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1

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.

2

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.

3

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.

4

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.

5

Taxonomy and palaeoecology of the Late Cretaceous (Campanian) Phymatellidae (lithistid demosponges) from the Miechów and Mogilno-Łódź synclinoria (southern and central Poland)

Świerczewska-Gładysz Ewa, Jurkowska Agata

Annales Societatis Geologorum Poloniae

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2023

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Vol. 93, No. 3

269--304

EN

Phymatellid demosponges are common fossils in the Campanian deposits of central Europe. In Poland, the Campanian phymatellids were known mostly from the opoka facies of the Miechów Synclinorium (southern Poland), where they occur mainly in the characteristic horizons of siliceous nodules in the lower Campanian opoka succession. Similarly preserved early Campanian phymatellids were identified in a redeposited lithistid assemblage in the Neogene gravels, exposed in the Bełchatów Lignite Mine (Mogilno-Łódź Synclinorium, central Poland). Rare phymatellids were noted for the first time in the upper Campanian gaize of the Miechów Synclinorium. The taxonomic descriptions of 16 phymatellid species presented here, including one new species, Kalpinella fragilis, completes existing knowledge of the taxonomic diversity of these sponges in the Late Cretaceous basins of central Europe. The present study also supplements the data on the stratigraphic ranges and spatial distribution of these species. The palaeoecology of Cretaceous phymatellids is discussed on the basis of their occurrence in the various facies.

6

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.

7

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.

8

Opoka – a mysterious carbonate-siliceous rock: an overview of general concepts

Jurkowska Agata, Świerczewska-Gładysz Ewa

Geology, Geophysics and Environment

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2022

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Vol. 48, no. 3

257--278

EN

The opoka is a carbonate-siliceous marine sedimentary rock, forming a thick succession of Upper Cretaceous age in Poland and in another regions of Europe. This rock has been studied for over 150 years, but only the use of modern analytical techniques enables for the formulation of its mineralogical definition, which identifies the distinct features of opoka and allows it to be distinguished from other rocks (e.g. chalk, gaize). Parallel to the petrographic research on opoka, its palaeobathymetric interpretations, which were based on the palaeotectonic models of Danish-Polish Trough inversion has been revised. Depending on the model of palaeotectonic history, opoka has been interpreted as a deep-water or shallow facies, without detailed petrographic studies of its mineralogical composition. The paper presents various aspects of opoka, including: history of the term, nomenclature, mineralogical composition, microtexture and palaeoecological significance of Cretaceous opoka. New data which permit precise definition of this rock term, and its mineralogical composition are discussed in the light of palaeoecological reconstructions, bathymetry and existing models of opoka distribution.

9

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.

10

Charakterystyka litofacjalna utworów jury górnej i kredy dolnej w rejonie Dąbrowa Tarnowska – Dębica w oparciu o interpretację danych sejsmicznych i otworowych

