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Origin of flints in the Upper Cretaceous and Danian Chalk of England, Denmark and the North Sea: Evidence from their geological setting, mineralogy, geochemistry, paramagnetic properties and ultrastructure

Jeans Christopher V., Wray David, Lampronti Giulio I., Sheikh Hassan A., Evtushenko Alexander

Acta Geologica Polonica

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2025

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Vol. 75, no. 4

art. no. e56

EN

Two types of flints are recognized in the Upper Cretaceous Chalk of England, the North Sea and Denmark. Alpha-quartz/moganite flints are associated with the high quartz smectite-mica clay assemblage that probably derived its silica from mainly oceanic sources related possibly to the development of the Atlantic Ocean, and opal-CT flints that are associated with the low-quartz smectite-mica clay assemblage that derived its silica ultimately from the deep weathering of continental rocks on the Mid-European Island. Eight different groups of alpha-quartz/moganite flints are described based on mineralogy, colour, core/cortex definition, size, relationship to bedding, and location. The presence of authigenic paramagnetic and non-paramagnetic minerals demonstrate that certain of these groups of flints developed in the oxic and suboxic diagenetic zones although the majority formed in the anoxic zone. Their major, minor and trace element chemistry is discussed in relation to the timing of their development. A predictive schematic model is put forward linking flint development with diagenesis, burrow-type and the plumbing system of the Chalk. The origin of flint veins and sheets is discussed within the context of the known relationship between pore size and the degree of super saturation needed for cement precipitation.

2

Liliowce (Crinoidea, Echinodermata) jako wskaźniki biostratygraficzne : przykłady z mezozoiku

Salamon Mariusz A., Niedźwiedzki Robert, Płachno Bartosz J.

Przegląd Geologiczny

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2024

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Vol. 72, nr 12-1

665--670

EN

The biostratigraphic potential of Mesozoic crinoids (Crinoidea, Echinodermata) is less than that of many groups of nektonic or planktonic organisms, especially for age correlation on a supraregional scale. Only the Cretaceous stemless crinoids, both planktonic (Roveacrinids) and some benthic (Uintacrinus and Marsupites), are important in bio¬stratigraphy on a supraregional scale. Other benthic crinoids can be used basin). Many data indicate that some crinoids, including stalked crinoids, can be successfully used in Mesozoic biostratigraphic correlations of marine sediments when standard index fossils such as ammonites, conodonts, nannoplankton and foraminifers are lacking or they are rare in a given region. The paper briefly presents a discussion on the stratigraphic potential of stalked crinoids using Mesozoic taxa as an example, and provides new literature data on the importance of Mesozoic stemless crinoids for dating rocks.

3

The serpulid tube worm Laqueoserpula reussi (Weinzettl, 1910) from the Upper Cretaceous of the Bohemian Cretaceous Basin – an alleged gastropod which has turned out to be a characteristic faunal element of marine nearshore high-energy environments

Jäger Manfred, Kočí Tomáš, Sklenář Jan, Zágoršek Kamil

Acta Geologica Polonica

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2024

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Vol. 74, no. 2

art. no. e12

EN

The serpulid tube worm Laqueoserpula reussi (Weinzettl, 1910), originally introduced as a gastropod named Burtinella(?) reussi, is described from the Upper Cenomanian and Lower Turonian of the Bohemian Cretaceous Basin. It had usually been confused with other species and genera before 2008. Comparison with specimens from the type locality of the type species of the genus Laqueoserpula Lommerzheim, 1979 confirms the affiliation of the Bohemian species to this genus. The simple prismatic (SP) ultrastructure of the tube wall of L. reussiagrees with an assignment to the tribe Serpulini Rafinesque, 1815. In the Upper Cretaceous, representatives of Laqueoserpula are exclusively found in nearshore deposits, where they are accompanied by a high diverse marine invertebrate fauna. By its compact, large and robust tube forming a spiral and extremely thick tube wall, L. reussi was well-adapted to live in nearshore high energy environments, where its tube could be encrusted by bryozoans, brachiopods and oysters, and infested by hydroids and borers.

