scholarly journals Types of river sources of the thin-grained aluminosilicaclastics for the Jurassic and lower cretaceous deposits of the West Siberian megabasin

2021 ◽  
Vol 63 (4) ◽  
pp. 52-61
Author(s):  
A. V. Maslov
Keyword(s):  
Lower Cretaceous ◽  
The Urals ◽  
River Systems ◽  
The West ◽  
Rock Composition ◽  
Fine Grained ◽  
The North ◽  
Catchment Areas ◽  
Cretaceous Deposits ◽  
West Siberian Basin

Background. The lithogeochemical features of fine-grained detrital rocks (mudstones, shales, and fine-grained siltstones) allow, with a certain degree of success, the main parameters of the formation of sedimentary sequences to be reconstructed. These parameters include (primarily in terms of their REE and Th systematics) the types of river systems supplying thin terrigenous suspension in the sedimentation area: the rivers of the 1st category – large rivers with a catchment area of more than 100,000 km2; 2nd category – rivers feeding on the products of erosion of sedimentary deposits; 3rd category – rivers draining mainly igneous and metamorphic rocks; and 4th category – rivers carrying erosion products of volcanic associations.Aim. To reveal, based on the analysis of interrelationships between such parameters as (La/Yb)N, Eu/Eu* and the Th content, the types of river systems that fed the Jurassic and Lower Cretaceous deposits of the Shaim oil and gas region (OGR) (Sherkalinsky, Tyumen, Abalak and Mulymya formations) and the region of the North Pokachevsky field of the Shirotnoe Priobye region (Sherkalinsky, Tyumen and Bazhenov formations, Lower Cretaceous deposits).Materials and methods. The ICP MS data for almost 100 samples of mudstones and fine-grained clayey siltstones were used to analyse the features of distribution of lanthanides and Th in the Jurassic and Lower Cretaceous clayey rocks of the Shaim OGR and the area of the North Pokachevsky deposits. Individual and average composition points for formations, members and layers were plotted on the (La/Yb)N-Eu/Eu*, (La/Yb)N–Th diagrams developed by us with classification areas of the composition of fine suspended material of modern rivers of different categories.Results and conclusion. The results presented in the article showed that during the formation of the deposits of the Shaim OGR in the Early and Middle Jurassic, erosion affected either mainly sedimentary formations or paleo-catchment areas that were very variegated in their rock composition. In the Late Jurassic, the source area was, most likely, a volcanic province, composed mainly of igneous rocks of the basic composition, and located within the Urals. This conclusion suggested that the transfer of clastic material from the Urals to the Urals part of the West Siberian basin “revived” much earlier than the Hauterivian. The Jurassic-Lower Cretaceous section of the vicinity of the North Pokachevsky field was almost entirely composed of thin aluminosilicaclastics formed due to the erosion of volcanic formations. These volcanic formations were located, as followed from the materials of earlier performed paleogeographic reconstructions, probably within the Altai-Sayan region or Northern Kazakhstan. Thus, the supply of detrital material in the considered territories of the West Siberian basin had a number of significant differences in the Jurassic and early Cretaceous.

The Arctic Caledonides and earlier Oceans

1972 ◽  
Vol 109 (4) ◽  
pp. 289-314 ◽  
Author(s):  
W. B. Harland ◽  
R. A. Gayer
Keyword(s):  
Barents Sea ◽  
The Arctic ◽  
Lomonosov Ridge ◽  
The Urals ◽  
The West ◽  
East Greenland ◽  
The North ◽  
Scandinavian Caledonides ◽  
The Baltic ◽  
North Greenland

SummaryConsideration of the arctic configuration of the Caledonides leads to a distinction between eastern and western geosynclinal belts. The western belt, comprising the East Greenland, East Svalbard and southern Barents Sea Caledonides is postulated to continue northwards into the Lomonosov Ridge, whilst the western Spitsbergen Caledonides are thought to have originated as part of the North Greenland geosyncline which is also thought to continue northwards to form the western part of the Lomonosov Ridge. The eastern Caledonian geosynclinal belt comprising the Scandinavian Caledonides appears to swing eastwards to link with the Timan Chain and possibly the Urals.The already postulated (‘Proto-Atlantic’) ocean concept is reviewed in the light of the Arctic Caledonides and named Iapetus. Faunal provincialism suggests that the ocean was in existence up to early Ordovician but had substantially closed by mid Ordovician times. Possible relics of the suture marking the closure of this ocean suggest that it lay to the west of the Arctic Scandinavian Caledonides trending NE to latitude 70° N and thence veered eastwards separating the southern Barents Sea Caledonides from those of Arctic Scandinavia, possibly connecting with the northern Uralian ocean. A previous branch of the ocean may have separated East Svalbard and East Greenland as an ocean-like trough. A further (pre-Arctic) ocean may have existed to the north of the North Greenland–Lomonosov Ridge geosynclines. This is named Pelagus.The closure of these oceanic areas and the deformation of the bordering geosynclines delineates three principal continental plates, namely, Baltic, Greenland and Barents Plates. Their relative dominantly E–W motion up to Silurian times produced compression between the Greenland and both the Baltic and Barents plates but dextral transpression and transcurrence between the latter plates. In Late Silurian to Devonian times an increasing northward component controlled late Caledonian transpression and sinistral transcurrence between the Greenland plate and the combined Baltic and Barents plates.

scholarly journals Lithology of the Upper Jurassic-Lower Cretaceous deposits of the eastern part of the Myrgovaam and Rauchua depressions, Western Chukotka

