ORIGINAL PAPER Geochemistry of amphibolitized eclogites and cross-cutting tonalitic–trondhjemitic dykes in the Metamorphic Kimi Complex in East Rhodope (N.E. Greece): implications for partial melting at the base of a thickened crust I. Baziotis Æ E. Mposkos Æ V. Perdikatsis Received: 13 April 2006 / Accepted: 10 February 2007 / Published online: 16 March 2007 Ó Springer-Verlag 2007 Abstract In the ultra-high pressure Metamorphic Kimi Complex widespread tonalitic–trondhjemitic dykes, with an intrusion age ca. 65–63 Ma, cross-cut boudins and layers of amphibolitized eclogites. Geochemical investi- gation proclaims the tied genetic relationship of the am- phibolitized eclogites and the associated tonalitic– trondhjemitic dykes. The major and trace element contents and rare earth element patterns of the amphibolitized eclogites indicate formation of their protoliths by fractional crystallization of tholeiitic magmas in a back-arc envi- ronment. The tonalites and trondhjemites are characterized by moderate to high Sr contents (>130 ppm), and low Y (<8.2 ppm) and heavy rare earth element contents (Yb content of 0.19–0.88 ppm). The chemical composition of the tonalitic and trondhjemitic dykes are best explained by partial melting of a tholeiitic source like the amphibolitized eclogites with residual garnet and amphibole, at the base of a thickened crust during Early Tertiary subduction/accre- tion at the southern margins of the European continent. Keywords Amphibolitized eclogites  Tonalites– trondhjemites  Partial melting  UHP Kimi Complex  Rhodope Introduction Understanding the petrogenesis of tonalite–trondhjemite– granites (TTG) is key to understanding the evolution of the early crust due to the predominance of TTG’s in Archean rock formations (e.g., Martin 1999; Smithies and Cham- pion 2000; Foley et al. 2002; Martin et al. 2005). Archean TTG’s as well as Cenozoic and Mesozoic felsic rocks of tonalitic–trondhjemitic composition have been studied extensively for clues to their geochemical and tectonic environments of formation (e.g., Gill 1981; Drummond and Defant 1990 and references therein). These studies have employed experimental, trace element, and isotopic meth- ods to investigate the origin of TTG magmas. Presently, two basic models have been proposed for TTG magma generation: (1) formation by fractional crystallization from a low-K basaltic parent (Arth et al. 1978; Singer et al. 1992), and (2) formation by partial melting of a sub-alka- line metabasaltic source (e.g., Arth et al. 1978; Drummond and Defant 1990; Beard and Lofgren 1991; Rapp et al. 1991; Wolf and Wyllie 1994). In the second case, some have proposed that melting takes place in a crustal envi- ronment from an amphibolite source (Beard and Lofgren 1991; Rapp et al. 1991; Sen and Dunn 1994; Wolf and Wyllie 1994). Alternatively, it has also been proposed that melting takes place in a subducting slab of eclogitic composition (i.e., Rapp et al. 1991). The Rhodope high-pressure (HP) province in the east- ernmost part of the Hellenic Orogen offers an opportunity to study TTG magma formation, because of the abundant outcrops present. The Rhodope system represents an Al- pine synmetamorphic thrust and nappe complex that incorporates several tectonic slivers of ultra-high pressure (UHP) and HP metamorphic rocks (Burg et al. 1996; Ricou et al. 1998; Liati and Gebauer 1999; Mposkos and Krohe I. Baziotis (&)  E. Mposkos Department of Mining and Metallurgical Engineering, Section of Geological Sciences, National Technical University of Athens, Heroon Polytechniou 9, 15780 Athens, Greece e-mail: baziotis@metal.ntua.gr V. Perdikatsis Department of Mineral Resources Engineering, Technical University of Crete, 73100 Chania, Greece 123 Int J Earth Sci (Geol Rundsch) (2008) 97:459–477 DOI 10.1007/s00531-007-0175-1