MINERALOGY,PETROGRAPHY AND CHEMISTRY OF THE CHONDRITE,KAMIOMI, SASHIMA-GUN,IBARAKI-KEN,JAPAN |
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| Authors: | Akihiko Okada Masako Shima Sadao Murayama |
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| Abstract: | The Kamiomi, Sashima-gun (Iwai-shi), Ibaraki-ken, Japan, chondrite (observed to fall in spring, during the period 1913–6), consists of olivine, orthopyroxene, nickel-iron and troilite with minor amount of plagioclase, clinopyroxene, apatite and chromite. The average molar composition of olivine (Fa19) and orthopyroxene (Fs17) indicates that Kamiomi is a typical olivine bronzite chondrite. From the well-recrystallized texture, the presence of poorly-definable chondrules, homogeneous composition of olivine and absence of glass, this chondrite could be classified in petrologic type 5. The bulk chemical composition, especially, total Fe (27.33%) and metallic Fe (17.00%) as well as Fetotal/SiO2(0.72), Femetal/Fetotal (0–633) and SiO2/MgO (1.59) support the above conclusion. Coexistence of heavily-shocked olivine grains in the matrix composed of olivines and pyroxenes which suffered from light to moderate shock effect suggest that impacting phenomena, small-scaled but locally strong, occurred on the Kamiomi parent body. |
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