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Tytuł:
Palynology and palaeoenvironments of the Silurian Coosglass Slate and Ferriter’s Cove formations in the Dunquin Inlier (Dingle Peninsula, Ireland)
Autorzy:
Higgs, K. T.
Williams, B. P. J.
Powiązania:
https://bibliotekanauki.pl/articles/2059151.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
palynology
palaeoenvironments
Silurian
Dingle
Ireland
Opis:
This study documents the first palynological data from the Silurian of the Dunquin Inlier of the Dingle Peninsula and focuses on the lower part of the succession. The previously undated Coosglass Slate Formation contains a low diversity Llandovery to early Wenlock acritarch assemblage, confirming the previously enigmatic Coosglass Slate Formation as the oldest formation in the Silurian succession. The lithofacies and acritarch biofacies suggest the mudstones of the Coosglass Slate Formation represent a low energy, offshore, muddy shelf palaeoenvironment. The Ferriter' s Cove Formation, a succession of five offshore to tidal-flat regressive marine cycles yielded more diverse palynological assemblages. Acritarchs and cryptospores from the Ferriter's Cove Formation confirm a Wenlock (Homerian) age for this formation. The integration of palynological and sedimentological data from four of the offshore to tidal-flat regressive cycles reveals three consistent palynomorph distribution trends: (1) offshore and shoreface depositional facies contain the most diverse palynological assemblages in which acritarchs with long and ramified processes dominate; (2) back-barrier tidal-flat facies are characterized by terrestrially derived palynomorphs, particularly cryptospores, together with a restricted acritarch assemblage of mainly micrhystrid and veryhachid forms with small simple processes; (3) back-barrier lagoonal facies with patch reefs are dominated by the sphaeromorph acritarch Leiosphaeridia.
Źródło:
Geological Quarterly; 2011, 55, 2; 95-108
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acritarch assemblages from the Silurian Pomeranian Caledonides and their foreland
Autorzy:
Jachowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059448.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Pomeranian Caledonides
Silurian
acritarch assemblages
Opis:
Comprehensive palynological studies of the Silurian rocks of the Pomeranian Caledonides are described, the first since Eisenack's (1972) work. 250 clastic rock samples were analysed, all from deep boreholes. Three of these boreholes (Lębork IG 1, Gdańsk IG 1 and Kościerzyna IG 1) are located NE of the Teisseyre-Tornquist Zone (TTZ) and contain horizontal successions of the western, marginal part of the East European Craton. Other boreholes studied (Bydgoszcz IG 1, Klosnowo IG 1 and Stobno 1) penetrated folded Lower Palaeozoic sediments, and lie SE of the TTZ. The investigations included a complete Silurian profile from the Llandovery to the Poidoli, which is documented in detail by graptolites. Associations of microflora (Acritarcha, Prasinophyceae, Sporites) and microfauna (Chitinozoa, Scolecodonta) varied in quality and quantity. There was considerable variability in the preservation and thermal maturity of the organic-walled microfossils. Detailed investigations of the acritarchs are described. 7 characteristic acritarch assemblages have been distinguished, and these are correlated with the graptolite biozones. Llandovery rocks contain assemblages with Domasia, Ammonidium and Tylotopalla genera. Wenlock deposits include Tylotopalla, Leptobrachion and Cymbosphaeridium. The Upper Ludlow deposits contain well preserved assemblages with Visbysphaera, Veryhachium, Onondagella and Leoniella, accompanied by Neoveryhachium carminae, Geron gracilis, and some Deflandrastrum and Visbysphaera species generally considered characteristic of Gondwana. Throughout the Silurian profile, individual specimens of typical Ordovician genera such as Acanthodiacrodium, Frankea, Striatotheca and Coryphidium occur. The acritarch assemblages overall show mixed characters, typical of both Baltica and Gondwana.
Źródło:
Geological Quarterly; 2000, 44, 3; 317-331
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Early Silurian (Llandovery) graptolite assemblages of Saudi Arabia: biozonation, palaeoenvironmental significance and biogeography
Autorzy:
Williams, M.
Zalasiewicz, J.
