Abstract: Early Eocene and Middle-Late Eocene flysch like fine grained sedimentary rocks in Gelibolu Peninsula were studied for their source rock possibility. Both facies consist of sand, mud, clayand normal flysch within different horizons. Fine grained rocks (claystone and mudstone) comprize% 80 of the total thickness of the sedimentary rocks. Organic geohemical parameters and clay mineralsparagenesis of the claystone and mudstone obtained from the measured stratigraphic section were investigated. According to the total organic carbon (TOC) and extractable organic material (EOM) dataSaz member may probably be considered as a source rocks however Karaağaç member may not bethe source rock. According to the vitrinite reflectance (Rm) data Saz Member rang young state andKaraağaç Member rang mature state. Oil and gas with low to awerage quality may be produced fromthem. According to the illite kristalinite index data Saz Member rank anchimetamorphism and metamorphism and Karaağaç Member is in the diagenetic stage.The clay minerals in the Saz and Karaağaç Members and their polimorphes indicated that those sediments may have been subjected to diagenesis at deepths between 30004700 meters.