4

Spit bar deposits from the Upper Cretaceous (Cenomanian) transgressive sequence in NE Bohemia (Czechia)

Chrząstek Alina, Wojewoda Jurand

Acta Geologica Polonica

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2024

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Vol. 74, no. 2

art. no. e9

EN

We propose a spit bar setting as the possible palaeoenvironment of the basal Late Cretaceous transgressive sequence in NW Bohemia. A new Cenomanian transgression model for the Bohemian Basin is also proposed. The uppermost Devět Křížů Sandstone, which has been conventionally referred to the Bohdašín Formation, probably represents the middle or lower upper Cenomanian (Upper Cretaceous), not the Triassic as previously supposed. We assume that this controversial unit was deposited before the main latest Cenomanian–early Turonian transgression. The spit bars were likely overgrown by vascular plants during their emergence in the late Cenomanian, and then inundated during the latest Cenomanian and early Turonian transgressive phases. The studied deposits had been intensively bioturbated, and the cf. Taenidium suite was recognized for the first time in them alongside the Thalassinoides assemblage (T. paradoxicus, T. suevicus, Thalassinoides isp., cf. Thalassinoides), which are characteristic of the Scoyenia and Glossifungites ichnofacies, respectively. The bioturbated, rhizolith-bearing horizon was presumably a paleosol.

5

On some Turonian and Coniacian ammonites from the Czech Republic

Kennedy William James, Summesberger Herbert

Acta Geologica Polonica

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2024

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Vol. 74, no. 2

art. no. e10

EN

Ammonites, chiefly from the Upper Turonian Prionocyclus germari Zone, the Lower Coniacian part of the Forresteria (Harleites) petrocoriensis Zone, and the Lower Coniacan Peroniceras (Peroniceras) tridorsatum Zone from the Czech Republic are figured and described, including classic material originally described by Fritsch (1872–1898) and Jahn (1892, 1896). In all, 25 species are recognised, including two, Pseudojacobites sp. and Muniericeras sp., that represent genera previously not known from the area.

6

Correlation of the Coniacian and Santonian stages of the Upper Cretaceous in the Anglo-Paris Basin

Gale Andrew Scott

Acta Geologica Polonica

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2024

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Vol. 74, no. 2

art. no. e8

EN

The correlation of the Coniacian and Santonian chalks of the Anglo-Paris Basin is described on the basis of detailed lithological logs and extensive records of macrofossils and microcrinoids. In the almost complete absence of ammonites, inoceramid bivalves afford the highest resolution correlation of these stages in chalks, but their value here is limited by the absence of key genera and species, most notably in the Upper Coniacian and middle and Upper Santonian. Echinoids and other macrofossils (brachiopods, stalked crinoids, belemnites) have proved useful, but many are long-ranging or uncommon. Some marker beds, including flints and marl seams, provide useful correlations across the basin, but are locally absent. For the Upper Santonian, the stemless benthonic crinoids Uintacrinus and Marsupites provide high-resolution correlation, both within the basin and to other regions. The successions on the basin margins, in the far north of France (Nord, Pas de Calais) and the southwest (Touraine) are condensed and yield ammonites in association with important inoceramid species. The controls on sedimentation caused by sea-level changes are evaluated on a basinal and global scale, most especially for the Upper Santonian.

7

Application of palynomorphs and palynofacies in Early Cretaceous paleoenvironmental reconstruction; Shushan Basin, Egypt

Mahmoud Magdy, Temraz Amal, Moawad Abdel-Rahim, Khalaf Miran

Acta Geologica Polonica

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2024

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Vol. 74, no. 2

art. no. e13

EN

An integration of palynomorph and palynofacies data from the Shushan-1X well is used to infer the paleoenvironmental conditions of the Valanginian to Middle Cenomanian (Cretaceous) section of the western Shushan Basin, northern Egypt. The data obtained contribute significantly to the depositional history of the basin. The low diversity of dinoflagellate cyst assemblages, along with the dominance of land-derived spores and pollen, suggest restricted (marginal) marine environments, in contrast to their coeval representatives from the Tethyan Realm. Open marine (inner shelf) environments developed at a few horizons in the Dahab and Bahariya formations, partly contemporary with the global Aptian and Cenomanian eustatic cycles. These environments were relatively more offshore than those described in the eastern and southeastern parts of the basin. The study of total palynological organic matter (TPOM) has contributed largely to these established environmental settings. It has also allowed the recognition of redox (suboxic to anoxic) conditions and the impact of a large magnitude of terrigenous influence.

