Fore-Sudetic Monocline Research Articles

GEOCHEMICAL CHARACTERISTIC OF AG-BEARING MINERALS OCCURRING IN COPPER ORE DEPOSIT AT THE FORE-SUDETIC MONOCLINE

Silver is the most important associated element in the copper ore deposit of the Fore-Sudetic Monocline. Besides its own minerals, such as native silver, amalgams, stromeyerite, mackinstryite, jalpaite and Cu-Fe-Ag system sulphides, the silver occurs as isomorphic substitutions in copper minerals. The aim of this work included geochemical characterization of Ag-bearing minerals and correlation of the occurrence of Ag-enriched Cu sulphides with the areas of native silver and amalgam mineralization. Distribution of silver in the ore deposit distinctly correlates with Cu concentrations, and the areas of the strongest Cu mineralization are accompanied by high silver concentrations. Results of the scanning electron microscopy and electron microprobe analysis indicate that the Cu sulphides contain up to several wt.% Ag as isomorphic substitutions. Distribution of Ag in Cu sulfides does not show regularity, as demonstrated by wide diversity of Ag contents in various minerals, ranging from 0.0X to dozen wt.% Ag.

VARIABILITY OF ORE MINERALIZATION IN THE NORTH-WEST-TRENDING EXTENSIONOF THE LUBIN–SIEROSZOWICE DEPOSIT

The Polish Geological Institute – NRI has conducted investigations of the Kupferschiefer series since 1957, when the giant sediment-hosted stratiform Cu-Ag ore deposit was discovered in the central part of the Fore-Sudetic Monocline. Until 1991, a number of drilling programs were completed by PGI-NRI and later research has been focusing mainly on cooperation with oil and gas industry and their core material. Over the last few years, thanks to systematic examination of the drill holes located in the north-western extension, many prospective areas have been recognized and delineated. These prospects are located between Lubin-Sieroszowice deposit and the eastern part of the Zielona Góra oxidized field. In the Kożuchów area, the lower part of Zechstein copper-bearing series contain only relict sulphide mineralization accompanied by iron oxides while reduced rocks with metal sulphides occur in the uppermost part of Zechstein Limestone or at the base of Lower Anhydrite. Grochowice area, where reduced facies prevail in copper-bearing series, is characterized by the predomination of rich Cu-Ag mineralization proximaly to oxidized area. The western part of studied area is dominated by Cu-S type sulphides (chalcocite, digenite, covellite) whereas the eastern part is represented by Cu-Fe-S type minerals (bornite, chalcopyrite) with high galena and sphalerite concentrations. The spatial variability of sulphide mineralization with respect to the oxidized rocks indicates that Bytom Odrzański deposit extends in the north-west direction, continuing in the form of a copper belt along the eastern border of the oxidized area. An extensive deep exploration drilling program is implemented to verify the resource potential within predicted copper belt.

ORIGIN AND HAZARDS OF HYDROGEN SULPHIDE AND HIGH-PRESSURE NATURAL GAS IN DEPOSITS OF POLKOWICE-SIEROSZOWICE AND RUDNA COPPER ORE MINES: PRELIMINARY ISOTOPIC AND MINERALOGICAL STUDIES

Composition of natural gas from the Zechstein Limestone (Ca1) strata of Rudna mine has been compared with the natural gas from Carboniferous, Rotliegend strata of the Fore-Sudetic Monocline and with gas generated from the organic matter of the Main Dolomite during hydrous pyrolysis experiments. The gas from Rudna mine is characterized by the normal methane-ethane-propane isotopic system which indicates formation in one stage from a single source rock probably of the Carboniferous age containing kerogen of mixed II/III type. Generation of the hydrogen sulphide resulted from the microbial sulphate reduction processes of the basal anhydrite has been proven by mineralogical and isotopic 13C/12C analyses of 12 carbonate and 34S/35S analyses of 14 sulphate samples. These samples were collected in the mine at the depth of about 900–1200 m at temperature range of 35–45°C and two samples of carbonates were taken from one core.

