DEFORMATION HISTORY OF JURASSIC KALUR CHERTS FROM THE MIRDITA NAPPE, ALBANIAN OPHIOLITES
R.Carosiˇ, A.Kodra*, M.Marroniˇ, and F.Mustafa**
ˇDipartimento di Scienze della Terra, Universita' di Pisa, Italy. *Institute of Geological Research, Tirana, Albania, ** GeoAlba, Tirana, Albania.
Key words: ophiolites, cherts, deformation history, Middle Jurassic - Early Cretaceous, Albania
ABSTRACT
The Jurassic Kalur Cherts (late Bajocian/early Bathonian - middle Bathonian/early Callovian) represent the sedimentary cover of the Jurassic ophiolite sequence belonging to the Mirdita nappe (Albania). They are characterized by a polyphase deformation history, which includes two phases of folding followed by faulting events. The first phase of folding consists of recumbent, tight to very tight F1 folds with geometry ranging from similar to parallel. The A1 axes are moderately scattered with a cluster between N120E/N150E. The D2 phase is marked by overturned and asymmetric F2 folds with approximately concentric geometry (classes 1b, 1c and 2 of Ramsay, 1967). The F2 folds show a short overturned limb associated with steep to gently inclined axial planes. The A2 axes range from N130E to N160E. The vergence of F1 and F2 folds is everywhere toward the SW. These deformations developed in the Middle Jurassic - Early Cretaceous time during the obduction of the ophiolite sequence. These folding phases can be related with the main gaps recognized in the sedimentary sequence overlying the ophiolites in the western belt of the Mirdita nappe.
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21, No.1