8

West to East in the Cretaceous – Greenhouse climate events and sea-level change

Wagreich Michael

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

77--77

EN

The Cretaceous greenhouse climate interval was characterized by intervals of extreme hothouse climate that lead to environmental Earth System events like the Oceanic Anoxic Events. In addition, the potentially ice-free hothouse, besides high magmatic activity due to final Pangaea breakup, fostered maximum sea-level with prolonged highstands more than 250 m above today’s sea level. The mid-Cretaceous interval, between OAE 1a (early Aptian) and OAE 2 (late Cenomanian), constitutes the time of most pronounced hothouse intervals leading to (nearly) global OAEs due to eutrophication of oceans, plankton blooms, expansion of oxygen minimum zones up to the photic zone, and down to the deep-sea bottom. This resulted regionally in black shale deposition and a minor extinction event of e.g. about 25% of planktic foraminifera. Taking OAE 2 as a case study, which constitutes the Cretaceous Thermal Maximum interval of at least more than 30–35°C equatorial ocean surface temperatures, high-precision stratigraphy based on cyclostratigraphy, astrochronology and numerical dating, a 300 to 700 ka OAE carbon isotope excursion interval can be reconstructed, ending in a recovery phase up to 1 Ma. Cyclostratigraphy results in 100 ka and 405 ka eccentricty signals, most significant in Tethyan areas and other lower latitude realms. Obliquity signals may be present in higher latitudes and may relate to higher precipitation, humid-arid and megamonsoon cycles. However, also during OAE 2, a significant cooling event, the Plenus Cold Event, is present, and may have resulted in intermittent ice shields on Antarctica. This cold snap is still represented in southern Tethys sections such as Tunisia based on stable isotopes and faunal migrations. Climate and temperature-have driven eustatic sea-level fluctuations, modulating the high sea level of the Cretaceous resulting from magmatic processes. During ice-free hothouse times, aquifer eustasy was the main process driving global sea level, at least on an amplitude of 30–50 m. Intermittent ice shields may conteract aquifer eustasy with higher magnitude glacial eustasy during cooler greenhouse phases like the Plenus Cold Event, but this is still under exploration. Major hothouse sea-level cycles have a cyclicity of about 1–1.2 Ma, showing precession- and eccentricity-modulated long-obliquity cycles in pelagic and shallow-water successions. This builds the basic sequence stratigraphy cycles during prominent greenhouse intervals of the Earth system, at least during the Mesozoic. Linking such greenhouse times models to our Anthropocene warming planet indicates a stronger hydrological cycle during warming and rising sea-levels.

9

The earliest Cretaceous carbonate platform destroyed by volcanism from the Ukrainian/Romanian Carpathians – reconstruction based on microfacies

Iwańczuk Joanna, Krobicki Michał, Feldman-Olszewska Anna, Hnyłko Oleh

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

31--31

EN

There is a unique tectonostratigraphic unit called Kaminnyi Potik occur in the Ukrainian-Romanian Carpathian transborder zone. In the Ukrainian part numerous outcrops of this unit can be observed in many streams near Rachiv city, but its most spectacular occurrence is in the Chyvchyn Mountains. The whole complex consists of volcanogenic-sedimentary rocks and is divided into two Berriasian formations: Chyvchyn and Kaminnyi Potik. In the section of the Chyvchyn Formation, at the base, there are pillow lavas (basalts and andesites/trachyandesites) and volcano-sedimentary breccia with clasts of lava, coral limestones and radiolarites (submarine debris flows), and peperites as well. The Kaminnyi Potik Formation is made up of fine-grained hyaloclastic and carbonate debris flows of a flysch character (including organodetrital limestones with fragments of: corals, bryozoans, echinoderms bivalves and foraminifera), which overlying breccias and coral limestones of the Chyvchyn Formation. The profile ends by thin-bedded cherty limestones. The thin sections analysis revealed the following microfacies: oolithic-echinoderm packstone/grainstone; coral lithoclastic quartz packstone/grainstone; oolithic-lithoclastic wackestone/packstone; lithoclastic-echinoderm packestone; lithoclastic packestone; radiolarian echinoderm packestone; radiolarian wackestone; radiolarian-calpionellid wackestone and mudstone. Pyroclastic material is often present in the matrix. The ooids observed in the thin sections and the remains of fauna such as corals, echinoderms and bivalves suggest that the original material came from a carbonate platform that was sheltered by a coral reef. As a result of volcanic eruptions and possibly accompanying earthquakes, the platform has been destroyed and its traces are visible in clasts. Sedimentological character of submarine debris flows, (e.g. fractional graiding, mixture of shallow-water fauna and lithoclasts with deep-marine microfauna (radiolarians and calpionellids) and hyaloclastic material present in the matrix document short-term episodes of a catastrophic nature, leading to the redeposition of shallow-water sediments to the deeper parts of the basin.

