Livadi Mafic-Ultramafic Complex and its metamorphic basement, N.E. Greece
Regional mapping of the Livadi area, lying west of Mt. Olympos in N.E. Greece, has revealed that the present tectonic juxtaposition of the Livadi Mafic - Ultramafic Complex and the metamorphic lithologies of the Pelagonian basement, results from an involved history of deformation and metamorphism. The Pelagonian basement comprises a sequence of psammitic and pelitic clastics, frequently of arkosic composition, and probably of Palaeozoic age. Granitic and, less commonly, amphibolitic intrusives are widespread, and the largest, the Livadi Granite, has been designated an Upper Carboniferous age by analogy with the Kataphygion Granite to the north (Yarwood, 1976). This igneo-sedimentary sequence is overlain by neritic carbonates of presumed Triassic-Jurassic age (Godfriaux, 1968). During Lower Cretaceous time, these lithologies were subjected to an upper greenschist-lower amphibolite grade metamorphism which resulted in the paragenesis of biotite, phengite, epidote, garnet hornblende, oligoclase and albite. It was associated with flattening, and the development of mylonitic zones and a strong L-S tectonite fabric. The shape of clastic pebbles deformed at this time indicate that the dominant strain was one of flattening, but that the greatest amount of finite distortional strain is located within the shear zones, where the deformation is constrictional. Subsequent to this event, but prior to the emplacement of the Livadi Mafic - Ultramafic Complex, deformation of the L-S tectonite fabric occurred about major fold axes oriented sequentially NE-SW and NW-SE, and resulted in the production of kilometre-scale interference patterns. Estimates of shortening across folds of the earlier phase vary between 40% and 45%. Fabrics associated with these fold periods are only locally important. The broadly cumulate stratigraphy of the Livadi Mafic - Ultramafic Complex comprises serpentinite and metamorphosed dunite, harzburgite, lherzolite and gabbro, which tectonically overlie the Pelagonian metamorphics in a number of small thrust klippen. The thrust surface that originally connected these mafic-ultramafic 'outliers' is essentially horizontal and truncates the above described structures of the Pelagonian basement. The history of the Livadi Mafic - Ultramafic Complex prior to this final emplacement is similar to that of the underlying metamorphics. An early period of isochemical serpentinization that was associated with an initial emplacement phase, occurred at the expense of most primary minerals. Continued tectonic movement of the Complex led to the development of a major overturned structure and was followed by a period of metamorphism of similar grade, and probably similar age, to that described above. Parageneses included ferrichromite, metamorphic olivine, talc and tremolite in the ultramafics, and epidote group minerals, tremolite, oligoclase, albite and quartz in the gabbros. Emplacement of the Livadi Complex into its present position was associated with cataclastic deformation and non-isochemical serpentinization that took place under lower greenschist conditions as evidenced by the paragenesis of low-Al2O3 tremolite, chlorite, and muscovite in the gabbros. A retrograde metamorphism of similar grade is also present in the underlying metamorphics, and the two events are believed to be associated. The orientation of linear features developed during emplacement, together with regional considerations, suggest that the Complex reached its present position from the SW., while a lower Tertiary age may be indicated by analogies with the Olympos thrust to the east (Barton, 1975a). Subsequent to its emplacement, the Livadi Mafic - Ultramafic Complex and its metamorphic basement were tectonically overridden by the Pelagonian lithologies of the Pieria allochthon along the E-W Mavroneri thrust. The orientation of linear structures, thrust surfaces, asymmetrical folds and imbricate slices associated with this movement are consistent with emplacement towards the south. Petrological and mineralogical data, together with regional considerations, suggest an ophiolitic origin for the Complex, and may imply its derivation from the Mesozoic Othris ocean.
Networked Digital Library of Theses and Dissertations