Boukhamsin, H.
Cesari, C.
Powiązania:
https://bibliotekanauki.pl/articles/2060177.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Saudi Arabia
Silurian
graptolites
biozonation
Opis:
Analysis of Silurian graptolite assemblages from 1017 sample horizons in 132 cores (from 65 boreholes) through the Qusaiba Member, Qalibah Formation of Saudi Arabia, provides a refined graptolite biostratigraphy for the Arabian Peninsula comparable in its resolution to that from the British Isles and the Czech Republic. Over 150 graptolite species characterize 11 biozones from the lowermost Rhuddanian lubricus Biozone to the lower Telychian guerichi Biozone, with sub-zonal resolution for several intervals. Graptolite biozonal boundaries and the Rhuddanian-Aeronian and Aeronian-Telychian stage boundaries can be placed with high precision. Detailed analysis of graptolite spatial distribution suggests persistent depth-stratified marine assemblages across the Silurian palaeo-Arabian Plate. Near-surface-dwelling assemblages probably occupied the mixed-layer of Silurian oceans, enabling colonization of shallow shelf environments. They are low-diversity (1-2 species) assemblages characterized by Neodiplograptus, Coronograptus, Neolagarograptus and Stimulograptus species and often are preserved in strata with extensive shelly faunas. Deeper marine assemblages are of higher diversity (up to 15 species per horizon), and are characterized by dorsally curved or helically coiled species of Spirograptus, Demirastrites, Lituigraptus, Rastrites and Torquigraptus. Recognition of depth-stratified graptolite assemblages provides an important tool for establishing palaeo-basin topography and water depth at the time of sedimentary deposition. At the species level, the graptolite assemblages of Saudi Arabia are remarkably similar to contemporaneous faunas from peri-Gondwanan Europe and, from the middle Rhuddanian onwards, also to the Avalonian and Laurentian Llandovery graptolites of the UK.
Źródło:
Geological Quarterly; 2016, 60, 1; 3--25
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Palaeomagnetic age of remagnetizations in Silurian dolomites, Rástla quarry (Central Estonia)
Autorzy:
Plado, J.
Preeden, U.
Puura, V.
Pesonen, L. J.
Kirsimäe, K.
Pani, T.
Elbra, T.
Powiązania:
https://bibliotekanauki.pl/articles/2060209.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Estonia
Baltica
Silurian
palaeomagnetism
remagnetization
dolomites
Opis:
Alternating field and thermal demagnetization of dolomite samples from the Silurian (Llandovery) horizontally-bedded sequence of central Estonia reveal two secondary magnetization components (A and B) both of chemical origin. A low-coercivity (demagnetized at -50 mT) component A (D = 60.7°, I = 7.7°, alfa95 = 16.6°) with high dispersion (k = 14.2), yields a palaeopole at 18.2°N and 139.5°E that points towards the Late Devonian — Mississipian segment of the Baltica APWP (Apparent Polar WanderPath). A high-coercivity component B (D = 13.5°, I = 60.7°, k = 67.0, alfa 95 = 4.7°) carries both normal and reversed polarities. Comparing the palaeopole (71.1°N and 173.3°E) with the European APWP reveals a Cretaceous age. These two remagnetizations are linked to mineral assemblages of magnetite and maghemite (A), and hematite (B) determined from mineralogical (X-ray, SEM and optical microscopy) and rock magnetic (acquisition and thermal demagnetization of a 3-component IRM; Lowrie-test) studies. The results suggest that the first (A) Palaeozoic remagnetization was caused by low-temperature hydrothermal circulation due to the influence of the Caledonian (more likely) or Hercynian Orogeny after the diagenetic dolomitization of carbon ates. Hematite, carrying the component B, and goethite, are the latest ferromagnetic minerals that have precipitated into the existing pore space (hematite) and walls of microscopic fractures (goethite) that opened to allow ac cess for oxygen-rich fluids during the Late Mesozoic.