10

Stop 6. Biała Woda valley – “mid”-Cretaceous basaltic olistolith

Oszczypko Nestor, Krobicki Michał, Salata Dorota

Geotourism / Geoturystyka

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2023

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nr 3-4 (74-75)

36--37

11

Stop 3. Bereśnik hill near Jaworki village (“mid”-Cretaceous pelagic shell beds, Late Cretaceous deposits and inversion structure)

Krobicki Michał

Geotourism / Geoturystyka

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2023

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nr 3-4 (74-75)

30--31

12

Jurassic and Cretaceous evolution of Tethys: Palaeoceanographic events

Yilmaz İsmail Ömer

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

81--81

EN

Jurassic and Cretaceous evolution of Tethys Ocean is characterized by extension of oceans basins, rifting, development of carbonate platforms and sea level fluctuations. Ocean basins and platform margins were sides of records of collaboration of oceanic, sea level and climate changes in different scales. Deposition of organic sediment increased on the margins of the ocean basins at certain time intervals due to changes in oceanic circulation and chemistry, productivity, climate and sea level. Oceanic Anoxic Events (OAE) stated to took place at aperiodic time intervals and generally associated with organic matter deposits and anoxic water columns. Records of oceanic anoxic event can also be associated by potential source rocks in Jurassic and Cretaceous along Tethys Ocean basins and can be tracked by stable isotope shifts, turnover of fossil groups, presence of black shales/organic rich mudstones, change in redox sensitive elements. Volcanic contribution in oceans is also considered as one of the collaborators of OAE generations. OAE records in Jurassic is seen in Toarcian interval and stated as Toarcian OAE. In Cretaceous, OAE records can be stated as Weissert, Faraoni, Selli (OAE1a), Noir, Fallot, Jacop, Kilian, Paquier (OAE1b), Leenhardt, Amadeus (OAE1c), Breistroffer (OAE1d), Bonarelli (OAE2), and OAE3. Generally, Cretaceous OAE are globally correlated or at least hemispherical. Some of them can be weakly correlated due to different duration and magnitude. Stratigraphic positions of OAE can also be used better marker levels in sequence stratigraphic interpretations. Therefore, positions of OAE are very important in terms of higher resolution for platform to basin correlations and even basin to basin. Cretaceous Oceanic Anoxic Events in eastern Tethys Ocean in Pontides and Taurides can be seen in Cretaceous successions (Mid-Barremian, Aptian, Albian, Cenomanian-Turonian) of Central Pontides (NW Turkey) and Central Taurides (S Turkey) (Yilmaz et al., 2004, 2010, 2012) as presence of black shales. The Mid-Barremian black shales (MBE) have been recorded within turbidite succession in deep marine setting in central Sakarya zone of Pontides following the drowning of the platform (Yilmaz et al., 2012). 2‰ shifts in carbon isotope curve is recorded in parallel with European basins, but with low TOC value. The Aptian black shales (OAE1a) are recorded in pelagic carbonate slope environments in central and north of Sakarya zone of Pontides and represented by a negative carbon isotope shift with 2‰, and TOC around 2% (Yilmaz et al., 2004; Hu et al., 2012). In Sakarya zone of Pontides, OAE2 is recorded in pelagic slope carbonates with carbon isotope curve more than 1‰ positive shift and >2% TOC. Another OAE2 was recorded in Antalya Nappes of Taurides without carbon isotope curve but TOC > 20% (Yurtsever et al., 2003, Bozcu et al., 2011). OAE1a equivalent in Tauride Carbonate platform can be interpreted as presence of dark colored thick stromatolite bearing platform carbonates transgressivley overlying the karstic sequence boundary. The OAE1a and OAE2 levels recorded in Turkey can easily be correlated with European examples and mainly controlled by sea level and tectonics in largescale and climate and oceanographic changes in small-scale. The most extensive distribution of the OAE records in Turkey belong to OAE1a and OAE2, and display potential for source rocks for hydrocarbon exploration.

