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Zasady klasyfikacji stratygraficznej czwartorzędu Polski i jej główne kategorie

Marks Leszek

Przegląd Geologiczny

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2023

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Vol. 71, nr 10

485--502

EN

A reliable stratigraphic subdivision of the Quaternary is extremely important, dependent firstly on primary significance of its deposits in geological investigations and every-day life of human societies. In the Cenozoic, the Quaternary is a period of the same stratigraphic rank as the Palaeogene and the Neogene, but it is much shorter. Traditional stratigraphic schemes of the Quaternary were based mostly on other criteria than of the older periods, because studies of the Quaternary were focused mainly on more easily accessible terrestrial deposits and a decisive role in their formation was played by climate-induced processes. These factors forced a specific approach to define the stratigraphic units and to create the stratigraphic subdivisions of the Quaternary. In the Quaternary investigations in Poland, several categories of stratigraphic classification are used, particularly lithostratigraphy (with pedostratigraphy and cryostratigraphy), morphostratigraphy, biostratigraphy (including palynostratigraphy, malacostratigraphy, teriostratigraphy and anthropostratigraphy), magnetostratigraphy, chronostratigraphy (synchronized with geochronology) and climatostratigraphy (combined with oxygen isotope stratigraphy). The main climatostratigraphic units can be treated as corresponding to the chronostratigraphic ones and it enables correlation in a regional and global scale. Acritical overview of the applied stratigraphic categories and the updated stratigraphic subdivision are presented for Poland.

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Further observations on the bio- and magnetostratigraphy of the J/K boundary interval in southern Ukraine

Wimbledon William A.P., Svobodova Andrea, Bakhmutov Vladimir, Poliachenko Ievgen, Hlavatskyi Dmytro

Geological Quarterly

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2022

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Vol. 66, No. 1

art. no. 11

EN

This is an account of finds of stratigraphically useful calcareous nannofossils and the magnetostratigraphy of the Jurassic-Cretaceous boundary interval of the eastern Crimean peninsula (southern Ukraine). We compare these new complementary results with those presented by our team in earlier publications. A missing interval in the Crimean sequence is filled, and the position of the Tithonian-Berriasian (J/K) boundary is confirmed.

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The proposal of a GSSP for the Berriasian Stage (Cretaceous System): Part 2

Wimbledon William A.P., Reháková Daniela, Svobodová Andrea, Elbra Tiiu, Schnabl Petr, Pruner Petr, Šifnerová Krýstina, Kdýr Šimon, Frau Camille, Schnyder Johann, Galbrun Bruno, Vaňková Lucie, Dzyuba Oksana, Copestake Philip, Hunt Christopher O., Riccardi Alberto, Poulton Terry P., Bulot Luc G., De Lena Luis

Volumina Jurassica

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2020

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Vol. 18, no. 2

121-160

EN

In part 1 of this work we discussed the possibilities for the selection of a GSSP for the Berriasian Stage of the Cretaceous System, based on prevailing practical methods for correlation in that J/K interval, traditional usage and the consensus over the best boundary markers that had developed in the last forty years. This consensus has developed further, based on the results of multidisciplinary studies on numerous sites over the last decade. Here in Part 2 we give an account of the application of those results by the Berriasian Working Group (ISCS), and present the stratigraphic evidence that justifies the selection of the locality of Tré Maroua (Hautes-Alpes, SE France) as the proposed GSSP. We describe a 45 m-thick section in the Calcaires Blancs vocontiens – that part of the formation covering the calpionellid Chitinoidella, Remanei. Intermedia, Colomi, Alpina, Ferasini, Elliptica and Simplex biozones. The stratigraphic data collected here has been compiled as part of a wider comparative study of complementary Vocontian Basin sites (with localities at Charens, St Bertrand, Belvedere and Le Chouet). Evidence from Tré Maroua thus sits in this substantial regional biostratigraphic and magnetostratigraphic context. For the purposes of the GSSP definition, here we particularly concentrate on the unbroken sequence and biotic markers in the interval immediately below the boundary, the Colomi Subzone (covering circa 675,000 years), and immediately above, the Alpina Subzone (covering circa 725,000 years). Particularly significant fossil datums identified in the Tré Maroua profile are the primary basal Berriasian marker, the base of the Alpina Subzone (a widespread event marked by dominance of small Calpionella alpina, with rare Crassicollaria parvula and Tintinopsella carpathica): the base of the Berriasian Stage is placed at the base of bed 14, which coincides with the base of the Alpina Subzone. Secondary markers bracketing the base of the Calpionella Zone are the FOs of the calcareous nannofossil species Nannoconus wintereri, close below the boundary, and the FO of Nannoconus steinmannii minor, close above. The Tithonian/Berriasian boundary level occurs within M19n.2n, in common with many documented sites, and is just below the distinctive reversed magnetic subzone M19n.1r (the so-called Brodno reversal). We present data which is congruent with magnetostratigraphic and biostratigraphic data from other key localities in France and in wider regions (Le Chouet, Saint Bertrand, Puerto Escaño, Rio Argos, Bosso, Brodno, Kurovice, Theodosia…), and thus the characteristics and datums identified at Tré Maroua are key for correlation and, in general, they typify the J/K boundary interval in Tethys and connected seas

