--> Abstract: Depositional and Diagenetic Patterns and Petroleum Potential of Cretaceous Carbonate Platforms, Ionian Islands, Greece, by Peter A. Scholle and Marios Patsoules; #90072 (2007)

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Depositional and Diagenetic Patterns and Petroleum Potential of Cretaceous Carbonate Platforms, Ionian Islands, Greece

Peter A. Scholle1 and Marios Patsoules2
1New Mexico Bureau of Geology, NM Tech, Socorro, NM
2Hellenic Petroleum S.A, Maroussi, Greece

Isolated Cretaceous (Aptian-Maastrichtian) carbonate platforms are found in the Preapulian Zone on several of the Ionian Islands in western Greece, including Zakinthos, Kephalonia, Lefkada, and Paxos. Each island has exposures of one or more thick carbonate platform complexes (hundreds of meters to >1000 m in thickness) or has indicators of nearby platforms that are not presently exposed. Platform interior facies consist of micritic (chalky) mudstones to wackestones and pass laterally towards platform margins though muddy rudistid patch reef facies and rudist wackestone to grainstone deposits. Shelf margins are dominated by massive rudist reefs and coarse, well-rounded rudist grainstones. Slope and toe-of-slope facies consist largely of reworked shelf limestone clasts in debris flows, slides, slumps, and turbidites.
Diagenesis of these deposits is dominated by synsedimentary marine and later meteoric processes. Primary low-Mg calcite marine cements largely occluded porosity in shelf edge carbonates. Meteoric leaching, associated either with pre-Eocene erosion or with Pliocene and later exposure, had more positive effects on porosity, creating extensive secondary pores (locally >20%) in shelf, shelf margin and slope facies. The secondary porosity includes molds of formerly aragonitic grains, vugs, solution-enlarged fractures, and chalky microporosity and, coupled with preserved primary inter- and intragranular porosity, yields excellent potential reservoirs. Although not as spectacularly karstic as its Mexican Cretaceous counterparts in the Golden Lane and Poza Rica fields, the extensive leaching of the Greek platforms should make them an attractive exploration target to the east of the Ionian Islands where such platforms are preserved below thrust sheets that could provide adequate seals.

 

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