13

A silicified wood from the Early Cretaceous sediments in the Kaligandaki Valley, west central Nepal

Paudayal Khum N., Paudel Lalu P., Uhl Dieter

Geotourism / Geoturystyka

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2023

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nr 1-2 (72-73)

55--55

EN

A silicified wood has been discovered from the Tethyan Cretaceous (Berriasian) deposits belonging to the Kagbeni Formation of north Central Nepal. The wood exhibits anatomical features which are well in accordance with Araucarioxylon nepalense described by Barale et al. (1976) from another locality in the Kagbeni Formation near Kagbeni in the Thakkhola Valley in Central Nepal. It is a pycnoxylic wood with mostly uniseriate and rarely biseriate bordered pits on radial tracheid walls. According to recent taxonomic opinions this type of wood should not be treated as Araucarioxylon, but as Agathoxylon Hartig. Thus we propose the name Agathoxylon nepalense comb. nov. for this type of wood. The sandstones of the Kagbeni Formation have been interpreted as delta-deposits, with a major flow direction from the south. This suggests that the wood originated from the northern margin of Indian sub-continent.

14

The Upper Turonian–Lower Coniacian (Upper Cretaceous) ammonites from the condensed phosphate beds of Mangyshlak, NW Kazakhstan

Kennedy William J., Walaszczyk Ireneusz

Acta Geologica Polonica

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2023

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Vol. 73, no. 4

635--660

EN

Eleven ammonites species are described from the condensed phosphate beds of Mangyshlak (in north-western Kazakhstan): Lewesiceras mantelli (Wright and Wright, 1951), Subprionocyclus neptuni (Geinitz, 1849), Prionocyclus spp., Allocrioceras angustum (J. de C. Sowerby, 1850), Hyphantoceras (Hyphantoceras) reussianum (d’Orbigny, 1850), Hyphantoceras (Hyphantoceras) cf. flexuosum (Schlüter, 1872), Eubostrychoceras (Eubostrychoceras) cf. saxonicum (Schlüter, 1875), Scalarites? bohemicus (Fritsch, 1872), Sciponoceras bohemicum bohemicum (Fritsch, 1872), Scaphites geinitzii d’Orbigny, 1850, and Scaphites kieslingswaldensis Langenhan and Grundey, 1891. They provide an incomplete record that spans at maximum upper Middle Turonian to Lower Coniacian and at minimum Upper Turonian to Lower Coniacian. Associated inoceramid bivalves span an interval from upper Middle Turonian (based on the known first occurrence of Inoceramus inaequivalvis Schlüter, 1872) to the lower and middle Lower Coniacian, based on the known last occurrence of Cremnoceramus crassus inconstans (Woods, 1912), in the lower and middle parts of the Lower Coniacian.

15

Stratigraphy of the Albian-Cenomanian (Cretaceous) phosphorite interval in central Poland: a reappraisal