GEOMICROBIOLOGY OF SUBSURFACE MINE OF THE FORE-SUDETIC MONOCLINE

The unique underground environment developed in the area of Fore-Sudetic Monocline as a result of mining activity. This environment is inhabited by bacteria, archaea and fungi. They are mainly lithobionts for which copper-bearing Kupferschiefer black shale is the source of carbon and energy as well as macro- and microelements. Among them, many interesting genera and species adapted to this unique environment were found. Particularly interesting are microbial communities that represent a variety of metabolic strategies: microorganisms using organic compounds (organoheterotrophs), utilizing only mineral compounds (chemolitoautotrophs), producing methane (methanogens) and degrading it (methanotrophs). Additionally, underground mines inhabit microorganisms resistant to heavy metals and high salinity. Microorganisms play an important role in the transformation of Kupferschiefer black shale, affecting its geochemical composition and physicochemical properties, and the groundwater chemistry. Microbial metabolic activity leads to biooxidation of fossil organic matter (including kerogen) and sulphide minerals. As a result of these processes a number of oxidized organic and inorganic compounds are formed. They are products of organic matter degradation, such as alcohols, organic acids, ketones and aldehydes as well as secondary inorganic compounds, including numerous biominerals (e.g. sulphates). Some of these compounds are mobilized to groundwater; some are immobilized in the form of sediments.

Pre- and Post-consolidated Sediment Deformations in the Transitional Terrigeneous Series PZt (Zechstein/Lower Buntsandstein)in the Grodziec Syncline, Sudetes: Process Interpretation and Regional Implications

In the Grodziec Syncline (Eastern part of the North-Sudetic Synclinorium) the uppermost Zechstein sediments are represented by mudstones and very fine grained sandstones, which smoothly continue into typical Buntsandstein deposits. These sediments belong to Transitional Terrigeneous Series (PZt), which uppermost part is developed as heterolithic tempestites. A zone abundant in pre- and post-consolidated sediment deformation structures was distinguished within heterolithic sediments. The pre-consolidated sediment deformation structures have numerous features of seismites, on the other hand post-consolidated deformation structures raise more doubts about their origin and require more future research. A zone of pre- and post-consolidated sediment deformation is an important correlation horizon for the Grodziec Syncline. Furthermore, such zone is also observed in the analogous deposits of the Fore-Sudetic Monocline in the Glogow–Rudna area.

Potential capacity of gas storage caverns in rock salt bedded deposits in Poland

The subject of this article is an estimation of the initial capacity of a gas storage cavern, depending on the thickness and the depth of a bedded salt deposit, and the cavern's capacity decrease in time due to its convergence. It was assumed that the relative rate of convergence depends on the depth, the range of the storage pressure and the cavern diameter to height ratio. The discussion will consider the shape of the cavern and the pressure range of natural gas storage. Also, potential locations in Poland for natural gas storage in bedded rock salt deposits in terms of geological and mining criteria are presented in this article. Based on Zechstein isopach maps, as well as maps of its top depth, potential storage capacity maps per unit area were developed. Presented examples will cover two potential regions i.e., bedded salt deposit in the Zatoka Gdańska region and Fore-Sudetic Monocline. These maps will be the basis for the analysis of the suitability of the bedded rock salt Zechstein deposit for natural gas storage.

Filtration of Components of Sieroszowice Mine Copper Ore Deposit Variogram Models by Means of Estimation Ordinary Kriging Technique

This paper presents the results of investigations into the spatial variation of the basic geological parameters of strategic mineral resources, i.e. the copper ore deposits in the Foresudetic Monocline in the Lubin-Sieroszowice area (SW part of Poland).The studies were based on data obtained by sampling the deposit with groove samples distributed mostly uniformly (at a spacing of 15÷20 m) over the area of Sieroszowice mine post-mining block S-1. The studies concerned the Cu grade in and the thickness of the (recoverable) deposit concentrated in Weissliegend sandstones, Zechstein copper-bearing shales, calcareous-dolomitic formations and moreover the accumulation (quantity) of the deposit.An evaluation of the basic statistics, an analysis of the distribution histograms and an examination of the correlation r between the values of the deposit parameters are presented against the geological structure of the copper ore deposit in block S-1. Isotropic and relative semivariograms of the deposit parameters were calculated. The shapes of the isotropic semivariograms were approximated using composite theoretical (geostatistical) models consisting of a cubic model and a spherical model, combined with the nugget effect.Estimated averages Z* and estimation standard deviation σk for the investigated deposit parameters in the centres of the elementary grid blocks were estimated taking into account the determined parameter values of the theoretical isotropic semivariogram models. An attempt was undertaken to successively filter off the individual components, making up the composite semivariogram models of the copper ore deposit parameters, using the ordinary (block) kriging technique. Nugget effect C0 and the cubic model, the spherical model and the sum of the cubic model and the spherical model were filtered off.As a result of the estimations a very detailed picture of the variation in the values of the basic deposit parameters within block S-1 was obtained, which was then presented on various raster maps of the surface distributions of averages Z* (together with the corresponding values of estimation standard deviation σk). The maps show the mineralization of the deposit rocks with copper compounds, broken down into the particular components corresponding to the adopted models and to nugget effect C0.Thanks to the filtering the mutual shares of the different model components in overall variation C of the considered parameters were identified and the scale and extent of both short- and longterm variation were assessed. Zones of elevated or reduced copper concentrations and subareas varying in the width of the mineralized lithological profile of the deposit series, i.e. in the thickness of the mineralized deposit rocks, and also of various accumulations (quantity) were identified within block S-1.

