PETROLOGY AND MINERAL CHEMISTRY OF ULTRAMAFIC AND ENCLAVES IN MASHHAD GRANITOIDS, NE IRAN.

摘要

The Mesozoic Mashhad granitoid plutons (MMGP) contain numerous ultramafic and mafic enclaves. They exhibit sharp contact relationship with granitoids with no metasomatic rims. Dunite, peridotite and pyroxenites are the common ultramafic enclaves, exhibiting relict poikilitic and cumulate textures. Pyroxenes show bent lamellae and exsolution of opaques, suggesting re-equilibration under sub-solidus conditions. Mafic enclaves (Cpx, Amp, Bt, Pl ,Ep,) contain magmatic amphiboles and pyroxenes. They show granulitic to granoblastic micro-textures suggesting that the mafic enclaves represent metamorphosed (meta-ophiolites) country rocks.