Źródło:
Geological Quarterly; 2008, 52, 3; 213-213
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Silurian volcanism recorded in sedimentary sections at the southwestern margin of the East European Platform: geochemical correlation and tectono-magmatic interpretation
Autorzy:
Kiipli, Tarmo
Powiązania:
https://bibliotekanauki.pl/articles/2058862.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Silurian volcanism
K-bentonites
Ukraine
Moldova
Scythian Platform
Opis:
X-ray fluorescence analyses of sixty-one K-bentonite samples from the Ludlow-Pridoli sections of western Ukraine and Moldova were used for correlation and source magma interpretation. The study reveals that source magmas of K-bentonites were low-temperature (~720oC) rhyolites indicating melting of continental crust during subduction of a hydrated oceanic plate. Volcanic sources were probably located within the developing Scythian Platform embracing the southeastern margin of the East European Platform. The present study demonstrates the potential of using immobile elements for correlating volcanic ash layers between different sections.
Źródło:
Geological Quarterly; 2021, 65, 1; 13
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Silurian of the Nida, Holy Cross Mts. and Radom areas, Poland - a review
Autorzy:
Modliński, Z.
Szymański, B.
Powiązania:
https://bibliotekanauki.pl/articles/2059315.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Silurian
lithology
biostratigraphy
lithostratigraphy
lithofacies
Źródło:
Geological Quarterly; 2001, 45, 4; 435-454
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facies analysis of the Silurian shale-siltstone succession in Pomerania (northern Poland)
Autorzy:
Jaworowski, K.
Powiązania:
https://bibliotekanauki.pl/articles/2059457.pdf
Data publikacji:
2000
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
northern Poland
Silurian
submarine silty debrites
turbidites
exoflysch
Opis:
The Silurian deposits of Pomerania occur in the foreland of the Pomeranian Caledonides which are the SE continuation of the Danish-North-German Caledonides. The Silurian sequence in Pomerania is represented largely by graptolitic clay- and mud-shales deposited in a hemipelagic environment. From the Wenlock through Late Ludlow, slow deposition of hemipelagic clays and muds was repeatedly interrupted by silty debris flows and turbidity currents. Many of the siltstone interbeds were reworked by bottom currents. Clastic material was sourced from the Caledonian accretionary prism stretching along the collision zone of Baltica and East Avalonia. The Silurian shale-siltstone succession in Pomerania represents a Caledonian exoflysch i.e. syn-collision clastics accumulated in a foredeep developed on the East European Craton. The diachronous appearance of siltstone interbeds in the graptolitic shales indicate that collision between Baltica and East Avalonia was associated with sinistral strike-slip movement along the edge of the East European Craton.
Źródło:
Geological Quarterly; 2000, 44, 3; 297-315
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Wenlock-Ludlow carbon isotope trend in the Vidukle core, Lithuania, and its relations with oceanic events
Autorzy:
Martma, T.
Brazauskas, A.
Kaljo, D.
Kaminskas, D.
Musteikis, P.
Powiązania:
https://bibliotekanauki.pl/articles/2058950.pdf
Data publikacji:
2005
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Lithuania
Silurian
carbon isotopes
oceanic events
sedimentary facies
Opis:
A Wenlock to Ludlow terrigenous-carbonate succession in the Vidukle core in Central Lithuania represents a deep shelf environment with a general upwards-shallowing trend, interrupted by brief deepening episodes. The carbon isotope trend, based on 115 whole-rock analyses, shows three main excursions: (1) a major excursion (δ13 C values reach 3.2‰) in the lower Wenlock, (2) low shifts (1.3‰ and 1.6‰) at two levels in the upper most Wenlock Siesartis Formation corresponding to the Monograptus ludensis Biozone, (3) the most prominent excursion (δ13 C values reach 8.2‰) occurs in the upper Ludlow Mituva Fm. The upper Ludlow excursion is dated by the last occurrences of Polygnathoides siluricus below the main shift and the appearance of Ozarkodina wimani and O. crispa above the excursion. The excursion stratigraphically coincides with the Lau oceanic Event and is correlated with the mid-Ludfordian Neocucullograptus kozlowskii-Bohemograptus bohemicus tenuis Biozone. Changes in the carbon isotope trend are in general harmony with some aspects of the rock (CaO, terrigenous component) and fossil content of the section. The data presented are consistent with an arid climate model for the Ludfordian isotope event.