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Magnetostratigraphy and magnetic susceptibility of the best developed Pleistocene loess-palaeosol sequences of Ukraine : implications for correlation and proposed chronostratigraphic models

Hlavatskyi Dmytro V., Bakhmutov Vladimir G.

Geological Quarterly

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2020

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Vol. 64, No. 3

723--753

EN

We provide a revised magnetostratigraphy and magnetic susceptibility stratigraphy of the most complete and thickest (to nearly 60 m) loess-palaeosol sequences in Ukraine spanning the past 1 My: the Roksolany (Black Sea Lowland) and Vyazivok (Dnieper Lowland) sections. The Matuyama-Brunhes boundary has been detected in both sequences in stratigraphically different palaeosol units according to current regional chronostratigraphic schemes. Hypotheses of a large magnetic lock-in depth at Vyazivok and lithostratigraphic incompleteness at Roksolany do not resolve this inconsistency. Instead, new chronostratigraphic models following the Chinese loess designation system, which are supported by correlation of the magnetic susceptibility records with the marine isotope record and estabilished magnetostratigraphic control points, are proposed. We conclude that the Matuyama-Brunhes reversal in the Roksolany and Vyazivok sections belongs to the same palaeosol unit, the Shyrokyne (according to our nomenclature, the U-S7), which corresponds to MIS 19. This novel interpretation resolves the inconsistency of the stratigraphic position of the Matuyama-Brunhes boundary in Ukrainian loess, ends long-standing debate regarding the chronostratigraphy of the Roksolany section, and allows precise correlation of the most representative loess-palaeosol sequences of Ukraine with those in the Danube Basin and the Chinese Loess Plateau. It is considered that the Roksolany Tephra in MIS 6 loess unit can be related to the L2 Tephra which is widely distributed in southeastern European loess records and lacustrine archives. In the light of our results, the Roksolany sequence may serve as a national lectostratotype of the Middle Zavadivka (U-L4) loess unit corresponding to MIS 10. Additionally, a generalized pedostratigraphic column of the past 1 My for central and southern Ukraine has been constructed and correlated with the Hungarian, Serbian and Chinese loess stratigraphies, as well as with the marine isotope record down to MIS 25.

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Integrated palynostratigraphy and magnetostratigraphy of the Middle and Upper Buntsandstein in NE Poland : an approach to correlating Lower Triassic regional isochronous horizons

Becker Anna, Fijałkowska-Mader Anna, Nawrocki Jerzy, Sobień Katarzyna

Geological Quarterly

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2020

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Vol. 64, No. 2

460--479

EN

Despite years of research, Lower Triassic deposits of the epicontinental Central European Basin still lack a detailed stratigraphy that would allow regional correlation of isochronous horizons. The best chronostratigraphic results have up to now been achieved by microspore-based biostratigraphy and magnetostratigraphy. Integrated palynostratigraphic and magnetostratigraphic investigations, carried out on Buntsandstein cores from northeastern Poland representing the eastern margin of the basin, have made precise correlations with the better-explored basin centre. The Lidzbark and Malbork formations of the Bartoszyce IG 1 borehole were examined by means of palynology and palaeomagnetic studies. Further palaeomagnetic studies were applied to the Lidzbark, Malbork and Elbląg formations of the Nidzica IG 1 borehole and the Elbląg Fm. of the Pasłęk IG 1. Two spore-poll en assemblages were distinguished representing the Densoisporites nejburgii Subzone of the D. nejburgii Zone within the lower part of the Lidzbark Fm. and the lowermost part of the Malbork Fm. Mostly reversed polarity was detected within the lower part of the succession investigated, whereas normal polarity prevailed within its upper part. A normal polarity local zone was correlated with the undivided Tbn6-Tbn7 standard magnetozones of western Poland. The reversely polarized part of the succession corresponds most probably to the Tbr5 standard magnetozone. The base of the Tbn6-Tbn7 magnetozone can serve as a good correlation horizon for regional reconstructions.

