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1

Analiza chemostratygraficzna różnowiekowych osadów budujących górotwór karpacki

Kowalska Sylwia

Nafta-Gaz

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2023

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R. 79, nr 10

623--639

PL

Artykuł prezentuje próbę przeprowadzenia analizy chemostratygraficznej dla różnowiekowych skał budujących górotwór karpacki. W pierwszej kolejności zdecydowano się stworzyć syntetyczny profil geologiczny dla osadów występujących we wschodniej części polskich Karpat. Wykorzystane próbki, w większości piaskowce, pochodziły z głównych poziomów stratygraficznych w obrębie jednostek skolskiej i śląskiej, gdzie zidentyfikowano skały od dolnej kredy po paleocen. Ze względu na dostępność materiału badawczego do badań wytypowano próbki o udokumentowanej stratygrafii z dwóch otworów, D-1 i H-1, zwracając głównie uwagę na ich klasyfikację stratygraficzną. Następnie dla porównania wykonano profil chemostratygraficzny dla otworu Kuźmina-1. Stwierdzono obecność bardzo dużego zróżnicowania składu chemicznego pomiędzy głównymi poziomami stratygraficznymi wyróżnianymi na podstawie badań paleontologicznych w badanych otworach, co pozwoliło wyznaczać zdecydowane granice pomiędzy poszczególnymi poziomami stratygraficznymi. Możliwość stworzenia unikalnych modeli chemostratygraficznych dla czterech analizowanych poziomów stratygraficznych: kredy górnej – senonu (warstwy inoceramowe), kredy górnej / paleocenu (warstwy istebniańskie), eocenu (warstwy pstre) oraz oligocenu (warstwy krośnieńskie) potwierdziło również wykonanie diagramu klasyfikacyjnego Herrona. Największe zróżnicowanie cech chemostratygraficznych uzyskano w przypadku utworów kredowych. Wstępnie badania wykonano w laboratorium akredytowanym Actlabs, tak aby móc później przeprowadzić ewaluację wyników uzyskanych za pomocą przenośnych spektrometrów (pXRF Titan, o zakresie pomiarowym od Mg do U, oraz pXRF Tracer, który umożliwia również pomiar zawartości Na, oba aparaty firmy Bruker). Potwierdzono, że wyraźne zróżnicowanie zawartości poszczególnych pierwiastków widoczne jest zarówno dla pierwiastków głównych, jak i śladowych. Pierwiastki najbardziej diagnostyczne to Na, Mg, Fe, K, Ca, również Si, choć w tym przypadku zakres zmienności jest nieco mniejszy. W przypadku pierwiastków śladowych są to S, P, Mn, Ti, Sr, Zr, Ba, Rb i Zn, które można również analizować za pomocą przenośnych spektrometrów pXRF. Wykonane porównanie wyników składu chemicznego uzyskiwanych przenośnym spektrometrem pXRF oraz w laboratorium Actlabs wykazało, że możliwe jest wykorzystanie na większą skalę samych pomiarów spektrometrem pXRF. Dla większości pierwiastków diagnostycznych uzyskano wystarczająco precyzyjne wyniki przy wykorzystaniu przenośnych spektrometrów pXRF.

EN

The article presents an attempt to conduct a chemostratigraphic analysis of the different-age rocks that form the Carpathian orogen. First, it was decided to create a synthetic geological profile for sediments occurring in the eastern part of the Polish Carpathians. The samples, mostly sandstones, were sourced from the primary stratigraphic layers in the Skole and Silesian Units, where rocks from the Lower Cretaceous to the Paleocene were identified. Due to the availability of research material, samples with well-documented stratigraphy were chosen from two wells, D-1 and H-1, with a particular focus on their stratigraphic classification. Subsequently, for comparison, a chemostratigraphic profile was generated for the Kuźmina-1 well. The analysis revealed significant disparities in chemical composition among the primary stratigraphic layers, which had been distinguished through paleontological studies in the examined boreholes. This made it possible to establish distinct boundaries between individual stratigraphic layers. The ability to create distinct chemostratigraphic models for the four examined stratigraphic horizons: Upper Cretaceous – Senonian (Inoceramian Beds), Upper Cretaceous/Paleocene (Istebnian Beds), Eocene (Variegated Shales), and Oligocene (Krosno Beds) was also confirmed through the creation of a Herrón classification diagram. The greatest variability of chemostratigraphic characteristics was observed in the Cretaceous formations. Initially, the tests were carried out in an accredited laboratory at ACTLABS, enabling the subsequent evaluation of results obtained using portable spectrometers (pXRF Titan, covering a measurement range from Mg to U, and pXRF Tracer, capable of also measuring Na content, both manufactured by Bruker). It was confirmed that clear variations in the content of individual elements were discernible for both major and trace elements. The most diagnostic elements include Na, Mg, Fe, K, Ca, and also Si, although the variability range is slightly narrower for the latter element. As for trace elements, these comprise S, P, Mn, Ti, Sr, Zr, Ba, Rb, and Zn, which can also be analyzed using portable pXRF spectrometers. A comparison between the chemical composition results obtained with the portable pXRF spectrometer and those from the ACTLABS laboratory revealed the feasibility of using pXRF measurements on a larger scale. For most diagnostic elements, sufficiently precise results were obtained using pXRF.

