Relation of Permian Base Metal Occurrences to the Variscan Paleogeothermal Field of the Fore-Sudetic Monocline (Southwestern Poland)

Speczik, Stanisław

doi:10.1007/978-3-662-02538-3_2

Cited by 4 publications

(2 citation statements)

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“…Thermal anomalies produced by this event may have played a role in the mineralizing process (Jowett 1986). From vitrinite reflectance and fluid inclusion data, the geothermal gradient is estimated at 40 to 85 C/km during early Permian (Burzewski 1983;Speczik 1988). Because of temporally decreasing geothermal gradient, the increasing burial depth of the Permian rocks during the Mesozoic did not result in significantly higher maximum burial temperatures (Majorowicz 1971).…”

Section: Geological Setting and Sample Descriptionmentioning

confidence: 98%

“…The adjacent oregrade mineralization in the order Cu/Ag±Pb±Zn is discordant to the bedding in the basal Zechstein sediments and grades into barren, pyritic Kupferschiefer distant to the Rote Fäule. Based on the relation of ore-grade mineralization to Rote Fäule and on geothermal reconstructions, copper enrichment is thought to have resulted from the migration of hot, oxidizing brines from the Rotliegendes strata toward the preZechstein paleohighs into shales rich in organic carbon (Majorowicz 1971;Rentzsch 1974;Rydzewski 1978;Burzewski 1983;Speczik 1988;Oszczepalski 1989).…”

Section: Introductionmentioning

confidence: 98%

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Geochemical and isotopic composition of organic matter in the Kupferschiefer of the Polish Zechstein basin: relation to maturity and base metal mineralization

Bechtel¹,

Gratzer²,

Püttmann

et al. 2000

International Journal of Earth Sciences

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Drill core samples from the Kupferschiefer of Poland were collected throughout the Zechstein basin. The samples included oxidized Kupferschiefer from Rote Fäule zones, adjacent Cu-mineralized Kupferschiefer of southwestern Poland, and drill cores from the central and northern parts of the Zechstein basin. The Kupferschiefer samples reflect differences in base metal mineralization and in burial depth (630±5067 m). The organic matter of the Kupferschiefer is characterized by Rock-Eval and GC-MS analyses. Classification of kerogen by hydrogen and oxygen indices (HI, OI), correlations of T max vs the present depth of the Kupferschiefer, soluble organic matter (SOM) yields, and relative proportions of saturated and aromatic hydrocarbons of the SOM provide evidence for an oxidative alteration of organic matter in highly mineralized Kupferschiefer samples near the Rote Fäule zones. This is confirmed by differences in the composition of the saturated and aromatic hydrocarbon fractions of the soluble organic matter: Saturated hydrocarbons from Rote Fäule samples are dominated by short-chain n-alkanes and higher abundances of pristane and phytane relative to heptadecane (n-C17) and octadecane (n-C18), respectively, compared with samples more distant to the Rote Fäule zone. Compositional changes of the aromatic hydrocarbon fractions with decreasing distance to that zone are characterized by the occurrence of polycyclic aromatic hydrocarbons and elevated ratios of phenanthrene to methylphenanthrenes that are attributed to demethylation reactions and resulted in a decrease of the methylphenanthrene index (MPI 1). Kupferschiefer samples from the barren zone of the Polish Basin do not show these alteration patterns. The observed variations in organic matter composition with burial depth are consistent with changes due to increasing thermal maturation. Maturity assessment is achieved from MPI 1 and the methyldibenzothiophene ratio (MDR). From the relationship between the maturity of organic matter in terms of vitrinite reflectance values and depth of the Kupferschiefer strata, a continuous increase in reflectance of vitrinite is obtained within the Polish Basin. The alteration pattern of organic matter related to base metal mineralization of the Kupferschiefer corresponds to changes in the isotopic composition of organic carbon and calcite. Kerogen within, or close to, Rote Fäule zone is enriched in 13 C caused by the preferential release of isotopically light organic compounds through progressive degradation of organic matter. The opposite tendency towards lower d 13 C and d 18 O values of calcite provides evidence for isotopic exchange between carbonate and the oxidizing, ore-bearing solutions and for organic matter remineralization. In contrast, organic matter and calcite from the Kupferschiefer do not show regular trends in d 13 C with increasing thermal maturation.

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Section: Geological Setting and Sample Descriptionmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 98%