The lead and zinc ore deposits in the vicinity of Chrzanów
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Abstract:
The Zn-Pb ore deposit in the vicinity of Chrzanow consists of about 90 ore bodies of varied size. Mineralization occurs within the Middle Triassic dolomites in form of bed-shape sphalerite concentrations, replacing the host rocks and various aggregates of sphalerite and galena, infilling their voids. Ore distribution within the rock massif is determined by lithology of the Triassic deposits and by tectonic structures but also an influence of paleohydrological factor on are body origin is assumed. The effect of these factors operation is the ore concentration in some beds, named “ore horizons” and resulted the tabular form of ore bodies and their position concordant with bedding of surrounding rocks. The influence of tectonic factor also determinates internal variability of are bodies, The described here deposit development could be assumed as typical for a part of the Silesian-Cracow ore province, located within the Upper Silesian Trough.Keywords:
Massif
Lithology
Polymetallic replacement deposit
Prospecting
Bedding
Ore genesis
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Cataclastic rock
Breccia
Mesothermal
Magmatic water
Stockwork
Protolith
Ore genesis
Dike
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Background . The Novo-Uchaly copper-zinc VMS deposit in the Southern Urals (54°10΄54˝N and 59°20΄45˝E) is represented by a steeply dipping lens of Eifelian volcanics (rhyodacites and basalts), which are crumpled into a strongly compressed anticlinal fold. The ore deposit is blind and localised at the convergence of felsic (bottom) and mafic (top) rocks. The deposit is located at depths of 550 m (in the northern part) and 1050 m (in the southern part). The deposit thickness reaches 186 m. The length along the strike and along the dip equals 1250 m and 900 m, respectively. The ore body is intruded by gabbro-diorite and gabbro-diabase dikes. The main ore minerals are pyrite, sphalerite and chalcopyrite, as well as non-metallic minerals, such as quartz, barite and calcite. Unlike most of the Ural VMS deposits, this deposit is the zinc subtype (Zn >> Cu). The ores are predominantly massive and solid sulphide, being banded or brecciated in some parts. The main elements extracted are copper, zinc and sulphur, but gold, silver, cadmium, indium, cobalt, nickel, selenium and tellurium are also obtained. Aim . To clarify the morphology of the ore deposit, to study the ore mineral composition of the upper horizons of its northern part and to determine the underlying reasons for the complex lenticular structure of the sulphide reserve. Materials and methods . In the period 2017—2019, employees of the Institute of Ore Deposits, Petrography, Mineralogy and Biochemistry of the Russian Academy of Sciences (IGEM RAS) together with geologists of the Uchaly Mining and Processing Plant carried out a geological and mineralogical mapping of the deposit in the course of exploration works. Results . The ore contours and mineral composition of the northern part of the ore body were significantly clarified. A series of dikes of variable morphology was identified. A comparison was made of the results with current theories about the structure of the ore deposit. Detailed geological sections were determined and illustrate the complex lenticular structure of the ore deposit complicated by pinch and swell areas. The deposit was formed by processes of dynamic metamorphism. Conclusion . The geological and mineralogical structure of the deposit determined in the study enabled us to propose a schematic reconstruction of the conditions leading to the formation of its folded structure. The findings will help to re-assess the reserves and improve the system of operational exploration and delineation.
Polymetallic replacement deposit
Diorite
Felsic
Bornite
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Deposits of copper and zinc at Johnson, Arizona, occur in metamorphosed Paleozoic limestone near a quartz monzonite stock probably of late Cretaceous or early Tertiary age. The metallic mineralization was preceded by a stage of thermal metamorphism during which pure carbonate beds were recrystallized and impure carbonate beds were altered to garnet, diopside, and other contact-metamorphic silicates. Silicate formation, which involved loss of carbon dioxide, was accompanied by shrinkage that reached a maximum of 30 percent. In the following metallic mineralization, the metamorphic rock was replaced by copper and zinc sulfides associated with some chlorite and other relatively low temperature gangue minerals. Nearly all the ore occurs as tabular masses and chimneys in particular beds in the Abrigo formation of Cambrian age.The recently discovered Moore ore body is a lenticular mass in the Abrigo formation about 400 feet below the present surface. Faulted and fractured limestone and dolomite beds of the Escabrosa limestone (Mississippian) crop out above the ore body. Local copper stains, which are abundant in the district, and a greater-than-average amount of faulting are somewhat meager geological evidence for the presence of ore.To determine if there was any geochemical evidence for the proximity of ore, outcrops of the Escabrosa limestone and part of the underlying Martin formation (Devonian), the fault zones, and soils were sampled both over the ore and in the adjoining area, and the samples were analyzed for traces of the ore metals.The ore-metal content varies widely and is determined in part by stratigraphy and structure. Large areas abnormally high in ore metal are indicated by samples from the fault zones. Composite chip samples of the rock between the faults show small high areas within the high areas indicated by the fault-zone samples. One of the chip-sample anomalies is over the Moore ore body but displaced somewhat to one side of the center of the body. Two other anomalies are over unexplored ground some distance from the ore body. Soil samples collected on low ridges, where contamination is unlikely, show the same general anomalies as the rock samples.A genetic relationship between the Moore ore body and the nearby geochemical anomaly is suggested by its proximity and by the presence in the anomaly area of fault zones which carry concentrations of ore metal and project toward the ore. Diamond drilling and further geochemical studies are suggested as possible means of checking the inferred relationship. At present, geochemical studies give promise of becoming a valuable adjunct of geology in prospecting the Johnson district and similar areas elsewhere.
