Pan-African high-pressure metamorphism in the Precambrian basement of the Menderes Massif, western Anatolia, Turkey
Abstract. The Menderes Massif is made up of Pan-African basement and a Paleozoic to Early Tertiary cover sequence imbricated by Late Alpine deformation. The Precambrian basement comprises primarily medium- to high-grade schists, paragneisses, migmatites, orthogneisses, metagranites, charnockites, and metagabbros. High-pressure relics in the Pan-African basement are divided into two groups: eclogites and eclogitic metagabbros. The mineral assemblage in the eclogites is omphacite (Jd 44)–garnet–clinozoisite–rutile. The eclogites occur as pods and boudinaged layers in the basement schists and paragneisses. Inclusions found in the cores of the garnets indicate a medium-pressure protolith. The eclogitic metagabbros are closely related to Precambrian gabbroic stocks. The igneous texture and relic magmatic phases are preserved in these high-pressure rocks, which are characterized by the mineral assemblage omphacite (Jd 25)–garnet–rutile±kyanite. The P–T conditions of the Pan-African high-pressure metamorphism in the eclogites are estimated to be 644°C with a minimum pressure of approximately 15 kbar. The eclogites are partly to completely retrograded to garnet amphibolites by a Barrovian-type overprint which developed under isothermal decompression conditions. For this post-eclogitic event, the P–T estimates are 7 kbar and 623°C. The eclogite relics provide strong support for a correlation of the Menderes Massif with the Bitlis Massif in terms of common Pan-African high-pressure evolution.