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Tytuł:
The Jurassic succession at Lisadele Lake (Tulsequah map area, British Columbia, Canada) and its bearing on the tectonic evolution of the Stikine terrane
Autorzy:
Shirmohammad, F.
Smith, P.
Anderson, R.
McNicoll, V.
Powiązania:
https://bibliotekanauki.pl/articles/2061004.pdf
Data publikacji:
2011
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
ammonites
chronology
Stikinia
terranes
Middle Jurassic
Lower Jurassic
Opis:
Jurassic rocks in the central Tulsequah map area include conglomerates and interbedded fossiliferous finer clastics of the Takwahoni Formation (Laberge Group) which unconformably overlie Triassic rocks. Ammonite collections document the Pliensbachian, Toarcian and Bajocian stages. We refine the age and provenance of episodes of coarse clastic input and confirm the progressive change of dominant clast lithology from reworked sedimentary rocks above the Triassic-Jurassic unconformity to volcanic, plutonic and then metamorphic clasts in the Upper Toarcian. The uppermost coarse clastic unit is a Bajocian chert-pebble conglomerate which, along with the immediately underlying black mudstone, we include in the Bowser Lake Group. Together with regional correlations, this confirms that the age of the basal part of the Bowser Lake Group is diachronous, younging southwards into Stikinia. Sandstone petrofacies trends and changes in conglomerate clast composition indicate arc uplift and dissection followed by Middle Jurassic orogen recycling. The isotopic ages of detrital zircons and granite clasts compared with the biochronologically constrained ages of the enclosing strata suggests that processes of intrusion, arc uplift, unroofing, and clastic deposition during the Early Jurassic occurred over intervals of significantly less than five million years.
Źródło:
Volumina Jurassica; 2011, 9, 1; 43-60
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Indirect biostratigraphy in condensed successions: a case history from the Bajocian of Normandy (NW France)
Autorzy:
Pavia, G.
Martire, L.
Powiązania:
https://bibliotekanauki.pl/articles/2061355.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
taphonomy
condensation
biostratigraphy
ammonites
Middle Jurassic
Normandy
Opis:
The fossil assemblages of the Bajocian of Normandy are affected by taphonomic condensation, and the use of these assemblages for biostratigraphy must be carried out with great care because of the taphonomic reworking (reelaboration) of most of them. Nevertheless such beautiful fossils, ammonites in particular, retain their value at least as taxonomic references if their relative stratigraphic position is recognized. Such a goal has been achieved in the Bretteville section, where the "Oolithe Ferrugineuse de Bayeux" Formation (OFB), consisting of 14 beds contained within 170 cm of strata, is exposed. Each bed contains a condensed ammonite assemblage in which the overall chronologic interval represented by fossils is longer than the time of sedimentation of the bed, and no ammonites can be defined as contemporaneous with the enclosing matrix, except for the topmost two beds. The timing of biologic and sedimentary events in this Fe-oolitic succession must thus be established in an indirect way, through a stratigraphy of fossils based on their taphonomically delayed first occurrence. In particular, we can only define the maximum age of each layer, constrained by the youngest recorded fossil. On the basis of this approach, the lower part of the OFB is shown to fall within the middle to upper part of the Bajocian Stage (Humphriesianum to Parkinsoni chrons), whereas the uppermost OFB can be referred to as the uppermost Bajocian (latest Parkinsoni Chron). We conclude that, at Bretteville and in general for the Fe-oolites of Normandy, fossiliferous horizons with condensed assemblages have no value for definition of the biostratigraphic standard scale, and that indirect biostratigraphy is useful to assign minimal chronologic values to taxa when (1) their stratigraphical range has not yet been established in expanded successions, (2) they are new taxa, and (3) they are present only in a condensed succession that suffered from the same taphonomic constraints as the Bajocian of Normandy.
