Evidences of Magma Mingling in the Eocene volcanic rocks inSouth of Zenogan area, Lut Block, east of Iran

In the area located in south Zenogan, in Lut Block, east of Iran the series of volcanic and volcanoclastic rocks of Eocene, Oligocene and Neogene are exposed. The Eocene volcanic rocks comprise of lave and pyroclastic rocks which have intermediateacidic compositions. The Eocene volcanic rocks flare up over the conglomerate, sandstone, marl including Nummulite-bearing limestone. Paleontology investigation of the lenticular Nummulite-bearing limestone revealed Eocene in age. The Eocene volcanic series unconformable covered by Oligocen and Neogene volcanoclastic and lava. The Eocene volcanic rocks comprise of basalt, basaltic andesite, andesite, trachy andesite, trachy dacite, dacite and rhyolite-ignimbrite. The Eocene volcanic products occur at four stages in south Zenogan, erupted locally in the aqueous but mostly in sub aerial environment. Petrography investigations indicate that magma mixing and magma mingling has important roles in generation and evolution of the Eocene rocks with intermediate in composition. Darkcolored but more mafic enclaves inside acidic groundmass with lobbed contact, alternations of rhyolitic flames with andesitic flames, plagioclase phenocrysts which display sieve texture, honeycomb structure and oscillatory zoning confirm this idea that magma mingling involve extensively in evolution of parental magma. In discriminating geochemical diagrams, the studied samples cluster in calc alkaline, high-k calc alkaline especially in shoshonitic trends. The normalized REE patterns and spider diagrams of studied samples display enrichments of LREE and LILE in relative to HREE and LILE indicating signatures of subduction elements. It seems that contamination of parentalbasic magma with acidic magma has important role in chemical variations of the studied volcanic rocks. We think that the Eocene volcanic rocks in south of Zenogan related to post-collision magmatism in Lut block which consequently related to closure and subduction of Neo-tethys branches in NE and SE of Iran.