Machalski Marcin, Olszewska-Nejbert Danuta, Wilmsen Markus

Acta Geologica Polonica

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2023

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Vol. 73, no. 1

1--31

EN

Several closely-spaced phosphorite beds stand out at the Albian–Cenomanian transition in the mid-Cretaceous transgressive succession at the northeastern margin of the Holy Cross Mountains, central Poland. They form a distinctive condensed interval of considerable stratigraphical, palaeontological, and economic value. Here, we correlate the classical section at Annopol with a recently investigated section at Chałupki. We propose a new stratigraphic interpretation of the phosphorite interval, based on lithological correlations, Rare Earth Elements and Yttrium (REE+Y) signatures of phosphorites, age-diagnostic macrofossils, and sequence stratigraphic patterns. This interval has long been considered as exclusively Albian in age. However, new macrofossil data allow us to assign the higher phosphorite levels at Annopol and Chałupki, which were the primary target for the phosphate mining, to the lower Cenomanian. In terms of sequence stratigraphy, the phosphorite interval encompasses the depositional sequence DS Al 8 and the Lowstand System Tract of the successive DS Al/Ce 1 sequence. The proposed correlation suggests that lowstand reworking during the Albian–Cenomanian boundary interval played an important role in concentrating the phosphatic clasts and nodules to exploitable stratiform accumulations. Our conclusions are pertinent to regional studies, assessments of natural resources (in view of the recent interest in REE content of the phosphorites), and dating of the fossil assemblages preserved in the phosphorite interval. On a broader scale, they add to our understanding of the formation of stratiform phosphorite deposits.

16

Review of the Cretaceous dinosaurs from India and their paleobiogeographic significance

Khosla Ashu, Lucas Spencer G.

Acta Geologica Polonica

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2023

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Vol. 73, no. 4

707--740

EN

The Indian Mesozoic dinosaur record is famous for documenting significant aspects of dinosaur evolution during the Triassic, Jurassic and Cretaceous periods. The Cenomanian–Turonian Nimar Sandstone, Lower Narmada valley, has produced fragmentary skeletal remains of Sauropoda indet. The Maastrichtian Lameta Formation has yielded at least 5 valid sauropod taxa and indeterminate titanosaurid remains, and at least 11 named (but likely oversplit) theropod taxa, i.e., 3 smaller-bodied species and 8 medium-to-large sized theropods. Apart from skeletal remains, Infra- and Intertrappean beds of peninsular India have yielded more than 10,000 dinosaur eggs belonging to 5 oofamilies and 15 oospecies. Most of the Indian ootaxa show distinct affinities with the Late Cretaceous ootaxa of four other continental areas – Spain, France, Argentina and Morocco. The presence of the two dominant oofamilies, Fusioolithidae and Megaloolithidae, in the Infra- and Intertrappean localities of peninsular India and three different continents (South America, Europe and Africa) further shows an ancient Gondwanan affinity and basic terrestrial association among these three landmasses. Based on the phylogenetic analysis of skeletal material, the most plausible pathway of dinosaur dispersal between India and Madagascar took place during the Late Cretaceous. The other conceivable dispersal pathway for the small animals was between India and Asia by means of the Kohistan Dras Volcanic Arc or a northeast pathway through Somalia, while the very large vertebrates, like theropod dinosaurs, may have emerged as a component of a ‘Pan Gondwanan’ model.

17

Middle Campanian (Late Cretaceous) sea-level rise; microfossil record of bathymetric changes

Fąfara Michał, Dubicka Zofia, Niechwedowicz Mariusz, Ciurej Agnieszka, Walaszczyk Ireneusz

Acta Geologica Polonica

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2023

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Vol. 73, no. 4

661--683

EN

A Middle Campanian (Late Cretaceous) eustatic sea-level rise recorded in the Belgorod succession (Russia; eastern North European Basin) was analyzed. The succession, dated for the Gavelinella annae and Globorotalites emdyensis foraminiferal zones (corresponding to the ‘Inoceramus’ azerbaydjanensis–‘Inoceramus’ vorhelmensis inoceramid Zone), records the deposition of pure chalk, with only trace terrigenous material. Its distal offshore position limited terrestrial nutrient delivery, driving oligotrophic conditions that influenced benthic foraminifera and organic-walled phytoplankton communities. Eustatic changes are recorded by planktonic foraminifera and additionally reflected in phytoclast abundance, organic-walled dinoflagellate cysts (dinocysts), calcareous dinoflagellate cysts (c-dinocysts), and δ13C and δ18O fluctuations. Most indices were primarily driven by variable terrestrial organic matter and freshwater influxes, acting as a function of sea depth and land topography.