Urbaniec Andrzej

Prace Naukowe Instytutu Nafty i Gazu

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2021

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nr 232

1--240

PL

Głównym celem monografii jest odtworzenie historii depozycji i rozwoju facjalnego utworów górnej jury i dolnej kredy, występujących w podłożu zapadliska przedkarpackiego, w oparciu o dostępne dane z otworów wiertniczych oraz sejsmikę 3D. Rejon badań usytuowany jest w środkowej części przedgórza Karpat, pomiędzy miastami Dąbrowa Tarnowska na północnym zachodzie i Dębica na południowym wschodzie. Nowe dane, uzyskane w roku 2015, w postaci zdjęcia sejsmicznego 3D, jak również informacji z głębokiego otworu O-1 przewiercającego pełen profil utworów mezozoiku, pozwoliły na znacznie lepsze rozpoznanie i udokumentowanie wielu szczegółów budowy geologicznej tego, dotąd słabo rozpoznanego, rejonu. Sedymentacja badanych utworów węglanowych przedgórza Karpat w epokach późnojurajskiej i wczesnokredowej odbywała się w strefie szelfowej północnego, pasywnego brzegu oceanu Tetydy. Cechą charakterystyczną utworów górnej jury jest ich duże zróżnicowanie facjalne, wynikające głównie z obecności rozbudowanych kompleksów biohermowych oraz pakietów warstwowanych osadów marglisto-wapiennych. W rozdziale 2 przedstawiono budowę geologiczną rejonu badań, uwzględniając wszystkie piętra strukturalne, rozwój litologiczny utworów poszczególnych jednostek, stosowane podziały litostratygraficzne i regionalne ramy paleogeograficzne. W rozdziale 3 szczegółowo omówiona została historia badań oraz aktualny stan rozpoznania kompleksu węglanowego górnej jury i dolnej kredy przedgórza Karpat. Rozdział 4 zawiera charakterystykę litologiczną badanych utworów węglanowych z podziałem na jednostki litostratygraficzne. Charakterystyka ta opracowana została na podstawie analizy cech makroskopowych dostępnego materiału rdzeniowego oraz profilowań geofizyki otworowej. Zamieszczone profile litostratygraficzne wybranych głębokich otworów wiertniczych z obszaru badań lub jego bliskiego sąsiedztwa dokumentują obecny stan wiedzy na temat litostratygrafii i rozwoju facjalnego utworów górnej jury i dolnej kredy. W rozdziale 5 przedstawiono charakterystykę mikrofacjalną i mikropaleontologiczną badanych utworów węglanowych, jak również przeprowadzono dyskusję dotyczącą możliwości określenia zasięgu wiekowego poszczególnych wydzieleń litostratygraficznych w oparciu o wyniki wieloletnich badań oraz dane literaturowe. W rozdziale 6 zaprezentowano wyniki analizy obrazu sejsmicznego, wykonanej w oparciu o wybrane atrybuty sejsmiczne. W ramach pracy omówiono następujące atrybuty: RMS Amplitude, Envelope, Instantaneous phase, Dominant frequency, Instantaneous bandwidth, Apparent polarity, Relative acoustic impedance, First derivative, Iso-frequency component, Time gain, Chaos, Variance (Edge method), Local flatness. Przeprowadzona analiza pozwoliła na uzyskanie dodatkowych istotnych informacji odnośnie wykształcenia litologicznego i rozprzestrzenienia utworów poszczególnych ogniw litostratygraficznych, jak również dała możliwość uszczegółowienia lokalizacji dyslokacji. Na podstawie interpretacji zapisu sejsmicznego w obrębie badanego kompleksu skalnego udokumentowano również występowanie niezgodności kątowych, stref zaburzeń i deformacji związanych z tektoniką synsedymentacyjną oraz przypuszczalnych osadów spływów grawitacyjnych. W rozdziale 7 zamieszczono przekroje litofacjalne, skonstruowane wzdłuż wybranych przekrojów sejsmicznych, prezentujące przestrzenny rozkład i wzajemne relacje pomiędzy utworami poszczególnych ogniw litostratygaficzych. W rozdziale 8 przeanalizowano rozmieszczenie kompleksów biohermowych górnej jury względem morfologii podłoża jury. Analiza rozmieszczenia wykartowanych na podstawie zapisu sejsmicznego budowli organicznych, należących do