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Wyszukujesz frazę "subduction zone" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
2-D seismic models of the lithosphere in the area of the Bransfield Strait, West Antarctica
Autorzy:
Grad, Marek
Guterch, Aleksander
Janik, Tomasz
Środa, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2052732.pdf
Data publikacji:
1993
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
West Antarctica
Bransfield Strait
deep seismic sounding
lithospheric structure
subduction zone
Źródło:
Polish Polar Research; 1993, 14, 2; 123-151
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and Tectonic Environments of Aphibolites Bethampudi Anorthosite Complex, Khammam Schist Belt, Telangana, India
Autorzy:
Brahmaiah, T.
Ravi, Ch.
Basha, U. Imran
Prasad, K. S. Sai
Powiązania:
https://bibliotekanauki.pl/articles/1075430.pdf
Data publikacji:
2019
Wydawca:
Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Tematy:
E-MORB and Subduction zone
Geochemistry and Tectonic Environments
MORB
N-MORB
Tholeiitic
Opis:
The Bethampudi anorthosite complex is essentially a leucograbbro (gabboric anorthosite and anorthositic gabbro), anorthosites, amphibolites, and pegmatite occur as concordant or discordent bodies. This work involves detailed geological geochemical investigations of amphibolites so as to reveal their possible protolith. The field relaltions, major, trace and rare earth element compositions of ampbibolites suggest that they are petrogenetically related to anorthosites by fractional crystallisation. Protoliths of the amphibolites show a tholeiitic signature that prevails over the sub-alkaline nature and E-MORB affinities. They were generated from a depleted mantle surface with the influence of a subduction and within-plate components.
Źródło:
World Scientific News; 2019, 126; 65-87
2392-2192
Pojawia się w:
World Scientific News
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemistry and tectonic setting of the Chah-Bazargan sub-volcanic mafic dykes, south Sanandaj–Sirjan Zone (SSZ), Iran
Autorzy:
Fazlnia, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059776.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
alkali sub-volcanic mafic dykes
Chah-Bazargan intrusions
phlogopite-spinel
lherzolite
subduction zone
Neotethys
Opis:
The Chah-Bazargan sub-volcanic mafic dykes (trachybasalt and basaltic trachyandesite) are located in the south of the Sanandaj–Sirjan Zone (SSZ), Iran. The dyke mineralogy mostly comprises amphibole, clinopyroxene, olivine, orthopyroxene, and plagioclase as phenocrysts and fine-grained plagioclase and some ferromagnesian minerals in the matrix. The rocks are alkaline and shoshonitic in composition. The mafic melts relate to Neotethys subduction activity beneath the southern SSZ in the ~Eocene–Miocene interval. Markedly positive Ba, U, K, Pb, and Sr and negative HFSE (high field strength elements: Nb, Ta, Zr, Hf, P, and Ti) anomalies demonstrate this subduction. The sub-volcanic mafic dykes were produced from a metasomatized upper lithospheric mantle wedge at a depth consistent with the stability field of phlogopite-spinel (or -spinel/garnet) lherzolite. Geochemical studies on the basis of the rare earth elements (REE) and HFSE, and large ion lithophile elements (LILE) display that the mantle wedge underwent degrees of partial melting averaging between 5 and 15% to form the Chah-Bazargan sub-volcanic mafic dykes. It is possible that the chemical composition of the rocks was changed due to fractional crystallization and crustal contamination during emplacement.
Źródło:
Geological Quarterly; 2018, 62, 2; 447--458
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Polish Geodynamic Expeditions - seismic structure of West Antarctica
Autorzy:
Guterch, Aleksander
Grad, Marek
Janik, Tomasz
Środa, Piotr
Powiązania:
https://bibliotekanauki.pl/articles/2052477.pdf
Data publikacji:
1998
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
West Antarctica
Antarctic Peninsula
Bransfield Strait
deep seismic sounding
crustal thickness
lithospheric structure
subduction zone
Źródło:
Polish Polar Research; 1998, 19, 1-2; 113-123
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
New geological interpretation of multi-channel seismic profiles from the Pacific Margin of the Antarctic Peninsula
Autorzy:
Okoń, Jan
Giżejewski, Jerzy
Janik, Tomasz
Powiązania:
https://bibliotekanauki.pl/articles/2046834.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Antarctica
Bransfield Strait
Glacier valleys
marine seismic
South Shetland Trench
Subduction zone
Volcanic structure
Nauki o Ziemi
Źródło:
Polish Polar Research; 2016, 37, 2; 243-268
0138-0338
2081-8262
Pojawia się w:
Polish Polar Research
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Geochemical and tectonic significance of the Arbat alkali gabbro-monzonite-syenite intrusions, Urumieh-Dokhtar Magmatic Arc, Iran
Autorzy:
Fazlnia, Abdolnaser
Powiązania:
https://bibliotekanauki.pl/articles/2058601.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
gabbro-monzonite-syenite complex
geochemistry
collisional zone
Neotethys subduction
Opis:
The Oligocene Arbat alkali intrusions of the Eastern Miandoab are located in the northwestern part of Iran and belong to the Urumieh-Dokhtar Magmatic Arc (UDMA). The intrusions show a ring structure with gabbro-monzogabbro-monzodiorite (mafic units) on the edges, with monzonite-monzosyenite-syenite (felsic units) gradually going towards the central parts. The textures in different rock types are cumulate, granular and laminated. The high values of (La/Sm)n and (La/Yb)n, contents of K, Rb and Cs (positive anomalies normalized on the basis of the primitive mantle), low concentrations of Hf, Nb, Zr and Ta (negative anomalies), and the changes in Th/Nb, Th/Ta, La/Nb and Ce/Pb ratios along with the geochemical and tectonic setting evidence exhibit a subduction-modified mantle origin for the formation of these rocks. Accordingly, the intrusions were formed between the Central Iran and the Arabian plates as a result of the partial melting of a mantle wedge at a syn-collision or post-collision arc-related environment. Our data suggested that, after the end of the oblique Neotethys subduction and during/after the continental collision, the break-off or rollback of the Neotethys slab beneath western Iran, in the Oligocene, might have occurred. Such a process led to the change in the geothermal gradient of the mantle wedge because of the subduction fluids, transtension, pressure reduction along the SE-trending lateral depth strike-slip fault zones in the upper part of the mantle wedge, decompression partial melting at the mantle, and the resulting formation of a mafic potassium-rich melt. The mafic magma was injected into crustal magma chambers; probably, the fractional crystaliization and partial contamination occurred with crustal components, forming the intermediate and felsic rocks in the intrusions. Geochemical evidence related to the variations in the ratios of Th/Yb, Ta/Yb, Rb/Y, and Nb/Y and Harker variation diagrams along with the spider diagrams confirmed fractional crystallization and partial FC (fractional crystallization) and AFC (assimilation and fractional crystallization) in the intrusions.
Źródło:
Geological Quarterly; 2019, 63, 1; 16--29
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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