Petrology and geochemistry of plagiogranites of the Nourabad-Harsin ophiolite complex (west of Iran)

Nourabad-Harsin plagiogranites are the part of ophiolite complex in the Zagros zone located between sheeted dikes and gabbroic rocks. Lithologically, they include tonalite and trondhjemite. Minearals in these rocks are quartz, plagioclase, alkali feldspar, amphibole and biotite. Micrographic, granular, granophyre and myrmekite are the most common texture in these rocks. Microprobe analyses show that plagioclases have albite composition and amphiboles belong to calcic series and magnesiohornblende to actinolite subgroup. The geochemistry studies reveal that the parent magma of these rocks is of M type, calc-alkaline, low K, metalumine and from oceanic plagiogaranites which developed in Supra-subduction zone. Chondrite, MORB and Primitive mantle-normalized REE patterns show an enrichmentin LREE along with an almost flat pattern of HREE and negative Eu anomalies. It appears that these rocks are resulted from the magma generated by the subduction of the Neotethys oceanic plate and fractional crystallization at higher levels of sequence and its emplacement due to the tectonic movements in the region.