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FIELD-TRIP SEDIMENTARY CARBONATE AND RESERVOIR SYSTEM IN ALBANIA

(27-28-29 September 2014)

R. Swennen1, A. Cerepi2, C. Loisy2, J. Le Goff2, Y. Rubert2, G. Heba3, K. Muska4, C. Durmishi4, A. Qorri4, A-T. Uta5

1 University of Leuven, Division of Geology, Celestijnenlaan 200 E, B-3001 Heverlee, Belgium 2 EA 4592 “Géoressources et Environnement”, ENSEGID-IPB, 1 allée Daguin, 33607, Pessac, France

3 Diagnos Inc, 7005 Taschereau Blvd, Suite 340, Brossard, Quebec, Canada, J4Z 1A7 4 Faculté de Géologie de Tirana, UPT, Tirana Albanie

5 Institute of Geosciences, Energy, Water and Environment, 60 Don Bosko Street, Tirana, Albania

For the Field-Trip pre-registration, contact:

Rudy Swennen University of Leuven, Division of Geology, Celestijnenlaan 200 E, B-3001 Heverlee, Belgium, Email :

Rudy.Swennen@ees.kuleuven.be, Phone : +32 16 32 75 83 Adrian Cerepi

EA 4592 “Géoressources et Environnement”, ENSEGID-IPB, 1 allée Daguin, 33607, Pessac, France, Email : adrian.cerepi@ipb.fr, Phone : 33 (0) 5 57 12 10 11

The field-trip aims to visit magnificent outcrops of Upper Cretaceous-Paleocene sedimentary carbonate and reservoir system in Albania (architecture, facies, diagenesis, heterogeneity etc…) as outcrop reservoir analogue (Fig. 1). Prograding Upper Cretaceous carbonate platforms from the Kruja Zone in the east, and from the Sazani Zone in the west, contributed as a distal source for the thick carbonate turbidites deposited in the Ionian Basin during the Late Cretaceous and Paleocene (Fig. 2A, B, C). These turbidites, which reworked platform carbonate material are interbedded within finer grained pelagic carbonates, and constitute the main hydrocarbon reservoirs onshore Albania, but also offshore in the Italian part of the Adriatic Sea. The tectonic map of Albania (Fig. 2C) is complex and shows a general NNW–SSE trending succession of thrusts limiting W-verging tectonic nappes (Fig. 2D). This nappe stacking constitutes the Albanides belt formed during the Tertiary Alpine orogeny. In the southwestern part of Albania, the Krasta–Cukali, the Kruja, and the Ionian tectonic zones correspond to the external Albanides. The Sazani zone is autochthonous and belongs to the Apulian domain (Fig. 2C). The thrusted formations of the external nappes are Triassic to Eocene in age. Northward, the Ionian and Kruja nappes are buried under the post-Eocene sediments of the peri-Adriatic depression, under which some formations constitute reservoir rocks for current petroleum exploitation (Fig. 2D). The evolution of the Ionian region is marked by a Triassic-to-Eocene phase of passive margin conditions followed by an Oligocene-to-Quaternary

EA 4592 G&E

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phase of orogeny. Palaeogeographically, the outcrops belong to the pelagic and hemipelagic limestones and the chert-bearing limestones of the Ionian Basin. This basin is narrow, and the platform/basin transition is faulted and involves deposit discontinuities and lateral facies variations (Fig. 2).

Figure 1 : Itinerary, stops and different sections across carbonate sedimentary system in Albania.

Stop 1 (Day ½) Kruja zone - Kruja section

Stop 2 (day 1)

Sazani zone - Llogara section

Stop 3 (Day 1)

Ionian zone - Pilur section

Stop 5 (Day 2)

Ionian zone - Ksamil section

Stop 4 (Day 1)

Ionian zone - Saranda Section

section

Stop 6 (Day 2)

