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Tytuł:
A new family of giant Jurassic–Cretaceous littorinoid gastropods from the northern Tethys shelf
Autorzy:
Harzhauser, M.
Schneider, S.
Powiązania:
https://bibliotekanauki.pl/articles/945827.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
mollusca
gastropoda
leviathania
carbonate platform
body size
jurassic–cretaceous
tethys
tithonian
ernstbrunn limestone
austria
Opis:
The giant, up to 40 cm high littorinoid gastropods from the Middle Tithonian to Berriasian carbonates of the Alpine-Carpathian northern Tethys margin are assigned to the genus Leviathania. The genus is distributed from Spain to the Caucasus. Some species formed dense populations in the wide-spread, highly productive lagoonal environments situated on the carbonate platforms of Ernstbrunn (Austria), Mikulov, Štramberk (both Czech Republic), and Nyzhniv (Ukraine). The conspicuous morphology, comprising very large shells with strongly angulated whorls and especially the phaneromphalous umbilicus exclude the traditional attributions of this genus to the families Purpurinidae and Purpuroideidae. Therefore, we establish the new family Leviathaniidae for the type genus Leviathania. The family comprises the largest pre-Cenozoic gastropods, represented by a yet unnamed gigantic Leviathania species from the latest Tithonian or early Berriasian of Ukraine. The gastropods are tentatively assumed to have fed omnivorous, i.e., on a mixed detrital-algal diet, based on comparable population densities as the large modern queen conch Lobatusgigas from the Caribbean Sea.
Źródło:
Acta Palaeontologica Polonica; 2014, 59, 2; 367-378
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A silicified wood from the Early Cretaceous sediments in the Kaligandaki Valley, west central Nepal
Autorzy:
Paudayal, Khum N.
Paudel, Lalu P.
Uhl, Dieter
Powiązania:
https://bibliotekanauki.pl/articles/24202093.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Tethys
Cretaceous
Nepal
Opis:
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.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 55--55
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Aptian greenhouse climate and icehouse interludes – alpine Tethyan archives revisited
Autorzy:
Weissert, Helmut
Powiązania:
https://bibliotekanauki.pl/articles/24202103.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Tethys
climate
Alps
Opis:
In this study we revisit two Cretaceous archives in the Alps, and we test hypotheses of major sea level falls related to ice age interludes in the Aptian. The first of the two successions in focus was formed along the northern margin of the alpine Tethys and is today preserved as Garschella Formation in the Helvetic nappes of Switzerland. Aptian phosphorites of the Luitere Beds containing Deshayites deshayesi and Dufreonia are overlain by up to tens of meters of siliciclastic shales, the Gams Beds. Gams Beds with low carbonate content are poorly dated, according to available biostratigraphies they are of Late Aptian age (nolani ammonite zone). Gams Beds are covered by up to 15 m glauconitic bioclastic sandstones and limestones (Brisi sandstone and limestone). The second locality we have revisited is Zürs in the Northern Calcareous Alps (NCA, Vorarlberg, Austria). There, a condensed succession of Jurassic-Cretaceous age records Southern Tethyan ocean history of a “submarine bank”. Jurassic radiolarian cherts are overlain by pelagic limestones of earliest Cretaceous age followed by an Aptian phosphorite hardground. These phosphorites are covered by an up to several meter thick succession of reworked crinoidal limestones and then by several tens of meters of “Kreideschiefer” (Lech Formation), which are of Albian to Cenomanian in age. Phosphorites at both localities record a time of hardground formation related to changes in Tethyan oceanography, triggered by a major perturbation of the global carbon cycle and by corresponding changes in climate and oceanography. Condensed sedimentation records intense current activity on submarine highs and along the northern Tethyan shelf. Remarkable is the poorly understood change in sedimentation following hardground formation at both locations during Late Aptian time. The Helvetic Gams Beds (Garschella Fm.) record increased shedding of siliciclastics along the northern Tethys, either related to increased weathering or to a drop in sea level. We propose, that an eustatic drop of seal level explains observed northern Tethyan shifts in Late Aptian sedimentation. A corresponding drop in sea level is recorded at other localities as the Oman Mountains, along the Algarve coast in Portugal or in the Basque-Cantabrian Basin. There, most prominent “cold snaps” or “ice age interludes during Aptian greenhouse climate” are dated as martinoides to nolani ammonite zone, they coincide with the deposition of the Gams Beds. Bioclastic limestones in the Helvetic succession and in the NCA record carbonate shedding at a time of renewed sea level rise following a major Aptian sea level drop. The Late Aptian prograding carbonate system of the NCA, considered as the source of crinoidal sands, was positioned along the northern margin of the evolving Eastern Alps while Brisi carbonate sands where shedded from a Northern Tethyan carbonate ramp. The Aptian condensed sediments of Helvetics and of NCA are indicators of extreme shifts in Aptian climate triggered by perturbations of the global carbon cycle. The Aptian-Albian Zürs succession provides additional information on the rapid transition of a passive continental margin with pelagic sediments into an Austroalpine foreland basin represented by “Kreideschiefer”.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 78--78
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Bositra limestones - a step towards radiolarites: case study from the Tatra Mountains
Autorzy:
Jach, R.
