Depositional Environments and Hydrocarbon Potential of Northern Ionian Sea

Depositional Environments and Hydrocarbon Potential of Northern Ionian Sea Vasiliki Kosmidou George Makrodimitras Nick Papatheodorou

Contents Area of Interest Studied Dataset Workflow SWIT and Paleolatitude Heat flow BHT and Vitrinite Reflectance Data Geochemical Data Erosion, Uplift and Flexural Rigidity 3D model Paleoenvironments Conclusions

Area of Interest Northern Ionian sea is the greater area of western Corfu and Paxos islands in Offshore Western Greece. Geologically, the area is bounded to the north by the Otranto Basin and to the south by the Kefalonia strike-slip fault. On the west there is the Apulian escarpment and from there westwards starts the Calabrian Ridge. On the east, there is the deep basinal area, the South Adriatic Basin, that is bounded on its eastern margin by the front of the Hellenides thrust-and-fold belt. The central part of the basin is the Apulian platform. Apulian Platform

Studied Dataset 6000km 2D seismic data (approx.) 2D multiclient seismic survey (2012, PGS) Legacy seismic surveys Yannadhes Paxi Gaios 1X Paxi 1 4 wells Paxi-Gaios 1X Paxi 1 East Erikousa 1 Yannadhes 1

Workflow SURFACE GRIDS Interpret key horizons in TWT. Depth conversion using sonic data. MODEL Depth converted horizon grids used in a 3D model with Haq's (1987) * sea level curves. Tectonic uplift, subsidence and sediment compaction were not modelled. * Modified by Miller, 2005 THERMAL PARAMETERS Sediment water interface temperature diagram from Wygrala (1989). Paleolatitude for Ionian Sea based on Torsvik et al. (2012). Heat flow scenario based on analogue cases and reference studies. Calibration data available from the AOI. EROSION, UPLIFT AND FLEXURAL RIGIDITY Erosion identification in seismic. Uplift scenario from literature. Flexural rigidity of 10 23 Nm (Allen & Allen, 2013) ORGANIC GEOCHEMISTRY Rock eval data from AGIP Rock - Eval Report for Paxi-Gaios 1X samples for Kerogen Type categorisation and source rock quality estimation

Latitude( o ) SWIT and latitude changes Time(Ma) 5-10 o C <5 o C 10-15 o C 15-20 o C 20-25 o C 25-30 o C 25-30 o C >30 o C North Ionian Sea Modified from Wygrala (1989)

Heat flow scenario

BHT and Vitrinite Reflectance Data

Very Little SR or no SR Gas SR Gas SR?

Erosion 500 m Seismic data suggest important erosional unconformities in the AOI. : Three intra-carbonate erosional unconformities (also observed in Italian outcrops). In the basinal areas unconformities are observed due to the introduction of calciturbidites in the basin. : Three main erosional unconformities in the Miocene sequence with the later and more important one the messinian unconformity. : Three Mass Transport Complexes associated with earthquake and thrust activity. Pliocene-Pleistocene MTC Miocene unconformities Cretaceous intra-carbonate unconformities

Uplift and Flexural Rigidity Uplift Flexural Rigidity o Uplift started in middle Pleistocene (Doglioni et al., 1994) associated with the deposition of two loads on the margins of Apulia. This, together with the KTF and isostasy, affected the geometry, tension and pressure profile of the AOI. o o o Allen & Allen (2013) suggest a displacement of the fore bulge towards Apennines by asymmetry of flexural rigidity of Adriatic. Hellenides D= 10 23 Nm Apennines D= 6 * 10 22 Nm o In the Middle Pleistocene, the platform was uplifted while the adjacent basinal areas were affected by subsidence (Mastronuzzi et al. 2011). o The maximum deflection is assumed w 0 =10km o Uplift rates from 0.4 to 0.2 (0.5-0.7) mm/yr (Cianrafi et al. 1988; Doglioni et al., 1994). (From Allen & Allen, 3 rd, 2013)

Triassic Terrestrial to shallow marine environment? Neotethys A-B -1500-500 0 20 40 60 80 100 120 140 160 180 200 500 1500 2500 3500

Triassic High Slopes indicative of Rifting Restricted basinal, marine environment adjacent to the carbonate platforms where we expect the deposition of formations equivalent to Burano Fm. C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

Jurassic

Jurassic Extensive platform A-B -1500-500 500 1500 0 20 40 60 80 100 120 140 160 180 200 Topographic highs that favour the development of Build Ups 2500 3500

Jurassic Rimmed Platform C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

Early Cretaceous

Early Cretaceous Isolated build-ups A-B -1500-500 0 20 40 60 80 100 120 140 160 180 200 500 1500 2500 3500

Early Cretaceous Extensive platform Isolated build-ups C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

Late Cretaceous

Late Cretaceous Carbonate Build-Ups covered by pelagic sediments

Late Cretaceous Subaerial erosion of the carbonate platform led to the development of calciturbidites transferred into the basin impeding the carbonate build up development A-B -1500-500 0 20 40 60 80 100 120 140 160 180 200 500 1500 2500 3500

Late Cretaceous Steep platform slope and intense erosion leads to redeposited carbonate sediments in the slope and proximal basin C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

Paleogene Prograding sediment infill from the east/ thrust propagading

Miocene Prograding sediment infill from the east/ thrust propagading

Messinian Highest slopes at the eastern margin match the seismic interpretation suggesting higher sediment infill from the east

Messinian Messinian Salinity Crisis Sea Level Drop

Messinian Zanclean Flooding

Messinian Highest slopes at the eastern margin match the seismic interpretation suggesting higher sediment infill from the east A-B -1500-500 0 20 40 60 80 100 120 140 160 180 200 500 1500 2500 3500

Messinian Highest slopes at the eastern margin match the seismic interpretation suggesting higher sediment infill from the east C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

Plio - Pleistocene Excessive deepening due to the KTF and the Uplift

Plio - Pleistocene Excessive deepening due to the KTF and the Uplift A-B -1500-500 500 1500 2500 3500 0 20 40 60 80 100 120 140 160 180 200

Plio - Pleistocene C-D -1500-500 0 20 40 60 80 100 120 500 1500 2500 3500

-1500-1000 -500 0 500 0 20 40 60 80 100 120 Lateral Migration of the basin depocenter from Jurassic to Present (C-D) 1000 1500 2000 2500 3000 3500

Paleoenvironments

Conclusions North Ionian Sea is characterized by a wide shallow water platform with occasionally steep slopes to the west and a deep basin to the east In the basinal part, three isolated carbonate build ups can be identified in the 2D seismic Rock-Eval data suggest good to excellent source rocks Paleothermal data suggest necessary conditions for the maturation of hydrocarbons in the past 3D model allowed the identification of high slope areas indicating the best locations for the development of bioclastic slope aprons and the location of carbonate build-ups 3D model helped the understanding of the lateral change of the basin depocenter due to the thrust activity

Questions?