Mineralogy, geochemistry and petrogenesis of protolith of amphibolites from the North east of Yan-Cheshmeh, South east of Zayandeh-rud lake

Amphibolite rocks with mylonitic texture exposed in the NE of Yan- Cheshmeh village (SE of Zayandeh-Rud Lake). Mineralogy of rocks include amphibole, plagioclase, quartz, rutile, clinozoesite, chlorite, titanite, biotite and opaque. Amphiboles are seen as fish. Basic igneous rocks are protolith of the amphibolites that have subalkaline nature. Ni (299-370 ppm), Cr (1169-1900 ppm) and SiO2 (44.91-49.20 %Wt) contents highly resemble to unfractionation magmas. Chondrite normalized REE patterns exhibit pronounced LREE enrichment relative to HREE without Eu anomaly. Low TiO2, Zr, P2O5 and Nb/Y contents with enrichment of LREE and negative Nb anomaly are pronounced characters of continental flood tholeiitic basalt within plate magmatism. Tholeiitic affinities, low values of alkali elements, high MgO, FeO, Cr and Ni contents suggest high partial melting in an extensional setting of continental within-plate with rapid decrease in pressure, resulting in high rate of partial melting and quick uplift which are effective factors for the formation of basaltic protolith of the amphibolites.