Powiązania:
https://bibliotekanauki.pl/articles/191672.pdf
Data publikacji:
2007
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
thin-shelled bivalves
Middle Jurassic
Krížna Basin
Carpathians
Western Tethys
Opis:
Bositra limestones of Aalenian–Lower Bathonian age crop out in the Krížna unit in the Western Tatra Mountains (Poland). They are sandwiched between pelagic red limestones and radiolarites and display lateral facies variation. Four facies were distinguished: (i) Bositra packstones/grainstones, (ii) crinoidal packstones/ grainstones, (iii) Bositra-crinoidal packstones, and (iv) Bositra-radiolarian wackestones. The Bositra packstones/ grainstones were laid down in high-energy setting, while Bositra-radiolarian wackestones in calm condition. Crinoidal packstones/grainstones represent density current deposits. Bositra-crinoidal packstones resulted from intense bioturbation and mixing of crinoidal packstones/grainstones with background Bositra-rich deposits. Topographic gradient affected the lateral facies variation. Taphonomic factors strongly controlled by energy of the sedimentary environment, ecological factors which caused domination of Bositra bivalves in benthos assemblage and dissolution eliminating non-calcitic bioclasts could resulted in formation of the Bositra limestones. The eutrophication of water column and remodelling of the Krížna Basin, which finally led to deposition of radiolarites seem to be of considerable importance. Hence, Bositra limestones can be regarded as the record of the interme- diate stage of the basin evolution towards radiolarite formation.
Wapienie bositrowe wczesnego aalenu–wczesnego batonu, które odsłaniają się w jednostce kriżniańskiej w Polskich Tatrach Zachodnich znajdują się w profilach pomiędzy pelagicznymi czerwonymi wapieniami a radiolarytami (Fig. 1, 2; Lefeld et al., 1985; Gradziński et al., 2004). Wapienie te wykazują wyraźne facjalne zróżnicowanie. Wydzielone zostały następujące facje: (i) bositrowe pakstony/greinstony, (ii) krynoidowe pakstony/greinstony, (iii) bositrowo-krynoidowe pakstony i (iv) bositrowo-ra diolariowe wakstony (Fig. 2, 3). Bositrowe pakstony/greinstony powstały w środowisku o stosunkowo wysokiej energii, a bositrowo- radiolariowe wakstony w warunkach niskiej energii. Krynoidowe pakstony/greinstony są interpretowane jako osady prądów gęstościowych, a bositrowo-krynoidowe pakstony jako osady prądów gęstościowych zbioturbowane i zmiksowane z osadami tła depozycyjnego. Zróżnicowana morfologia basenu wpłynęła na oboczną zmienność facjalną omawianych wapieni i przestrzenny rozkład facji (Fig. 4). Powstanie wapieni bositrowych było warunkowane przez czynniki natury tafonomicznej, związane z energią środowiska sedymentacji, natury ekologicznej decydujące o dominacji bositr w zespole bentosu i procesy rozpuszczania eliminujące nie kalcytowe bioklasty. Postępująca eutrofizacja wód (Bartolini & Cecca, 1999; Cobianchi & Picotti, 2001) i przemodelowanie basenu kriżniańskiego związane z procesami ryftingu Zachodniej Tetydy, które ostatecznie doprowadziły do depozycji radiolarytów, wydają się mieć zasadniczy wpływ na powstanie wapieni bositrowych. Tak więc, wapienie bositrowe reprezentują przejściową fację poprzedzającą w czasie powstanie tetydzkich jurajskich radiolarytów.
