Petrology of metabasites in the south of Arousan, northeastern Isfahan province

Metagabbro، metadiabase and metabasalt of the Chah Palang and Me''raji mountains associated with Lower Paleozoic metamorphites are situated in the south of Arousan. Metabasites of these areas are relatively similar in terms of mineralogy and geochemical characteristics. Rock-forming minerals of the Me''raji metabasites are feldspar، amphibole، biotite، sphene، epidote، chlorite ± calcite. Metagabbro and metadiabase of the Chah Palang area are similar to the Me''raji metabasites in mineralogy and geochemistry. Volcanic rocks are overlain by metagabbros and consist of plagioclase، biotite، sphene، sanidine، chlorite، epidote and iron oxides. The rigid dykes، which are found in the volcanic units are associated with metagabbros and mineralogically are similar to the metavolcanics. Amphibolitic dykes are composed of amphibole، plagioclase and biotite with preferred orientation. Metabasites show limited range of differentiation. Me''raji metabasites are basalt and trachy-basalt in composition، whereas the Chah Palang ones present basalt and trachy-basalt composition. Similar to metabasites of the other parts of Iran، the studied basic rocks demonstrate alkaline to transitional chemical characteristic and are formed in an extensional environment by low-degree partial melting of a garnet-spinel peridotite. Metamorphic episodes have changed the studied rocks to amphibolite and greenschist، but the primitive igneous textures are preserved.