ABSTRACT: In Gelibolu PenlnsuJa olay minerals n>fsamples ftom flysoh outorops of Karaburun Formation (1000 m thick) of Early Bocine mge consisting- of alternattng nıttdstone and saıulstoiK;, and Burgas Forınalion (700 m tMck) of BfladteXate Eocene age mmMkig of sandstone, detrlta! lim^tone and claystane with tuffaeeousi ini< roalationH were investigat^l to order to assess ttueir degree of dïa^-n^sïs. Botiı flysch levels of the above mention^ formations contain abundant organic eompounds nmÛ therefore may be con« slderad as a potential source roek for petroleum. Orystallinity index and sharpness ratio of mite and presence of other clay minerals have been studied by X^ray diffraction, In clay» o* two macron fraction, sedimentary chlorite was identified by r14Aö f TA% 4,1A° and 8,5A° whereas illite was Iden^fled by reflecttons at 10A% 5A° and S,SAe. Upon heating at Sr?5-400°Oj ^e intensities of 14Ae and particularly 7Ae peaks considierably diecrea§6d, indicating the presence of sadimeiitary chlorite. In the traces of unoriented aggregates Ib monpolytypes of sedimentary chlorite were also îndentîfled. The crystaliinity taidex of Mlite decreases while the sharpness ratio increases with burial depth. If the studies of Weaver (1961 a), Kubier (1966), Burst (1989), Moort (1071), and Foscolôs-Kodama (19T4) are taken in to oonßideration, the types of clay miiK^ruls found im the flysch levels show that these sedfanentä may have been subjected to diagenesis at a depth of over 4000 meters.