2

Geochemistry of the carboniferous coal-bearing series and the miocene cover within the Upper Silesian Coal Basin - a case study

Krzeszowska Ewa

Gospodarka Surowcami Mineralnymi

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2023

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T. 39, z. 4

107--122

EN

This paper presents geochemical data for 171 core samples of the Carboniferous coal-bearing series and the Miocene cove from the central part of the Upper Silesian Coal Basin. Major oxide concentrations (Al2O3, SiO2, Fe2O3, P2O5, K2O, MgO, CaO, Na2O, K2O, MnO, TiO2, and Cr2O3) were obtained using XRF. Trace and major elements (Mo, Cu, Pb, Zn, Ni, Co, U, Cr, V, Mn, As, Th, Sr, Cd, Sb, Bi, Ba, Ti, W, Zr, Ce, Nb, Ta, Be Sc) were analysed ICP-MS. The main goals of this study were to demonstrate the distribution, as well as the stratigraphical variability, of the selected elements and to determine whether chemostratigraphy tools could be effectively applied to analyze Carboniferous and Miocene deposits of the USCB. Geochemical studies have shown showed different geochemical features of the samples from the Carboniferous and the Miocene. The diversity is mainly expressed in the enrichment of Miocene sediments in Ca and Sr related to biogenic carbonate material. It was also stated that the concentrations of trace elements associated with the detrital fraction, such as Zn, Cr, Co, Ba, Ti, Zr, Nb, and Sc show slightly higher values in Carboniferous sediments. On the basis of the content of Ti, Zr, and Nb, as well as ratios such as Th/U, Zr/Th, Ti/Zr, and TiO2/K2O, units with different inputs of the terrigenous fraction can be identified in both Carboniferous and Miocene formations. The paper shows that chemostratigraphy can be used as a stratigraphic and correlation tool for the Carboniferous and the Miocene deposits of the USCB.

PL

W pracy przedstawiono dane geochemiczne dla 171 próbek skał osadowych z karbońskiej serii węglonośnej i pokrywy mioceńskiej z centralnej części Górnośląskiego Zagłębia Węglowego. Udziały głównych tlenków (Al2O3, SiO2, Fe2O3, P2O5, K2O, MgO, CaO, Na2O, K2O, MnO, TiO2 i Cr2O3)oznaczono za pomocą XRF. Pierwiastki główne i śladowe (Mo, Cu, Pb, Zn, Ni, Co, U, Cr, V, Mn, As, Th, Sr, Cd, Sb, Bi, Ba, Ti, W, Zr, Ce, Nb, Ta, Be i Sc) analizowano przy pomocy ICP-MS. Głównym celem badań była analiza koncentracji i zmienności stratygraficznej wybranych pierwiastków głównych i śladowych, jak również ocena możliwości stosowania chemostratygrafii w analizie karbońskich i mioceńskich osadów GZW. Badania geochemiczne wykazały odmienne właściwości geochemiczne próbek z karbonu produktywnego oraz miocenu. Zróżnicowanie to wyraża się głównie wzbogaceniem osadów miocenu w Ca i Sr, związane z biogenicznym materiałem węglanowym. Stwierdzono również, że stężenia pierwiastków śladowych, związanych z frakcją detrytyczną, takich jak: Zn, Cr, Co, Ba, Ti, Zr, Nb, Sc, wykazują nieco wyższe wartości w osadach karbonu. Na podstawie koncentracji pierwiastków Ti, Zr i Nb oraz wskaźników geochemicznych Th/U, Zr/Th, Ti/Zr, TiO2/K2O można zidentyfikować jednostki o różnym udziale frakcji terygenicznej, zarówno w osadach karbonu i miocenu. W pracy wykazano, że chemostratygrafia może być z powodzeniem wykorzystywana jako narzędzie stratygraficzne i korelacyjne dla utworów karbonu i miocenu Górnośląskiego Zagłębia Węglowego.

