| Research Abstract |
Twelve martian meteorites are well known so far as SNC meteorites (Shergottites (S), Nakhlites (N) and Chassignites (C)), which are believed to have originated from Mars. All the martian meteorites are igneous rocks formed by crystallization of a magma on the parent planet, Mars, during recent history of the solar system (116 Ma -1.3 Ga) except one specimen. Most martian meteorites show a typical crystalline igneous texture with intense shock, and only two specimens (ALH84001 and Yamato-793605) show the monomict brecciaed texture. Especially, ALH84001 is orthopyroxene monomict breccia indicating a remarkably old age of 4.5 Ga, and suggest the past life on Mars. Recently more three specimens were recovered and identified to martian origin. They are Y-1071(tentative), Dar al Ghani 476 and Lucky 13.
According to their textures, martian meteorites are briefly separated into two textural groups : crystalline and breccia. A crystalline group includes cumulate, poikilitic and gabbroic - basaltic textures. They are preliminary classified into following five rock types of dunite, lherzolite, Clinopyroxenite, orthopyroxenite and gabbro-dolerite from their texture, mineral assemblages and chemical compsitions along with their crystallization.
1. Dunite (Chassignites) : Chassigny
2. Lherzolite : ALH-77OO5, LEW88516, Yamato-7936O5, Y-1075
3. Clinopyroxenite (Nakhlites) Nakhla, Lafayette, Governador Valadares
4. Orthpyroxenite : ALH84001, (Dar al Ghani 476)
5. Gabbro-dolerite (Shergottites) : Shergotty, Zagami, EETA79OO1, QUE94201, (Lucky 13)
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