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Biostratigraphy and magnetostratigraphy of the uppermost Tithonian–Lower Berriasian in the Theodosia area of Crimea (southern Ukraine)

Bakhmutov V. G., Halásová E., Ivanova D. K., Józsa Š., Reháková D., Wimbledon W. A. P.

Geological Quarterly

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2018

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Vol. 62, No. 2

197--236

EN

We present evidence for the uppermost Jurassic-lowest Cretaceous interval in Crimea, coastal southern Ukraine. Three facies zones are distinguished in the upper Dvuyakornaya and the Mayak formations of the eastern Crimean Peninsula: basinal, slope and toe-of-slope zones. In this interval we identify the lowest Berriasian Jacobi and Grandis subzones of authors, in expanded form, exceeding 160 metres in thickness. We present new magnetostratigraphic interpretations, and identify two normal and two reversed polarity intervals, assigned to M19n, M18r, M18n and M17r, with M19n2n, M19n1r and M19n1n identified in the uppermost Dvuyakornaya Formation. In the Mayak Formation we record the top of M19n.1n, with M18r, M18n and a thick M17r above. In these two formations component calpionellid species have been identified which characterise the Alpina, Ferasini and Elliptica subzones (Calpionella Zone). In M19n, the FADs of the calcareous nannofossils Hexalithus strictus, Cruciellipsis cuvillieri, Nannoconus wintereri, N. steinmannii minor and N. kamptneri minor are found, which is consistent with other Tethyan regions. N. steinmannii steinmannii and N. kamptneri kamptneri first appear in M18r at Ili Burnu . Specimens of the apparently Tithonian foraminiferan index Anchispirocyclina lusitanica are found, but in the Berriasian lower Mayak Formation.

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Keuper magnetostratigraphy in the southern Mesozoic margin of the Holy Cross Mts. (southeastern edge of the German Basin)

Wójcik K., Kołbuk D., Sobień K., Rosowiecka O., Roszkowska-Remin J., Nawrocki J., Szymkowiak A.

Geological Quarterly

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2017

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Vol. 61, No. 4

946--961

EN

Magnetostratigraphy of the Keuper succession in the southern Mesozoic margin of the Holy Cross Mountains is presented based on investigations of two sections of Brzeziny and Wolica. They cut an ~60 m thick succession of variegated siltstones and claystones, which overlies the Reed Sandstone (Stuttgart Formation). The succession has been correlated with the Patoka Member of the Grabowa Formation, defined in the Upper Silesia region as an equivalent of the Steinmergelkeuper (Arnstadt Formation). The primary Late Triassic magnetization was obtained from component B carried by fine-grained haematite. Twelve magnetic polarity zones, six of normal and six of reversed polarity, have been defined. The obtained polarity pattern corresponds to the Norian (E13–E16 Newark zones) according to the Long-Rhaetian option of the Late Triassic Magnetic Polarity Time Scale. The mean normal polarity characteristic direction (N = 24, D/I = 31/62, k = 28.24, α95 = 6.04) differs significantly from the reversed one (N = 18, D/I = 223/-25, k = 16.38, α95 = 8.65): the primary magnetic signal is partly overlapped by component A carried by magnetite of recent viscuous remanent magnetization. Some samples do contain also coarse-grained haematite that, however, does not form any clustered magnetization. The palaeopole position calculated from the transposed reversed and normal polarity directions of component B corresponds to the Late Triassic (Norian) segment of the reference Baltica/Europe Apparent Polar Wander Path.

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Magnetostratigraphy of the Oligocene Lower Krosno Beds from the Hulskie section (Outer Carpathians in Poland)

Nawrocki J., Malata T., Rosowiecka O.

