On volatile/mobile trace element trends in E3 chondrites

Abstract

Contents of 3 non-mobile trace elements (U, Co, Au) and 12 slightly-to-highly volatile ones (Rb, Sb, Ag, Ga, Se, Cs, Te, Zn, Cd, Bi, Tl and In) determined by RNAA in the Yamato (Y)-691 and Qingzhen E3 chondrites generally fall within ranges reported for E4 chondrite falls. Contents of most elements are similar in the two E3 chondrites : highly volatile Cd, Bi and Tl differ markedly, with the Y-691 data falling at C1 levels and those of Qingzhen near the bottom of the E4 ranges. Trace element abundances and interelement comparisons indicate that both E3 chondrites compositionally reflect only nebular condensation, with Y-691 parent material having condensed at lower temperatures than Qingzhen. Both escaped the post-accretionary metamorphic episode that compositionally altered other enstatite chondrites. For volatiles, E3,4 chondrites differ markedly from E5,6 : for siderophiles, E3-5 differ markedly from E6. These trends could reflect enstatite chondrites' origin in 1 or 2 parent bodies : we interpret the data as indicating a single body.