Ionian zone - Muzina Section

Stop 7 (Day 2) Vanister-Goranxia section

Stop 8 (Day 2) Kremenar section

C D

E

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Figure 2: Palaeogeographic context of the Ionian Basin, Kruja platform and Apulian platform. A: Palaeogeographic map of the Ionian basin and the surrounding Apulian and Kruja platforms and its continuation in the Adriatic platform, during the middle Liassic to late Cretaceous (after Zappaterra, 1994). The straight line indicates the approximate location of the cross-section in B. B: Palaeogeographic cross-section between the Sazani zone and the Mirdita–Pindos ocean during the upper Cretaceous; Geological context of the study; C: Simplified tectonic map of Albania with the different tectonic zones and locations of the studied outcrops (star). D: Seismic line interpretation of the external Albanides; E: Detailed geological map of southern Albania with the studied Piluri, Muzina, and Vanister outcrops indicated (Rubert et al. 2012).

STOP 1 (day 1/2): Kruja Section. Kruja Upper Cretaceous and Paleocene-Eocene shallow-water platform carbonate system. Kruja platform is located along the Apulian passive margin of Albania extended on both sides of the Adriatic and Ionian Sea (Fig. 3). The stratigraphic succession of Kruja platform is largely dominated by Upper Cretaceous and Paleocene-Eocene neritic carbonates, limestones and dolomites, containing benthic foraminifera that were deposited in a confined subtidal to supratidal environment. In the central Kruja platform (Kruje-Dajt Massif), Kruja section is located along the right side of national road (Fig. 3). The Late Cretaceous to Palaeogene carbonate deposits of Kruja section displays eleven sedimentary facies (F1 to F11), ranging from subtidal to supratidal environments (Plate I). The deepest environments are characterized by limestones showing oblique stratifications (F6). Shallow subtidal environments are represented by: rudist debris-bearing limestones (F4), rudist patch reef limestones (F3), dolomicrosparites displaying bioturbation traces (F5), and bioclastic limestones (F11) containing large hyaline foraminifera (Nummulites and Discocyclines). Intertidal environments are represented by laminated limestones (F1), rudist storm deposit limestones (F2), bird’s-eyes-bearing dolomites (F7), miliolids-bearing limestones (F10), and brecciated dolomites (F9) typical of intertidal channels. Supratidal environments are represented by laminated dolomites displaying desiccation cracks (F 8). The major regression in Kruja section began at the end of the Early Maastrichian and extended for about 3 Ma where CsB7 foraminifera biozone (Upper Maastrichtian) is missing. The second regression is characterized by the presence of bauxite and lasted about 5 Ma during the Early Eocene.

Figure 3: Location and lithology of the Kruja section, and biostratigraphy of Late Cretaceous to Eocene interval of Kruja platform ‘Albania) (Heba and Prichonnet, 2006).

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STOP 2 (day 1): Llogara section. Sazani sedimentary carbonate system and Apulian platform during Upper Cretaceous. The Apulian platform outcrops on both sides of the Adriatic Sea. Many studies relate to the tectono-sedimentary evolution of Apulia during Upper Cretaceous on its western side (Italian side). However, none have been issued on its easternmost side. In Albania, the Sazani zone exposes the whole Upper Cretaceous succession up to the Paleocene, with about 1500 meters of deposits. Investigations have been held in order to describe in detail this section along the Llogara mountain pass. From shallow water conditions during Cenomanian with a broad setting of microbial laminites and benthic foraminifera Packstone, the system gradually evolves towards a subtidal shelf setting. The latter is evidenced by (mainly) radiolitid Floatstones to Bounstones during Senonian. This transitional evolution is brought out through a large number of shallowing-upwards sequences comprising several identified facies, ranging from peritidal / supratidal depositional settings to subtidal ones (Fig. 4). The top of the section is affected by large scale slump-like mass movements, referring to major destabilizations. These deposits clearly record regional peri-adriatic events and mark a brutal turn of sedimentation processes, from platform settings to proximal-slope re-sedimentation. On field sedimentary study, paleontological study and isotopic measurements (87Sr/86Sr) together contribute to link up sedimentary processes, environmental conditions and timing of deposition in the Upper Cretaceous succession.

