6533b7d9fe1ef96bd126d5f4

RESEARCH PRODUCT

Lamproites as indicators of accretion and/or shallow subduction in the assembly of south-western Anatolia, Turkey

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IntroductionThe Western Anatolian region of Tur-key is tectonically one of the mostcomplex parts of the Alpine–Himala-yan orogenic belt (Fig. 1) because ofits long accretional palaeotectonicevolution. One of the major tectonicfeatures shaping the structure ofwestern Anatolia is the Menderesmetamorphic massif, which consistsof several assembled and imbricatedterranes exhumed during the exten-sion that affected the entire Aegeanprovince during the Late Miocene(Yilmaz et al., 2000; Okay, 2002).The Menderes Massif is usually inter-preted as a core complex delineated bylow-angle detachment faults (Bozkurtand Park, 1994; Hetzel et al., 1995;Ring et al., 2003). An alternativeexplanation associates it with shallowsubduction of the southern Neoteth-yan oceanic lithosphere that was laterdelaminated; this is based on thermalmodelling and on the interpretationthat the faults originally formed assteep normal faults (Westaway, 2006).The characteristics of the mantlelithosphere can help distinguishbetween above models for the originof the Menderes Massif: if the westernAnatolian mantle resembles shallowcontinental lithospheric mantle similarto that below western and centralEurope, it should be spinel lherzolitegrading towards harzburgite, withprevious depletion by melt loss notexceeding 25% and with olivine Mg#lower than 92 (Downes, 2001); if it isderived from shallowly subductedoceanic lithosphere, the newly ac-creted mantle should display strongerdepletion with higher olivine Mg# upto 94 (Boyd, 1989), especially if itoriginated in a supra-subduction zone(SSZ) environment (Parkinson andPearce, 1998).Mantle xenoliths are not found inthe area and therefore the mantle-derived volcanic rocks and theirmacrocryst populations that eruptedcontemporaneously with the majoruplift phases are the best indicatorsof mantle character. In this respect,lamproites are particularly useful fortracing western Anatolian lithosphericprocesses (Prelevic´ et al., 2008a)because they store the chemical signalsof both depleted mantle and later re-enrichment particularly well (Prelevic´et al., 2008b). Mediterranean lampro-ites are mantle-derived rocks charac-terized by high K