Constraining the Origin and Evolution of Confined Turbidite Systems: Southern Cretan Margin, Eastern Mediterranean Sea (34°30-36°N)

Tiago M. Alves¹, Vasilis Lykousis², Dimitris Sakellariou², Stamatina Alexandri², and Paraskevi Nomikou^2
1Cardiff University, Cardiff, United Kingdom
²Hellenic Centre of Marine Research, Attiki, Greece

Bathymetric, sidescan sonar (OKEAN), seismic reflection and sediment-core data were used in the analysis of two tectonic troughs south of Crete, Eastern Mediterranean Sea, where up to 1.2 s two-way travel time of strata have accumulated since the Middle Miocene in association with extension in the South Aegean region. The study area comprises >100-km-long by ~25-km-wide basins filled by sediments subdivided into two seismic units: (1) an upper Unit 1 deposited in sub-basins which follow the present-day configuration of the southern Cretan margin; (2) a basal Unit 2, more than 500 ms (TWTT) thick, accumulated in deeper half-graben/grabens. The interpreted seismic units have been correlated with the onshore stratigraphy, demonstrating that denudation processes occurring on Crete and Gavdos in response to major tectonic events have been responsible for high sedimentation rates along the proximal southern Cretan margin. Topographically confined sedimentary units have been deposited south of Crete in the last 12 Ma, including turbidites and other mass-flow deposits fed by evolving transverse and axial channel systems. Surface processes controlling facies distribution include the direct inflow of sediment from alluvial-fan systems and incising mountain rivers onto the Cretan slope, where significant sediment instability processes occur at present. Seismic profiles reveal eight different types of stratigraphic contacts on basin-margin highs and evidence of halokinesis and/or fluid escape. The acquired data gives significant insights on the evolution of ancient extensional/transtensional basins, namely the relative importance of active fault systems in basin compartmentalization and regional reservoir distribution, providing valid ‘ground-truthing' for 3D seismic-reflection data.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece