitation of columnar and fibrous calcite was largely restricted to joints reactivated as strike-slip faults. Collapse: the collapse-related mineralisation is the most abundant. Wide-spread fluid flow was channelized by normal faults resulting in fibrous calcite and quartz-calcite along these faults whereas several blocky and drusy calcite generation and single high temperature quartz-calcite assemblage precipitated in numerous adjoining joints.

7

Quartz cements in the Cambrian sandstones, Żarnowiec region, N Poland : a fluid inclusion study

Jarmołowicz-Szulc K.

Kwartalnik Geologiczny

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1998

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Vol. 42, nr 3

311-318

EN

Fluid inclusion studies were conducted in quartz cements of the Cambrian sandstones from two boreholes in the Żarnowiec regions (northern Poland). The research based on the microscope observations of inclusions aiming at their petrography and fluorescence characteristics as well as it comprised the routine microthermometric runs. The cathodoluminescencce studies resulted in determination of generation of quartz cementing the sandstones. Two types of fluid inclusions have been found --aqueous and hydrocarbon ones. They are connected with two genetrations of the quartz cements in the sandstones under discussion. The aqueous inclusions yield homogenisation temperatures of about 100 C and salinities of about 8% eq. NaCl. The hydrocarbon inclusions studied display three temperature groups ranging from 71 to 110 C. An attempt of interpretation of the entrapment conditions of coeval oil and aqueous inclusions was made resulting in p-T values. Due to the limited number of fluid inclusions in the cements the representativeness of the data is however, rather poor.

PL

W czasie tworzenia się cementów diagenetycznych w mikroprzestrzeniach minerałów powstają mikrowrostki - inkluzje fluidalne. Mogą one byś użyte do określania paleotemperatur przy wprowadzeniu szeregu założen. Inkluzje fluidalne badano w cementach kwarcowych skał kambru środkowego w rejonie Żarnowca. Badania przeprowadzono mikroskopowo w specjalnie obustronnie polerowanych preparatach z użyciem aparatury wymrażająco-grzewczej Fluid Inc. I zestawu fluorescencyjnego Nikon. Inkluzje fluidalne zaobserwowano w cemencie kwarcowym typu obwódek wokół ziaren detrytycznych oraz wtórnych zabliźnień kwarcem spękań i mikroszczelinek. Generalnie w piaskowcach z otworów Żarnowiec istnieją dwa typy inkluzji (wodne i węglowodorowe). Genetycznie wiążą się one z dwoma rodzajami spoiwa kwarcowego piaskowców. Wrostki te są bardzo małe i nieliczne. Charakterystyczny dla nich jest brak zabarwienia w świetle przechodzącym. Inkluzje o wyraźnie biało-niebieskiej fluorescencji (UV) występują przede wszystkim w asocjacji Q3 i przeważają w otworze wiertniczym Żarnowiec, zwłaszcza w górnej partii opróbowanej. Wykonano badania eksperymentalne homogenizacji inkluzji wodnych i węglowodorowych. Oba typy inkluzji dwufazowych homogenizowały w fazę ciekłą, a temperatury wyniosły odpowiednio 87-90 0 107 C. Pomiar zasolenia był utrudniony z racji małej wielkości inkluzji wodnych, ale uzyskane wyniki odpowiadają wartościom około 8% wag. NaCl. Temperatury homogenizacji dla inkluzji węglowodorów grupują się w trzech przedziałach wartości, ogólnie w obrębie 74-110 C. Przeprowadzona została próba wspólnej interpretacji izochorycznej obu typów inkluzji fluidalnych. Izochory uzyskane na podstawie przeprowadzonych prac badawczych i założeń metodycznych, przecinają się w punkcie o współrzędnych temperatury i ciśnienia, które interpretować można jako przybliżenie warunków uwięzienia tych fluidów w spoiwie kwarcowym. Jest to pierwsza próba przeprowadzenia tego typu interpretacji na obszarze Żarnowca i w obrębie basenu kambryjskiego, przy czym z racji niewielkiej liczebności współwystępujących inkluzji pożądane są dalsze badania w celu sprawdzenia wyników i polepszenia ich wiarygodności.