serii wielkich bioherm gąbkowo-mikrobialnych, wskazuje na dwa główne obszary ich występowania, tj. rejon NW (kompleks biohermowy „N”), w którym występuje dosyć rozległy kompleks biohermowy, a jego dokładny zasięg jest trudny do ustalenia ze względu na późniejsze procesy regionalnej dolomityzacji oraz rejon centralny (kompleks biohermowy „S” w okolicach otworu O-1), w którym stwierdzono kompleks kilku wysokich budowli o dosyć stromych krawędziach. Rozdział 9 poświęcony jest zagadnieniu historii depozycyjnej późnojurajsko-wczesnokredowego basenu sedymentacyjnego przedgórza Karpat oraz omówieniu roli najważniejszych czynników wpływających na rozkład facji w obszarze badań. Wykazano, że cechą charakterystyczną znacznej części osadów jurajskich jest silnie diachroniczny charakter rozprzestrzenienia poszczególnych facji, uwarunkowany głównie paleogeomorfologią dna zbiornika sedymentacyjnego, jak również czynnikami lokalnymi, związanymi z tektoniką synsedymentacyjną. Seria gąbkowo-globuligerinowa, rozpoczynająca profil utworów górnej jury i reprezentująca najgłębszy etap sedymentacji w warunkach otwartego szelfu, cechuje się stosunkowo dużą jednorodnością wykształcenia na całym obszarze przedgórza. Kompleks biohermowy „S” rozwinął się w nadkładzie elewowanej strefy, złożonej z kilku mniejszych elementów tektonicznych, natomiast kompleks biohermowy „N” wykształcił się na rozległej, wyniesionej części strefy zrębowej, gdzie w podłożu występuje jeden główny blok tektoniczny. Intensywnie rozwijające się kompleksy biohermowe „N” i „S” wywierały coraz większy wpływ na dalszy rozwój sedymentacji osadów górnej jury w badanym rejonie, dostarczając jednocześnie materiału dla osadów redeponowanych w głębsze partie zbiornika w wyniku podmorskich spływów grawitacyjnych. W strefie przylegającej od SE do kompleksu biohermowego „S”, na profilach sejsmicznych dostrzegalny jest charakterystyczny, wysokoamplitudowy zapis obejmujący cały pakiet refleksów sejsmicznych o zmiennych kątach upadów. Częste zmiany polarności, dostrzegalne w obrębie tej strefy w odtworzeniu atrybutu Apparent polarity, podobnie jak i skrajnie zmienny zakres wartości atrybutu Relative acoustic impedance, świadczą o silnym zróżnicowaniu litologicznym tego kompleksu skalnego. W tytonie, w trakcie sedymentacji utworów serii koralowcowo-onkolitowej, nastąpiło wyraźne ujednolicenie warunków sedymentacji na całym obszarze przedgórza Karpat, związane głównie z zanikiem paleomorfologicznego zróżnicowania powierzchni dna morza. Przypuszczalnie w tym samym czasie miał miejsce kolejny etap reaktywacji dyslokacji, o czym świadczy powierzchnia niezgodności kątowej, i związane z nią efekty erozji osadów starszych. Rozprzestrzenione na całym obszarze badań utwory serii muszlowcowo-oolitowej dolnej reprezentują różnego typu płytkowodne środowiska sedymentacji (w tym środowisko równi pływowej, lagunowe i stref barierowych), jakie wykształciły się na obszarze przedgórza Karpat, na pograniczu późnej jury i wczesnej kredy. Środowisko sedymentacji utworów serii marglisto-muszlowcowej, datowanej na berias, określić można jako skrajnie płytkowodne, z facjami lagunowymi i wpływem środowisk brakicznych. Utwory najwyższych serii dolnej kredy (tj. mułowcowo-wapiennej i muszlowcowo-oolitowej górnej) reprezentują facje płytkomorskie związane z transgresją morską, która miała miejsce w walanżynie. Przedstawiona historia depozycyjna późnojurajsko-wczesnokredowego basenu sedymentacyjnego przedgórza Karpat, w połączeniu z opisem cech makroskopowych rdzeni wiertniczych, analizą mikrofacjalną i mikropaleontologiczną poszczególnych jednostek litostratygraficznych oraz interpretacją obrazu sejsmicznego, pozwala na kompleksową charakterystykę analizowanych utworów oraz wskazanie procesów mających największy wpływ na obecny charakter i stan zachowania badanych serii skalnych.