18

Microcrinoids (Roveacrinidae) from the Middle–Upper Cenomanian Grey Chalk Subgroup, Dover (Kent, United Kingdom): biostratigraphy and re-evaluation of cup structure in roveacrinids

Gale Andrew Scott

Acta Geologica Polonica

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2023

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Vol. 73, no. 4

685--705

EN

New material of Roveacrinidae from the Middle–Upper Cenomanian Grey Chalk Group of the Kent coast (Folkestone-Dover) is described. The fauna includes 10 taxa, including a new genus and species (Dubrisicrinus minutus) and three new species (Styracocrinus shakespearensis, Roveacrinus aboudaensis and Dentatocrinus serratus). The biostratigraphical significance of roveacrinid faunas is placed in a global context, and it is demonstrated that the roveacrinid zone CeR5, previously recorded only from Morocco, is approximately equivalent to the upper Middle Cenomanian Acanthoceras jukesbrownei ammonite Zone, and zone CeR6 – to the Calycoceras guerangeri ammonite Zone. The new material also provides novel information on the cup structure of roveacrinids, which is reviewed and placed in a phylogenetic context.

19

A marker band folgen stratigraphy for the Cenomanian Chalk of England and its extension to northen Germany and France

Jeans Christopher Vincent

Acta Geologica Polonica

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2023

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Vol. 73, no. 2

135--180

EN

A novel stratigraphical scheme within the Folge Concept is described for the Cenomanian Chalk of England that is particularly suitable for investigating the regional changes in the lithofacies, diagenesis, geochemistry, and mineralogy of the sediments of the Chalk Sea leading up to the Cenomanian–Turonian Oceanic Anoxic Event. It is based on “isochronous” marker bands defined largely by calcitic macrofossil assemblages, and it avoids problems caused by the poor or non-preservation of ammonite assemblages and lateral changes in chalk lithofacies. Eight folgen are based on one, two, or more marker bands. Their sequences, lithologies and calcitic macrofossil assemblages are described from 33 exposures in the Northern Chalk Province of England. The folgen are named, in ascending order, the Belchford, Stenigot, Dalby, Bigby, Candlesby, Nettleton, Louth and Flixton, after villages in Lincolnshire and Yorkshire, England. The folgen are traced throughout the Transitional and Southern Chalk provinces of England. They are present in the Cenomanian chalk of northern Germany and northwest France. Regionally, an individual folge may display considerable vertical and lateral variation in general lithology and lithofacies whilst still maintaining their defining marker bands. The possibility of further refinement to the scheme is discussed.

20

Upper upper Albian (Mortoniceras rostratum Zone) cephalopods from Clansayes (Drôme, south-eastern France)

Jattiot Romain, Lehmann Jens, Latutrie Benjamin, Tajika Amane, Vennin Emmanuelle, Vuarin Pauline, Brayard Arnaud, Fara Emmanuel, Trincal Vincent

Acta Geologica Polonica

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2022

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Vol. 72, no. 2

187--233

EN

We document an upper upper Albian (Mortoniceras rostratum Zone) cephalopod assemblage from Clansayes (Drôme, south-eastern France). Although fossils are rare in local exposures and in the single sampled level, a decade of intensive fossil collecting yielded 290 ammonite and 5 nautilid specimens. In total, we describe 1 species of nautilid and 24 species (within 17 genera) of ammonites, including 13 heteromorphs. Only two of these ammonite taxa were previously recorded from the upper upper Albian at Clansayes, which demonstrates the value of this fauna with regard to taxonomy, palaeobiology and palaeobiogeography. Based on morphological and biometric analyses performed on an extensive material (104 specimens), we discriminate two species for the heteromorphic ammonite genus Mariella Nowak, 1916 within the Mortoniceras rostratum Zone. In addition, we investigate shell chirality patterns in Mariella from the late Albian of southern France. Upon comparison of the Clansayes material with older material from the immediately underlying upper Albian Mortoniceras fallax Zone at the neighbouring Salazac locality, we identify an increase in the proportion of sinistral specimens. This observed increase in the frequency of sinistral Mariella specimens may hypothetically be part of a global evolutionary pattern, considering that nearly all documented younger Cenomanian Mariella (and more generally Cenomanian turrilitids) are sinistral.