Geological Quarterly

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2016

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Vol. 60, No. 4

935--942

EN

The Oligocene flysch sequence from the Hulskie section in the Polish Outer Carpathians was palaeomagnetically examined. The flysch complex containing the Jasło and Zagórze limestone horizons revealed palaeomagnetic properties sufficient for a magnetostratigraphy to be established. The correlation of the local to the global magnetic polarity scale indicates that the Jasło limestone was deposited very close to the Rupelian and Chattian boundary i.e. ca. 28.4 Ma. In the same way, the age of the Zagórze limestone was defined as close to ca. 27.6 Ma. The entire450 mof studied section was formed between ca. 29 and 26.5 Ma. It implies an average sedimentary ratio of about 18 cm per thousand years. The palaeomagnetic directions from the Hulskie section do not display the Fisher type distribution and do not fit the reversal test and therefore cannot be used for any regional tectonic reconstruction.

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Magnetostratigraphy of the Campanian/Maastrichtian boundary succession from the Middle Vistula River section, Central Poland

Plasota T., Nawrocki J., Walaszczyk I.

Geological Quarterly

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2015

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Vol. 59, No. 4

831--842

EN

The magnetic polarities of the upper Upper Campanian–Lower Maastrichtian interval of the Middle Vistula River composite section (central Poland), were studied. Sixty-six hand-oriented samples for palaeomagnetic studies were taken from the sections of Raj, Raj North, Podole, Kłudzie and Dziurków. The inter-correlation between them is based primarily on bio-events. The sampled rocks generally revealed a very weak magnetic signal, however quite reliable results were obtained. The whole interval studied, well constrained biostratigraphically, is referred to magnetostratigraphic chron C32n. The Campanian–Maastrichtian boundary, placed biostratigraphically in the upper part of the ‘Inoceramus’ redbirdensis inoceramid Zone, is located near the top of the C32n2n Subchron. Thin reversed polarity intervals in the rocks correlated with the C32n2n chron most probably result from their partial remagnetization (maghemitization).

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Magnetic polarity of Upper Triassic sediments of the Germanic Basin in Poland

Nawrocki J., Jewuła K., Stachowska A., Szulc J.

Annales Societatis Geologorum Poloniae

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2015

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Vol. 85, No. 4

663--674

EN

Palaeomagnetic results are presented for 205 samples of cores from the Książ Wielkopolski IG-2, Woźniki K1 and Patoka 1 wells, drilled in the Polish part of Germanic Basin. The magnetic polarity stratigraphy is based on the inclination of the characteristic remanent magnetization, isolated in 60% of the total samples and found to be in general agreement with the expected Late Triassic inclination at the sampling sites. A total of 22 magnetozones from the integration of the three records correspond to about 25% of the published polarity zones for the Upper Triassic sediments that were combined in the worldwide composite polarity-time scale. The magne- tic polarity pattern, defined for the Schilfsanstein, fits very well with the one defined in the Tethys area for the upper part of the Julian sub-stage. According to the magnetostratigraphic data, the uppermost part of the Upper Gypsum Beds (equivalent to the Ozimek Member of the redefined Grabowa Formation) and the lowermost part of the Patoka Member, containing the Krasiejów bone-breccia horizon, can be correlated with the latest Tuvalian (~228.5 Ma) or with the middle part of Lacian (~225 Ma). However, if the “Long-Tuvalian” option for the Late Triassic Time Scale is taken into consideration, the parts of these substages mentioned above should be correlated with ~221.5 Ma and ~218.5 Ma, respectively.

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Magnetostratigraphy of the Upper Berriasian “Zavodskaya Balka” section (East Crimea, Feodosiya

Guzhikov A., Bagayeva M., Arkadiev V.

Volumina Jurassica

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2014

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Vol. 12, no. 1

175--184

EN

The results of magnetostratigraphic investigations in the Upper Berriasian Zavodskaya Balka section (Feodosiya, Crimea) are presented: magnetic polarity information, data on magnetic susceptibility, its anisotropy (АМS), frequency dependence (FD-factor) and other petromagnetic parameters. The analysis of the thermomagnetic and magnetic saturation curves has proved the presence of magnetite, being the main carrier of the remanent magnetization. Magnetic cleaning with alternating field and with temperature mostly has revealed the two-component composition of the magnetization, and the magnetostratigraphy is based on the directions of the most stable of them, with unblocking field from 35–50 mT and temperature from 300 to 540°C. The palaeomagnetic column presented specifies four heteropolar magnetozones – analogous to the M16 and M15 magnetic chrons (full M16n and M15r, parts of M16r and M15n). The existence of the M16n.1r subchron (“Feodosiya”) is substantiated, and it should be included into the Geomagnetic Polarity Time Scale. By bio- and magnetostratigraphic correlation, the section studied is an age analogue of the Paramimounum, Picteti and Alpillensis (probably Otopeta) subzones of the Boissieri Zone. The calculated sedimentation rate varied from 26.6 to 29.5 m/My.