EN

The main subject of this monograph is a reconstruction of the history of deposition and facial development of Upper Jurassic and Lower Cretaceous deposits in the basement of the Carpathian Foredeep, based on data available from boreholes and a 3D seismic survey. The research area is located in the central part of the Carpathian Foreland, between two cities: Dąbrowa Tarnowska in the north-west and Dębica in the south-east. The new 3D seismic survey made in 2015 and the O-1 deep borehole – drilled in the same year and portraying a full profile of the Mesozoic sediments – allowed for much better recognition and documentation of many details of the geological structure of this previously poorly mapped area. The sedimentation of the carbonate formations of the Carpathian Foreland during the Late Jurassic and the Early Cretaceous took place in the shelf zone of the northern, passive margin of the Tethys Ocean. A characteristic feature of the Upper Jurassic sediments is their high facies diversity, due mainly to the presence of biohermal complexes and sets of layered marly-limestone sediments. Chapter 2 presents the geological structure of all structural stages in the area under study, including the lithological development, the lithostratigraphic divisions applied, and the regional palaeogeographic frameworks. Chapter 3 discusses both the history of research and the current state of knowledge regarding the Upper Jurassic and Lower Cretaceous carbonate sediments of the Carpathian Foreland. Chapter 4 describes the lithological characteristics of the carbonate sediments, considering lithostratigraphic units. This characterisation is based on a macroscopic examination of the available core material and analysis of the well logs. The lithostratigraphic profiles of selected deeper boreholes from the research area and its close vicinity document the current state of knowledge on lithostratigraphy and the facies development of the Upper Jurassic and Lower Cretaceous deposits. Chapter 5 features the microfacies and micropalaeontological characteristics of the carbonate sediments under study. Based on the results of many years of research and literature data, the possibilities of determining the age of every lithostratigraphic unit are discussed. Chapter 6 presents the analysis of the seismic 3D image based on selected seismic attributes. As part of the work, the following attributes are discussed: RMS Amplitude, Envelope, Instantaneous phase, Dominant frequency, Instantaneous bandwidth, Apparent polarity, Relative acoustic impedance, First derivative, Iso-frequency component, Time gain, Chaos, Variance (Edge method), and Local flatness. The analysis revealed additional important information regarding both the lithological development and the spatial range of sediments of individual lithostratigraphic units, at the same time facilitating the detailed location of fault zones. Based on the interpretation of the seismic image within the studied rock complex, the occurrence of angular unconformity, disturbance, and deformation zones related to synsedimentary tectonic as well as probable gravity-flow deposits are also documented. Chapter 7 presents lithofacial cross-sections constructed along selected seismic sections reflecting the spatial distribution and relationships between the sediments of individual lithostratigraphic units. Chapter 8 analyses the distribution of Upper Jurassic biohermal complexes in relation to the morphology of the Jurassic base surface. An analysis of the distribution of organic buildups belonging to the Huge Sponge-Microbial Bioherms Series, interpreted indirectly from seismic image, indicates two main areas where they can be found. These are the north-west part of the study area – where a quite extensive biohermal complex occurs (‘Complex N’), the exact range of which is difficult to determine due to later regional dolomitisation processes – and the area located in the central part of the seismic survey, where a complex of several very tall buildups with steep edges was found (‘Complex S’). Chapter 9 is devoted to the issue of the depositional history of the Late Jurassic–Early Cretaceous sedimentary basin of the Carpathian Foreland and to a discussion of the role of the most important factors influencing facies distribution in the research area. It has been shown that a characteristic feature of a large part of the Jurassic sediments is the strongly diachronic nature of the distribution of facies controlled by the varying bottom relief of the sedimentation basin and by some local factors related to synsedimentary tectonic episodes. The Sponge-Globuligerinid Series, beginning the profile of the Upper Jurassic sediments and representing the deepest sedimentation stage in the open shelf conditions, is characterised by a relatively high homogeneity of lithology in the whole Carpathian Foreland area. The ‘S’ biohermal complex developed over the elevated zone composed of several smaller tectonic elements, whilst the ‘N’ biohermal complex developed on a large, elevated part of the horst zone. The intensively developing ‘N’ and ‘S’ biohermal complexes affected successive deposition of the Late Jurassic sedimentary basin in the study area more and more. Those biohermal complexes were the source of the material redeposited into deeper parts of the sedimentary basin. On seismic profiles in the south-east neighbourhood of the ‘S’ biohermal complex, there is a characteristic high-amplitude record including the entire reflection set of variable dip angles. The frequent polarity changes which are visible within this zone in the Apparent polarity attribute, as well as the extremely variable range of values the Relative acoustic impedance attribute, prove the strong lithological differentiation of this rock complex. During the Tithonian time (sedimentation of the Coral-Oncolite Series), there was clear unification of the sedimentation conditions in the entire Carpathian Foreland area, mainly due to disappearance of the bottom relief diversity. At the same time another stage of dislocation reactivation occurred, as evidenced by the angular unconformity and the erosion traces of older sediments associated with this unconformity. The deposits of the Lower Shellbed-Oolite Series scattered throughout the research area represent various types of shallow-water sedimentation environments (including tidal, lagoon, and barrier zones) that developed in the Carpathian Foreland area on the borderline between the Late Jurassic and the Early Cretaceous. The sedimentation environment of the Marly-Shellbed Series dated to the Berriasian can be described as extremely shallow-water, with lagoon facies and under the influence of brackish environments. The sediments of the last two series of the Lower Cretaceous (i.e. the Mudstone-Limestone and Upper Shellbed-Oolite Series) represent the shallow-marine facies associated with marine transgression that took place during the Valanginian. The processes that have had the greatest impact on the current character and preservation of the rock series under study can be pinpointed and a comprehensive characterisation of these formations can be undertaken thanks to the depositional history of the Late Jurassic – Early Cretaceous sedimentary basin of the Carpathian Foreland presented herein, the macroscopic examination of the available core material, the microfacial and micropalaeontological analysis of individual lithostratigraphic units, and the interpretation of the seismic image.

11

Sedimentology of the Godula Formation in the Moravskoslezské Beskydy Mts. (Outer Western Carpathians, Czech Republic)

Maceček Lukáš

Annales Societatis Geologorum Poloniae

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2021

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Vol. 91, No. 3

309--325

EN

The present account summarizes the results of lithological and facies analysis of representative sections of the Godula Formation, in order to contribute to the understanding of the lithofacies structure of this formation, the processes involved in its development and the character of the depositional environment. The sedimentology of different parts of the Godula Formation was investigated in six representative sections in the western and central parts of the Moravskoslezské Beskydy Mts. The Godula Formation is made up mainly of Upper Cretaceous siliciclastic turbidites and was formed during the most significant depositional phase of the filling of the deep-sea Silesian Basin. On the basis of sedimentological research, five facies classes (including four subclasses) were defined: 1) conglomeratic sandstones, 2) sandstones, 3) sandstones with mudstones, 4) mudstones with sandstones and siltstones, and 5) mudstones with siltstones. The methodology of facies analysis allowed the identification of several facies association, corresponding to the medial and distal parts of a turbidite fan and associated siliciclastic apron. The facies of depositional lobes, lobe transitions and the apron are described. The sandstone and mudstone facies (F3) occurs mostly in the depositional lobes. The sandstone facies (F2) and mudstone with sandstone and siltstone facies (F4) are present only to a lesser degree. The facies of the lobe transitions include lithologic associations of the lobe fringe and channel levee environments. They comprise mainly the mudstones with sandstones and siltstones (F4) and the mudstone with siltstone facies (F5). In the apron deposits, the sandstone facies (F2) and the conglomeratic sandstone facies (F1) predominate. Palaeocurrent analysis from measurements made in selected profiles showed that in the Moravskoslezské Beskydy Mts., the dominant direction of sediment transport was from SW to NE. After applying correction of the known counterclockwise rotation of the nappes of the Outer Carpathians, this corresponds to a longitudinal direction along the original axis of the basin.