Źródło:
Annales Societatis Geologorum Poloniae; 2007, 77, No 2; 161-170
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Campanian–Maastrichtian foraminiferal stratigraphy and palaeoenvironment of the Lower Tar Member in the Wadi Tar section, Western Sirte Basin (Libya)
Autorzy:
Tshakreen, S. O.
Gasiński, M. A.
Machaniec, E.
Mącznik, A.
Powiązania:
https://bibliotekanauki.pl/articles/191767.pdf
Data publikacji:
2017
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Southern Tethys
Western Sirte Basin
Lower Tar Member
foraminifera
biostratigraphy
palaeoenvironment
late Campanian–Maastrichtian
Opis:
Upper Campanian–Maastrichtian sections on the western flank of the Hun Graben in the Western Sirte Basin (WSB) are displaying two major type facies based on the foraminiferal assemblages. The first one indicates open-marine to outer-shelf conditions, and is represented by numerous bathy-pelagic planktonic foraminiferal species referable to the Radotruncana calcarata, Globotruncana aegyptiaca and the lower part of the Gansserina gansseri Zone (all late Campanian).The second type facies indicates an inner-shelf environment and is represented in the middle-upper part of the Gansserina gansseri Zone (early Maastrichtian) and Racemiguembelina fructicosa (late Maastrichtian) dominated by epi-pelagic planktonic and large benthic foraminifers. Large benthic foraminiferal index species Siderolites calcitrapoides Lamarck and Omphalocyclus macroporus (Lamarck) occur in abundance by the middle–late Maastrichtian. Correlation between planktonic foraminiferal zonation and large benthic foraminiferal zonation is given. An open-marine to outer-shelf environment passed into shallower marine conditions during the late Campanian–early Maastrichtian to late Maastrichtian, then a slight deepening and again shallowing is noticed.
Źródło:
Annales Societatis Geologorum Poloniae; 2017, 87, 4; 349-362
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cephalopod fauna and stratigraphy of the Adnet type red deposits of the Krížna unit in the Western Tatra Mountains, Poland
Autorzy:
Myczyński, R.
Jach, R.
Powiązania:
https://bibliotekanauki.pl/articles/191903.pdf
Data publikacji:
2009
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
ammonites
nautiloids
Toarcian
Western Tethys
Opis:
The Lower Jurassic Adnet type red limestones and marlstones (Kliny Limestone Member, Huciska Limestone Formation) of the Krížna unit in the Tatra Mountains comprise cephalopod fauna represented by ammonites, belemnites and rarely by nautiloids. Ammonites belong to the families Phyloceratidae, Lytoceratidae, Hildoceratidae and Dactylioceratidae and indicate Early Toarcian Serpentinum Zone, Middle Toarcian Bifrons Zone (most probably Sublevisoni and Bifrons Subzones) and Late Toarcian Pseudoradiosa Zone. Hence, the age of Adnet type deposits may be estimated as Early Toarcian-Late Toarcian. Relatively moderate diversity of ammonite assemblage is noticed. Ammonites and nautiloids are preserved mainly as internal moulds, only some specimens display preserved calcified shells. Part of this macrofauna has resedimented character. Studied ammonite assemblage is closely related to that of the Mediterranean Province.
Źródło:
Annales Societatis Geologorum Poloniae; 2009, 79, No 1; 27-39
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of the Mid-Polish Troughversus Late Jurassic evolution in the Carpathian Foredeep area
Autorzy:
Matyja, B. A.
Powiązania:
https://bibliotekanauki.pl/articles/2059116.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Mid-Polish Trough
Late Jurassic
northern Tethys shelf
sponge megafacies
Štramberk-type coral reefs
Opis:
Late Jurassic is the key epoch for an idea of the existence of the southeastern segment of the Mid-Polish Trough. New data on the evolution of Upper Jurassic deposits in the Carpathian Foredeep substrate provide information that there is a complete Oxfordian through Valanginian succession in the area of thick Oxfordian and Kimmeridgian deposits, proving the occurrence of the trough. Thickness of the Oxfordian and Kimmeridgian succession is twice to three times smaller than previously assumed. The facies development patterndistinguishes this area from the rest of the Late Jurassic basin. The sponge megafacies ranges up into the lower most Tithonian in this region.Tithonian Štramberk-type reefs occur near the Carpathian thrust front and alongside. The Late Jurassic and earliest Cretaceous facies are latitudinally arranged. Starting from the latest Middle Jurassic, the study area showed strong structural and facies relations to the Tethys do main. The collected data contradict the hypothesis that the Mid-Pol ish Trough continues in the Carpathian Foredeep substrate.