Figure 4: An example Shallowing–upwards sequence, from subtidal settings (rudists interval) to intertidal settings (microbial laminate interval (Le Goff, 2013). STOP 3 (day 1): Pilur Section. Upper Cretaceous - Paleocene proximal calciturbidite system (Fig. 5). Comparing to Muzina & Vanister outcrops, several differences indicate the proximal character of Piluri. The Piluri sections display higher average grain size with more numerous calcirudites. The Piluri calciturbidites are thick-bedded and display some relatively rapid lateral variations of thickness and granulometry (Fig. 5). In the Piluri outcrop, the deformed levels are thinner and consist of undulating beds, which are less folded than those found in Vanister and Muzina.

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Figure 5: Calciturbidite system: outcrop panoramas. For each outcrop panorama, the deformed units (named S1 to S3 for Muzina and Vanister outcrops) are intercalated within the stratified units (named t1 to t4 for Muzina and Vanister outcrops). The thick white lines are the position of the logged sections (Rubert et al. 2012). STOPS 4 & 5: Saranda and Ksamil sections. Upper Cretaceous - Paleocene proximal calciturbidite system. In the Saranda anticline several Upper Cretaceous till Eocene outcrops have been studied (Fig. 6). Attention was especially paid to the calcite cemented vein systems and their relationship to burial and tectonic stylolites (Fig. 6). Most veins seem to be host rock buffered explaining that their petrographical (especially cathodoluminescence) and stable isotopic signal vary from outcrop to outcrop. Due to the lack of widespread crosscutting relationships it was however not entirely possible to work out a detailed paragenesis. Nevertheless an overall evolution has been worked out.

Figure 6: A) Detailed geological map of the Saranda anticline. The studied outcrops are indicated on the map and identified by numbers 1 to 8; B) Example of crosscutting relationship between calcite vein (fracture generation 2) and Bed Parallel Stylolites (BPS).

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STOPS 6 & 7: Muzina and Vanister sections. Upper Cretaceous - Paleocene distal calciturbidite system. For the Muzina and Vanister outcrops, the logged sections are subdivided into seven units (Figs. 5 and 8): three main decametric deformed levels (S1 to S3) intercalated within four plurimetric to hectometric units of stratified deposits (t1 to t4). In the Piluri outcrop, the distribution of these units is less clear because deformed levels are more numerous and thinner. For the Piluri and Muzina outcrops, key beds were chosen (P0 to P15 and M1 to M7, respectively) based on their visibility and continuity throughout the cross-sections. Unit t1 is approximately 130 m thick at Muzina and approximately 150 m thick at Piluri. The facies description is largely based on the observations from the Muzina and Vanister outcrops because of the good outcropping conditions. Seven facies are defined based on the sedimentary structures, the lithology variations, and the sequence thicknesses. The various internal sedimentary structures encountered are presented in Fig. 7. Original bed surfaces are often invisible because they are either stylolitised or they are welded to the underlying bed, as a consequence of diagenetic processes. Among the different facies defined, several were sampled to visualize the microfacies and the nature of the rock constituents.

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Figure 7: Facies of carbonate gravity deposits encountered in the field. On the left side are the predominant schematic sequences for each facies with the Ta to Tf divisions observed relative to Bouma (1962) and their association with the facies classification of Mutti (1992). On the right side, pairs of photographs illustrate the different facies. The entire scale bar represents 10 cm, except when otherwise indicated (Rubert et al., 2012).

