Late cretaceous to early Eocene geological history of the eastern Ionian Basin, southwestern Greece: A sedimentological approach
2nd International Conference and Expo on Oil & Gas
December 02-03, 2019 | Dubai, UAE
University of Patras, Greece
Keynote : J Ind Environ Chem
Sedimentological studies of the Upper Cretaceous–Lower
Eocene limestones in the western part of the Ionian basin
(Araxos area) indicate that these sediments are composed
of calciturbidites interbedded with breccia-microbreccia.
Breccia - microbreccia deposits are structureless, display
channelized geometry with calciturbiditic blocks internally
to the channels. Most of the clasts were sourced from
the underlying Lower Cretaceous "Vigla limestones".
Calciturbidites include Ta to Te Bouma sub-divisions and are
organized in cycles that form channelized deposits with a
high degree of amalgamation. Statistical analysis confirms the
presence of order in the sub-division sequence. The thickness
of the calciturbidite event beds of the section is also well
characterized by a lognormal statistical distribution, possibly
produced by multiplicative processes during carbonate
gravity flow sedimentation. The microfacies analysis suggests
that most of the examined samples represent allochthonous
bioclastic material that has been transported from a nearby
platform/reef environment of deposition. In this case, the
depositional environment should be defined as a top of
slope or toe of slope environment, where microbrecciated
or brecciated deposits rested and accumulated. The nature
of the bioclasts and lithoclasts that constitute the respective
deposits represent shallow shelf environments, thus the
allochthonous material originated from the platform.
Resuspension or slumping of platform edge sediments produced turbidity currents (calciturbidite unit) that were time-equivalent to the debris flows (breccia unit) formed by the slumping of the platform margin. Breccia deposits and calciturbidites with Ta to Tc sub-divisions are more proximal deposits, whereas microbreccia and calciturbidites with the complete Bouma sequence were located in more distal positions from the source. By the uppermost Cretaceous, reefs built up on the platforms within the Ionian basin (Fig. 25) and contributed detritus to the microbreccia/breccia unit.
Following the facies analysis and the suggested depositional environments and their conditions indicated that the Ionian Basin was influenced by intense tectonic activity during the early Cretaceous. Synthetic and antithetic faults caused the formation of asymmetric grabens with their uplifted shoulders serving as major sediment contributors into the basin. As a result, a significant amount of coarse-grained material was delivered into the basin. During the late Cretaceous, the shoulders of these asymmetric grabens were most active causing erosion of the pre-existing deposits of Lower Cretaceous “Vigla Formation”, developing the channelized microbreccia and breccia. The basin asymmetry and variations of water depth resulted in variable thicknesses of the breccia/microbreccia channels and calciturbidites.
The early Cretaceous to early Eocene depositional history in the Ionian Basin indicates that the regional tectonic activity, rather than the eustatic sea-level changes, was the major factor that influenced the basin evolution, suggesting a synrift stage being active from the Jurassic to the early Eocene.
Avraam Zelilidis was graduate Geologist in 1984 and earned PhD in 1988 from the Department of Geology of the University of Patras. He was appointed as a lecturer in 1993 and since 2009 as a full professor in the Department of Geology of the University of Patras. He served as Dean of the Faculty of Natural Sciences at the University of Patras from 2006 to 2010. Research deals with the Analysis of Sedimentary Basins, Sequence Stratigraphy, Seismic Stratigraphy and Petroleum Geology. Have produced many research projects for oil companies using data in both surface and subsurface, while he organized many field seminars for foreign oil companies. He has published more than 100 papers in International journals, most of which refer to the Hydrocarbon potential in Greece and have been presented in International conferences in an effort to highlight the issue of existence-exploitation of Hydrocarbon fields in Greece.
E-mail: [email protected]