Źródło:
Geological Quarterly; 2009, 53, 1; 49-49
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Norian (Triassic) corals from the Northern Calcareous Alps, Austria, and the intra-Norian faunal turnover
Autorzy:
Roniewicz, E.
Powiązania:
https://bibliotekanauki.pl/articles/20215.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Early Norian
Triassic
coral
Alps Mountains
Austria
faunal turnover
paleontology
Scleractinia
Hexanthiniaria
taxonomy
Norian
Dachstein
Tethys
Opis:
The first description of early Norian coral fauna from the Northern Calcareous Alps (Dachstein Plateau and Gosaukamm), Austria, is presented: 31 scleractinian species from 24 genera (including three corals not formally determined), and three hexanthiniarian species belonging to two genera. The stratigraphical position of the main part of the fauna discovered in the South Dachstein Plateau at the Feisterscharte is determined by means of the conodont Epigondolella quadrata (Lacian 1); single finds are from the horizons with Epigondolella triangularis and Norigondolella navicula (Lacian 3), and one close to the horizon with Epigondolella cf. multidentata (Alaunian 1). Rare corals from the Gosaukamm are from the Lacian 1 and Alaunian. Five species are described as new: Retiophyllia vesicularis, Retiophyllia aranea, Margarosmilia adhios, Hydrasmilia laciana; one new genus and species from the family Coryphylliidae, Margarogyra hirsuta; one new genus and species, Thamnasterites astreoides, cannot be assigned to a family. Two hexanthiniarian species, Pachysolenia cylindrica and Pachydendron microthallos, known exclusively from the Tethyan lower Norian, represent stratigraphically valuable species. A regularly porous coral from the family Microsolenidae, Eocomoseris, which up to now has only been known from the Jurassic and Cretaceous, is here identified from the Triassic strata (originally described as Spongiomorpha [Hexastylopsis] ramosa). Predominant taxa show solitary and phaceloid (pseudocolonial) growth forms and an epithecal wall; pennules−bearing corals are common. Carnian genera and genera typical of the Lacian and Lacian–early Alaunian prevail; a hydrozoan genus Cassianastraea has also been encountered as well as a scleractiamorph coral, Furcophyllia septafindens). The faunal composition contrasts with that of well known late Norian–Rhaetian ones, the difference being observed not only at the generic but also at the family level. The post−early Norian change in coral spectrum documents the turnover of the coral fauna preceding that at the Triassic/Jurassic boundary.
Źródło:
Acta Palaeontologica Polonica; 2011, 56, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Triassic conodonts in Western Tethys
Autorzy:
Kolar-Jurkovšek, Tea
Powiązania:
https://bibliotekanauki.pl/articles/24202124.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Tethys
Triassic
biostratigraphy
Opis:
Conodonts are phosphatic, tooth-like elements of extinct jawless vertebrates that are classified in the independent class Conodonta. Due to their rapid evolution, wide palaeogeographic distribution and high resistance, conodonts are one of the most significant microfossil groups in the biostratigraphy of the Paleozoic and Triassic. Animals with conodonts were bilaterally symmetrical, exclusively marine organisms, where they inhabited a variety of habitats. These include both open sea habitats, whereas some species adapted to shallow habitats of epicontinental seas. For this reason, conodonts are extremely important for understanding of the palaeoecological and palaeogeographic conditions of the Paleozoic and Triassic. They were unquestionably one of the most successful animal groups, since they existed more than 300 million years and their elements are widely used as index fossils. Conodonts have shown their value for Triassic biostratigraphy. Based on international criteria the Permian-Triassic system boundary is defined with the first appearance of the conodont species Hindeodus parvus (Kozur & Pjatakova). The Permian-Triassic interval strata of the GSSP section in Meishan (China) are next to the platform-bearing gondolellids marked by the presence of Hindeodus-Isarcicella population that enabled to introduce also a conodont zonation for shallow facies. A standard conodont zonation is, except for the two lowermost Triassic zones, based on gondolellid genera that lived in deeper water: Clarkina, Sweetospathodus, Neospathodus, Novispathodus, Borinella, Scythogondolella, Icriospathodus, Triassospathodus and Chiosella. Certain Dienerian and Smithian strata of Western Tethys are marked by shallow water and euryhaline genera and due to the absence of global biozonation markers, a stratigraphic value of some genera (Hadrodontina, Pachycladina, Eurygnathodus, Foliella, Platyvillosus) is recognized. These shallow water genera were ecologically controlled (temperature, oxygen levels) that have been adapted to the epicontinental ramp environment and were particulary instrumental in forming the western part of the Tethyan province.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 36--36