Źródło:
Volumina Jurassica; 2009, 7, 1; 67-76
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Provenance of heavy minerals to the Middle and Upper Jurassic epicontinental deposits of NW Poland
Autorzy:
Bembenek, Kinga
Woronko, Barbara
Ziółkowski, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2058859.pdf
Data publikacji:
2021
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Middle Jurassic
Upper Jurassic
weathering indices
sea level change
stratigraphic gaps
Opis:
The source of clastic material supplied to the epicontinental sea during the Middle and Late Jurassic in the Pomeranian Segment of the northern part of the Mid-Polish Trough is analysed, using deposits from the Rzeczyn PIG-1 borehole that represent the Łyna, Chociwel, Brda, Pałuki, Kcynia and Rogoźno formations. Heavy mineral analysis, including weathering indices (ZTR, GZI, RZI and Q) and standardised scores for each mineral species, shows that each formation is characterized by a different heavy minerals association. In each association, transparent minerals include both ultrastable minerals (zircon, tourmaline and rutile), occurring in various proportions, and unstable minerals. This indicates that deposits subject to earlier multiple reworking were eroded from the surrounding landmasses. Most probably these deposits represented Triassic rocks, although fresh weathering covers were also eroded. The main direction of clastic material supply was from the N and NW, and to a lesser degree from the NE. The main reasons for changes in the source areas were probably sea level oscillations, while during regressions, exposed parts of the seabed became source areas of clastic material. Conversely, during transgressions, parts of the seabed became cut off from the supply of clastic material from eroded landmasses.
Źródło:
Geological Quarterly; 2021, 65, 1; 2
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Femur of a morganucodontid mammal from the Middle Jurassic of Central Russia
Autorzy:
Gambaryan, P P
Averianov, A.O.
Powiązania:
https://bibliotekanauki.pl/articles/23231.pdf
Data publikacji:
2001
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Morganucodontidae
Middle Jurassic
mammal
anatomy
Mammalia
morganucodontid
Russia
femur
Jurassic
locomotion
Opis:
We describe a nearly complete mammalian femur from the Middle Jurassic (upper Bathonian) from Peski quarry, situated some 100 km south east of Moscow, central Russia. It is similar to the femora of Morganucodontidae in having a globular femoral head, separated from the greater trochanter and reflected dorsally, fovea capitis present, both trochanters triangular and located on the same plane, distal end flat, mediolaterally expanded, and somewhat bent ventrally, and in the shape and proportions of distal condyles. It is referred to as Morganucodontidae gen. et sp. indet. It is the first representative of this group of mammals in Eastern Europe from the third Mesozoic mammal locality discovered in Russia. Exquisite preservation of the bone surface allowed us to reconstruct partial hind limb musculature. We reconstruct m. iliopsoas as inserting on the ridge, which starts at the lesser trochanter and extends along the medial femoral margin for more than half of the femur length. On this basis we conclude that the mode of locomotion of the Peski morganucodontid was similar to that of modern echidnas. During the propulsive phase the femur did not retract and the step elongation was provided by pronation of the femur.
Źródło:
Acta Palaeontologica Polonica; 2001, 46, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Temperature and isotopic relations in carbonate minerals in the Middle Jurassic sideritic rocks of central and southern Poland
Autorzy:
Jarmołowicz-Szulc, K.
Kozłowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/2060537.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
fluid inclusions
isotopes
carbonate minerals
sideritic rocks
Middle Jurassic
Opis:
The present study assesses the physico-chemical character of the fluids responsible for the genesis of carbonate minerals in the Middle Jurassic sideritic rocks at the northeastern margin of the Holy Cross Mts. and in the Częstochowa region. These rocks occur at present at depths between 30 and 600 m. Fluid inclusion and isotopic analyses have been performed in the carbonate minerals from sideritic sandstones, clayey siderites and sideritic coquinas. Siderite is the main carbonate mineral of the sideritic rocks. Calcite and ankerite are also present. The siderite is represented by two varieties, Mg-rich siderite (sideroplesite, less commonly – pistomesite) and siderite. Two generations of siderite have been distinguished – an early and a late one. The early siderite was formed at temperatures of about 20°C in the zone of microbiological methanogenesis from marine waters with some influence of meteoric waters (δ18O from –7.84 to –1.92‰ VSMOW). The late siderite crystallized at temperatures of about 62–110°C from pore waters enriched in 18O (δ18O >0‰ VSMOW) as compared with the isotopic composition of the waters responsible for the early siderite generation. The conducted fluid inclusion analyses point to formation of the cements from complex fluids of brine and carbon dioxide character, with densities slightly exceeding 1 g/cm3 and salinities varying from 10.5 to 16.9 wt.% NaCl eq. and from 6.4 to 14.0 wt.% NaCl eq. in the Holy Cross Mts. and in the Częstochowa region, respectively. The homogenization temperatures lie in the intervals of 62–110°C and 60–97°C, respectively and represent elevated values compared with data from the Polish Lowlands. Apart from burial, other heat sources must have been important for the lithogenesis of the Middle Jurassic deposits.
Źródło:
Geological Quarterly; 2016, 60, 4; 881-892
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cyclic sedimentation in the Middle Jurassic of central Poland
Autorzy:
Dadlez, J.
Powiązania:
https://bibliotekanauki.pl/articles/2059894.pdf
Data publikacji:
2002
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Central Poland
Middle Jurassic
stratigraphy
cyclic sedimentation
salt mobility
Opis:
Nine boreholes were drilled in the late eighties in central Poland to investigate the Middle Jurassic sedimentary successions. The boreholes were arranged in three lines (Ciechocinek, Brześć Kujawski and Wojszyce lines) running across three anticlines underlain by salt pillows. Long intervals of boreholes have been cored, often with 100% core recovery, thus enabling a detailed examination of sedimentary evolution. Sequences are composed of a full range of clastic rocks, from conglomerates through sandstones and heteroliths to shales. They are arranged in sedimentary cycles, predominantly regressive (coarsening upwards). These are interpreted as deposited in a shallow, wave/storm-dominated, shelf environment, each cycle being a result of progradation of fore-shore to near-shore heteroliths and sands over the shales of an open sea. The basin was probably non-tidal or microtidal. These essential (lower order) cycles, equivalents of the IVth order cycles in the world-wide scheme, are assembled in higher order cycles which resemble the IIIrd order cycles of that scheme. The bases of the higher order cycles are good lithostratigraphic markers, three of them being probably equivalents of chronostratigraphic boundaries (bases of the upper Aalenian, upper Bajocian and Bathonian, respectively). Correlation of borehole sections points to limited salt movement of the Ciechocinek and Wojszyce salt pillows during the Middle Jurassic. These are indicated, first of all, by thickness reductions seen in boreholes located above the tops of salt pillows. In the Ciechocinek area, the upward movement of salt occurred during the latest Bajocian/earliest Bathonian while in the Wojszyce area - during the early Bathonian. Coarser clastics were shed into the basin from the south-west, north-west (along the Mid-Polish Trough) and north-east during the Aalenian, and mainly from the north-east (from the East European Craton) in later times.
Źródło:
Geological Quarterly; 2002, 46, 3; 321-336
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Bajocian (Middle Jurassic) marine gastropod assemblage from the Badamu Formation, Central Iran
Autorzy:
Ferraris, M.
Binazadeh, T.
Kaim, A.
