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Abstract

The presented article describes the relationship between lithological and facies development of reservoir rocks in the area of the roof elevation of the Weissliegend sandstones, with a particular emphasis on the influence of elevation on the occurrence of low mineralization zones in the deposit area. To illustrate the variability of the deposit parameters, closely related to the facies and lithological conditions of the host rocks, three-dimensional lithological and geochemical models for two research areas were developed using the geostatistical methods and based on field observations and the sampling of the deposit. The research area includes parts of the Northern Elevation of Rudna and the surrounding depressions within the boundaries of the Sieroszowice and Rudna deposits. Based on cross-sections of the 3D models, a different deposit formation in the roof elevation area of sandstone formations has been characterized; the lithological profile is defined as „atypical” due to the absence of a copper-bearing shale series, the most characteristic layer for copper ore deposits in the Fore -Sudetic monocline. Large variations in the shape of the deposit and the irregular boundaries of both balance mineralization and enclaves of gangue have been confirmed. The presence of large-scale enclaves of igneous rock in the entire profile of the Lower Zechstein rocks (areas without the balance copper mineralization) and small areas of gangue (sandstone) enriched with anhydrite binders adjacent to the parts of balance deposit located in argillaceous sandstone has been revealed. The possibility of the occurrence of gangue, in the area of the roof elevation of the Weissliegend sandstones directly adjacent to the border with calcareous dolomite, and irregular gangue partings in sandstone formations in the balance deposit was indicated. In addition, small areas of strong enrichment in Cu sulphides were observed in the contact zones between sulphate and clay binders in the Weissliegend sandstone series.
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Abstract

In 2011, the Miedzi Copper Corporation (MCC) initiated its exploration program involving deep Cu-Ag deposits in the Fore-Sudetic Monocline. A very vast study area was adopted, along with the use of a wide range of research instruments. In the years 2011–2013 the exploration of MCC involved 21 concession areas. The location of concessions for exploration as well as exploration and prospecting was based on the known prognostic and hypothetical areas with confirmed contact of the Rote Fäule facies with the reduced facies, placed in the proximity of the Zechstein elevations. In 2012 and 2013, historical boreholes drilled mainly by the petroleum industry were logged, and in cases where the preservation of rock material allowed, samples were collected for chemical analyses. Moreover, a wide range of specialized examinations was performed, involving organic chemistry, coal macerals, vitrinite reflectance and petrography, with a particular emphasis on the Rock Eval method. The latter allows the presence of the so-called strong Rote Fäule associated with the presence of the richest mineralized horizons to be established. It was equally important for the purpose of exploration to perform the reprocessing of geophysical data using the innovative method of effective reflection coefficients. This allows transforming a conventional seismic image into an impulse form of seismic records, meaning a temporal sequence of coefficients, whose sections can be correlated with the logs of historical boreholes in order to trace the course of lithological series. This method provides a much higher accuracy for determining structural elements crucial for exploration than before, suggesting the presence of various tectonic phenomena important for mineralization. As a result, a more detailed mineralization distribution model was obtained and the so-called sweet spots were pinpointed, becoming an object of further drilling exploration. The number of active concessions was reduced to 6, which resulted largely not just from the absence of ore, but also from economic premises. The drilling program initiated in 2013 and still continued today allowed the discovery and preliminary documentation of three copper and silver deposits in the Fore-Sudetic Monocline. These are the Mozów and Sulmierzyce deposits, where the presence of prospective areas was previously recorded, as well as the Nowa Sól deposit, discovered in the so-called green field, where no ore exploration was previously conducted. At the current stage of identification, each of these deposits contains resources exceeding 5 million tons of equivalent copper, and the performed economic analyses indicate the viability of their extraction using the modern methods of shaft sinking, air conditioning and waste management.
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Abstract

The “Sulmierzyce-Odolanów” study area analyzed in the present paper constitutes an example of the presence of deep Zechstein metallic mineralization in the Fore-Sudetic Monocline. Unlike the shallow deposits which are being mined nowadays, these types of areas were not previously considered in terms of their possible extraction. However, in recent years, due to the development of modern mining technologies, this situation has changed and these areas have become prospective for the future documenting of mineral deposits. The threshold parameters delimiting an ore deposit, recommended for use when preparing geological documentation and not compulsory, have been established by the regulation of the Minister of Environment. In the case of stratabound Zechstein deposits they take the equivalent percentage and productivity of only two metals, i.e. copper, as the main useful component, and silver into account. This leads to the underestimation of the resources of ore which also contains other metals, including zinc and lead, which is particularly disadvantageous in the case of deep deposits, which from an economic standpoint, it is advisable to focus on their richest parts and to document, and in the future to extract all the useful metals. Also, the regulation of the Minister of Environment does not take into account the fluctuations of the market prices of metals over time, the impact of which on the equivalent content and productivity of these elements in the deposit is considerable. This paper presents the authors’ own formulas intended to calculate polymetallic equivalent content and productivity taking the share of four elements in the ore into account: copper, silver, zinc and lead. They also enable determining these values for arbitrarily selected time intervals and tracing their changes over time. Apart from the quality parameters it is also possible to calculate the value of mineral resources in the deposit expressed in American dollars per one square meter of its area for each selected time interval. The calculations used the results of chemical analyses of historical drill cores originating from the studied area. A total of 135 historical holes located within its boundaries were analyzed. Based on the obtained figures, the time-varying resources of the polymetallic equivalent (Cu-Ag-Zn-Pb) were estimated along with their market value expressed in American dollars for each year in the time interval of 2012–2016.
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