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of the Western Tethys as seen from the Western Carpathians’ perspective
Autorzy:
Plašienka, Dušan
Powiązania:
https://bibliotekanauki.pl/articles/24202134.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Tethys
Carpathians
evolution
Opis:
The palaeogeographic positions of the pre-Cretaceous Tethys “western ends” (Kovács, 1992) and their relationships to easterly located oceanic domains remain to belong to the most challenging issues in deciphering the structure and tectonic evolution of the European Alpides (e.g. Schmid et al., 2020). Due to the westward increasing paucity of direct indications of ancient oceanic domains and their discontinuous occurrences, a number of sometimes considerably different reconstructions have been proposed by several authors. All these are based on various data and authors’ preferences; therefore achievement of a widely accepted model seems not to be probable at present. In general, searching for evidences of former oceanic domains in the nappe edifice of collisional mountain belts, commonly in the suture zones, is based on several fundamental criteria: 1) ophiolite slivers and ophiolite-bearing mélanges as vestiges of consumed oceanic lithosphere; 2) blueschistto eclogite-facies metamorphosed units recording the subduction/exhumation processes within a subduction channel and/ or accretionary prism; 3) deep-marine synorogenic sedimentary complexes like wildflysch or olistostromes; 4) mixture of these in chaotic units within an accretionary wedge; and 5) a specific case of intraoceanic subduction resulting in ophiolite obduction, but this is not considered as a continental collisional tectonic setting. Indirectly, position of past oceanic basins can be detected by: a) secondary occurrences of an oceanic crust-derived detritus, including the heavy mineral spectra, in syn- to early post-orogenic sedimentary clastic formations and clues to their source areas; b) shelf-slope-continental rise facies polarity of former passive margins; c) progradational trend of collisional thrust stacking of the lower plate with a suture (often totally destroyed) in the uppermost structural position in the rear part of an orogenic pro-wedge; d) subduction-related calc-alkaline magmatism accompanying the active margin; e) upper plate back-arc extension, or retro-wedge thrusting opposite to the pro-wedge in a bivergent orogen with the suture in its axial zone; f) major crustal-scale discontinuities revealed by deep seismic sounding connected to surface fault zones separating palaeogeographically distinct domains indicating possible plate boundaries. All these potential clues have been considered while reconstructing the Mesozoic tectonic evolution of the Western Carpathians (Plašienka, 2018 and references therein). It should be noted that no single criterion characterized above, even not a few indirect signs are enough to define a particular orogenic zone or unit as an evidence for an oceanic suture. There is only one Western Carpathian zone which fulfils most of them. It is represented by units and rock complexes grouped in a tectonic superunit known as the Meliaticum and respective oceanic realm as the Meliata Ocean. The Meliata-related units bear clear signs of criteria 1, 2, 3, 4 and indirect indicators a, b, c and e. Whatever different are the interpretations of the Meliata Ocean origin (e.g. born as a back-arc basin initiated by the northward subduction of Palaeotethys, or simply as a northern margin or embayment of Neotethys), or even its existence as an independent domain (regarded as a facies zone only), all palaeotectonic interpretations of the Alpine tectonic evolution of the Western Carpathians have to take into account these pieces of evidence.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 57--57
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foraminiferal assemblages as palaeoenvironmental bioindicators in Late Jurassic epicontinental platforms: Relation with trophic conditions
Autorzy:
Reolid, M.
Nagy, J.
Rodriguez-Tovar, F.J.
Oloriz, F.
