Introduction: Comets are small bodies composed mainly of a mixture of ice and dust particles and were formed during accretion of the planetary system. Their reservoirs are the Kuiper belt (30-55 AU) and the Oort cloud (50,000 AU). The classical picture about the formation of short-period comets (e.g. Comets Borrelly, Temple 1, Wild 2; [1]) is condensation of material beyond the frost line in th...

Abstract We have determined rare-earth element (REE) abundances in oldhamites (CaS) from 13 unequilibrated and equilibrated enstatite chondrites (5 EH 8 EL) a few enstatites by situ, laser ablation ICP-MS. In chondrites, oldhamite REE patterns vary the most primitive petrographic types (EH3) to metamorphosed (EH5). EH3, CI-normalized are convex downward with strong positive Eu Yb anomalies, whe...

Weisberg, D. S. Ebel, H. C. Connolly Jr., N. T. Kita and T. Ushikubo. Dept. Phys. Sci., Kingsborough College, City University New York, Bklyn, NY 11235 and Dept. Earth and Environmental Sci., The Graduate Center of CUNY 365 5 Ave., NY, NY. ([email protected]). Dept. Earth Planet. Sci., American Museum Natural History, NY, NY 10024. Dept. Geology and Geophys., University Wisconsin-Madison,...

The silicon isotope composition of three carbonaceous chon-drites (Orgueil, Murchison, and Vigarano), three ordinary chon-drites (Parnallee, Bovedy, Bremervörde), one enstatite chondrite (Sahara 97158) and nine terrestrial samples (7 peridotites, 1 mid-ocean ridge basalt, 1 ocean island basalt) were measured to high precision and accuracy using the high resolution Nu Plasma 1700 MC-ICPMS at ETH...