3

Nowoczesne metody chemokorelacji i możliwości ich wykorzystania w dokumentowaniu złóż

Krzeszowska E., Kokowska-Pawłowska M.

Górnictwo Odkrywkowe

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2016

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R. 57, nr 5

58--63

PL

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

EN

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.

4

Geologiczne składowanie ditlenku węgla (CCS) jest metodą bezpieczną : dowody geologiczne

Pieńkowski G.

Przegląd Geologiczny

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2015

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Vol. 63, nr 1

48–-54

EN

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.

5

How many Upper Triassic bone–bearing levels are there in Upper Silesia (southern Poland)? A critical overview of stratigraphy and facies

Szulc J., Racki G., Jewuła K., Środoń J.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 4

587--626

EN

At least three widely separated bone-bearing intervals in the Upper Triassic succession of Upper Silesia, ranging in age from the Carnian to Rhaetian (i.e., in the interval of 25 Ma), are presented in papers by the Warsaw research group, led mainly by Jerzy Dzik and/or Grzegorz Niedźwiedzki. The stratigraphic arguments are reviewed for the vertebrate localities studied so far, in particular for the well-known middle Keuper sites at Krasiejów and Lipie Śląskie, to show that the previously proposed age assignments are still inadequately documented and questionable. This unreliability is exemplified by the evolving stratigraphic correlation of the fragmentary Silesian sections (8–18 m thick) with informal subsurface units from central-western Poland and with the German standard succession, ultimately not corroborated by comparison with the composite reference succession of the Upper Silesian Keuper, including new profiles (ca. 260 m thick) from the Woźniki K1 and Patoka 1 wells. Based on a multidisciplinary stratigraphic study covering consistent litho-, bio-, climato- and chemostratigraphic premises, focused on the regional reference section, two bone-bed levels only are recognized in the Patoka Marly Mudstone-Sandstone Member (= Steinmergelkeuper) of the Grabowa Formation, not very different in age (Classopollis meyeriana Palynozone; probably IVb Subzone): (1) the localized Krasiejów bone breccia level (early Norian in age) in the Opole region, and (2) the far more widely distributed Lisowice bone-bearing level (middle Norian) in a vast alluvial plain (braided to anastomosing river system) during the Eo-Cimmerian tectonic-pluvial episode. As a consequence of the principal uncertainties and controversies in Upper Triassic terrestrial stratigraphy, this is still a somewhat preliminary inference. Typical skeletal concentra- tions of a combined hydraulic/sedimentologic type, related to fluvial processes, are common in the Upper Silesian Fossil-Lagerstätten, although factors governing preservation are probably important, as well.

6

Integrated stratigraphy of the Oxfordian global stratotype section and point (GSSP) candidate in the Subalpine Basin (SE France)

Pellenard P., Fortwengler D., Marchand D., Thierry J., Bartolini A., Boulila S., Collin P., Enay R., Galbrun B., Gardin S., Huault V., Huret E., Martinez M., Smith C.

Volumina Jurassica

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2014

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Vol. 12, no. 1

1--44

EN

An integrated biostratigraphic approach, based on ammonites, calcareous nannofossils, dinoflagellates, combined with sedimentology, carbon-isotope and physical stratigraphy, is proposed for the Subalpine Basin (Thuoux and Saint-Pierre d’Argençon sections). Within the expanded marl deposits of the Terres Noires Fm., the Callovian-Oxfordian boundary is particularly well defined by ammonite taxa from different families (i.e. Cardioceratidae, Oppeliidae, Aspidoceratidae and Perisphinctidae), calcareous nannoplankton (first occurrence of large-sized Stephanolithion bigotii) and dinoflagellate cysts (first occurrence of Wanaea fimbriata). This precise biostratigraphy and diversity of ammonites permit long-range correlations with Boreal and Pacific domains. The exceptional outcrop conditions and continuous sedimentation allow high-resolution chemostratigraphy and cyclostratigraphy to be used. Variations of the δ13C record (1.5‰ increase during the Lamberti Zone), consistent with data from other sections of the Subalpine Basin and with the Paris Basin, provide additional markers to characterise the Callovian-Oxfordian boundary. Promising results from cyclostratigraphy should serve to constrain the duration of biostratigraphic units and thus improve the Late Jurassic Geologic Time Scale. Comparisons are made with the two other candidates for an Oxfordian GSSP, Redcliff Point (UK) and Dubki (Russian Platform). Finally, the advantages of the Subalpine Basin sections support the proposal of Thuoux as a suitable GSSP candidate for the base of the Oxfordian Stage

7

Early Aptian bay deposits at the southern margin of the Lower Saxony Basin : Integrated stratigraphy, palaeoenvironment and OAE 1a

Lehmann J., Friedrich O., Bargen D., Hemker T.