Powiązania:
https://bibliotekanauki.pl/articles/22691.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
foraminiferal assemblage
paleoenvironmental bioindicator
Late Jurassic
epicontinental platform
trophic condition
Jurassic
Foraminifera
neritic shelf
Boreal Realm
Tethys Ocean
Opis:
Foraminiferal assemblages from the neritic environment reveal the palaeoecological impact of nutrient types in relation to shore distance and sedimentary setting. Comparatively proximal siliciclastic settings from the Boreal Domain (Brora section, Eastern Scotland) were dominated by inner−shelf primary production in the water column or in sea bottom, while in relatively seawards mixed carbonate−siliciclastic settings from the Western Tethys (Prebetic, Southern Spain), nutrients mainly derived from the inner−shelf source. In both settings, benthic foraminiferal assemblages increased in diversity and proportion of epifauna from eutrophic to oligotrophic conditions. The proximal setting example (Brora Brick Clay Mb.) corresponds to Callovian offshore shelf deposits with a high primary productivity, bottom accumulation of organic matter, and a reduced sedimentation rate for siliciclastics. Eutrophic conditions favoured some infaunal foraminifera. Lately, inner shelf to shoreface transition areas (Fascally Siltstone Mb.), show higher sedimentation rates and turbidity, reducing euphotic−zone range depths and primary production, and then deposits with a lower organic matter content (high−mesotrophic conditions). This determined less agglutinated infaunal foraminifera content and increasing calcitic and aragonitic epifauna, and calcitic opportunists (i.e., Lenticulina). The comparatively distal setting of the Oxfordian example (Prebetic) corresponds to: (i) outer−shelf areas with lower nutrient input (relative oligotrophy) and organic matter accumulation on comparatively firmer substrates (lumpy lithofacies group) showing dominance of calcitic epifaunal foraminifera, and (ii) mid−shelf areas with a higher sedimentation rate and nutrient influx (low−mesotrophic conditions) favouring potentially deep infaunal foraminifers in comparatively unconsolidated and nutrient−rich substrates controlled by instable redox boundary (marl−limestone rhythmite lithofacies).
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 4
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Foraminifers from the early basin of the Polish Outer Carpathians: relationship with the Western and Eastern Tethys (Tithonian)
Autorzy:
Szydło, Andrzej
Powiązania:
https://bibliotekanauki.pl/articles/24202099.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Polish Outer Carpathians
Tethys
foraminifers
Opis:
The formation of the Polish part of the Outer Carpathian Basin was initiated by the rifting process which led to the collapse and disintegration of the southern margins of the European Platform in the Late Jurassic. Fragments of carbonate platform were incorporated into the basin structures which divided the area into several sedimentary zones located at different depth. Under these conditions, most of the carbonate sediments were transported to the basin in the form of submarine landslides and gravity flows of varying densities, or accumulated during pelagic sedimentation. These deposits belong to two formations exposed in the westernmost part of the Polish Outer Carpathians, located near the Polish-Czech border. The first is mainly represented by the Tithonian marls (Vendryne Fm.) which also contain redeposited carbonate rocks and fossils (Oxfordian-Tithonian), the second is composed of limestones and marly shales of the late Tithonian-Berriasian (Cieszyn Limestone Fm.). These oldest sedimentary rocks in the Polish Outer Carpathians contain mainly benthic foraminifers and very scarce plankton occurring in exotic blocks and sometimes directly in sediments forming both formations. The first group includes forms with calcareous walls and also cemented with siliceous or calcareous material. Calcareous benthic forms belong mainly to Vagulinidae (Vaginulina, Vaginulinopsis, Astacolus, Citharina, Citharinella, Lenticulina, Palmula), Nodosariae (i.e. Frondicularia, Nodosaria, Dentalina), Epistominidae (Epistomina), and Polymorphinidae (Guttulina), while agglutinated taxa are represented by Verneulinidae (Uvigerinammina, Paleogaudryina, Belorussiella, Verneuilina), Andercotrymidae (Praedorothia, Protomarssonella, Pseudomarssonella) and Textulariopsidae (Bicazammina, Hagimashella, Textulariopsis). They can be related to the Jurassic shelf microfauna, which are known both from the Tethys and the European Platform. Among foraminiferal benthos there are also very rare aggluinated taxa belonging to several genera: Melathrokerion, Buccicrenata, Alveosepta, Pseudocyclammina, and the more common