Perspectives of using the geological subsurface for hydrogen storage in Poland

The increasing share of renewable energy in electricity production in Poland is part of the growing interest in the hydrogen underground storage. In the search for suitable locations for this purpose it is useful to have the knowledge on the geological structures for underground storage of gases, including carbon dioxide.This article presents the possibilities of geological storage of hydrogen in underground geological structures in Poland (salt caverns, depleted oil and natural gas fields, and deeply seated aquifers). The study results confirm that there are favorable conditions to achieve this goal – in many areas of Poland it is possible to realize some type of hydrogen underground storage.The paper presents prospective areas for different options of hydrogen underground storage at specified conditions. For locations in salt caverns, rock salt deposits from the following areas are proposed: Łeba Elevation, Fore-Sudetic Monocline, Carpathian Foredeep, and salt stocks in the Polish Lowlands. For depleted oil and natural gas fields in the Polish Lowlands, Carpathians and Carpathian Foredeep, a few tens of fields are indicated, most of them are natural gas deposits. In the Polish Lowlands, several anticlinal structures in the Lower Cretaceous and Lower Jurassic formations have been selected. These pre-designated locations may be the basis for further work and detailed considerations in order to find the best and most appropriate locations intended for hydrogen underground storage.

Origin of placer gold and other heavy minerals from fluvial Cenozoic sediments in close proximity to Rote Fäule-related Au mineralisation in the North Sudetic Trough, SW Poland

Detailed morphological and geochemical studies of placer gold grains and other heavy minerals from Cenozoic fluvial clastic sediments in the area of the Zimnik Creek drainage basin (North Sudetic Trough, Lower Silesia) allowed the description of their specific features: shape and morphology, flatness index, internal textural features and chemical composition of the gold grains. It enables an estimation of the distance from the source area and determination of the source of the ore mineralisation, along with establishing the feeder areas for placer mineralisation including Rote Faule-related gold hosted by Rotliegend-Zechstein transitional sediments. The comparison of the heavy mineral contents of placer grains from the Zimnik Creek drainage basin makes it possible to identify the area of origin for the gold particles. The crystalline Au-Ag-Pd-Hg (polymetallic) alloy grains of fluvial gold are assumed to come from the transitional sediments between the Rotliegend and the Zechstein in the North Sudetic Basin. The morphological and geochemical features of the polymetallic grains strongly suggest that the grains from the upper course of the Zimnik Creek valley sediments represent what has eroded from the local gold mineralisation and this mineralisation is probably in the vicinity of the upstream sampling site. The bimodal chemical composition of the Au-Ag-Pd-Hg alloy grains with electrum and medium-Ag grains (<15 wt.% Ag) found in the study area is typical of the Rote Faule and Kupferschiefer-related gold mineralisation on the southern side of the North Sudetic Trough and the Sieroszowice-Polkowice copper mining district of the Fore-Sudetic Monocline. The study of the Ag contents of placer grains from the Zimnik Creek drainage basin highlights the contrast between the placer gold grains derived from Paleozoic orogenic gold mineralisation in the Sudetes (typically simple Au-Ag alloys containing between 5 and 20 wt.% of Ag) and the one formed by the oxidizing chloride hydrothermal systems. The grains identified in this manner as originating from the oxidizing hydrothermal system of the transitional zone can be distinguished from the placer gold derived from other styles of mineralisation, which are not Rote Faule-related. It is particularly important considering the ongoing reconnaissance exploration in the North Sudetic Trough (SW Poland), which employs gold grain analyses as a prospecting tool for the detection of potentially economic primary gold mineralisation.

