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DESCRIPTION, CHEMICAL COMPOSITION AND NOBLE GASES OF THE CHONDRITE NOGATA
Author(s) -
Shima Masako,
Murayama Sadao,
Okada Akihiko,
Yabuki Hideo,
Takaoka Nobuo
Publication year - 1983
Publication title -
meteoritics
Language(s) - English
Resource type - Journals
eISSN - 1945-5100
pISSN - 0026-1114
DOI - 10.1111/j.1945-5100.1983.tb00580.x
Subject(s) - chondrite , ordinary chondrite , parent body , chondrule , geology , geochemistry , radiogenic nuclide , olivine , chemical composition , meteorite , mineralogy , carbonaceous chondrite , plagioclase , chemistry , astrobiology , mantle (geology) , physics , paleontology , quartz , organic chemistry
An ordinary chondrite weighing 472 g kept in the Shinto shrine, Suga Jinja, Nogata‐shi, Fukuoka‐ken, Japan, as treasure, was said to have fallen in the precinct of the shrine, approximately 130°45.0′E. and 33°43.5′N., on May 19, 861 A.D. The date of fall was confirmed by old literature, as well as written script on, and 14 C age determination of, the lid of the wooden box in which it has been stored. The chondrite was named Nogata after the present name of the place of fall. Although the Fe content of Nogata is a little too low, the bulk chemical composition, comparison of the norm with average H‐, L‐ and LL‐group chondrites, the relation of Fe metal /Ni versus Fe metal /Fe total , and molar composition of olivine and orthopyroxene indicate that Nogata is an L‐group chondrite. From the well recrystallized structure, extreme obliteration of the primary chondrule texture, homogeneous composition of olivine and orthopyroxene, absence of igneous glass and interstitial and well‐developed plagioclase, it should be classified as petrologic type 6. Nogata appears lightly shocked, upper b or the border of b and c by Van Schmus and Ribbe's classification, whereas most L6 chondrites are more heavily shocked. Nogata contains rather high amounts of both radiogenic and spallogenic light noble gases, and gives gas retention ages and cosmic‐ray‐exposure ages (e.g. 21 Ne age) of 4.5 and 4.7 × 10 3 years and 4.00 × 10 7 years, respectively. From such results combined with the light shock effects of Nogata, it is concluded that metamorphism of this chondrite was completed just after the formation of the parent body in a very short interval, > 10 8 years, with subsequent quiescence.