Powiązania:
https://bibliotekanauki.pl/articles/191652.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
gastropoda
Middle Jurassic
systematics
palaeobiogeography
Badamu Formation
Central Iran
Opis:
Nine species of gastropods are reported from the Bajocian (Middle Jurassic) part of the Badamu Formation of Central Iran. This is the first report of a gastropod assemblage of this age from the shelves of the Kimmerian Continent. Seven species belong to the Vetigastropoda and two to the Caenogastropoda. Two new species, the pleurotomariid Bathrotomaria iranica sp. nov. and the eucyclid Eucycloidea badamuensis sp. nov., are described. The remaining species are left in open nomenclature owing to poor preservation. The composition of the gastropod association is strongly reminiscent of other Tethyan gastropod faunas, in particular those from the southern shores of the Tethys (India and Arabia) and from southern Europe. This indicates a relatively uniform distribution of gastropod faunas along the Middle Jurassic shores of the western Tethys.
Źródło:
Annales Societatis Geologorum Poloniae; 2016, 86, 3; 329-340
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New sauropod trackways from the Middle Jurassic of Portugal
Autorzy:
Santos, V F
Moratalla, J.J.
Royo-Torres, R.
Powiązania:
https://bibliotekanauki.pl/articles/22749.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
new sauropod
sauropod
paleontology
trackway
Middle Jurassic
Jurassic
Portugal
Dinosauria
Sauropoda
morphotype
Opis:
The Galinha tracksite reveals a sequence of Bajocian–Bathonian limestones belonging to the Serra de Aire Formation (West−Central Portugal) and is one of the few sites in the world where Middle Jurassic sauropod dinosaur tracks can be found. This tracksite is characterised by the presence of long, wide gauge sauropod trackways, the Middle Jurassic age of which suggests these dinosaurs were more widely distributed over time than previously thought. Two trackways contain unique pes and manus prints with morphologies that allow a new sauropod ichnotaxon to be described: Polyonyx gomesi igen. et isp. nov. On the basis of different manus/pes prints and trackway features, the proposal is made to subdivide Sauropodomorpha ichno−morphotypes into five groups: Tetrasauropus−like, Otozoum−like, Breviparopus/Parabrontopodus−like; Brontopodus−like, and Polyonyx−like. Polyonyx gomesi igen. et isp. nov. is thought to represent a nonneosauropod eusauropod, with a well developed manus digit I. The posterior orientation of this digit print suggests they were made by a eusauropod dinosaur with a posteriorly rotated pollex. The manus print morphologies observed in two trackways suggest a stage of manus structure intermediate between the primitive non−tubular sauropod manus and the tubular metacarpal arrangement characteristic of more derived sauropods. The low heteropody (manus:pes area ratio 1:2) of the trackway renders it possible they could have been made by eusauropods such as Turiasaurus riodevensis, which has a similar manus:pes area ratio. The Polyonyx igen. nov. trackway was made by non−neosauropod eusauropod, and suggests that wide gauge sauropod trackways were not exclusively made by Titanosauriformes.
Źródło:
Acta Palaeontologica Polonica; 2009, 54, 3; 409-422
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comment and reply on "Palaeoenvironmental control on distribution of crinoids in the Bathonian (Middle Jurassic) of England and France" by Aaron W. Hunter and Charlie J. Underwood
Autorzy:
Hunter, A.W.
Underwood, Ch.J.
Powiązania:
https://bibliotekanauki.pl/articles/20228.pdf
Data publikacji:
2010
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
paleontology
paleoenvironment control
discussion
distribution
crinoid
Bathonian
Middle Jurassic
Jurassic
England
France
Źródło:
Acta Palaeontologica Polonica; 2010, 55, 1
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
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:
Sedimentological study of the Nikolčice Formation : evidence of the Middle Jurassic transgression onto the Bohemian Massif (subsurface data)
Autorzy:
Nehyba, S.
Opletal, V.