calcareous forms of Andersenolina, Neotrocholina, Trocholina, Paalzowella, as well as of Discorbis, which inhabited shallow marine environments formed around the elevations within the basin as well as on its coast. Recently, apart from the benthic microfauna isolated Globigerina-like forms have been also found in the Tithonian deposits. These few forms resemble early planktonic foraminifera of the Western Tethys (Gl. oxfordiana, F. hoterivica) as well as the taxa known epicontinental and subTethyan seas located north (“Gl.” stellapolaris) and east (Gl. balakhmatovae, G. terquemi) of the studied area. The taxonomy, abundance and state of preservation of the described foraminifera from the early basin of the Polish Outer Carpathians indicate a connection with the gradually degraded areas of the platform inhabited by benthic and plankton communities from both the Tethyan and Boreal seas. The studied foraminifera resemble the microfauna of Western and Eastern Tethys and adjacent platforms.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 70--70
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry of the Triassic–Jurassic lateritic bauxites of the Salt Range: implications for eastward extension of the Tethyan bauxite deposits into Pakistan
Autorzy:
Iqbal, Saqib
Bibi, Mehwish
Wagreich, Michael
Powiązania:
https://bibliotekanauki.pl/articles/24202138.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Pakistan
geochemistry
Tethys
Opis:
Bauxite deposits are residuals of intense lateritic weathering under warm and humid palaeoclimates. The Triassic– Jurassic Boundary (TJB) interval in the Salt Range, Pakistan, provides one such case of bauxite deposits formation along the SW tropical Neo-Tethyan passive margin. Thick, red bauxites/bauxitic clays occur at the contact of the Upper Triassic Kingriali Formation and the Lower Jurassic Datta Formation. These bauxites are rich in kaolinite, haematite, boehmite (Al2O3 and Fe2O3), and are depleted in silica (SiO2). Geochemical proxies of the succession signal intense chemical weathering of the parent siliciclastics under Mesozoic “greenhouse” conditions. Certain trace elements and Rare Earth Elements (REEs) are enriched up to seven times compared to mean Upper Continental Crust (UCC) values. These bauxites are synchronous with the Amir-Abad bauxites of the Alborz Mountains, central Iranian Plateau, that occur between the thick Triassic dolomite/dolomitic limestones of the Elika Formation and the Lower Jurassic Shemshak Formation. Thus, the Salt Range, Pakistan, provides evidence for the eastward extension of the Irano-Himalayan bauxites that are extended westward into Mediterranean bauxites, and the western Tethys by correlation with European bauxites. The TJB bauxites in the Salt Range support increased chemical weathering on the SW Neo-Tethyan passive margin and correspond to an associated sea-level fall during this time interval. This supports the Neo-Tethyan tectonics contribution in the formation of bauxite deposits during the Triassic–Jurassic in addition to the widely studied karst-bauxites that formed in response to the subduction and orogenic processes in the Paleo-Tethys.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 30--30
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geological history of the NW Indian Plate Tethyan passive margin in the Salt Range, Pakistan
Autorzy:
Iqbal, Saqib
Powiązania:
https://bibliotekanauki.pl/articles/24202115.pdf
Data publikacji:
2023
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Tethys
Pakistan
geology
Opis:
The generally east-west trending Salt Range, located in northern Pakistan, is a part of the foreland zone of the Himalayan Fold and Thrust Belt (HFTB). The 5,000–1,000 m thick Precambrian to Pleistocene sedimentary archives of the Salt Range provide an excellent opportunity for the reconstruction of sedimentation style, palaeoclimatic conditions, and tectonic history of the northwestern margin of the Indian Plate. The Precambrian evaporites of the Salt Range Formation are the oldest rocks in the area and represent the westward extension of the Precambrian evaporitic belt that includes the Hormuz Salt Basin (Iran) and Ara Salt (Arabian Plate). A highly weathered igneous body “Khewrite” occurs in the upper part of the formation and can be correlated with the volcanic record during the Ediacaran-Cambrian transition in the Arabian Plate. The clastic-dominated Lower Cambrian succession in the area is directly overlain by the Permian Tobra Formation and with a gentle angular unconformity. The poorly sorted conglomerates of the Tobra Formation indicate deposition during the Permo-Carboniferous glaciation and the irregular distribution of the Tobra and Dandot formations in the area supports their deposition during the syn-rifting phase