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...

An accurate description of the effect extreme pressure and temperature on physical properties materials is required to understand structure composition mantle Earth similar planets. One such enstatite MgSiO 3 , which causes increased interest in investigating its behavior under intense dynamic loads. It proposed consider shock-wave loading as a mixture quartz oxides SiO 2 MgO periclase an equal...

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...

Liquidus phase relationships determined on the join CaAIzSi20 8 (anorthi te)-MgzSiO 4 (forsteri te)-SiO 2 (quartz) at 10 kbar show that increasing pressure causes the forsterite and anorthite primary phase fields to shrink and the spinel, enstatite and silica fields to expand. The boundary line between the enstatite and forsterite fields and that between the enstatite and quartz fields both mov...