12

A lost carbonate platform deciphered from clasts embedded in flysch : Štramberk-type limestones, Polish Outer Carpathians

Hoffmann Mariusz, Kołodziej Bogusław, Kowal-Kasprzyk Justyna

Annales Societatis Geologorum Poloniae

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2021

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Vol. 91, No. 3

203--251

EN

Limestones designated the Štramberk-type are the most common carbonate exotic clasts (exotics) embedded in the uppermost Jurassic–Miocene flysch deposits of the Polish Outer Carpathians. About 80% of stratigraphically determinable carbonate exotics from the Silesian, Sub-Silesian and Skole units (nappes) are of Tithonian (mostly)–Berriasian (sporadically Valanginian) age. A study of these exotics revealed eight main facies types: coral-microbial boundstones (FT 1), microencruster-microbial-cement boundstones (FT 2), microbial and microbial-sponge boundstones (FT 3), detrital limestones (FT 4), foraminiferal-algal limestones (FT 5), peloidalbioclastic limestones (FT 6), ooid grainstones (FT 7), and mudstones-wackestones with calpionellids (FT 8). Štramberk-type limestones in Poland and the better known Štramberk Limestone in the Czech Republic are remnants of lost carbonate platforms, collectively designated the Štramberk Carbonate Platform. Narrow platforms were developed on intra-basinal, structural highs (some of them are generalized as the Silesian Ridge), with their morphology determined by Late Jurassic synsedimentary tectonics. An attempt was made to reconstruct the facies distribution on the Tithonian–earliest Cretaceous carbonate platform. In the inner platform, coral-microbial patch-reefs (FT 1) grew, while the upper slope of the platform was the depositional setting for the microencruster-microbial-cement boundstones (FT 2). Microbial and microbial-sponge boundstones (FT 3), analogous to the Oxfordian–Kimmeridgian boundstones of the northern Tethyan shelf (also present among exotics), were developed in a deeper setting. In the inner, open part of the platform, foraminiferal-algal limestones (FT 5) and peloidal-bioclastic limestones (FT 6) were deposited. Poorly sorted, detrital limestones (FT 4), including clastsupported breccias, were formed mainly in a peri-reefal environment and on the margin of the platform, in a high-energy setting. Ooid grainstones (FT 7), rarely represented in the exotics, were formed on the platform margin. Mudstones-wackestones with calpionellids (FT 8) were deposited in a deeper part of the platform slope and/or in a basinal setting. In tectonic grabens, between ridges with attached carbonate platforms, sedimentation of the pelagic (analogous to FT 8) and allodapic (“pre-flysch”) Cieszyn Limestone Formation took place. The most common facies are FT 4 and FT 1. Sedimentation on the Štramberk Carbonate Platform terminated in the earliest Cretaceous, when the platform was destroyed and drowned. It is recorded in a few exotics as thin, neptunian dykes (and large dykes in the Štramberk Limestone), filled with dark, deep-water limestones. Reefal facies of the Štramberk Carbonate Platform share similarities in several respects (e.g., the presence of the microencrustermicrobial-cement boundstones) with reefs of other intra-Tethyan carbonate platforms, but clearly differ from palaeogeographically close reefs and coral-bearing facies of the epicontinental Tethyan shelf (e.g., coeval limestones from the subsurface of the Carpathian Foredeep and the Lublin Upland in Poland; the Ernstbrunn Limestone in Austria and Czech Republic). Corals in the Štramberk Limestone and Štramberk-type limestones are the world’s most diverse coral assemblages of the Jurassic–Cretaceous transition. The intra-basinal ridge (ridges), traditionally called the Silesian Cordillera, which evolved through time from an emerged part of the Upper Silesian Massif to an accretionary prism, formed the most important provenance area for carbonate exotic clasts in the flysch of the Silesian Series. They are especially common in the Lower Cretaceous Hradiště Formation and the Upper Cretaceous–Paleocene Istebna Formation. The Baška-Inwałd Ridge and the Sub-Silesian Ridge were the source areas for clasts from the Silesian and Sub-Silesian units (e.g., in the Hradiště Formation), while the Northern (Marginal) Ridge was the source for clasts from the Skole Unit (e.g., in the Maastrichtian–Paleocene Ropianka Formation).