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Berriasian bio- and magnetostratigraphy and magnetic susceptibility of the Barlya section (Western Balkan Unit, Bulgaria) – preliminary results

Grabowski J., Lakova I., Schnabl P., Sobień K., Petrova S.

Volumina Jurassica

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2014

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Vol. 12, no. 1

185--194

EN

Integrated bio- and magnetostratigraphic data from the Lower to Upper Berriasian of the pelagic succession at Barlya (Western Balkan, Bulgaria) are presented. The investigated interval, 24 m thick, covers the top of the Calpionella elliptica, Calpionellopsis simplex and Calpionellopsis oblonga subzones. Magnetozones from the upper part of M17r up to M16n were identified. The boundary between the Elliptica and Simplex subzones correlates with the lower part of M16r, while the boundary between the Simplex and Oblonga subzones is situated in the lower part of M16n. The magnetic susceptibility reveals an increasing trend from the middle part of M16r which accounts for the increasing supply of fine clastic sediments to the basin.

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Magnetostratigraphy of the Buntsandstein (Lower Triassic) in the Gorzów Wielkopolski IG 1 borehole, eastern German Basin in Poland: evidence of substantial diachronism of palynostratigraphic macrospore zones

Becker A., Nawrocki J.

Geological Quarterly

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2014

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Vol. 58, No. 2

369--378

EN

Palaeomagnetic research on the lower and middle Buntsandstein section of the Gorzów Wielkopolski IG 1 borehole, located in middle western Poland, showed the possibility of existence of short reversed subzones within the first normal polarity zone of the lowermost Buntsandstein (magnetozone Tbn1). The earlier established magnetozones Tbn2 and Tbn4 were not detected. The stratigraphic gap between the middle and upper Buntsandstein included at least magnetozones Tbn6 and Tbr6. The magnetostratigraphic correlation between the investigated section and the Otyń IG1 section indicates a substantial diachronism of palynostratigraphic zones based on macrospores in the lowermost and middle Buntsandstein.

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Magnetostratigraphy of the Jurassic/Cretaceous boundary interval in the Western Tethys and its correlations with other regions: a review

Grabowski J.

Volumina Jurassica

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2011

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Vol. 9, no. 1

105-128

EN

Magnetostratigraphy is an important method in regional and worldwide correlations across the Jurassic/Cretaceous boundary. The M-sequence of magnetic anomalies, embracing this boundary, provides an easily recognizable pattern which might be identified in biostratigraphically calibrated land sections. The polarity chrons between M21r and M16n are well correlated to calpionellid and calcareous nannofossil stratigraphy in the Tethyan Realm. This results in a very high precision of stratigraphic schemes of pelagic carbonates (ammonitico rosso and maiolica limestones), integrating the two groups of fossils with magnetostratigraphy. The main clusters of the reference sections are located in the Southern Alps and Apennines, but the database was recently enriched by sections from the Western Carpathians and Eastern Alps. Quite a few Jurassic/Cretaceous boundary sections with magnetostratigraphy are known in the Iberian Peninsula and south-eastern France but their importance relies on the integration of magnetostratigraphy also with the Tethyan ammonite zonation. Correlation of Boreal and Tethyan regions still remains a major problem. Just two sections with reliable correlation to the global polarity time scale are documented outside Tethys: a shallow marine to non-marine Tithonian–Berriasian–Valanginian sequence in southern England (Portland–Purbeck beds) and the marine clastic Upper Tithonian–Middle Berriasian (= Middle Volgian–lowermost Ryazanian) sequence at Nordvik Peninsula (Siberia). The Volgian/Ryazanian boundary at Nordvik seems to be located in the lower part of magnetochron M18n, while the most commonly accepted definitions of the Tethyan Jurassic/Cretaceous boundary are situated either within magnetochron M19n (A/B calpionellid zonal boundary, Durangites/Jacobi ammonite zonal boundary), or at the boundary of M19n/M18r (Jacobi/Grandis ammonite subzonal boundary).

