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Wyszukujesz frazę "K-Ar ages" wg kryterium: Temat


Wyświetlanie 1-2 z 2
Tytuł:
K/Ar dating and stable isotope analysis of the Baszkówka and Mt. Tazerzait L5 chondrites
Autorzy:
Hałas, S.
Wójtowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/2059307.pdf
Data publikacji:
2001
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Baszkówka
Tazerzait Mountains
chondrites
K/Ar ages
oxygen isotopes
sulphur isotopes
Opis:
We have determined the content of 40Ar* (1.49 nmol/g) and 4He (1.75 nmol/g) in the Baszkówka meteorite by static vacuum mass spectrometry. The radiogenic argon content was calculated from the measured argon spectrum using the equation: 40Ar* = 40Ar - 295.536Ar assuming a potassium content of 680 ppm wgt. We have obtained K/Ar ages of 3.78 Ga for the chondrules and 3.47 Ga for a bulk sample of Baszkówka. A similar 4He content (1.47 nmol/g) but larger 40Ar* (2.32 nmol/g) content was found for the Mt. Tazerzait bulk sample. The K/Ar age of this meteorite on the basis of the K content (732 ppm) is 4.34 Ga. Sulphur isotope analysis of troilite specimens from both meteorites reveals essentially negative delta 34S values: -1.25š0.06o/oo for Baszkówka and -1.18š0.06o/oo for Mt. Tazerzait expressed on the V-CDT scale. This indicates that both chondrites may have a common origin. The oxygen isotope data (delta 18O = 4.88š0.03o/oo and delta 17O = 3.66š0.10o/oo) suggests that Baszkówka belongs to the L chondrites.
Źródło:
Geological Quarterly; 2001, 45, 3; 315-318
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Neogene calc-alkaline intrusive magmatism of post-collisional origin along the Outer Carpathians: a comparative study of the Pieniny Mountains and adjacent areas
Autorzy:
Pécskay, Z.
Gméling, K.
Molnár, F.
Benkó, Z.
Powiązania:
https://bibliotekanauki.pl/articles/973597.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Outer Carpathians
Pieniny Klippen Belt
Neogene intrusive magmatism
K-Ar ages
boron concenrations
Opis:
A petrographical and geochemical analysis was carried out on intrusive rocks from the Pieniny and Moravian areas, with special attention to boron content and K-Ar radiometric ages. The intrusions form medium- to high-potassium calc-alkaline andesitic suites, which are compositionally slightly different from each other and from the other calc-alkaline sequences in the Carpathian-Pannonian Region. No significant geochemical differences were observed within the different phase intrusions in the Pieniny areas. However, there is a slight difference in major and trace element composition between the Moravian and Pieniny intrusions. The andesitic rocks in the Pieniny and Moravian area are enriched in large ion lithophile elements and light rare earth elements and depleted in high field strength elements, indicating a metasomatized mantle source of the parent magmas. The low boron concentration of the andesitic rocks in the Pieniny area is in the range measured in back-arc, intraplate basalts of the Bakony-Balaton Highland volcanic field, whereas the higher boron content of the Moravian rocks overlaps with that of the Western Carpathian andesites. This may indicates the heterogeneity of the mantle lithosphere below the areas, or indicates different magma evolution histories. On the basis of the systematic geochronological study, the intrusive rocks along the Outer Carpathians can be divided on three groups, which overlap with each other temporally. The oldest magmatism occurred from 14.8 Ma to 11.0 Ma in the Uhersky Brod area, Moravia, which was followed by the emplacement of andesitic dikes and sills in the Pieniny Mts., south Poland (13.5–10.8 Ma). In the Pieniny area, two intrusive phases were distinguished. Partly overlapping with this area, but generally younger than this magmatism, the emplacement of the youngest intrusions is referable to the Poiana Botizei-Ţibleş-Toroiaga-Rodna-Bârgâu intrusive area, Romania, where magmatic activity started at ~11.8 Ma and terminated at 8.0 Ma.
Źródło:
Annales Societatis Geologorum Poloniae; 2015, 85, 1; 77-89
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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