Powiązania:
https://bibliotekanauki.pl/articles/2060331.pdf
Data publikacji:
2017
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Nikolčice Formation
Middle Jurassic
provenance
shallow marine
nearshore depositional environment
Opis:
The Jurassic sedimentary succession along the eastern margin of the Bohemian Massif starts with mostly fluvial deposits of the Gresten Formation and continues after marine transgression with the deposition of the Nikolčice Formation (Middle Jurassic, Callovian). The provenance and depositional environment of the Nikolčice Formation showed that deposition occurred within offshore, transitional zone, shoreface, foreshore and littoral sand bar environments; however, shoreface and foreshore deposits dominate in the cores studied. The crystalline units along the eastern margins of the Bohemian Massif represent the primary source of deposits of the Nikolčice Formation. An important role was played by acidic and intermediate plutonites and highly metamorphosed metasedimentary rocks (granulite and amphibolite metamorphic facies), which indicates an advanced stage of erosion of the source area. The role of volcanic and intrusive rocks was small. The primary source was followed by an additional recycled source from older sedimentary rocks (especially the Moravo-Silesian Paleozoic deposits – the Líšeň Formation, the Myslejovice Formation). A similarity of the source areas for the Nikolčice Formation and the underlying Gresten Formation was recognized. Identified differences in their source areas are mainly explained by varied erosional levels due to successive exhumation of the source Variscan orogen and possibly also by an expansion of the source area.
Źródło:
Geological Quarterly; 2017, 61, 1; 138--155
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry of Middle Jurassic mudstones (Kraków-Częstochowa area, southern Poland): interpretation of the depositional redox conditions
Autorzy:
Szczepanik, P.
Witkowska, M.
Sawłowicz, Z.
Powiązania:
https://bibliotekanauki.pl/articles/2059479.pdf
Data publikacji:
2007
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Middle Jurassic
Częstochowa Clay Formation
palaeoenvironment
geochemical parameters
redox conditions
Opis:
Middle Bathonian iron-bearing dark grey mdstones and claystones from the Kraków-Czestochowa Upland (southern Poland) were subjected to geochemical and mineralogical study in order to evaluate palaeo-redox conditions of their deposition and diagenesis. They are mainly composed of kaolinite, with smaller amounts of other clay minerals and detrital quartz. Organic matter is composed of type III and/or IV kerogen and its d13C is between -23 and -24‰, suggesting a mainly terrigenous source, with a possible admixture of marine input. Most geochemical parameters: (total organic carbon) TOC/S, U/Th, Ni/Co, V/Cr, (Cu+Mo)/Zn ratios, authigenic uranium content, and Fe-TOC-S relationship, indicate deposition under oxygenated bottom water conditions. By contrast, DOP (degree of pyritization) and V/V+Ni indices suggest a dysoxic environment. However, DOP probably reflects redox conditions in the sediment during diagenesis rather than in the over laying water column. The composition of the organic matter and the domination of pyrite euhedra over framboids indicates that the V/V+Ni ratio may not be reliable for determination of redox conditions in the rocks studied. There is no significant difference between the geochemical indices of host rocks with nodules and those with out them.
Źródło:
Geological Quarterly; 2007, 51, 1; 57-66
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Berthierine in the Middle Jurassic sideritic rocks from southern Poland
Autorzy:
Kozłowska, A.
Maliszewska, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059646.pdf
Data publikacji:
2015
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
berthierine
sideritic rocks
Middle Jurassic
Holy Cross Mountains
Częstochowa region
Opis:
A characteristic green and yellow-brown clay mineral from sideritic rocks was studied from 14 boreholes penetrating the Middle Jurassic strata of the northeastern margin of the Holy Cross Mountains and Częstochowa region, using polarizing and scanning electron microscopes, cathodoluminescence and X-ray analysis and revealing the presence of berthierine. In these sideritic rocks, berthierine occurs mainly in Lower and Middle Bathonian strata deposited in shoreface and deltaic environments of the northeastern margin of the Holy Cross Mountains, and in Upper Bajocian deposits of both areas studied. It forms the clay cement of sideritic rocks, fills voids in bioclasts and is also present in ooids. Ooids consisting of berthierine have been affected by mechanical compaction and mainly carbonate replacement. Berthierine ooids, replaced by sideroplesite, pistomesite, Fe-calcite or ankerite, and rarely by pyrite and altered by kaolinite, occur commonly. Berthierine ooids of the Bathonian sideritic rocks are typically better preserved, compared to those from the Bajocian and Aalenian. Berthierine crystallised in the eodiagenesis stage in suboxic conditions below the water-sediment interface, where iron-bearing freshwater mixed with sea water. It is chemically and structurally unstable and, during the mesodiagenetic stage at higher temperatures, could transform to chamosite by recrystallisation.