Źródło:
Geological Quarterly; 2005, 49, 2; 223--234
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Wenlock biostratigraphy and the Pristiograptus virbalensis group (Graptolithina) in Lithuania and the Holy Cross Mountains
Autorzy:
Radzevičius, S.
Powiązania:
https://bibliotekanauki.pl/articles/2059231.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Silurian
upper Wenlock
biostratigraphy
Graptolithina
Opis:
Graptolites from Lithuania and the Holy Cross Mountains comprise a succession of the lundgreni, parvus (except for the Holy Cross Mts.), nassa, praedeubeli, deubeli and ludensis biozones of the upper Wenlock, the parvus, praedeubeli and deubeli biozones being recognized for the first time in Lithuania, where a graptolite-free interval may also be distinguished. P. virbalensis Paskevicius, 1974 and the virbalensis group are not widely known, and are discussed here. Analysis of P. virbalensis shows this to be an independent taxon, closely related to P. auctus. There are three species - P. virbalensis, P.jaegeri and P. auctus - in the virbalensis group.
Źródło:
Geological Quarterly; 2006, 50, 3; 333-344
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Facies transition and biostratigraphic correlation of the Upper Silurian and Lower Devonian in West Bulgaria
Autorzy:
Boncheva, I.
Sachanski, V.
Lakova, I.
Yaneva, M.
Powiązania:
https://bibliotekanauki.pl/articles/2059515.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Bulgaria
Upper Silurian-Lower Devonian
conodonts
graptolites
facies transition
Opis:
Upper Silurian and Lower Devonian shelf deposits in West Bulgaria are exposed in three main Alpine tectonic units: the West Balkan Unit, the Lyubash Monocline and the Morava Unit. The West Balkan and Lyubash units consist of siliciclastic deposits: black graptolitic shales, banded pale shales and black siltstones. The Ludlow, Pridoli, Lochkovian, Pragian and Emsian were recognized on the basis of graptolite and tentaculite faunas. In the Morava Unit, the Ludlow black shales are progressively replaced by clayey limestones and nodular and micritic limestones in the Pridoli and Early Devonian. Newly obtained conodonts show the presence of the siluricus, eosteinhornensis, woschmidti, postwoschmidti, delta-pesavis, sulcatus, dehiscens and gronbergi zones. Petrographic study of the Morava Unit shows an increasing carbonate content and shallowing conditions upwards. The biostratigraphical correlation and facies interpretation reveal the coeval existence of two different depositional environments within the same shelf basin as well as a gradual shift in proximal direction.
Źródło:
Geological Quarterly; 2007, 51, 4; 407-418
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and petrology of the Upper Silurian greywackes from the Holy Cross Mountains (central Poland) : implications for the Caledonian history of the southern part of the Trans-European Suture Zone (TESZ)
Autorzy:
Kozłowski, W.
Domańska-Siuda, J.
