VOLUME 38 (1-3)/December 2009

This paper focuses on the study of the Quaternary morphotectonic evolution of the Lefkas Island using morphological and tectonic data. Based on our mainly morphological studies, two principal tectonic structures have been distinguished: (i) the Nydri-Vasiliki Fault Zone (NVF) and (ii) the Ionian Zone overthrust onto the Paxos Zone, which both divide the island into three morphotectonic units of Karya (KMTU), Maradochori (MMTU) and Athani (AMTU).
   Paleogeographically, it has been suggested that the broader Lefkas area was dominated by a NE–SW to ENE–WSW compressional regime since the early Pliocene that continuous in our days, resulting in the uplift of the southwestern part of the island and the submergence of the northeastern part of the island. This deformation is characterized by principal fault structures of a N110°–130° strike. These structures, combined with a fault system of N40°–60° strike representing an older Miocene fault zone, control the main morphological characteristics such as watersheds and streams and are responsible for the KMTU formation producing a northeastward plunging monoclinal en-echelon structure.
   During the Early Pleistocene, a shift of the compressional regime towards the east was responsible for the formation of a N70°–90° strike fault system. These faults had a morphotectonic effect throughout the island, controlling the watersheds and stream evolution. The continuous compressional regime recorded in our days results in the formation of fault structures, striking N20°–40° and N170°–190° that bound almost exclusively the coastal area of the island.

This article is focused on pollen morphology of some of the most abundant fossil pollen types from late Miocene sediments in Sofia Basin (Southwest Bulgaria). The investigation includes detailed morphological characteristic of the pollen types using observations under light and scanning electron microscope. Materials from the C-14 core near the village of Katina are the subject of this study. The age was determined as middle and upper Pontian on the basis of molluscs and mammals. Three pollen types from gymnosperm plants (Glyptostrobus type, Pinus diploxylon type and Tsuga canadensis type) and ten pollen types from angiosperm plants (Alnus sp., Betula sp., Carpinus sp., Corylus sp., Quercus robur type, Ulmus sp., Liquidambar sp., Juglans sp., Carya sp., Chenopodiaceae gen. ind.) have been described.

We have determined the deformation features along the southern and south-western contacts of the Rila-Rhodope batholith, as well as in the host metamorphic rocks, in order to clarify the deformation conditions and emplacement mechanism of this large granitic pluton. The studied area is located in the southwest Bulgaria, northeast of the town of Gotse Delchev. The field and microstructural observations along cross-sections of the contact suggest syntectonic emplacement of the Rila-Rhodope batholith relative to the last amphibolite facies metamorphism. The features of the granites and their host rocks that support this conclusion are: (1) conformity of the magmatic foliation and lineation to the solid-state foliation and mineral stretching lineation in the granites, as well as in the host metamorphic rocks; (2) identical synkinematic shear determined in both the granites and their host rocks indicating top-to-the SW direction of the tectonic transport; (3) presence of non-deformed veins of granitoid material indicating the existence of granitic melts after the imposing of the ductile deformation; (4) solid-state deformation at amphibolite facies conditions. The intrusion of the granites could be related to the period of extension of the Rhodope Massif resulting in exhumation of the deeper parts of the crust and the development of the Rhodope metamorphic core complexes during Paleogene times.
   Another ductile shear zone existing between the two distinguished metamorphic units is also reported. It predates the one along the contact of the batholith and is characterized by higher degree of shearing deformation.