Źródło:
Geological Quarterly; 2015, 59, 3; 551--564
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Lower and Middle Jurassic ammonoids of the Shemshak Group in Alborz, Iran and their palaeobiogeographical and biostratigraphical importance
Autorzy:
Seyed-Amami, K
Fursich, F.T.
Wilmsen, M.
Majidifard, M.R.
Shekarifard, A.
Powiązania:
https://bibliotekanauki.pl/articles/21183.pdf
Data publikacji:
2008
Wydawca:
Polska Akademia Nauk. Instytut Paleobiologii PAN
Tematy:
Middle Jurassic
biostratigraphy
Lower Jurassic
Ammonitida
ammonoid
paleontology
Jurassic
Alborz Mountains
paleobiogeography
Shemshak Group
Iran
Opis:
The Shemshak Group at Shahmirzad (northern Iran) is characterized by the most frequent and extensive marine intercalations and contains the most abundant and diverse ammonite faunas hitherto known from the Lower and lower Middle Jurassic strata of the Alborz Range. So far, 62 ammonite taxa have been recorded from this area, including 25 taxa from earlier studies. The taxa belong to the families Cymbitidae, Echioceratidae, Amaltheidae, Dactylioceratidae, Hildoceratidae, Graphoceratidae, Hammatoceratidae, Erycitidae, and Stephanoceratidae with the new species Paradumortieria elmii and Pleydellia (P.?) ruttneri. The fauna represents the Late Sinemurian, Late Pliensbachian, Toarcian, Aalenian, and Early Bajocian. Palaeobiogeographically, it is closely related to the Northwest European (Subboreal) Province, and exhibits only minor relations with the Mediterranean (Tethyan) Province.
Źródło:
Acta Palaeontologica Polonica; 2008, 53, 2
0567-7920
Pojawia się w:
Acta Palaeontologica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Tubular tempestites from Jurassic mudstones of southern Poland
Autorzy:
Leonowicz, P. M.
Powiązania:
https://bibliotekanauki.pl/articles/2059866.pdf
Data publikacji:
2016
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
tubular tempestite
shallow-marine mudstone
omission surface
Lower Jurassic
Middle Jurassic
Silesian-Cracow region
Opis:
This paper presents tubular tempestites from southern Poland and their application for environmental and sequence stratigraphy interpretation. Tubular tempestites are present in muddy successions of the Lower Jurassic Ciechocinek Formation and in the Middle Jurassic Częstochowa Ore-Bearing Clay Formation in the Silesian-Kraków region. They occur as sand-filled tubes of Spongeliomorpha and Thalassinoides entrenched in the mudstone, which form two characteristic horizons. Tubes were emplaced in semi-consolidated substrate and filled with sand brought by storm-generated bottom currents. The trace fossils reveal features typical of Glossifungites ichnofacies associated firmgrounds, which record discontinuities in the stratigraphical record, linked with a depositional hiatus or condensation and erosion of the sea-floor. The coincidence of these horizons with early phases of regional transgressions suggests that they represent transgressive surfaces of erosion. Their limited spatial extent probably resulted from varying intensity of erosion, which locally scoured deeply down to already consolidated substrate, whereas in other places erosion was weaker or even absent, and thus it is not marked in the sedimentary record there.
Źródło:
Geological Quarterly; 2016, 60, 2; 385--394
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 66

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