PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników
Powiadomienia systemowe
  • Sesja wygasła!

Znaleziono wyników: 8

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  bajos
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Long-term shoreline shifts on continental blocks during the Bajocian: an updated interpretation based on synthetic stratigraphical and palaeogeographical developments on regional scales
Ruban Dmitry A., Sallam Emad S.
Geologos
|
2019
|
Vol. 25, No. 1
43--50
EN
Available reconstructions of Jurassic global sea level changes differ and are in need of an update. New stratigraphical charts and palaeogeographical developments for a number of large continental blocks or their portions of these (e.g., Germany, India, northeast Africa, northwest Australia, the Russian Platform and western Siberia) reveal regional long-term shoreline shifts (i.e., transgressions and regressions) during the Bajocian Stage (168.3–170.3 Ma). A comparison of these allows to document only a single coherent feature, namely the earliest Bajocian transgression, in the majority of the continental blocks considered. Undoubtedly, this event was triggered by a eustatic rise. However, long-term shoreline shifts were either weak to absent or differed between the blocks during almost the entire Bajocian, thus providing evidence of the apparent stability of global sea level and the importance of regional tectonic activity as a control mechanism on particular transgressions and regressions. Interestingly, it appears that the earliest Bajocian eustatic rise was a constituent of a long-term eustatic pattern; the nature of this event has yet to be fully understood. Generally, the findings presented here are in better agreement with Anthony Hallam’s view of Jurassic eustasy and question some other global sea level reconstructions.
2
Content available Genetic sequence stratigraphy on the basis of ichnology for the Middle Jurassic basin margin succession of Chorar Island (eastern Kachchh Basin, western India)
Darngawn Jehova L., Patel Satish J., Joseph Jaquilin K., Shitole Apuva D.
Geologos
|
2019
|
Vol. 25, No. 1
31--41
EN
Synrift basin margin successions are greatly influenced by eustatic sea level changes, tectonics and accommodation space filled in by sediments. The Middle Jurassic (Bajocian–Callovian) of Chorar Island (western India) comprises a ~109-m-thick synrift basin margin succession of clastic, non-clastic and mixed siliciclastic-carbonate rocks which are here analysed and categorised into nine lithofacies. The succession is bioturbated to varying intensities; 16 identified ichnogenera can be assigned to environmentally related groups of five trace fossil assemblages, which include Gyrochorte, Hillichnus, Rhizocorallium, Skolithos and Thalassinoides. These ichnoassemblages document the Skolithos and Cruziana Ichnofacies which marks a change in energy conditions, sedimentation dispersal patterns and bathymetry in a shallow-marine environment. The Bajocian–Callovian succession is further analysed on the basis of sedimentological and ichnological data that show two genetic sequences consisting of Transgressive Systems Tract and Highstand Systems Tract bounded by Maximum Flooding Surface. The synrift basin margin succession of the Middle Jurassic of Chorar Island shows cyclicity in deposition; the Bajocian–Bathonian succession represents progradational to retrogradational coastlines, while the Callovian succession documents an aggrading progradational coastline.
3
Content available Detailed biostratigraphic scales as based on the palaeobiogenetical approach (an example of the Upper Bajocian – Lower Bathonian ostracod scale of the Russian Platform)
Shurupova Y. A., Tesakova E. M.
Volumina Jurassica
|
2017
|
Vol. 15, no 1
121--138
EN
Two new species of ostracods of the family Progonocytheridae Sylvester-Bradley Camptocythere (C.) lateres Tesakova et Shurupova, sp. nov. and C. (C.) angustius Tesakova et Shurupova, sp. nov. from the Michalskii and Besnosovi ammonite zones (Upper Bajocian – Lower Bathonian, Middle Jurassic) of the Sokur section (Saratov) are described. The changes in ontogenesis in the phylogeny of Camptocythere (C.) lateres Tesakova et Shurupova in the stratigraphical interval corresponding to the Palaeocytheridea kalandadzei ostracod Zone, and especially to the beds with C. (C.) lateres, have been studied. The levels of the change in the predominant type of sculpture (corresponding to evolutionary boundaries) are recognized in the sculpture development among the adult representatives of the species in its phylogeny. This palaeobiogenetic (heterochrony) approach allows subdivision of the beds with C. (C.) lateres into three stratigrapical intervals characterized by changes in the type of sculpture.