The influence of variability of calculation grids on the results of numerical modeling of geothermal doublets - an example from the Choszczno area, north-western Poland

The numerical modeling enables us to reduce the risk related to the selection of best localization of wells. Moreover, at the stage of production, modeling is a suitable tool for optimization of well operational parameters, which guarantees the long life of doublets. The thorough selection of software together with relevant methodology applied to generation of numerical models significantly improve the quality of obtained results. In the following paper, we discuss the impact of density of calculation grid on the results of geothermal doublet simulation with the TOUGH2 code, which applies the finite-difference method. The study area is located between the Szczecin Trough and the Fore-sudetic Monocline, where the Choszczno IG-1 well has been completed. Our research was divided into the two stages. At the first stage, we examined the changes of density of polygon calculation grids used in computations of operational parameters of geothermal doublets. At the second stage, we analyzed the influence of distance between the production and the injection wells on variability in time of operational parameters. The results demonstrated that in both studied cases, the largest differences occurred in pressures measured in production and injection wells whereas the differences in temperatures were less pronounced.

Prospective copper resources in Poland

Abstract The most significant copper reserves in Poland are confined to sediment-hosted stratiform Kupferschiefer-type deposits that occur at the Zechstein/Rotliegendes transition in the Fore-Sudetic Monocline and North-Sudetic Trough. Gradual depletion of shallow reserves results in exploitation of deeper beds. Latest studies of numerous drill hole cores strongly indicate that the Kupferschiefer series in SW Poland (outside the Lubin-Sieroszowice Copper District) contains a very large volume of prognostic, prospective and hypothetical resources. 38 prospects have been delineated (including 6 areas with prognostic resources, 4 with prospective resources, and 28 areas with hypothetical resources). Among the prospective areas, particular attention is paid to the areas adjacent to the existing mines of Lubin-Sieroszowice copper district, with prognostic resources (Białołęka, Grochowice, Kulów, Luboszyce). Also the areas: Nowiny, Żarków and Mirków are interesting due to accessible depths, Sulmierzyce and Janowo areas due to considerable resources and reasonable depth, and Mozów area – because of high Cu-Ag grading mineralized body with credible continuation to south east through Jany and Grochowice prospects, towards the Lubin-Sieroszowice mining district. It can be estimated that approximately 179 million tons Cu and 346 thousand tons Ag concentrated as potential resources in prospects of SW Poland for future mining, which will be possible, when geological and technological barriers (depth, temperature, oil and gas) will meet economic trends in the world market. Expected progress in underground mining at depths exceeding 1500 m (a depth limit for economic categories) will make this approach effective and technically possible. Additional six prospective areas have been delineated in the contact zone between Upper Silesia and Małopolska blocks, where porphyry-type Mo-Cu-W mineralization (locally with skarns) occurs within porphyry/granitoid rocks and Ediacaran, Ordovician, Silurian, Devonian and Carboniferous metasediments and other sedimentary formations. It should be noted, however, that irregular network of examined drill holes tended to simplify the ranges of prospects and to overestimate resource evaluation. Extensive deep exploration drilling is required to verify resource potential of granted and applied exploration licenses in several targets. The long-term challenges require new solutions for mining industry of the future and industrial market within the EU, to enable the reindustrialization of Europe.

New Methods for Modeling Laterolog Resistivity Corrections

The paper presents methods for laterolog response modeling. In Coulomb’s charges method, Laplace’s equation is solved for the electric field distribution in rock medium with internal boundaries between different resistivity layers. There, the boundary problem is reduced to Fred-holm integral equation of the second kind. The second method uses a finite element array to model apparent resistivity from laterolog. The task is treated as DC problem and the Laplace equation is solved numerically. The presented methods were applied to borehole data covering a typical stratigraphie section of the Fore-Sudetic Monocline in southwestern Poland. Apparent resistivity was calculated using the Coulomb’s charges method and alternatively modeled using a finite element method which gave similar results. Then, a series of linear corrections for borehole, shoulder bed, and filtration effects for apparent resistivity obtained by the Coulomb’s charges method demonstrated the feasibility of calculating true resistivity of virgin and invaded zones. The proposed methods provide a flexible solution in modeling which can be adapted to other logs.