Acta Geologica Polonica

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2012

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Vol. 62, no. 1

35-62

EN

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.

8

Calcite cements and the stratigraphical significance of the marine [delta^13]C carbonate reference curve for the Upper Cretaceous Chalk of England

Jeans C., Hu X., Mortimore R.

Acta Geologica Polonica

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2012

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Vol. 62, no. 2

173-196

EN

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.

9

The Pliensbachian/Toarcian boundary in the Almonacid de la Cuba section (Iberian Range, Spain)

Goy A., Comas-Rengifo J., Gomez J., Gonzales J., Herrero C., Palencia A., Perilli N., Rodrigo A.

Volumina Jurassica

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2006

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Vol. 4, no. 1

164-166

EN

The Almonacid de la Cuba section, representative of the Pliensbachian-Toarcian transition in the Iberian Range (Fig. 1), is reviewed. It is an expanded section where no important discontinuities have been detected. Four successive assemblages of ammonites, which are characterized by the presence of Pleuroceras (BH14-CU14), Canavaria (CU16-CU32), Dactylioceras (E.) (CU35.2-CU44) and Dactylioceras (O.) (CU44-CU87), are distinguished. The Pliensbachian/Toarcian boundary is located at the base of level CU35.2 with the first record of Dactylioceras (Fig. 2). These assemblages are mainly constituted by taxa typical of the NW European Province, such as Pleuroceras, Dactylioceras (O.) and P. paltum. However, frequent Mediterranean Province taxa such as Emaciaticeras, Canavaria, Lioceratoides, Neolioceratoides, Dactylioceras (E.) and P. madagascariense, are also recorded. In the Tenuicostatum Zone, dactylioceratidae are dominating with respect to harpoceratinae. In the Mirabile Subzone, species of Dactylioceras (E.) are coexisting with P. paltum. Brachiopods show two successive assemblages. The lower one is composed generally of the Pliensbachian taxa and the upper assemblage includes more endemic taxa. Coinciding with the Early Toarcian OAE, almost all these species disappeared at the end of the Tenuicostatum Chron. Foraminiferal assemblages are rich and diversified. Calcareous hyaline taxa are dominated by suborder Lagenina, agglutinated foraminifera are scarce, the suborders Spirillinina and Miliolina are represented by few specimens and taxa, and specimens of Robertinina have been recovered throughout the whole stratigraphic interval. The main biostratigraphical foraminiferal events can be recognized and compared with other sections of the Iberian Range and with another ones of selected NW European Basins. Ostracod assemblages of the Spinatum Zone are dominated by healdiids and cytheraceans, which decrease at the base of the Tenuicostatum Zone, where the cypridaceans are better represented. In the Semicelatum Subzone, coinciding with the disappearance of the healdiids, the cytheraceans become dominants.Calcareous nannofossils assemblages are rich and well preserved. This allowed locating precisely the biochronostratigraphical position of the main markers and events and comparing them with these recorded in other basins of Western Tethys. A magnetic polarity column for the Pliensbachian/Toarcian boundary has been constructed on the basis of the polarities of the 2C Component (Fig. 2). The lower boundary of the Toarcian is located within the R2 magnetozone. A relatively large magnetozone N3 of normal polarity is located within the Tenuicostatum Zone.

10

Pliensbachian – lowermost Toarcian chemostratigraphy (elemental and TOC) of the Peniche section (Lusitanian Basin, Portugal)

Veiga de Oliveira L., Duarte L., Rodrigues R.