13

The erratic rocks of the Upper Cretaceous Chalk of England: how did they get there, ice transport or other means?

Jeans Christopher V., Platten Ian M.

Acta Geologica Polonica

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2021

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Vol. 71, no. 3

287--304

EN

Rare erratic clasts - extraneous rock types - occur in the Upper Cretaceous Chalk, including a local basal facies, the Cambridge Greensand. The underlying Upper Albian Gault Clay and the Hunstanton Red Chalk Formations have also yielded erratics. The discovery of these erratics, their description and the development of hypotheses to explain their origins and significance are reviewed. They became the subject of scientific interest with the interpretation of a particularly large example “The Purley Boulder” by Godwin-Austen (1858) as having been transported to its depositional site in the Chalk Sea by drifting coastal ice. Thin section petrography (1930–1951) extended knowledge of their diverse provenance. At the same time the Chalk Sea had become interpreted as warm, so drifting ice was considered out of context, and the preferred agents of transport were entanglement in the roots of drifting trees, as holdfasts of floating marine algae, or as stomach stones of marine reptiles or large fish. Reconsideration of their occurrence, variable nature and sedimentary setting suggests that there are three zones in the English Chalk where erratics may be less rare (1) near the base of the Cenomanian in the Cambridge area, (2) the Upper Cenomanian-Middle Turonian in Surrey, and (3) the Upper Coniacian and Lower Santonian of Kent. The assemblage from each level and their sedimentary setting is subtly different. Present evidence suggests that the erratics found in the Upper Albian-Lower Cenomanian and the Upper Cenomanian-Middle Turonian zones represent shallow water and shoreline rocks that were transported into the Chalk Sea by coastal ice (fast-ice) that enclosed coastal marine sediments as it froze. The Upper Coniacian and Lower Santonian erratics from Rochester and Gravesend in Kent are gastroliths.

14

Redox conditions, glacio-eustasy, and the status of the Cenomanian-Turonian Anoxic Event: new evidence from the Upper Cretaceous Chalk of England

Jeans Christopher V., Wray David S., Williams C. Terry, Bland David J., Wood Christopher J.

Acta Geologica Polonica

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2021

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Vol. 71, no. 2

103--152

EN

The nature of the Cenomanian–Turonian Oceanic Anoxic Event (CTOAE) and its δ13 C Excursion is considered in the light of (1) the stratigraphical framework in which the CTOAE developed in the European shelf seas, (2) conclusions that can be drawn from new detailed investigations of the Chalk succession at three locations in England, at Melton Ross and Flixton in the Northern Province where organic-rich ‘black bands’ are present, and at Dover in the Southern Province (part of the Anglo-Paris Basin) where they are absent, and (3) how these conclusion fit in with the present understanding of the CTOAE. The application of the cerium anomaly method (German and Elderfield 1990) at Dover, Melton Ross and Flixton has allowed the varying palaeoredox conditions in the Chalk Sea and its sediments to be related to the acid insoluble residues, organic carbon, δ18O (calcite), δ13C (calcite), δ13C (organic matter), Fe 2+ and Mn2+ (calcite), and P/TiO2 (acid insoluble residue). This has provided evidence that the initial stages of the δ13C Excursion in England were related to (1) a drop of sea level estimated at between 45 and 85 metres, (2) influxes of terrestrial silicate and organic detritus from adjacent continental sources and the reworking of exposed marine sediments, and (3) the presence of three cold water phases (named the Wood, Jefferies and Black) associated with the appearance of the cold-water pulse fauna during the Plenus Cold Event. Conditions in the water column and in the chalk sediment were different in the two areas. In the Northern Province, cerium-enriched waters and anoxic conditions were widespread; the δ13C pattern reflects the interplay between the development of anoxia in the water column and the preservation of terrestrial and marine organic matter in the black bands; here the CTOAE was short-lived (~0.25 Ma) lasting only the length of the Upper Cenomanian Metoicoceras geslinianum Zone. In the Southern Province, water conditions were oxic and the δ13C Excursion lasted to the top of the Lower Turonian Watinoceras devonense Zone, much longer (~1.05 Ma) than in the Northern Province. These differences are discussed with respect to (1) the Cenomanian–Turonian Anoxic Event (CTAE) hypothesis when the ocean-continent-atmosphere systems were linked, (2) limitations of chemostratigraphic global correlation, and (3) the Cenomanian-Turonian Anoxic Event Recovery (CTOAER), a new term to define the varying lengths of time it took different oceans and seas to recover once the linked ocean-continent-atmosphere system was over. The possibility is considered that glacio-eustasy (the glacial control hypothesis of Jeans et al. 1991) with the waxing and waning of polar ice sheets, in association with the degassing of large igneous provinces, may have set the scene for the development of the Cenomanian-Turonian Anoxic Event (CTAE).