Nawrocki, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059739.pdf
Data publikacji:
2014
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
greywackes
provenance
arc-continent collision
foreland
Silurian
Holy Cross Mountains
Opis:
The Ludlovian greywackes of the Holy Cross Mountains (HCM) represent a part of the sedimentary cover of the Łysogóry and Małopolska terranes located in the Trans-European Suture Zone, central Poland. The rocks form the sedimentary infill of the Caledonian foreland basin that developed at the Tornquist margin of Laurussia and had source-areas located on the orogen side of the basin. Until the present, the source terrane of the basin has not been identified in its potential location – at the south-west margin of the East European Platform. The Ludlovian greywackes of both parts of the HCM show a lot of similarities in clast spectrum, timing, and geochemical features, which implies similar sources of the clastic material. The petrographic modal composition and geochemical features indicate recycled orogen signatures with a distinct undissected, evolved magmatic arc component. The latter is particularly evident from the extraclast spectrum that contains andesite, trachyte and dacite clasts. Beside the volcanic rocks, the source area consisted of sedimentary and metasedimentary rocks with high amounts of cherts. The geochemical and petrological features in the rock succession point to an evolution of the tectonic setting from an active to a more passive margin type indicating synorogenic formation of the studied rocks. Based on the rock record, we suggest that the Upper Silurian greywackes originated as a result of the collision of the Tornquist margin of Laurussia with a volcanic arc (here: the Teisseyre Arc) – located probably at the easternmost extent of the Avalonian Plate. In this scenario, the arc-continent orogen was composed of an uplifted filling of the forearc basin, an accretionary prism, volcanic arc rocks, and an exhumed foreland basement - analogously to the present-day Taiwan orogen. The second key issue is the palaeogeographical relation between the Małopolska (Kielce Region) and the Łysogóry terranes in the Late Silurian. Despite the analogous grain composition and clast types, the Łysogóry Region greywackes are composed of distinctly more altered detritus, which is in accordance with the more distal character of the Łysogóry Basin. The latter is manifested, e.g., in the lack of Caledonian deformations. The present-day adjacency of both domains containing correlative greywacke formations coupled with contrasting alteration and Late Silurian transport directions parallel to the terrane boundary imply small to medium-scale (below palaeomagnetic resolution) left-lateral movements of the Małopolska and Łysogóry crustal blocks along the Holy Cross Fault in post-Silurian times.
Źródło:
Geological Quarterly; 2014, 58, 2; 311--336
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Silurian of southwestern margin of the East European Platform (Ukraine, Moldova and Romania) : lithofacies and palaeoenvironments
Autorzy:
Radkovets, N.
Powiązania:
https://bibliotekanauki.pl/articles/2059822.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
East European Platform
Silurian
lithofacies
reef
shelf of Baltica
palaeoenvironments
Opis:
Silurian strata, stretching along the western margin of the East European Platform from the Baltic to the Black Sea, represent a potential target for both conventional and unconventional hydrocarbon exploration. Distribution of the black shale facies, prospective for shale gas, and the reef facies, prospective for oil, has been studied in respect of palaeoenvironments. The Silurian sequence has been investigated in the territory of Ukraine (Volyn-Podillyan Plate, Dobrogean Foredeep) and correlated with the data on Moldova and Romania (Moldovian Platform). The occurrence of Silurian strata, their thickness, and petrographic and lithological characteristics allowed reconstructing the distribution of open-shelf, reef and lagoonal facies. The reef facies migrated during the Wenlock–Middle Pridoli, shifting towards the open sea and back towards the shore, and therefore has been termed a migrating reef facies. Correspondingly, the boundary between the open-shelf and reef facies was shifting. The facies distribution was controlled by the transgressive-regressive cycles, which caused the fluctuations of the shelf water depth in different time intervals of the Silurian. The shelf water depth of about 100 m, where the top of the oxygen-minimum layer impinged on the sea bottom, was the boundary between the open-shelf facies, represented by organic-rich sediments, and the reef buildups.
Źródło:
Geological Quarterly; 2015, 59, 1; 105--118
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ordovician–Silurian boundary in the Bardo Syncline, Holy Cross Mountains, Poland—new data on fossil assemblages and sedimentary succession
Autorzy:
Masiak, M.
Podhalańska, T.
Stempień-Sałek, M.
Powiązania:
https://bibliotekanauki.pl/articles/2058822.pdf
Data publikacji:
2003
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Bardo Syncline
Ordovician-Silurian boundary
lithology
graptolites
acritarchs
Opis:
A gradual transition from sandy through silty to clayey strata occurs near the Ordovician–Silurian (O/S) boundary in the southern part of Holy Cross Mountains, in the Bardo Syncline. Three graptolite biozones are distinguished for the O/S boundary interval deposits: ?persculptus, ascensus-acuminatus and vesiculosus. The first, rare graptolites appear below “graptolitic shales” in the ?persculptus Biozone. The diversity of the assemblage increases in the next two biozones. An analysis of acritarch frequency shows a decrease of acritarch frequency at the O/S boundary and then a gradual increase in the lower part of the ascensus-acuminatus biozone with a maximum in the vesiculosus Biozone. The taxonomic diversity of the acritarch assemblage shows a similar trend although the maximum of acritarch frequency observed in the vesiculosus Biozone do not coincide the maximum of acritarch taxonomic diversity.
