Les olistholites du Riou d'Entraix et leur signification paleostructurale

1966 ◽  
Vol S7-VIII (3) ◽  
pp. 401-404
Author(s):  
Philippe Artru
Keyword(s):  
Middle Jurassic ◽  
Deep Basin ◽  
Upper Bajocian

Abstract The upper Bajocian (middle Jurassic) heterogeneous polygene breccias of the Riou d'Entraix (southeast France) are interpreted as olistostromes formed by gravity sliding along a paleoscarp. The scarp was to the east, in the area presently covered by overthrusts, and separated a euxinic deep basin from a well-oxygenated shallow shelf. Similar deposits in the Barcelonette window and the semi-window at Embrun are probably of the same origin.

scholarly journals First record of an erymid lobster (Crustacea, Decapoda) from the upper Bajocian of Northwest Bulgaria

2021 ◽  
Vol 50 (2) ◽  
pp. 69-74
Author(s):  
Lubomir Metodiev ◽  
Docho Dochev ◽  
Svetlozar Seferinov ◽  
Silviya Petrova
Keyword(s):  
Eastern Europe ◽  
Middle Jurassic ◽  
First Record ◽  
Upper Bajocian ◽  
Single Locality

Fossil chela of an erymid lobster from a single locality of the upper Bajocian in the Western Fore-Balkan Mts (NW Bulgaria) was studied. Two segments of the thoracic appendages, probably belonging to one individual, were described: 1) P1 propodus with partially preserved pollex and dactylus; and 2) P1 carpus and P1 merus attached. These elements of the first pair of pereiopods of a lobster were identified as Eryma compressum (Eudes-Deslongchamps, 1842). Eryma compressum a is well-known taxon from numerous Jurassic localities in Europe but has not been recorded in Bulgaria to date. Therefore, albeit being an isolated finding with only a few elements, the Bulgarian example contributes to the overall record of European erymid faunas from the Middle Jurassic, and especially in Eastern Europe, from where only a few erymids have been reported.

scholarly journals Shallow marine syn-rift sedimentation: Middle Jurassic Pelion Formation, Jameson Land, East Greenland

2003 ◽  
Vol 1 ◽  
pp. 813-863 ◽  
Author(s):  
Michael Engkilde ◽  
Finn Surlyk
Keyword(s):  
Sea Level ◽  
Middle Jurassic ◽  
Large Scale ◽  
Significant Shift ◽  
Shallow Marine ◽  
East Greenland ◽  
Upper Bajocian ◽  
Stacking Pattern ◽  
Facies Associations ◽  
Middle Callovian

The Middle Jurassic Pelion Formation – Fossilbjerget Formation couplet of Jameson Land, East Greenland, is a well-exposed example of the Middle Jurassic inshore–offshore successions characteristic of the rifted seaways in the Northwest European – North Atlantic region. Early Jurassic deposition took place under relatively quiet tectonic conditions following Late Permian – earliest Triassic and Early Triassic rift phases and the Lower Jurassic stratal package shows an overall layer-cake geometry. A long-term extensional phase was initiated in Middle Jurassic (Late Bajocian) time, culminated in the Late Jurassic (Kimmeridgian–Volgian), and petered out in the earliest Cretaceous (Valanginian). The Upper Bajocian – Middle Callovian early-rift succession comprises shallow marine sandstones of the Pelion Formation and correlative offshore siltstones of the Fossilbjerget Formation. Deposition was initiated by southwards progradation of shallow marine sands of the Pelion Formation in the Late Bajocian followed by major backstepping in Bathonian–Callovian times and drowning of the sandy depositional system in the Middle–Late Callovian. Six facies associations are recognised in the Pelion–Fossilbjerget couplet, representing estuarine, shoreface, offshore transition zone and offshore environments. The north–southtrending axis of the Jameson Land Basin had a low inclination, and deposition was sensitive to even small changes in relative sea level which caused the shorelines to advance or retreat over tens to several hundreds of kilometres. Eight composite sequences, termed P1–P8, are recognised and are subdivided into a total of 28 depositional sequences. The duration of the two orders of sequences was about 1–2 Ma and 360,000 years, respectively. The Upper Bajocian P1–2 sequences include the most basinally positioned shallow marine sandstones, deposited during major sealevel lowstands. The lowstands were terminated by significant marine flooding events, during which sandstone deposition was restricted to northern, more proximal parts of the basin. The Upper Bajocian – Middle Bathonian P3–4 sequences show an overall progradational stacking pattern. The sequence boundary at the top of P4 marks a significant shift in stacking pattern, and the Upper Bathonian – Middle Callovian P5–8 sequences show large-scale backstepping, terminating in a widespread condensed succession at the distal, southern end of the basin. The largescale backstepping was governed by combined tectonically-induced subsidence, reflecting increased rates of extension, and eustatic sea-level rise. The depositional trends of the Pelion Formation – Fossilbjerget Formation couplet provide a well-exposed analogue to contemporaneous subsurface deposits which form major hydrocarbon reservoirs on the west Norway shelf, and in the Northern North Sea.