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Pliocene age of the oldest basaltic rocks of Penguin Island (South Shetland Islands, northern Antarctic Peninsula)

Pańczyk M., Nawrocki J.

Geological Quarterly

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2011

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Vol. 55, No. 4

335-344

EN

The Penguin Island volcano is located on the southern shelf of King George Island (South Shetland Islands, West Antarctica). Its activity is regarded as connected with the opening of the Bransfield Strait. Penguin Island is dominated by a 180 m high basaltic stratocone (Deacon Peak) with a 350 m wide crater containing a small basaltic plug inside and radial dykes, and it has a second principal vent – the Petrel Crater maar – that was formed during a phreatomagmatic eruption about 100 years ago. A low-potassium, calc-alkaline sequence of basaltic lava flows with intercalations of beach deposits (Marr Point Formation) forms the basement of the stratocone. The Marr Point Formation lava flows have never been dated before. Combined whole rock 40Ar-39Ar isotopic dating and magnetostratigraphy were applied for this purpose. We obtained an isotopic 40Ar-39Ar plateau age of 2.7 š0.2 Ma, and together with the palaeomagnetic data, middle Pliocene age (Piacenzian) is implied for the basaltic plateau of Penguin Island.

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Isotopic ages of selected magmatic rocks from King George Island (West Antarctica ) controlled by magnetostratigraphy

Nawrocki J., Pańczyk M., Williams I.

Geological Quarterly

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2011

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Vol. 55, No. 4

301-322

EN

Isotopic and palaeomagnetic studies were carried out in the central part of King George Island. Selected mafic to intermediate igneous rocks were sampled for this purpose. Single-grain U-Pb dating of zircons from basalts to dacites was controlled by a whole rock 40Ar-39Ar data and the magnetostratigraphy. Five magmatic activity phases were distinguished in the SE coast of King George Island. The oldest, late Cretaceous (Campanian) phase represented by basalts of the Uchatka Point Formation are followed by the early to middle Eocene (~53–43 Ma) phase documented by the lava flows whose ages decrease from SW to NE. Next younger magmatic activity phases were recorded by the lava flows or vertical intrusions emplaced in the late Eocene (~37–35 Ma), late Oligocene (~~28-25 Ma) and late Pliocene to Holocene. The early to middle Eocene magmatic activity phase was the most extensive, producing the largest volume of magma in the study area. The new age determinations allow a more precise and credible stratigraphic correlation of the interbeds of sedimentary rocks observed in some places within the magmatic succession. The glacial provenance of the Herv' Cove diamictite is not obvious. It might represent a mountain river environment. Intense volcanic activity could be additional factor modelling the climate conditions of Antarctica in Paleogene

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Geochronology of selected andesitic lavas from the King George Bay area (SE King George Island)

Pańczyk M., Nawrocki J.

Geological Quarterly

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2011

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Vol. 55, No. 4

323-334

EN

Volcanic rocks from the Lions Rump area, which are the basement for a sequence of glaciomarine sediments of the Polonez Cove Formation, and lava flows from the Turret Point–Three Sisters Point area were sampled for thermogeochronological and palaeomagnetic investigations. Generally, andesitic lavas from King George Bay area consist mainly of clinopyroxene (Ti-augite) orthopyroxene (hyperstene) and plagioclase phenocrysts. The groundmass comprises mostly plagioclase laths, clinopyroxene, titanomagnetite and rare orthopyroxene crystals. However, the modal content, size, shape and distribution of phenocrysts are variable and specific for each sample. The Ar-Ar plateaus ages calculated for lavas from the Lions Rump area are very homogenous and point to middle Eocene age (Lutetian, ~44.5 Ma). The similar and consistent ages for volcanic basement for that area excluded the thesis about separate tectonic evolution of the Warszawa and Kraków blocks at least since the middle Eocene. The lavas from Turret Point and Three Sister Point are younger and were emplaced during the late Eocene (Bartonian/Priabonian: 37.3 š0.4 Ma and Priabonian: 35.35 š0.15 Ma, respectively). The results of isotopic investigations are consistent with magnetic polarities of the rocks indicating that the samples from the Lions Rump area are coeval with the lower part of the C20 polarity chron whereas the sample from Turret Point can be correlated with the upper part of the C17 polarity chron

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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.

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Jurassic cyclostratigraphy: recent advances, implications and problems

Coe A., Weedon G.