Źródło:
Geological Quarterly; 2003, 47, 4; 311--330
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microphytoplankton from middle palaeolatitudes of the Southern Hemisphere : a record from climate change strata of Baltica’s O/S boundary
Autorzy:
Masiak, Monika
Stempień-Sałek, Marzenna
Podhalańska, Teresa
Powiązania:
https://bibliotekanauki.pl/articles/2058561.pdf
Data publikacji:
2020
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Polska
Ordovician boundary
Silurian boundary
palynology
acritarch frequency
bathymetry
climate
Opis:
In the present study, data on the diversity of acritarch and prasinophyte microphytoplankton were collected from Ordovician-Silurian transitional strata at three different geological localities in Poland: southern part of the Holy Cross Mountains (Małopolska Block, southern Poland), East European Platform (Baltica), and Koszalin-Chojnice Zone (NW Poland). The material represents the mucronata (trilobite) to vesiculosus (graptolite) biozones. The Ordovician microphytoplankton assemblages are characterized by low frequency and low diversity: up to 110 specimens and 12 genera per slide, in contrast to Silurian ones that are more frequent and more diverse - >3000 specimens and 16 genera per slide (diversity at the species level is also higher). Throughout the Ordovician part of the succession, typical Ordovician genera occur, such as Acanthodiacrodium, Ordovicidium, Orthosphaeridium and large Baltisphaeridium, together with isolated occurrences of typical Silurian genera, especially in the upper part of the Hirnantian (e.g., Diexallophasis). The Silurian assemblages are typified by high frequency of prasinophytes followed by typical Siluran acritarchs: Tylotopalla, Ammonidium, Domasia and Oppilatala. The palynological material from Poland is compared with material known from other localities: the Rapla and Valga boreholes (Estonia) and Anticosti Island (Canada), as well as others placed in different palaeocontinents and different bathymetric zones. Palynological assemblages obtained from Polish material confirm that bathymetry played the key role in taxonomic diversification of the microphytoplankton assemblage. This supports the existing models of distribution: dominance of prasinophytes (leiospheres) and cryptospores is characteristic for shallow-water environments. In deeper water, dominance of acanthomorphs is observed. In the deepest-water zones - mixed assemblages occur. For the Holy Cross Mountains, microphytoplankton frequency is compared with a TOC curve in the same interval.
Źródło:
Geological Quarterly; 2020, 64, 1; 86--103
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sedimentology of deposits from around the Late Caledonian unconformity in the western Holy Cross Mts.
Autorzy:
Malec, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059319.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Holy Cross Mountains
Upper Silurian-Lower Devonian
stratigraphy
sedimentology
Late Caledonian unconformity
Opis:
The Upper Silurian-Lower Devonian section of the western part of the Holy Cross Mts. is composed of greywackes of the Niewachlów Beds, Kielce Beds and Miedziana Góra Conglomerates. They are separated from the terrestrial Gruchawka Conglomerates and Barcza Beds by an erosional surface. Depositional structures recorded in the Silurian greywackes indicate the deep-water sedimentary environment of a flysch facies. The uppermost part of the Kielce Beds and the Miedziana Góra Conglomerates accumulated on a submarine delta fan. These deposits correspond to Late Caledonian molasse and are associated with closure of the Late Silurian basin in the Holy Cross Mts. The Gruchawka Conglomerates, containing fish remains, mark the beginning of the Early Devonian marine transgression. Together with the overlying sandstones and mudstones of the Barcza Beds they form the Old Red Sandstone succession. The Late Caledonian unconformity occurs between the Upper Silurian molasse deposits and Lower Devonian Old Red Sandstone facies, and the stratigraphic gap most likely spans the Pridoli, Lochkovian and lower Pragian. Large thicknesses of Silurian greywackes in the NW part of Kielce, and the high degree of thermal maturity of organic matter, indicate a geotectonic affinity of this region with the Łysogóry Block.
Źródło:
Geological Quarterly; 2001, 45, 4; 397-416
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 17

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