Scholarly record

CRYSTALLINE BASEMENT OF THE ZONE OF DARDANIA IN THE GJILAN REGION (KOSOVE): STRUCTURE AND METAMORPHISM

Islam Fejza

Abstract

The Dardanian zone (Serbian-Macedonian massif) represents the western part of the Rhodope crystalline basement. This zone was structured and metamorphosed during the Hercynian and post Hercynian tectonic st ages. The geological mapping at 1:25.000 [1] show that a of the studied region is built of crystalline Pale ozoic basement. The important aspects have been identified in the structure and metamorphism from this part of western Rhodopes. The study of the deformed Variscian and Hercynian tectonic phases are difficult to estimate because the post-Hercynian tectonic stages have cleared them. We can say that we have at least two stages before the Jurassic deformation. The most visible is the schistosity of the last Hercynian stage marked with the symbol S 1. In our sheet are evident the distortions that have affected the entire Dardanian zone, that means the Hercynian basement, as well as the Mesozoic and Cenozoic sediments. S 2 is a penetrating schistosity while S 3 represents the crenulation schistosity. The fracture schistosity is also present. A structural analysis of deformation fields was possible especially for S 2 because the field measurements show that the D 2 deformation is strongly homogenous. This stru ctural overview provides us an analysis and an evaluation of the structural history of the post- Hercynian period, especially those related to the ophiolite obduction on the micro-block of Dardania. The main event of the Hercynian tectonic pe riod that structured the rocks forming the sheet of eastern Gjilan is associated with the regional deformation D 2. Its intensity is depending on the type of rocks, but it is noted an increase of the in tensity from west to east. The associated schistosity S 2 is an axial plane schistosity of the isoclinals folds S0, S1. The schistosity S 2 is homogenous, with an average strike direction of 345В° and dip direction of 45В°. The intersection lineation (L 2) and the fold axis (B 2) are very homogenous with the dip azimuth toward N (350В°) and dip angle of 10В°. The deformation D 3 is associated with the crenulations of schistosity S 3. The schistosity S 3 represents the axial plan of the kink fold and crenulation. The schistosity S 3 is very heterogenous and it is difficult to arrive at conclusions regarding the average direction of this planar structure also to judge the kinematic aspects of the movement. Likewise, 11th International Multidisciplinary Scientific GeoConference SGEM2011 www.sgem.org International Multidisciplinary Scientific GeoConference SGEM 2011 44 the axis of the crenulation B3 and L 3 lineation represent relative heterogeneous linear structures. The deformation D4 is associated with the fracture schistosity S4. The schistosity S4 often show the axial plan of the open parallel folds. The schistosity S4 is homogenous with the range East-West with symmetric drop (in the N and S), by proving that we are dealing with a phase of deformation with an extens ional tectonic regime (with the direction N- S). The metamorphism of gneiss, marble and micaschists is associated with the deformation D 2 belong to the age of 150 up to 130 million years [2]. The deduction of this age is based on the dating of similar metemorphic events from the neigh boring regions [2], [17]. The crenulation schistos ity has a heterogeneous behaviour proving that it belongs to the deformation field of ductile-brittle.The fracture schistosity presents a homogenous behaviour with extension but with a strong dip towards the N and S. The nature and the age of the metamorphi sm related to the deformations D 3 and D 4 are difficult to estimate.

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