Redox conditions during sedimentation of the Middle Jurassic (Upper Bajocian–Bathonian) clays of the Polish Jura (south-central Poland)

Facies ◽  
2008 ◽  
Vol 55 (1) ◽  
pp. 103-114 ◽  
Author(s):  
Michał Zatoń ◽  
Leszek Marynowski ◽  
Patrycja Szczepanik ◽  
David P. G. Bond ◽  
Paul B. Wignall
Keyword(s):  
Middle Jurassic ◽  
Redox Conditions ◽  
Central Poland ◽  
South Central ◽  
Upper Bajocian

Detailed biostratigraphic scales as based on the palaeobiogenetical approach (an example of the Upper Bajocian – Lower Bathonian ostracod scale of the Russian Platform)

2017 ◽  
pp. 121-0 ◽  
Author(s):  
Yana Shurupova ◽  
Ekaterina TESAKOVA
Keyword(s):  
New Species ◽  
Middle Jurassic ◽  
Russian Platform ◽  
Its Phylogeny ◽  
Upper Bajocian ◽  
Predominant Type ◽  
The Family ◽  
Two New Species ◽  
Ammonite Zones ◽  
Lower Bathonian

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.

Note preliminaire sur le Bathonien inferieur du Bugey (Jura meridional)

1964 ◽  
Vol S7-VI (4) ◽  
pp. 529-534
Author(s):  
Charles Mangold ◽  
R. Enay ◽  
Pierre Dominjon
Keyword(s):  
Geographic Distribution ◽  
Middle Jurassic ◽  
Western Europe ◽  
Jura Mountains ◽  
Southern England ◽  
Upper Bajocian ◽  
Relationship Of ◽  
The Relationship ◽  
Lower Bathonian

Abstract The recent discovery of lower Bathonian (upper middle Jurassic) ammonites at several places in the Bugey region of the southern Jura mountains of eastern France resolves the problem of the relationship of the Bajocian to the Bathonian in this key region. Fauna of upper Bajocian (lower middle Jurassic) and middle and upper Bathonian had long been known but lower Bathonian was unknown. One bed is particularly rich in a varied fauna of ammonites, pelecypods, gastropods, and echinoderms in a remarkable state of preservation. The faunal association shows the coexistence of the forms of the Zigzag beds of England and the Wuerttembergicus beds of Germany, thus confirming the homology of these two horizons. The geographic distribution of type genera of the lower Bathonian in western Europe permits the identification of two faunal domains overlapping in Lorraine and the northern Jura mountains as well as the Bugey region. The genus Zigzagiceras extends from southern England through Switzerland, the Jura mountains, and the Basses-Alpes to Sicily, and also has been found in Portugal. The western limit of the species Parkinsonia (Oraniceras) wuerttembergica occurs in Germany, Lorraine, the Jura mountains, and Sicily. It appears that the genera Morphoceras and Ebrayiceras may have an even greater distribution.