15

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

16

Not simply volcanoes – the geoheritage of the Cretaceous system in the Land of the Extinct Volcanoes Geopark, West Sudetes (SW Poland)

Migoń Piotr, Pijet-Migoń Edyta

Geotourism / Geoturystyka

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2020

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nr 1-2 (60-61)

3--22

EN

Volcanic geoheritage is emphasized as the main asset and distinctive characteristic of the Land of Extinct Volcanoes Geopark in the West Sudetes (SW Poland). However, the geoheritage values of the region are not limited to the legacy of ancient volcanism but include various other elements. This paper explores the contribution of geosites that expose sedimentary rocks of Cretaceous age and landforms developed upon these rocks. Six localities from the Geopark area, included in the comprehensive regional inventory of geosites, are presented. They represent natural and man-made sandstone outcrops and show, among others, lithological variations, small- and large-scale post-sedimentary deformation structures, landforms arising from differential weathering (rock shelters, honeycombs), boulder fields and a sandstone xenolith in volcanic rocks. Next, five localities from outside the Geopark, but still within the Pogórze Kaczawskie region, are described. Qualitative and quantitative evaluation of both groups is attempted, and the results show that, in general, geosites within the Geopark rank higher. However at least two from the other group also have significant geotourist potential. Finally, a brief comparative analysis with other parts of the Sudetes, where Cretaceous sedimentary rocks occur, is offered.

PL

Dawny wulkanizm jest uznawany za główny walor i wyróżniającą się cechę Geoparku Kraina Wygasłych Wulkanów w Sudetach Zachodnich, jednak dziedzictwo Ziemi w regionie nie ogranicza się do reliktów aktywności wulkanicznej i zawiera różne inne elementy. W tym artykule są zaprezentowane miejsca (geostanowiska), w których można oglądać naturalne i sztuczne odsłonięcia skał osadowych wieku kredowego i formy rzeźby zbudowane z tych skał. Sześć z nich jest zlokalizowanych na obszarze Geoparku i zostały one uwzględnione w regionalnej inwentaryzacji obiektów dziedzictwa Ziemi. Zagadnienia, które można omówić na przykładzie tych miejsc, obejmują między innymi zróżnicowanie litologiczne, postsedymentacyjne struktury deformacyjne w małej i dużej skali, formy będące efektem zróżnicowanego wietrzenia (schroniska podskalne, „plastry miodu”), pokrywy blokowe i ksenolit piaskowca w skałach wulkanicznych. W dalszej części opisano pięć stanowisk spoza Geoparku, z pozostałej części regionu Pogórza Kaczawskiego. Rezultaty jakościowej i ilościowej oceny stanowisk z obu grup pokazują, że obiekty położone w Geoparku mają większą wartość, ale przynajmniej dwa z drugiej grupy mają istotny potencjał geoturystyczny. W części końcowej zostało przedstawione krótkie porównanie z innymi fragmentami Sudetów, gdzie występują skały wieku kredowego.

17

Intrastratal flow in the Cretaceous Gyeokpori Formation (SW South Korea)

Byun Uk Hwan, Van Loon A.J. (Tom), Kwon Yi Kyun, Ko Kyoungtae

Geological Quarterly

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2020

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Vol. 64, No. 3

611--625

EN

Intrastratal flow is a process that is still poorly understood, rarely described and difficult to interpret in ancient rocks. Sediments in the Cretaceous lacustrine Gyeokpori Formation of southwestern South Korea contain some chaotically deformed sandstone layers with deformed mudstone clasts that are ascribed to this process. The interpretation is based on the fact that these layers cannot be explained as a result of subaqueous debris flows or mass transport, whereas the sedimentary context, including the presence of other soft-sediment deformation structures, indicates that intrastratal flow must have been physically possible. The sedimentary setting was a lake in which mainly siliciclastic rocks were deposited, with some interbedded volcaniclastics. The nearby volcanic activity caused seismic shocks that affected the unstable lake margins resulting in the dominance of gravity-flow deposits, but also in a high sedimentation rate that facilitated soft-sediment deformation partly caused by intrastratal flow. This must have happened fairly frequently during a probably limited time-span, as several layers showing traces of intrastratal flow are present within a succession of only <1 m thick. The combined data on the geological setting and our findings regarding the origin of the various soft-sediment deformation structures may help to recognize the traces left by intrastratal flow elsewhere in the geological record.

