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Find of ureyte and jadeite-bearing pyroxens in chondrules and matrix of Chelyabinsk LL5 ordinary chondriteтезисы доклада
- Авторы: Zinovieva N.G., Glazovskaya L.I., Pletchov P.Yu
- Сборник: 45th LPSC, Houston, U.S., March 17-21, 2014, Abstract book
- Том: 1329
- Тезисы
- Год издания: 2014
- Место издания: Houston, U.S
- Первая страница: #1059
- Аннотация: Ureyite was found in ordinary and carbonaceous chondrites, documented aggregates of chromite with plagioclase in chondrules of the Elenovka L5 chondrite and suggested that some of the chromite objects in ordinary chondrites are pseudomorphs after some older minerals (for example, ureyite). We found and described acicular and tabular crystals with exsolution textures, consisting of regularly oriented aggregates of chromite and plagioclase in pyroxene-olivine porphyritic chondrules of the Berdyansk L6 and Ra-guli H3.8 ordinary chondrites. The bulk compositions of the protocrystalline phase correspond to composite of pyroxenes rich in Na-, Cr- and Al. We found analogous compos-ite pyroxenes in the Chelyabinsk LL5 chondrite, which fell on February 15, 2013, not far from Lake Che-barkul in the Urals, Russia. The finds of relict grains of jadeite-ureyite clinopyroxene that crystallized from both the chondrule and the matrix melts of the Chelyabinsk LL5 equilibrated chondrite confirm our earlier conclusion about a magmatic nature of chondrites and testify that their parent bodies started to crystallize under significant pressures. The pressure under which the relict jadeite-ureyite clinopyroxene crystallized in the chondrules and matrix of the Chelyabinsk LL5 chondrite (calculated by the clinopyroxene barometer]) varies within a nar-row range of 67-71 kbar (at T = 900ºC) or 65-70 kbar (at T = 1000ºC). These values are close to the pressure values (67-73 kbar at T = 1000ºC) for the crystalliza-tion of jadeite-ureyite clinopyroxene in chondrules of the Berdyansk L6 equilibrated chondrite
- Добавил в систему: Глазовская Людмила Ивановна