Volumina Jurassica

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2006

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Vol. 4, no. 1

217-218

EN

In Portugal, the Peniche section constitutes one of the most continuous series of Lower Jurassic. This study is based on a detailed chemostratigraphic analysis of the Pliensbachian - lowermost Toarcian marly limestones, belonging to the Vale das Fontes, Lemede and Cabo Carvoeiro formations. 196 samples of limestones and marls were analyzed in terms of minor and major elements (Fig. 1). Total organic carbon (TOC) was determined in 233 samples. Besides the stratigraphic distribution of these geochemical parameters, the aim of this work is to perform a discussion about biogenic influx and aluminosilicate phasefluxes. The Al concentrations are a good indicator of detrital flux and good correlations between them signify aluminosilicate affiliation. In Peniche, K (0.98), Si (0.96) and Ti (0.98) show, in all section, excellent correlation with Al2O3. Mg (0.82), Ba (0.80), Cr (0.78), Li (0.80), Na (0.74), Sc (0.80), V (0.81) and Zr (0.86) correlate well with Al2O3 but other secondary factors, beyond the detrital flux, affect the resultant concentrations. The Pearson's coefficients between Al2O3 and CaO is strongly negative (-0.98), suggesting divergent behaviours for this elements. Al2O3 and Fe2O3 correlate moderately (0.61). However, the correlation coefficients calculated for each stratigraphic unit show variable values. Lemede Formation and the Members Marls and Limestones with Uptonia and Pentacrinus (MLUP), Lumpy Marls and Limestones (LML), to the Vale das Fontes Formation, and CC1, to the Cabo Carvoeiro Formation, show high correlation coefficients between Al2O3 and Fe2O3 (0.87, 0.91, 0.88 and 0.97, respectively). On the other hand, the Member CC2 has moderate correlation (0.67) and the Member Marls and Limestones with Bituminous Shales (MLBF) has weak correlation (0.20). These variations suggest that the elemental inputs change during the Pliensbachian - lowermost Toarcian, in the Peniche area. Ba enrichment is considered an indicator of high flux of biogenic material and high surface-water productivity. But, in the studied section, correlation between Al2O3 and Ba is high (0.80) and Ba lacks any correlation with TOC (0.17). Thus, in the Peniche region, the distribution of Ba is dominated by the original detrital flux and transported to the basin, mainly, as a constituent of clays. The mainly TOC values in the Pliensbachian - lowermost Toarcian of the Peniche section are below 2. But the MLBF (Ibex to Margaritatus zones) represents a high TOC interval with concentrations up to 15%, correlated with the 2nd order flooding interval, well know in the Lusitanian Basin.

11

Apparent sea-level change at times of extraordinary sediment supply: integrated facies analysis and chemostratigraphy of Early Toarcian Oceanic Anoxic Event, Peniche, Portugal

Hesselbo S., Jenkyns H., Duarte L., Veiga de Oliviera L.

Volumina Jurassica

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2006

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Vol. 4, no. 1

171-172

EN

The Toarcian Oceanic Anoxic Event in the Early Jurassic was a time of major environmental change characterized by widespread deposition of organic-rich black shales in both deep- and shallow-marine settings. Facies evidence, mainly from the European area, has been used to argue for a major sea-level rise in concert with oceanic anoxia, extinction of certain groups, and perturbation of the carbon cycle. However, in a number of locations, such as in the Lusitanian Basin, Portugal, it has also been argued previously that the start of the event was characterized by sea-level fall rather than rise, as evidenced by the initiation of gravity-flow deposition. In this study we combine new marine and terrestrial carbon-isotope and lithological data to suggest an alternative model for development of facies patterns in this basin, whereby an abrupt increase in sediment flux from the hinterland led to slope instability and gravity-flow deposition that lasted as long as the carbon-cycle perturbation. This interpretation is supported by existing osmium and strontium isotope data, which have been interpreted to indicate a significant continental transient increase in continental weathering fluxes. In effect this event provides a good example from the rock record where the assumption of constant sediment supply is demonstrably false, but in which the facies patterns may still be predictable on a variety of scales.

12

Granica baden–sarmat w zapisie geochemicznym osadów w północnej części zapadliska przedkarpackiego : implikacje stratygraficzne

Gąsiewicz A., Czapowski G., Paruch-Kulczycka J.

Przegląd Geologiczny

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2004

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Vol. 52, nr 5

413–-420

EN

Results of distribution analysis of major, minor, and trace elements content as well as isotopic features and organic matter (TOC) concentration within clastic (mudstones and claystones with sandy interbeds) of the Middle Miocene (Badenian–Sarmatian) Machów Formation in the northern part of the Carpathian Foredeep (southern Poland) are presented in this paper. A chemostratigraphic study shows that theMachów Fm, underlain by evaporites (Krzyżanowice Fm) may be subdivided from the base to the top into three complexes: A, B, and C. Lithologically, the boundaries between the complexes are continuous but the contrasting geochemical difference occurs between A and B+C complexes. According to geochemical features, supported by palaeontological data, this chemostratigraphic boundary is assumed as the Badenian–Sarmatian one. Such approach reveals that the chemostratigraphic boundary occurs much higher (up to several metres) than the palaeontological one. The discordance in the boundary location is ascribed to palaeoecological factors.