Eocene to Early Oligocene turbidite sedimentation in the SE Aegean (Karpathos Island, SE Greece): stratigraphy, facies analysis, nannofossil study,and possible hydrocarbon potential

Authors: GEORGE PANTOPOULOS, AVRAAM ZELILIDIS

Abstract: Paleogene turbidite deposits that outcrop at the SE Aegean (Karpathos Island, SE Greece) were investigated using sedimentological, biostratigraphical, and organic geochemical techniques. Results indicate that turbidite sedimentation in the area took place from the Early Eocene (NP12-14) to Late Eocene-Early Oligocene (NP20-21). Six different units were recognized in the turbidite succession based on sedimentological characteristics, outcropping in 2 major areas of the island (1 in the north and 1 in the south) and having a thickness of less than 1000 m. Deposition and spatial arrangement of sedimentary facies was affected by the already deformed carbonate substratum and changes in the prevailing sediment source between siliciclastic and carbonate sources. Tectonic activity was mainly responsible for the evolution of the turbidite system, but a eustatic sea level lowstand during the Early Eocene also affected sedimentation. The Late Eocene was characterized by the deposition of lenticular sand-rich fan sediments containing terrigenous organic material. High density (hyperpycnal) flows caused by direct river input of sediment largely contributed to the observed sand-rich fan sedimentation, which is closely related with tectonic activity. Organic geochemical analysis of organic rich samples from the Late Eocene sand-rich fan sediments reveals source rock potential for gaseous hydrocarbons of mature/postmature stage. The time span and the tectonic setting of deposition reveal similarities with turbidite sedimentation of the Pindos and/or Pelagonian Zones of southern Greece and also with Eocene turbidite deposits outcropping in the area of the Lycian Nappes (SW Turkey). Based on the latter, the present study cautiously highlights the need for correlation of the studied sediments with age-equivalent clastic deposits in SW Turkey (Yavus Thrust Sheet/Yavuz-Elmalı turbidites), closely related with the advance of the Lycian Nappes during the Eocene-Early Oligocene.

Keywords: Turbidites, facies, Eocene, hydrocarbons, Aegean, Karpathos, Greece

Full Text: PDF