Prospecting
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At the Boleslaw mine the Zn-Pb ore bodies occur within the Middle Triassic (ore-bearing) and the Lower Triassic dolomites. It is an exceptional feature in the Silesian-Cracow ore district. The Roethian ore bodies are small and irregular, formed of rich ore surrounded by the aureole of dispersed sulfides, monheimite and barite. They lie preferably in synsedimentary breccias, solution breccias (often superimposed on the previous ones) and collapse breccias. Mineralogical composition of the arc is simple: sphaleritc-galena-marcasite with abundant colloidal varieties (mostly brunckite) precipitated during four stages of mineralization at 95-115oC. The ore bodies were formed partly by the replacement, partly by the open space filling, formed due to hydrothermal karstification of the host dolomites
Breccia
Marcasite
Ore genesis
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Breccia
Ore genesis
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The orebody lies in a dolomitized zone at the base of a limestone bed in a series of lower Cambrian sediments. The sediments are isoclinally folded and the ore is in the upper limb of the fold. The ore minerals are pale-colored iron-free sphalerite, and galena. Silver is virtually absent but cadmium is associated with the sphalerite. Pyrite and some pyrrhotite are present.The major control of ore deposition has been open and overturned folding. In places the folding is accompanied by brecciation and minor pre-mineral faulting. The ore occurs in the troughs and on the limbs of the folds. The sediments have been intruded by granite, which has formed a tactite or skarn zone beneath the ore. This zone is in places overfolded and high-grade ore occurs around the nose and within the overfold.The deposit is typical of a type of world-wide distribution normally far removed from any igneous masses. The adjacent granite is not necessarily the source of the ore solutions.Trace element analyses show considerable zinc in the overlying argillite and this is considered to be a possible source of the mineralization that has been concentrated in a favorable zone in the limestone by meteoric water.
Lead (geology)
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The Journal of the Japanese Association of Mineralogists Petrologists and Economic Geologists (1959)
The copper deposit of the Hamanaka area is located in the southern part of East Hokkaido. This ore deposit was discovered in the outer zone of Kuril arc, and is considered to be originated by the igneous activies of alkaline basic rocks. It must be a remarkable thing. The geological complex developed in the neighbourhood of this ore deposit are the Hamanaka formation with alkaline rocks of upper Cretaceous and some deposits of Quaternary age. The ore deposit is generally observed as massive or stratified bodies in the alternation member of black mudstone and tuffaceous sandstone, and these ore bodies consist of yellowish massive ore and dark gray Kuroko-like ore. The important minerals are pyrite and chalcopyrite, with minor quantities of sphalerite, galena, marcasite, quartz, and rarely calcite and barite. After all, this ore deposit is considered to be a cupriferous iron sulfide deposit from its geological situation, occurrence of ore bodies, and its distinctive character of ore. And it is an ore deposit that have been replaced by hydrothermal solutions.
Marcasite
Polymetallic replacement deposit
Ore genesis
Hypogene
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The Journal of the Japanese Association of Mineralogists Petrologists and Economic Geologists (1964)
In the Miocene formations distributed in the east and the north of the Iide mountainland there occur many black-ore type deposits which are mainly composed of gypsum containing pyrite, chalcopyrite, galena, sphalerite, anhydrite, barite and calcite. These ore-deposits can be found in several formations and they clearly cross the bedding plane. Moreover, the structures of mother rocks are sometimes left in the massive alabaster ore body. In the rhyolite covering the upper part of the deposits, network ore-vein and impregnated ore can sometimes be found. From these facts it is considered that the gypsum ore deposits in this area may be formed by the hydrothermal solution genetically related to the igneous action which occurred after the country rocks had been formed.
Anhydrite
Supergene (geology)
Ore genesis
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Lithology
Prospecting
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The lead-zinc deposits occur in the margin carbonate rocks, formed from low temperature hydrothermal. The deposits are located in three paleoaquifer that consist of sandstone and overlying carbonate rocks. Ore-bodies are all found in the breccia-rocks which contain lead-zinc minerals, and the ore-bodies and breccia-rocks are of complex shape, and occurred as no regular. The rich bodies are often found in the middle of breccia-rock. The major factor affecting the shape of ore-body are the interface between sandstone and carbonate rocks, faults, alterated by low temperature hydrothermal, and the property of wall-rocks. The lead-zinc, copper and iron mineralizations in this area are all in one ore-forming system. The wall-rock of zinc(lead) deposits mostly is carbonate rocks, that of copper is amaranth sandstone and carbonate rocks, and that of lead is grey sandstone. The studies on the ore deposits geology show that there are enormous exploring foreground in this area and in the deep of deposits.
Breccia
Wall rock
Carbonate minerals
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