4
Content available Integrated biostratigraphy across the Aalenian/Bajocian boundary of the Central High Atlas, Morocco
Sadki D.
Volumina Jurassica
|
2015
|
Vol. 13, no. 1
27--42
EN
This work presents an integrated biostratigraphic study across the Aalenian/Bajocian boundary of the Central High Atlas of Morocco. The data that are the basis for this study were obtained from the region of Rich that is located in the center of the basin of the Moroccan High Atlas. This region presents a thick Aalenian–Bajocian succession with continuous marine sedimentation, which offers a rich and varied fauna whose analysis enables the compilation of an integrated biostratigraphy based on the different paleontological groups: ammonites, belemnites, brachiopods, bivalves, gastropods, calcareous nannofossils, foraminifera and ostracods.
5
Content available Pozycja stratygraficzna i paleogeograficzne znaczenie bajoskich wapieni krynoidowych w ewolucji pienińskiego basenu skałkowego
Krobicki M., Wierzbowski A.
Volumina Jurassica
|
2004
|
Vol. 2, no. 1
69-82
EN
The chronostratigraphical position of the crinoidal limestones in the Pieniny Klippen Belt (Carpathians, Poland) is well documented by ammonite faunas. It corresponds to the stratigraphical interval from the uppermost Propinquans and lowermost Humphriesianum zones of the Lower Bajocian to the Garantiana Zone of the Upper Bajocian. The hiatus recognized at the base of the crinoidal limestone complexes covers the time interval of the Laeviuscula Chron and a bulk of the Propinquans Chron of the Early Bajocian. The sedimentological features found in the basal beds of the crinoidal limestones include: presence of numerous phosphatic concretions, occurrence of pyrite framboids, as well as numerous rests of fauna (mostly ammonites and belemnites), all of them showing a slow sedimentation rate. The rapid change of sedimentation from dark shales of oxygen-depleted environment (Skrzypny Shale Fm. – Aalenian to earliest Bajocian) to overlying light crinoidal grainstones (Smolegowa Limeston Fm., Flaki Limestone Fm.) corresponded to an important geodynamic event that took place during Early Bajocian – the origin of the mid-oceanic Czorsztyn Ridge.
6
Content available Pedicellarie ze środkowojurajskich iłów rudonośnych i ich znaczenie w strategii życiowej jeżowców
Boczarowski A.
Volumina Jurassica
|
2004
|
Vol. 2, no. 1
141-150
EN
Numerous, well-preserved globiferous and ophiocephalous pedicellariae of echinoids have been found in samples from several brickyards of Central Poland: Gnaszyn and Kawodrza (Częstochowa), Blanowice (Zawiercie), Wrzosowa. This is the first study of the uppermost Bajocian and Bathonian pedicellariae from the Ore Bearing Częstochowa Clay Formation. Four new morphotypes are described. Effectiveness of the defensive echinoid strategy is discussed; the structures observed indicate the presence of poison in some but not all spines and pedicellariae of both living and fossil species. All main morphological types of pedicellariae are compared. Morphotype I of globiferous pedicellariae and morphotype III of ophiocephalous pedicellariae are similar to those from the recent family Parechinidae. Jurassic echinoid Pelanechinus has ophiocephalous pedicellariae reminding morphotype II, as described from the Polish Bathonian.
7
Content available Charakterystyka palinofacjalna najwyższego bajosu i batonu okolic Włocławka
Barski M.
Volumina Jurassica
|
2003
|
Vol. 1, no. 1
7-12
8
Content available Biostratygrafia amonitowa formacji częstochowskich iłów rudonośnych (najwyższy bajos - górny baton) z odsłonięć w Częstochowie
Matyja B., Wierzbowski A.
Volumina Jurassica
|
2003
|
Vol. 1, no. 1
3-6
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.