of the Neo-Tethys opening. The overlying Upper Permian and Mesozoic strata indicate deposition on the northwestern passive margin of the Indian Plate facing the southern margin of the Neo-Tethys. This represents the drift sequence with multiple phases of passive margin rejuvenation during the Mesozoic. The drift sequence is unconformably overlain by the Paleocene Hangu Formation. Karst bauxites mark this contact and hint at exhumation and exposure in the distal part of the underthrusting plate margin. The Hangu Formation grades upward through the Lockhart Limestone into black shales of the Patala Formation supporting deepening and the possible establishment of a trench setting in the area. The presence of thick evaporites of the Bahadar Khel Salt and Jatta Gypsum in the western part of the area (Kohat Plateau) indicates a restricted lagoonal setting during the closure of the Neo-Tethys during the Eocene. The absence of the Oligocene strata hints at the uplift and exhumation of the area during the Himalayan Orogeny. The Neogene strata of the area consist of fluvial-continental detritus and represent molasse sedimentation. Thermal history modelling based on Apatite Fission Tract (AFT) data indicates three major cooling (uplift) episodes separated by two burial phases in the area. The first cooling event (ca. 520 Ma) coincides with the emplacement of the Mansehra Granite just north of the area (ca. 516 Ma) and supports exhumation correlatable with the Pan-African Orogeny. This was followed by the first burial phase (ca. 500–370 Ma) that supports Late Cambrian–Devonian sedimentation in the area. The second cooling event (ca. 300–280 Ma) coincides with the initial rifting and exhumation associated with the Neo-Tethys opening. Therefore, it appears that the Late Cambrian–Devonian strata were deposited in the Salt Range but were subsequently eroded during the exhumation induced by the Neo-Tethys opening during Permo-Carboniferous. This was followed by Neo-Tethyan passive margin deposition throughout the Mesozoic. An additional cooling episode is observable at around ca. 60 Ma and is supported by the presence of karst bauxites at the base of the Hangu Formation. Provenance analysis of the Paleocene strata suggests that detritus for the Hangu Formation was supplied from the south (Indian Plate). The overlying Patala Formation indicates the onset of sediment supply from the north and hence the uplift of the Himalayan Orogen. The overlying Kuldana Formation supports detritus supply only from the north verifying the Neo-Tethys closure by the end of Eocene. Thus the Paleogene strata represent syn-collisional deposition of the Neo-Tethys in the Salt Range. The second burial event (ca. 20–6 Ma) occurred during the Neogene in response to molasse sedimentation in the foreland of the uplifting Himalayan Orogen that was followed by the final cooling and uplift event (ca. 4 Ma) along the Salt Range Thrust. Thus the stratigraphic successions of the Salt Range provide key information regarding the reconstruction of the northwestern Neo-Tethyan margin of the Indian Plate which can help in the understanding of Neo-Tethyan tectonics in regional and global context.
Źródło:
Geotourism / Geoturystyka; 2023, 1-2 (72-73); 29--29
1731-0830
Pojawia się w:
Geotourism / Geoturystyka
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Glaucony from the condensed Lower-Middle Jurassic deposits of the Križna Unit, Western Tatra Mountains, Poland
Autorzy:
Jach, R.
Starzec, K.
Powiązania:
https://bibliotekanauki.pl/articles/191514.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
High-Al autochthonous glaucony
K-Ar dating
Carpathians
Tethys
Opis:
Lower-Middle Jurassic glaucony-bearing deposits crop out in the Polish part of the Križna Unit in the Western Tatra Mts. These deposits, up to 20 cm thick, consist of glaucony-rich marls and limestones. The glaucony grains constitute up to 30% volume of the deposits. They represent an evolved stage of glauconitization since they contain more than 7% K2O. The content of Al2O3 is high (up to 19.97%, average 16.98%) while the content of Fe2O3 is low (not more than 23.48%, average 12.84%). These features are interpreted as a product of diagenetic processes. The glaucony-bearing deposits were formed at an upper bathyal depth and their rate of deposition was very low, what allowed long-lasting evolution of the glaucony grains. The K-Ar age of the glaucony grains is much younger than the biostratigraphic age of the studied section. The lowering of the K-Ar dates is interpreted as a result of loss of radiogenic Ar from the lattice of the glaucony.
Źródło:
Annales Societatis Geologorum Poloniae; 2003, 73, No 3; 183-192
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 54

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