scholarly journals The age of the Pre-Callovian Jurassic sequence at the southwest of Tatarstan (central Russia, Tarkhanovskaya Pristan’–Dolinovka reference section) and the status of the Upper Bajocian “Garantiana-beds”, previously described from here

2019 ◽  
Vol 27 (6) ◽  
pp. 29-40
Author(s):  
A. P. Ippolitov ◽  
D. B. Gulyaev
Keyword(s):  
Critical Review ◽  
Middle Jurassic ◽  
Basal Part ◽  
Volga River ◽  
Central Russia ◽  
Upper Bajocian ◽  
The Status ◽  
The Republic ◽  
Reference Section ◽  
Jurassic Sequence

In the present paper we describe and discuss belemnite finds from the basal part of the middle Jurassic sequence at the southwest of the Republic of Tatarstan (Tetyushi district). The belemnites were collected from the outcrops located along a shoreline of the Kuybyshevskoye reservoir (Volga river) between the place Tarkhanovskaya pristan and the former village Dolinovka. These belemnites indicate that the basal part of the Jurassic sequence is Early Bathonian (Ishmae Zone) or, less probable, Middle Bathonian in age. Such dating triggers a critical review for the age of the middle Jurassic sequence in the region. In particular, poorly preserved ammonites previously collected from the same outcrops higher in the succession and interpreted as members of the Late Bajocian subfamily Garantianinae, are in fact Late Bathonian Gowericeratinae. Consequently, Beds with Garantiana nominally the most ancient ammonite-based biostratigraphic unit within the whole Jurassic of European Russia, based on this assemblage, is invalid.

EXPERIENCE OF D. HOUSKNEСHT DIAGRAM FOR IMPACT ASSESMENT OF CONSOLIDATION AND CEMENTATION ON POROSITY OF THE LOWER-MIDDLE JURASSIC SANDSTONES OF THE NYUROLKA DEPRESSION AND THE KOLTOGOR-URENGOY MEGATROUGH

2020 ◽  
pp. 30-42
Author(s):  
E. A. Predtechenskaya ◽  
Keyword(s):  
Middle Jurassic ◽  
Pore Space ◽  
Depth Interval ◽  
Pressure Solution ◽  
Leading Role ◽  
Upper Bajocian ◽  
Terrigenous Rocks ◽  
Tomsk Region ◽  
Mechanical Consolidation ◽  
Main Factor

Using D. U. Hausknecht diagram, the degree of impact of authigenic cementation, pressure solution and mechanical consolidation on the reduction of porosity and intergranular volume of the Lower - Middle Jurassic sandstones in the territory of the Tomsk region was determined. Sandstones of the Nadoyakha (Lower Toarcian – Lower Aalenian, bed Yu15), Vymskoye (Lower Bajocian, beds Yu11–Yu14), Leontievskiy (Lower-Upper Bajocian, beds Yu8–Yu10) and Malyshevka (Upper Bajocian – Bathonian, beds Yu3–Yu6) were analyzed horizons penetrated by a number of wells in western regions of the Nyurolka depression and the southern part of the Koltogor-Urengoy megatrough in the depth interval 2702–3326 m. It was found that the reduction in the intergranular volume of studied rocks is associated not only with their genesis, material composition, and structural and textural features, but also with the amount, type and composition of cement. It was revealed that the main factor influencing the reduction of the primary volume of the pore space of terrigenous rocks to a depth of ~ 2900–3000 m is the authigenic cementation, and below 3000 m the leading role is played by mechanical consolidation and dissolution of detrital grains under pressure. For Late Toarсian-Aalenian sandstones in the studied areas, the contribution of the factor of mechanical consolidation and pressure solution on the reduction of the primary intergranular volume was 38–53%, and for sandstones of the Bajocian – 20–30%. For the latter, the share of authigenic cementation was 24–56%. The work also considers circumstances that limit this method and possibilities of its application for other types of rocks.

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