A new occurrence of microdiamond-bearing metamorphic rocks, SW Rhodopes, Greece.

Schmidt S., Nagel T.J. & Froitzheim N.

Abstract

We describe a new locality with microdiamond-bearing, ultrahigh-pressure metamorphic rocks near the village Sidironeroin the Rhodope Metamorphic Province in northern Greece, about 70 km west of the nearest known location at Xanthi. High- andultrahigh-pressure metamorphic conditions are preserved in an intensely strained me´lange zone which is sandwiched between uppergreenschistto lower-amphibolite-facies rocks in the footwall (Pangaion-Pirin Complex) and upper-amphibolite-facies rocks in thehanging wall (Rhodope Terrane). The me´lange zone consists of various paragneisses, orthogneisses and metamafics. A strongoverprint at upper-amphibolite-facies conditions associated with migmatisation in the orthogneisses and subsequent intense mylonitisationat lower-amphibolite-facies conditions almost obliterates peak-pressure assemblages. Relics of high-pressure conditionsare preserved in mafic boudins and in garnet-kyanite-mica schists. Garnet in garnet-kyanite-mica schists displays inclusions ofmicrodiamonds and swarms of non-oriented rods of rutile and quartz. The lithological and structural appearance of the me´lange zoneresembles the exposure of ultrahigh-pressure metamorphic rocks further east at Xanthi, whereas the location at Kimi may occupy ahigher structural level.