K/Ar dating and stable isotope analysis of the Baszkówka and Mt. Tazerzait L5 chondrites

• Autorzy: Hałas S. , Wójtowicz A.
• Języki publikacji: EN

Abstrakty

EN

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.

Słowa kluczowe

EN

Baszkówka; Tazerzait Mountains; chondrites; K/Ar ages; oxygen isotopes; sulphur isotopes

• Wydawca: Państwowy Instytut Geologiczny - Państwowy Instytut Badawczy
• Czasopismo: Geological Quarterly
• Rocznik: 2001
• Tom: Vol. 45, No 3
• Strony: 315--318
• Opis fizyczny: Bibliogr. 8 poz., tab., wykr.

Twórcy

autor

Hałas S.

• Institute of Physics, Maria Curie-Skłodowska University, Pl. M. Curie-Skłodowskiej 1, PL-20-031 Lublin, Poland

autor

Wójtowicz A.

• Polish Geological Institute, Rakowiecka 4, PL-00-975 Warszawa, Poland

Bibliografia

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• 3. HAŁAS S. (1995) - Isotope geochronology based on radioactive disintegration of 40 K (in Polish only). Prz. Geol., 43 (12): 993-998.
• 4. HAŁAS S. and MACIOCHA T. (2000) - Application of isotope dilution for determination of potassium concentration (in Polish only). In: Dating of Minerals and Rocks: 17-23. Conference abstracts, 10-12 February 2000, Kraków.
• 5. KAPLAN I. R. and HULSTON J. R. (1966) - The isotopic abundance and content of sulfur in meteorites. Geochim. Cosmochim. Acta, 30: 479-496.
• 6. ROBINSON B. W. and KUSAKABE M. (1975) - Quantitative preparation of sulfur dioxide for 34S/32S analyses, from sulfides by combustion with cuprous oxide. Anal. Chem., 47: 1179-1181.
• 7. SHIMA M. (1986) - A summary of extremes of isotopic variations in extra-terrestrial materials. Geochim. Cosmochim. Acta, 50: 577-584.
• 8. WLOTZKA F., SCHERER P., SCHULTZ L., OTTO J. and STĘPNIEWSKI M. (1997) - Petrography and noble gases of the unusual L5 chondrites Baszkówka and Mt. Tazerzait. 60th Meteorite Meeting, July 21-25, Maui, Hawaii, USA.