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Mineralizacja Cu-Ag w utworach cechsztynu : zarys historii poszukiwań i badań prowadzonych przez PIG

Oszczepalski Sławomir, Chmielewski Andrzej

Przegląd Geologiczny

2019

Vol. 67, nr 7

587--593

Discovered by J. Wyżykowski in 1957, the Lubin-Sieroszowice deposit is a classic representative of the giant Kupferschiefer-type Cu-Ag stratabound deposit. Its disclosure and documentation was provided by the research work of many geologists of the Polish Geological Institute and many other institutions. During the period of 60 years, the mining and metallurgical industry has been developed to such extent that Poland is now among the world’s major producers of copper and silver. This discovery marked the beginning of the recognition of the S Oszczepalski A Chmielewski deposit and gave rise to further exploration for prospective areas elsewhere in SW Poland. Detailed studies of Rote Fäule alteration have shown that redox boundary is the principal guide to exploration. Later studies of numerous boreholes allowed the researchers to distinguish 38 prospective areas on the reductive side of the redox border and Au-Pt-Pd enrichments in oxidized rocks. The Kupferschiefer-type deposits were long considered classic examples of syngenetic mineralization. However, the close relationship between the occurrence of Cu-Ag orebodies and oxidized altered areas, and ore zones progressively transgressive to bedding relative to the Rote Fäule front indicates that these deposits were formed as a result of fluid-rock interaction caused by ascending migration of moderately low-temperature basinal chloride brinesfrom the underlying red beds within reasonable periods of diagenesis of the reduced hosts. The hematitization was the result of an influx of oxidizing solutions across the centers of oxidized areas that acted as the innermost parts of the telescoped Rote Fäule/ore systems. The early-to-late diagenetic timing of mineralization is constrained by paleomagnetic age of hematite, K-Ar dating of authigenic illite and Re-Os dating of Cu sulfides. The fluid circulation was due to paleogeothermal activity, compactive expulsion, recirculation and (or) seismic movements, corresponding to intracontinental Permian-Triassic rifting. Due to the depletion of shallow resources, extensive deep exploration drilling is required to verify the resource potential in concession prospects existing around the documented deposits. The long-term challenges related to the substantial copper and silver scarcity problems in the future demand for overcoming geological barriers (considerable depths, high overburden pressure, elevated temperature, gas hazard) require the use of innovative technology, creation of favorable investment conditions and preparation of a long-term raw materials strategy.

Modelowanie 3D złóż Cu-Ag LGOM dla prognozowania jakości urobku

Mucha J., Wasilewska-Błaszczyk M.

Przegląd Górniczy

2013

T. 69, nr 7

83--92

Podano przykłady modelowania 3D fragmentu złoża Cu-Ag Lubin z zastosowaniem geostatystycznej procedury krigingu zwyczajnego. Sformułowano wstępne warunki wiarygodnego modelowania jakości złóż Cu-Ag. Zwrócono uwagę na konieczność oceny rodzaju i wielkości błędów opróbowania i weryfikacji poprawności rejestracji wyników opróbowań w bazach danych. Do badania błędów opróbowania zalecono stosowanie metod statystycznych dla danych sparowanych oraz formuły Gy. Przedstawiono podstawowe kroki geostatystycznego algorytmu modelowania złoża wraz z trudnościami ich realizacji: regularyzację próbek cząstkowych, wyznaczanie powierzchni granicznych między seriami litologicznymi, zasady opisu zmienności zawartości Cu i Ag za pomocą semiwariogramów, dobór rozmiarów komórek elementarnych i elipsoidy wyszukiwania danych, szacowanie zawartości Cu i Ag w komórkach elementarnych przy zastosowaniu krigingu zwyczajnego, sposób wyznaczania złoża bilansowego oparty na modelu 3D. Stwierdzono, że zasięg modelowania 3D dla potrzeb prognozy jakości urobku nie powinien w zasadzie wykraczać poza przestrzeń wyznaczoną przez skrajne punkty opróbowania. Jedynie w wyjątkowych sytuacjach można ekstrapolować model ale na odległość nie większą niż 25÷50 m od linii skrajnych punktów opróbowania.

Examples of 3D modeling of a fragment of Lubin Cu-Ag deposit with the application of geostatistical ordinary kriging procedure were presented. Preliminary conditions of reliable modelling of Cu-Ag deposit quality were formulated. Particular attention was paid to the necessity of assessment of the type and errors’ magnitudes of sampling as well as to the verification of correctness of sampling results recorded in a database. In order to effectively analyze the errors, statistical methods for paired data and Gy formula were recommended. Basic steps of the geostatistical algorithm of deposit modelling and the difficulties of their execution were indicated: regularization of partial samples, determination of boundary surface between the lithological series, principles of describing the variability of Cu and Ag contents by means of semivariograms, selection of dimensions of the elementary cells (voxels) and data search ellipsoid, estimation of Cu and Ag contents in elementary cells with the application of ordinary kriging procedure, method of defining the boundary of economic deposit on the basis of a 3D model. It was stated that the range of 3D modelling for the purposes of the prediction of the output quality may not exceed the extreme sample points. It is possible to extrapolate the model in some extraordinary cases, however, only at a distance between 25 and 50 m from the extreme sample points line.