Petrochemical study of the Yamato-691 enstatite chondrite (EH3) I: Major element chemical compositions of chondrules and inclusions

The major element chemical compositions of more than 120 chondrules and inclusions in Yamato (Y)-691 were obtained using a defocussed beam of an electron-probe micro-analyzer. Most chondrules in Y-691 are depleted in Fe, Mn, Cr, and Ca in comparison to the Y-691 whole rock composition, indicating that the depleted elements reside in sulfides and/or metals occurring outside chondrules. Compared with the solar system abundances, radial-Px, porphyritic and granular chondrules are depleted in all elements studied except for Si, but the Sinormalized contents of Al, Ti, Mg, and alkalies are similar to the Y-691 whole rock composition. On the other hand, barred-Ol-Px chondrules are enriched in refractory and moderately-refractory lithophiles (Al, Ti, Ca, and Mg) and poor in moderately-volatile elements (Mn, K, and Na). Some inclusions show chemical compositions similar to fine-grained CAI\u27s and amoeboid olivine inclusions in carbonaceous chondrites