How to localize an Underground Gas Storage (UGS) in a salt structure of the Fore-Sudetic Monocline in light of its geomechanical properties

Work realized within statutory research program of Faculty of Drilling, Oil and Gas, No. 11.11.190.565

Application of turning bands technique to simulate values of copper ore deposit parameters in Rudna mine (Lubin-Sieroszowice region in SW part of Poland)

ABSTRACTThe turning bands simulation is a valuable and highly useful tool in solving various geological-mining, environmental and geological-engineering problems when it is essential to determine the uncertainty of the estimates of simulated values Zs (realizations) and assess the risk. This paper presents an investigative methodology and the results of calculations connected with the use of conditional turning bands simulation and bundled indicator kriging, making it possible to analyse the risk at different levels of uncertainty in the solution of optimization of the exploitation problems encountered in the mining of the polymetallic copper ore deposits in the Lubin-Sieroszowice region (Foresudetic monocline, the SW part of Poland). Examples of the evaluation of simulated values Zs and probability P average values Z* of the deposit parameters within the block located in the Rudna Mine (the block R-3) area are provided.

Structural and Parametric Models of the Załęcze and Żuchlów Gas Field Region, Fore-Sudetic Monocline, Poland – An Example of a General Static Modeling Workflow in Mature Petroleum Areas for CCS, EGR or EOR Purposes

Zalecze and Żuchlow are strongly depleted natural gas fields in aeolian sandstones of the Rotliegend, located in the central part of the Fore-Sudetic Monocline. A set of three static 3D models was generated to check the possibility of CO2 injection for Enhanced Gas Recovery (EGR) and to check the safety of storage by means of geomechanical modeling: one regional model (ZZA) and two local models – the first for Zalecze (ZA) gas field and the second for Żuchlow (ZU) gas field. The regional model is composed of 12 stratigraphic complexes (zones) from the base of the Rotliegend to the ground surface. The local models comprise only the three lowermost complexes: fluvial deposits of the Rotliegend, aeolian sandstones of the Rotliegend (Reservoir I) and basal Zechstein limestone, Ca1. The key elements of the modeling procedure include: Quality Control (QC) of the data, interpretation of missing parameters necessary for static modeling and their integration within a geomodel. The processing workflow was elaborated to produce convergent regional and local models. The regional static model is a framework for a regional geomechanical model. The local models are the basis for dynamic simulations and local geomechanical modeling. The presented workflow could be used with some changes for geomodeling of many mature gas and oil fields.

A characterisation of the geothermal potential of the Muschelkalk deposits’ location, with the prospective of its utilization in balneology and recreation (southern Poland)

Analysis of geothermal potential of the Muschelkalk deposits was carried out from the point of view of utilising hot groundwater in balneology and recreation. As a result of a number of analytical studies, the area situated in the southern part of the Polish Lowland was selected as one of prospective areas for the location of geothermal intakes. This area encompasses a southern part of the Fore-Sudetic Monocline, a southern part of the Łodź Trough, and a small section of the Miechowska Trough. The deposits are buried at depths of between 500 m b.s.l and 1500 m b.s.l., their thicknesses are from 100 m to 300 m, the temperature at the top in most cases is about 30 - 50 °C, TDS in most cases does not exceed 60 g/dm³, mineralised water flood tide is from 0.4 m³/h to 13.8 m³/h, porosity is between 9 % and 23 %, and permeability is from 25 mD to 340 mD. As a result of the analyses, the most favourable conditions for development of balneotherapy and recreation in the Muschelkalk deposits in the three locations of the selected area were found to be where the boreholes Trzebnica IG- 1 (first area), Wierzchlas 3, Rzeki IG- 1 (second area), and Trzonow 2 (third area), were located.

Numerical Simulations of Enhanced Gas Recovery at the Załęcze Gas Field in Poland Confirm High CO2Storage Capacity and Mechanical Integrity

Natural gas from the Zalecze gas field located in the Fore-Sudetic Monocline of the Southern Permian Basin has been produced since November 1973, and continuous gas production led to a decrease in the initial reservoir pressure from 151 bar to about 22 bar until 2010. We investigated a prospective enhanced gas recovery operation at the Zalecze gas field by coupled numerical hydro-mechanical simulations to account for the CO 2 storage capacity, trapping efficiency and mechanical integrity of the reservoir, caprock and regional faults. Dynamic flow simulations carried out indicate a CO 2 storage capacity of 106.6 Mt with a trapping efficiency of about 43% (45.8 Mt CO 2 ) established after 500 years of simulation. Two independent strategies on the assessment of mechanical integrity were followed by two different modeling groups resulting in the implementation of field-to regional-scale hydro-mechanical simulation models. The simulation results based on application of different constitutive laws for the lithological units show deviations of 31% to 93% for the calculated maximum vertical displacements at the reservoir top. Nevertheless, results of both simulation strategies indicate that fault reactivation generating potential leakage pathways from the reservoir to shallower units is very unlikely due to the low fault slip tendency (close to zero) in the Zechstein caprocks. Consequently, our simulation results also emphasise that the supra-and subsaliniferous fault systems at the Zalecze gas field are independent and very likely not hydraulically connected. Based on our simulation results derived from two independent modeling strategies with similar simulation results on fault and caprock integrity, we conclude that the investigated enhanced gas recovery scheme is feasible, with a negligibly low risk of relevant fault reactivation or formation fluid leakage through the Zechstein caprocks. © Ł. Klimkowski et al.

What can be learned from the K-Ar ages of illite from Rotliegend sandstones of the Fore-Sudetic Monocline, SW Poland?

The all available K-Ar data of authigenic illite from Rotliegend aeolian sandstones of the Fore-Sudetic Monocline, including the results from six samples examined in the present study, are reviewed in terms of their geological meaning, relation to diagenetic processes occurring in the sandstones, and implications for a petroleum system. The majority of ages fall in the range between 195 and 150 Ma, i.e. they correspond to Jurassic times. The results may be grouped in several time intervals, which are almost identical to those identified for Rotliegend sandstones of central and western Europe, and which are interpreted as pulses of intensive illite growth. The K-Ar data corroborate the long-held assumption that throughout the entire Southern Permian Basin Jurassic illite growth was triggered by the same, large-scale underlying processes, which manifested themselves in enhanced heat flow. These processes may also have caused the expulsion of hydrocarbons from source rocks.

Extracellular compounds produced by bacterial consortium promoting elements mobilization from polymetallic Kupferschiefer black shale (Fore-Sudetic Monocline, Poland)

Culture experiments employing Fe-deficient medium showed that a consortium of indigenous microorganisms isolated from Kupferschiefer black shale produced a mixture of extracellular compounds containing siderophores which could form complexes with a wide range of elements and were able to mediate element mobilization from polymetallic black shale. The mobilization of a diverse array of elements including a number of essential trace elements (Co, Cu, Mn, Mo, Zn) and toxic species (As) was shown. Since the bacteria used in this study were originally obtained from a subsurface copper deposit, these results highlight the potential importance of extracellular compounds in biogeochemical cycles of elements in underground environment and their ecological significance in promoting the uptake of essential trace metals and resistance to toxic elements.

Pore-lining sudoite in Rotliegend sandstones from the eastern part of the Southern Permian Basin

AbstractSudoite, an aluminium-rich di-trioctahedral chlorite, is known primarily from highgrade diagenetic/ low-temperature metamorphic Al-rich rocks and from hydrothermal deposits in Alrich terrains. This contribution reports a rare occurrence of pore-lining sudoite in Permian red beds from the eastern part of the Southern Permian Basin. Sudoite is a ubiquitous mineral in aeolian sandstones of the Eastern Erg, a large dune field buried in the subsurface of the Fore-Sudetic Monocline, SW Poland. Sudoite crystals are arranged in a honeycomb texture and often associated with high-porosity intervals. It is concluded that sudoite crystallized at the expense of early diagenetic dioctahedral smectite at a temperature lower than 180°C under the influence of hot, Mgrich and K-poor fluids, which migrated from a basement and/or deep part of the basin upward through permeable aeolian sandstones and mixed with colder pore solutions. Tosudite was a likely intermediate phase in the smectite to sudoite conversion.