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Wyszukujesz frazę "shelf" wg kryterium: Temat


Wyświetlanie 1-5 z 5
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:
Sediment discharge and storage over the last deglacial highstand period on the central Vietnam shelf off Nha Trang
Autorzy:
Dung, Bui Viet
Stattegger, Karl
Kieu, Nguyen Van
Thanh, Nguyen Trung
Thong, Bui Xuan
Vu, Pham Nguyen Ha
Man, Ha Quang
Trang, Pham Hong
Powiązania:
https://bibliotekanauki.pl/articles/2058662.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sediment budget
Nha Trang shelf
central Vietnam
Holocene highstand
sequence stratigraphy
Opis:
A sediment budget for the central Vietnam shelf off Nha Trang over the last deglacial Holocene highstand period has been investigated on the basis of shallow seismic and sediment core data and empirical equations. The annual suspended sediment discharge to the Nha Trang shelf ranges from: 4.3 to 5.4 Mt/year. Estimates based on published empirical equations suggest that the sediment discharge by three main local mountainous rivers (the Cai, Dinh and Van Phong rivers) that enter the Nha Trang shelf ranges between 1.7 and 4 Mt/year, which implies that the local rivers discharge approximately 75% of the total annual sediment input to the shelf. The annual sediment supply of the Cai River is approximately 2 and 6 times higher than that of the Dinh and Van Phong rivers, respectively. The highstand sediment depocentre of the Nha Trang shelf is mostly attached to the local river outflows, indicating their importance as the principal sediment supply sources to the shelf. Additional sources of sediment supply to the Nha Trang shelf can probably be related to along-shore transport from the nearby shelves. Calculations based on seismic and sediment core data indicate that the net sediment volume storage on the Nha Trang shelf is approximately 2.15 Mt/year. Approximately 50% of the total sediment yield supplied to the shelf is probably transported along-shore to the south. The sediment budget model for highstand deposits on the Nha Trang shelf is typical for a small mountainous river basin, which is significantly different from that of the large river delta systems in Vietnam such as the Mekong and Red rivers where 90% of the river sediments are captured on the delta plain/subaqueous part and only 10% of the river sediments are transported to the nearby shelf. In contrast, most of the sediments supplied by small mountainous rivers off Nha Trang are transported to the mid-shelf, forming a shore-parallel mud depocentre.
Źródło:
Geological Quarterly; 2019, 63, 2; 395--406
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Jurassic facies succession of the Kleszczów Graben area (southern border of the Łódź Depression, peri-Tethyan shelf, central Poland)
Autorzy:
Olchowy, Piotr
Krajewski, Marcin
Felisiak, Ireneusz
Powiązania:
https://bibliotekanauki.pl/articles/2058630.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Late Jurassic
outer-inner ramp facies
Oxfordian
Kimmeridgian
Tithonian
North Tethys Shelf
Opis:
Numerous fully cored boreholes completed in the last years in central Poland (Kleszczów Graben area, southern border of the Łódź Depression) enabled the researchers to obtain new sedimentological data on the Oxfordian-Tithonian continuous sedimentary record in the Polish part of the northern Tethys shelf. Twenty-two facies were distinguished in the sedimentological succession. The facies represent the outer-, mid- and inner-ramp environments, including evaporitic episodes and palaeosols. The facies document that the Oxfordian-Lower Kimmeridgian (up to Hypselocyclum) carbonate ramp has evolved to the Upper Kimmeridgian-Tithonian carbonate-siliciclastic ramp. Among the Kimmeridgian deposits, numerous hardgrounds, tidal channel deposits and gravity flow sediments were identified. The Kleszczów Graben sedimentary succession is discussed along with the lithostratigraphical units known from the adjacent regions of southern and central Poland.
Źródło:
Geological Quarterly; 2019, 63, 4; 657--682
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Cyclops Mountains Massif (New Guinea, Indonesia) as the provenance area for metal-bearing shelf sediments from the Carolinian Sea
Autorzy:
Zglinicki, Karol
Szamałek, Krzysztof
Powiązania:
https://bibliotekanauki.pl/articles/2059672.pdf
Data publikacji:
2020
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
continental shelf sediments
Cyclops Mountains
New Guinea
heavy minerals
geological prospection
marine minerals
Opis:
In 2009, on the initiative of PT Halmahera Perkasa the “Jayapura” exploration project was carried out in Indonesia. As part of this project, exploration of the sea bottom in the northern coast of New Guinea was carried out over a distance of ~45 km. The suction dredge collected 59 samples of loose sediments from the shelf bottom surface of the Carolinian Sea (to a depth of 60 m below the sea-floor). The extracted samples are usually poorly and moderately sorted sands (5 samples), medium-grained sands (21 samples), and fine-grained sands (33 samples). The sand composition shows, among others, a wide spectrum of heavy minerals of ultra-mafic (Cr-garnet, chromium spinel, Mg-olivine) and metamorphic (epidote, clinochlore, amphibole, titanite) origin. The content of heavy minerals in the sediments is up to 54.77 wt.%. It was found that the source of heavy fraction in the eastern and western parts of the coast is the rock of the ophiolite series building the Cyclops Mountains Massif. The mineral composition of sediments from the central coastal zone corresponds to the types of rocks building the metamorphic core of the Cyclops Mountains (amphibolite, gneisses, andesite). Three mineral-geochemical subprovinces were determined on the basis of analyses of heavy mineral decomposition and chemical analyses of sediments. Shelf sediment from the eastern part of the coast is characterized by an increased content of strategic metals (Ni up to 3560, W up to 3130 and Co up to 142 ppm). In the central zone, the V content increases up to 244 ppm and the Ag content up to 5 ppm. In the shelf sediments there is a strong depletion in the REE.
Źródło:
Geological Quarterly; 2020, 64, 2; 480--491
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of the Mid-Polish Troughversus Late Jurassic evolution in the Carpathian Foredeep area
Autorzy:
Matyja, B. A.
Powiązania:
https://bibliotekanauki.pl/articles/2059116.pdf
Data publikacji:
2009
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Mid-Polish Trough
Late Jurassic
northern Tethys shelf
sponge megafacies
Štramberk-type coral reefs
Opis:
Late Jurassic is the key epoch for an idea of the existence of the southeastern segment of the Mid-Polish Trough. New data on the evolution of Upper Jurassic deposits in the Carpathian Foredeep substrate provide information that there is a complete Oxfordian through Valanginian succession in the area of thick Oxfordian and Kimmeridgian deposits, proving the occurrence of the trough. Thickness of the Oxfordian and Kimmeridgian succession is twice to three times smaller than previously assumed. The facies development patterndistinguishes this area from the rest of the Late Jurassic basin. The sponge megafacies ranges up into the lower most Tithonian in this region.Tithonian Štramberk-type reefs occur near the Carpathian thrust front and alongside. The Late Jurassic and earliest Cretaceous facies are latitudinally arranged. Starting from the latest Middle Jurassic, the study area showed strong structural and facies relations to the Tethys do main. The collected data contradict the hypothesis that the Mid-Pol ish Trough continues in the Carpathian Foredeep substrate.
Źródło:
Geological Quarterly; 2009, 53, 1; 49-49
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-5 z 5

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