Volumina Jurassica

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2006

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Vol. 4, no. 1

156-157

EN

About 70% of the Jurassic is now covered by floating astronomical timescales based on the recognition of Milankovitch cycles. Astronomical timescales provide the highest resolution robust timescales over the tens of thousands to millions and even tens of millions of year timescales. This presentation will provide a summary of the status of the Jurassic astronomical timescale, including the outstanding problems and possible solutions. The oldest sea-floor magnetic anomaly pattern is Callovian. For earlier stages the scaling for the Geological Timescale 2004 (Gradstein et al. 2004), other than minimum estimates from direct counts of stratigraphic cycles, relied on a combination of c. 20 radiometric dates, the number of ammonite subzones and an assumption that the rate of change of seawater 87Sr/86Sr ratio for the Early Jurassic was linear over intervals of millions of years. However, this assumption has recently been questioned and thus there is an additional need to improve the cyclostratigraphic and radiometric databases. Cyclostratigraphy for much of the Early Jurassic has been completed using sections in England and the Alps. There is no cyclostratigraphy for the Bajocian and Bathonian. For the Late Jurassic, the existence of a sea-floor magnetic anomaly pattern together with recent and ongoing cyclostratigraphic and magnetostratigraphic studies on the same sections in the UK provide the potential to produce a high-resolution integrated timescale for the Callovian to Tithonian (c. 15 Ma duration). However, construction of the Late Jurassic timescale is complex because of the high number of magnetic reversals, the provincialism of the ammonites used for biostratigraphy and lack of agreement on the stages. Weedon et al. (2004) identified regular cycles in the Kimmeridge Clay Formation in England and used these to construct a floating 7.5 Ma astronomical timescale for the latest Oxfordian (as defined in the Tethyan province), Kimmeridgian and most of the Early Tithonian. Comparison of this astronomical timescale with the GTS2004 reveals that the Early Tithonian is c. 1 Ma (25%) longer according to the cyclostratigraphy. This mismatch may be resolved via better correlation of the magnetozones that were defined in France (Tethyan Province) and the Kimmeridge Clay Formation (Boreal Province). For the Oxfordian and Callovian a high-resolution magnetostratigraphy based on sections in the UK has recently been compiled. Work is currently being conducted to produce a floating astronomical timescale using exactly the same exposures.

20

Faunal and floral distribution, biostratigraphy, cyclostratigraphy and magnetostratigraphy of the T/J boundary

Michalík J., Soták J., Ruckwied K., Götz A., Grabowski J.

Volumina Jurassica

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2006

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Vol. 4, no. 1

292-292

EN

The Rhaetian and Hettangian sequence in the Zliechov Basin, Western Carpathians, comprises records of several environmental crises which could contributed to the global Triassic/Jurassic Boundary Events. The Upper Triassic Fatra Formation is characterized by bioclastic limestones and fine-grained clastics overlain by dark claystones with intercalated sandstones (Cardinia Sandstein) of the Kopieniec Formation. The diversity of benthic fauna decreased at the base of the "Transition Beds" - the uppermost member of the Fatra Formation. The fauna comprises important index forms of bivalve molluscs (Chlamys valoniensis), corals, brachiopods (Austrirhynchia cornigera) and foraminifers (Triasina hantkeni, etc.). The palynofacies of the entire succession is dominated by terrestrial components and by high amount of phytoclasts. The few marine organic particles indicate a very shallow marine depositional environment. The palynomorph assemblage of the Fatra Formation is characterized by numerous specimens of Ricciisporites tuberculatus. The marine fraction of the lower part of the section is dominated by the dinoflagellate cyst Rhaetogonyaulax rhaetica. The palynomorph assemblage of the Kopieniec Formation is characterized by a significant increase of trilete laevigate spores, mainly Deltoispora spp. and Concavisporites spp. The dinoflagellate cyst Dapcodinium priscum replaces Rhaetogonyaulax rhaetica in the marine fraction. These changes may be caused by a regression at the Triassic/Jurassic boundary and by an important fresh water input. The boundary between the Fatra and the Kopieniec formations is sharp, denoted by sudden termination of carbonate sedimentation followed by non-carbonate Boundary Clay of the Kopieniec Formation. Magnetostratigraphic record is in procession, it is hampered by complicated pattern of geomagnetic reversals at the end of the Triassic and at the beginning of the Jurassic period.