2020 ◽  
Vol 65 (4) ◽  
Author(s):  
Elena V. Vatrushkina ◽  
◽  
Marianna I. Tuchkova ◽  
Keyword(s):  
Lower Cretaceous ◽  
Upper Jurassic ◽  
Coarse Grained ◽  
Fine Grained ◽  
Tectonic Environment ◽  
The Matrix ◽  
Siliciclastic Rocks ◽  
Facies Variation ◽  
Felsic Volcanic ◽  
Cretaceous Deposits

Upper Jurassic-Lower Cretaceous deposits were formed on the South-Western margin of the Chukotka terrane in active tectonic environment. Their stratigraphic units characterized by sedimentary structures and lithology similarities, facies variation and scarcity of reliable fauna findings. Detailed lithological studies are necessary due to the absence of a unified approach to the stratigraphic division of deposits. The paper presents petrographic, geochemical, and isotope-geochemical characteristics of Upper Jurassic-Lower Cretaceous rocks. The stages of changing the sedimentation conditions and sources, which determined the differences in sedimentological features and the composition of the studied strata, are reconstructed. The Oxford-Kimmeridgian section is composed of sandy debris flow deposits with an arcosic composition of psammitic differences. Among their sources, ancient granitoids dominated, while siliciclastic rocks, volcanites and metamorphic complexes were secondary. Volgian-valanginian interval is characterized by the accumulation of sediments in various parts of the submarine fan. In Volgian sequences fine -, medium - and coarse-grained turbidites with lenses of small-pebble conglomerates are identified. A large number of simultaneous pyroclastic material in the Volgian deposits indicates the synchronous volcanic activity. In the Volgian period, the province was dominated by volcanites, mainly of the basaltic and andesitic composition, siliciclastic rocks were present in smaller amount. The Berriasin section is composed of fine-grained turbidites with single horizons of medium-grained turbidites and gravelitic lenses, as well as slope deposits in the form of rhythmically interbedded sandstones and mudstones with slump structures. Sandstones have greywacke composition and contain an admixture of ash material in the matrix. The main sources for Berriasian deposits were siliciclastic rocks and felsic volcanic complexes. The Valanginian section is represented by fine and medium-grained turbidites with horizons of amalgamated sandstones. Sandstones are classified as arkoses by the ratio of rock-forming components. The dominant source in the Valanginian time was ancient granitoids, while siliciclastic rocks and volcanites were secondary.

scholarly journals Facies changes in the Cenomanian (Cretaceous) of the northwestern Elbe Valley near Dresden (Saxony, Germany)

2017 ◽  
Vol 67 (1) ◽  
pp. 135-144 ◽  
Author(s):  
Karl-Armin Tröger
Keyword(s):  
Upper Cretaceous ◽  
The South ◽  
The West ◽  
The North ◽  
Near Shore ◽  
Bohemian Cretaceous Basin ◽  
Early Late ◽  
Rich Fauna ◽  
Cretaceous Deposits

Abstract The Upper Cretaceous of the Elbe Valley in Saxony and the erosion outliers west of it mark an Upper Cretaceous NW-SE-running strait between the Westsudetic Island in the NE and the Mid-European Island to the west. This street connected the NW-German-Polish Basin in the north and the Bohemian Cretaceous Basin (and adjacent regions of the Tethys) in the south. However, post-Cretaceous erosion north of Meißen removed any Upper Cretaceous deposits but erosion outliers at Siebenlehn and especially north of the Forest of Tharandt proof the presence of a marly through silty belt in this area. Three transgressions (base of uppermost Lower to Middle Cenomanian, base of Upper Cenomanian and base of the geslinianum Zone in the mid-Upper Cenomanian) have taken place. The sedimentation was influenced by the topography of the mentioned islands and by movements at structural lines in the Proterozoic and Palaeozoic basement. During the early Late Cenomanian, a marly-silty sedimentation (Mobschatz Formation) in the north existed besides sandy sedimentation in the south (Oberhäslich Formation). The transgression at the base of the geslinianum Zone caused the final submergence of island chains between Meißen, Dresden and Pirna, and a litho- and biofacies bound to cliffs and submarine swells formed. A silty-marly lithofacies, a mixed sandy-silty lithofacies (Dölzschen Formation) and a sandy lithofacies in the south (Sächsisches Elbsandsteingebirge) co-existed during the latest Cenomanian. The first mentioned biofacies yields a rich fauna mainly consisting of oysters, pectinids, rudists, and near-shore gastropods accompanied by echinids and, in some cliffs, teeth of sharks. The Pennrich fauna (Häntzschel 1933; Uhlig 1941) especially consists of the very common serpulids Pyrgopolon (P.) septemsulcata and Glomerula lombricus (formerly Hepteris septemsulcata and G. gordialis).

New Evidence Concerning the Original Order of Deposition of the Longmyndian Rocks

1948 ◽  
Vol 85 (2) ◽  
pp. 107-109 ◽  
Author(s):  
John Challinor
Keyword(s):  
Coarse Grained ◽  
The West ◽  
North West ◽  
The Road ◽  
Fine Grained ◽  
Original Order ◽  
The North ◽  
The Hill ◽  
New Evidence ◽  
The Village

During the war a large new quarry was opened in the Longmyndian rocks of Haughmond Hill, Shropshire. It is near the south-east edge of the hill, to the west of the road running north from Upton Magna and one mile from the village. On the sketch-map in the Shrewsbury Memoir (p. 58) two arrows are shown, at about this locality, recording dips of 50° in a south-easterly direction. I was told that there was a very small quarry here before the large quarry was excavated. The present quarry is even larger than that near Haughmond Abbey (Shrewsbury Memoir, p. 48), on the north-west side of the Pre-Cambrian outcrop, and the two quarries offer extensive and splendidly displayed exposures of Longmyndian rocks, one in the coarse-grained Western Longmyndian and the other in the fine-grained Eastern Longmyndian.

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