18

Upper Albian, Cenomanian and Upper Turonian ammonite faunas from the Fahdène Formation of Central Tunisia and correlatives in northern Algeria

Kennedy William James

Acta Geologica Polonica

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2020

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Vol. 70, no. 2

147--272

EN

Over 130 species are documented from the Upper Albian, Cenomanian and Upper Turonian Fahdène Formation and correlatives in Central Tunisia and northern Algeria, based on material described by Henri Coquand (1852, 1854, 1862, 1880), Léon Pervinquière (1907, 1910), Georges Dubourdieu (1953), Jacques Sornay (1955), and new collections. The material consists predominantly of limonitic nuclei, together with adults of micromorphs. There is no continuous record, and a series of faunas are recognised that can be correlated with the zonation developed in Western Europe. These are the Upper Albian Ostlingoceras puzosianum fauna, Lower Cenomanian Neostlingoceras carcitanense and Mariella (Mariella) harchaensis faunas, the upper Lower to lower Middle Cenomanian Turrilites scheuchzerianus fauna, Middle Cenomanian Calycoceras (Newboldiceras) asiaticum fauna, Upper Cenomanian Eucalycoceras pentagonum fauna, and the Upper Turonian Subprionocyclus neptuni fauna. Two new micromorph genera are described, Coquandiceras of the Mantelliceratinae and Cryptoturrilites of the Turrilitinae. Most of the taxa present have a cosmopolitan distribution, with a minority of Boreal, North American and endemic taxa.

19

Roveacrinidae (Crinoidea, Articulata) from the Cenomanian and Turonian of North Africa (Agadir Basin and Anti-Atlas, Morocco, and central Tunisia): biostratigraphy and taxonomy

Gale Andrew Scott

Acta Geologica Polonica

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2020

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Vol. 70, no. 3

273--310

EN

Successions exposed in the Agadir Basin (upper Albian to middle Turonian), in the Anti-Atlas (lower Turonian) in Morocco and in central Tunisia (Cenomanian–Turonian) yield abundant microcrinoids of the family Roveacrinidae, which are described and assigned to 32 species and formae, in ten genera. The following new taxa are described: Fenestracrinus gen. nov. with the type species F. oculifer sp. nov., Discocrinus africanus sp. nov., Styracocrinus rimafera sp. nov., Lebenharticrinus quinvigintensis sp. nov., L. zitti sp. nov., Euglyphocrinus cristagalli sp. nov., E. jacobsae sp. nov., E. truncatus sp. nov., E. worthensis sp. nov., Roveacrinus gladius sp. nov., R. solisoccasum sp. nov. and Drepanocrinus wardorum sp. nov. In addition, the new subfamily Plotocrininae is erected. The stratigraphical distribution of the taxa in two important localities, Taghazout in the Agadir Basin (Morocco) and Sif el Tella, Djebel Mhrila (central Tunisia), is provided. The faunas from the uppermost Albian and lowermost Cenomanian of the Agadir Basin are nearly identical to those recorded from central Texas, USA, some 5,300 km away, and permit a detailed correlation (microcrinoid biozones CeR1 and CeR2) to be established across the southern part of the Western Tethys, independently supported by new ammonite records. For the middle and upper Cenomanian, rather few detailed records of microcrinoids are available elsewhere, and the North African record forms the basis for a new zonation (CeR3–CeR6). The distribution of Turonian Roveacrinidae in North Africa is evidently very similar to that described in the Anglo-Paris Basin, and zones TuR1–3, TuR9, 10 and 14 are recognised for the first time in the Tethys.

20

A new type of slumping-induced soft-sediment deformation structure: the envelope structure

Byun Uk Hwan, van Loon A. J. (Tom), Kwon Yi Kyun, Ko Kyoungtae

Geologos

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2019

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Vol. 25, No. 2

111--124

EN

The sediments of the Cretaceous Gyeokpori Formation in south-western South Korea accumulated in a lake in which mainly siliciclastic rocks were deposited, with some interbedded volcaniclastics. The nearby volcanic activity resulted in unstable lake margins inducing a dominance of gravity-flow deposits. The high sedimentation rate facilitated soft-sediment deformation on the sloping margin. The deposition of numerous gravity-flow deposits resulted in a vertically heterolithic stratification. The slumps are composed of different lithologies, which is expressed in different types of deformation due to the difference in cohesion between sandy and mussy layers within the slumps. Coarser-grained (cohesionless) slumps tend to show more chaotic deformation of their lamination or layering. The difference in slumping behaviour of the cohesive and non-cohesive examples is explained and modelled. A unique soft-sediment deformation structure is recognized. This structure has not been described before, and we call it ‘envelope structure’. It consists of a conglomerate mass that has become entirely embedded in fine-grained sediment because slope failure took place and the fine-grained material slumped down with the conglomerate ‘at its back’. The cohesive laminated mudstone formed locally slump folds that embedded the non-cohesive overlying conglomerate unit, possibly partly due to the bulldozing effect of the latter. This structure presumably can develop when the density contrast with the underlying and overlying deposits is exceptionally high. The envelope structure should be regarded as a special – and rare – type of a slumping-induced deformation structure.