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Figure 8: Lithostratigraphic logs of the Piluri, Vanister, and Muzina sections. Biostratigraphical position of the sections on the right side is given and completed by planktonic foraminifera determinations. The logged sections consist of deformed units (named S1 to S3) intercalated within stratified units (t1 to t4). The different encountered facies are as follows: the autochthonous sedimentation represented by pelagic limestones; the fine-, medium-, and coarse-grained resedimented sequences associated with the F9, F7/F8–F9, and F4/F5–F9 facies of Mutti (1992), respectively; the mass flow deposits; the deformed levels; and the particular medium-grained sequence showing largescale sedimentary structures (Rubert et al. 2012). STOP 8 (day 2): Kremenara section: Upper Cretaceous-Paleocene distal calciturbidite system. Calciturbidites and debris flows were studied in the Kremenara anticline, which serves as an outcrop reservoir analogue for producing oil field in central Albania and the Adriatic sea. Their study helps to understand and predict reservoir characteristics. The relative timing of diagenetic events has been placed into the burial history (especially the existence of burial and tectonic (i.e. layer parallel shortening stylolites- LPSS) are very useful). Reservoir characteristics of Upper Cretaceous to Eocene deep marine carbonates is controlled by sedimentary setting (i.e. turbidites & debris flows) as well as diagenesis (especially fracturing and fracture reactivation). The diagenesis can be split into (1) Eogenetic stage 1 (ES1) with dissolution and formation of syntaxial & isopacheous framework stablizing cement in the marine burial environment; (2) Mesogenetic stage 1 (MS1) with pre-orogenic fracturing, compaction (development of bed parallel stylolites – BPS1). Fluids are mainly host rock buffered. In some areas some meteoric alteration has been recognised in relation to pre-bulge settings; (3) Post BPS1 – pre LPSS (syn-orogenic prior to thrust emplacement) (PP) with fracturing (e.g. crack & seal fractures, hydrofractures) and cementation by host rock buffered fluida. As shown in figure 9 the development of framework stabilizing cements, tectonic stylolites as well as the reactivation of fractures and joints exert a major control on reservoir properties.

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References BREESCH, L., SWENNEN, R., DEWEVER, B. AND MEZINI, A., 2007, Deposition and diagenesis of carbonate conglomerates in the Kremenara anticline, Albania: a paragenetic time marker in the Albanian foreland fold-and-thrust belt, Sedimentology, 54, 483-496, doi: 10.1111/j.1365-3091.2006.00835.x DEWEVER, B., BREESCH, L., SWENNEN, R. AND ROURE, F., 2007, Sedimentological and marine eogenetic control on porosity distribution in Upper Cretaceous carbonate turbidites (central Albania), Sedimentology, 54, 243-264, doi: 10.1111/j.1365-3091.2006.00833.x. HEBA G. & PRICHONNET G. 2006: L’intervalle Crétacé terminal-Éocène de la marge passive d’Apulie en Albanie (Massifs de Kruje-Dajt et de Makareshi, Zone de Kruja): Faciès, organismes et cycles sédimentaires d’une plate-forme carbonatée. Bulletin de la Société Géologique de France 177, 5, 249-266. RUBERT, Y., JATI, M., LOISY, C., CEREPI, A., GJERGJI, F., MUSKA, K., 2012, Sedimentology of resedimented carbonates: facies and geometrical characterisation of an upper Cretaceous calciturbidite system in Albania, Sedimentary Geology, Vol. 257-260, p. 63-77. CEREPI, A., RUBERT, Y., LOISY, C., FOTO, GJ., 2011, The Upper Cretaceous calciturbidite system in Southwest of Albania: facies, geometry and reservoirs properties, 28th IAS Meeting of Sedimentology to be held in Zaragoza (Spain) on 5th-8th July, 2011. RUBERT, Y., LOISY, C., CEREPI. A., FOTO, GJ., 2011, The Upper Cretaceous calciturbidite system in Southwest of Albania: facies, geometry and reservoirs properties, 13e congrès français de sédimentologie, Dijon, du 14 au 16 novembre 2011. RUBERT, Y., JATI, M., CEREPI, A., LOISY, C., FOTO, G., & KRISTAQ, M., 2010, Reservoir properties of resedimented carbonates of Upper Cretaceous turbiditic system in Albania. 6th workshop of the ILP Task Force on Sedimentary Basins (Tirana, Albania, 7 au 12 novembre 2010). RUBERT, Y., Mohamed, J., LOISY, C., CEREPI, A. & FOTO, G., 2010, Sedimentology of resedimented carbonates: facies and geometrical characterisation of Upper Cretaceous calciturbidite system in Albania. 6th workshop of the ILP Task Force on Sedimentary Basins (Tirana, Albania, 7 au 12 novembre 2010). Poster et communication orale.

Figure 9: Examples of oil bearing (brown) calciturbidites with stylolite development (Bed Parallel Stylolites (BPS) and Tectonic Stylolites (TS).