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Chemostratygrafia (stratygrafia chemiczna) zajmuje się charakterystyką geochemiczną osadów, wykorzystując zawartość pierwiastków w skałach do korelacji sekwencji skał osadowych. W ostatnich latach ze względu na dostępność nowych technik analitycznych tego typu badania mają coraz większe zastosowanie w geologii górniczej. Chemostratygrafia korzysta z zapisu geochemicznego osadów i skał osadowych, czyli udziału pierwiastków głównych i śladowych lub izotopów do celów korelacyjnych i stanowi doskonałe narzędzie szczególnie w połączeniu z lito- bio- i magnetostratygrafią. Badania geochemiczne znajdują szerokie zastosowanie w identyfikacji i korelacji horyzontów morskich, szczególnie tworzących się w warunkach anoksycznych. W artykule przedstawiono wstępne wyniki badań chemokorelacyjnych morskiego poziomu korelcyjnego Dunbarella (najwyższa część westfalu A) z otworów wiertniczych Lubelskiego Zagłębia Węglowego
Chemostratigraphy, or chemical stratigraphy, uses major element and trace element geochemistry to characterize and correlate sedimentary sequences. Due to the availability of new analytical techniques such research are becoming increasingly applied in mining geology in the recent years. Chemostratygrafia uses geochemical record of sediments and sedimentary rocks, that is concentration of major and trace elements or isotopes for correlation and it is an excellent tool especially when combined with litho- , bio- and magnetostratigraphy. Geochemical studies are widely used in the identification and correlation marine horizons, especially formed under anoxic conditions. The paper presents preliminary results of chemocorrelation studies of the marine horizon Dunbarella (the highest part of the Westphalian A) of the boreholes from Lublin Coal Basin.
CO2 capture and geological storage (CCS) should be implemented in Poland, if combustion of coal will remain as a main source of energy in Poland, and European Union climate policy requirements are to be met. Despite existing experience and number of existing operational projects worldwide, a common fear concerning safety of the onshore, large scale geological storage of CO2 still occurs. Because of that fear, some European countries substantially limited even demonstration CCS projects. However, opinions on the method's safety should be based on solid geological evidence, not fears. Herein I provide some evidence from the Lower Jurassic basin in Poland that the method is safe. The key issue is the geological integrity of a seal. High-resolution sequence stratigraphy verified by chemostratigraphical correlation based on 13C isotope correlation, proved that one of key seal formations, the lower Toarcian Ciechocinek formation composed of clayey-muddy rocks with sandstone intercalation, is integral in terms of its lithology and spatial extent over the larger part of the Polish basin and provides an excellent seal. Origin of such favourable properties is attributed to climatic conditions (supergreenhouse conditions on land) during the Toarcian Oceanic Anoxic Event and high sea level at that time. Moreover, similar conditions occurred for four times during the Early–Middle Jurassic times, creating another over-regional seal formations in the large parts of the Polish Mesozoic epicontinental basin. It can allow a tiered sequestration method, using several sequestrartion systems (reservoir-seal couples) one above another, thus allowing much more voluminous and effective storage of CO2 and methane (for economic purposes) in selected structures.
The present study establishes a lithostratigraphic subdivision, a bio- and chemostratigraphy and describes the sedimentology of the Alstatte Bay at the southern margin of the Lower Saxony Basin in northern Germany. The socalled Fischschiefer is developed in the lower part of the section, a 2.1 m thick laminated interval that shows TOC values of up to 2 % and is interpreted as local expression of the global Oceanic Anoxic Event 1a (OAE 1a). The basal part of the Fischschiefer is fairly continuously laminated, whereas its upper part is characterized by an alternation of laminated and non-laminated beds. Stable carbon isotopes ([delta^13]C[carb]) show a characteristic pattern for the Fischschiefer interval that can be correlated with sections from the Tethyan Realm. Immediately above the Fischschiefer, however, the studied section might reveal a diagenetic overprint as indicated by very negative carbon stable isotope values. The remaining part of the section is characterized by a rather monotonous claystone succession, terminated by a greenish layer rich in glauconite overlain by glacial till of Pleistocene age. The fauna is typically Boreal in the lower part of the section, but changes around 2 m above the Fischschiefer towards an assemblage indicating a distinct Tethyan influx. The faunal shift is considered to be due to the maximum flooding of the continuous, long-term sea level rise of the Early Aptian which led also to a supposed shift from a restricted to open bay environment.
The hypothesis of Jarvis et al. (2006) that a [delta^13]C (calcite) reference curve based upon bulk samples from the Upper Cretaceous Chalk of England can be used as a primary criterion for trans-continental correlation is reviewed in the light of new stable isotope data from the Upper Albian and Cenomanian chalks of eastern England and from the Cenomanian to Campanian chalks of southern England. Evidence demonstrates that in the coloured chalks of eastern England the cements invariably have positive [delta^13]C values (up to 3.5[per mil]) except where they have been affected by hardground development when the cements have negative [delta^13]C values down to -6.5[per mil]. in contrast, the White Chalk of southern England may have cements with [delta^13]C values as negative as -8[per mil]. Modelling indicates that the coloured chalks may preserve a truer record of the primary palaeo-oceanographic [delta^13]C signal than the white and grey chalks of southern England. it is suggested that (1) many of the 72 isotope events described from the [delta^13]C (calcite) reference curve and proposed for correlation may reflect the effects of variations in the type and extent of calcite cementation; and (2) until much more is known about the patterns of calcite cementation in the Upper Cretaceous Chalk the use of minor isotope events for trans-continental stratigraphic correlation can only be applied with the utmost caution.
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