As Lower Cretaceous “Vigla” shales have been suggested as one of the main source rocks for the Io... more As Lower Cretaceous “Vigla” shales have been suggested as one of the main source rocks for the Ionian Basin in Greece, a geochemical analysis was performed for “Vigla” shales in Kastos Island and the Araxos peninsula, far from the already studied areas. Results, based on Rock-Eval VI analysis, sample fractionation, and biomarkers analysis, showed that the studied rocks could be of low production capacity, are type II/III of kerogen, and can produce liquid and gas hydrocarbons for Kastos Island. Organic matter (total organic carbon-TOC 0.02–3.45%) of the studied samples is thermally immature, in the early stages of diagenesis, and was accumulated in an anoxic environment. Additionally, the geochemical analyses confirmed the combination of marine and terrestrial origin of the organic matter. On the other hand, TOC (0.01–0.72%) from the Araxos peninsula shows fair oil potential and type IV kerogen. The results based on the Odd–Even Predominance, OEP (27–31), OEP (2), and OEP (1), value...
The new approach on depositional conditions of the Messinian evaporites in Zakynthos Island indic... more The new approach on depositional conditions of the Messinian evaporites in Zakynthos Island indicates that the evaporites in the Kalamaki and Ag. Sostis areas were redeposited during the Early Pliocene. They accumulated either as turbiditic evaporites or as slumped blocks, as a response to Kalamaki thrust activity. Thrust activity developed a narrow and restricted Kalamaki foreland basin with the uplifted orogenic wedge consisting of Messinian evaporites. These evaporites eroded and redeposited in the foreland basin as submarine fans with turbiditic currents or slumped blocks (olistholiths) that consist of Messinian evaporites. These conditions occurred just before the inundation of the Mediterranean, during or prior to the Early Pliocene (Zanclean). Following the re-sedimentation of the Messinian evaporites, the inundation of the Mediterranean produced the “Lago Mare” fine-grained sediments that rest unconformably over the resedimented evaporites. The “Trubi” limestones were deposi...
Kefalonia Island is situated in western Greece and geologically corresponds to the Apulian Platfo... more Kefalonia Island is situated in western Greece and geologically corresponds to the Apulian Platform Margins (APM), with the Apulian Platform lying to the west and the Ionian Basin to the east. The studied deposits, with a thickness up to 164.5, extend along the 650 m long Agia Efimia bay, ranging from the Middle Paleocene (Selandian) to the uppermost Eocene (Priabonian), during the latest part of the rift stage. Fieldwork measurements of soft-sediment deformation structures (SSDS), paleocurrent directions, the size and abundance of siliceous concretions (SC) and siliceous beds (SB), and shale horizons were correlated with the age of selected samples, and thus, the relation of the tectonic regime with the depositional conditions was presented. As SSDS could represent an indicator of tectonic activity and instability of the basin floor instability, the size and the abundance of the SSDS whereas used to identify the parameters that produced the basin floor instability like the intensit...
Μικροφασική ανάλυση, φασικές ζώνες και προσδιορισμός ηλικιών: Στο νησί του Κάστου με βάση λιθολογ... more Μικροφασική ανάλυση, φασικές ζώνες και προσδιορισμός ηλικιών: Στο νησί του Κάστου με βάση λιθολογικά και ιζηματολογικά χαρακτηριστικά, έχουν αναγνωριστεί τα ακόλουθα περιβάλλοντα απόθεσης: βαθιάς θάλασσας και περιβάλλον με βαθιά υφαλοκρηπίδα, η βάση της κατωφέρειας προς κατωφέρεια και ανοιχτή θαλάσσια προς περιορισμένη λεκάνη. Ασβεστοτουρβιδίτες και εξέλιξη λεκάνης: Οι ασβεστοτουρβιδίτες περιλαμβάνουν τις υποδιαιρέσεις της Bouma από το Τa έως το Te και είναι οργανωμένοι σε κύκλους που σχηματίζουν καναλοειδείς αποθέσεις με υψηλό ποσοστό συγχώνευσης τους (amalgamation). Η στατιστική ανάλυση επιβεβαιώνει την παρουσία της σειράς της ακολουθίας των υποδιαιρέσεων της Bouma. Η μικροφασική ανάλυση των ασβεστολίθων παρουσιάζει αποθέσεις βαθιάς θάλασσας και επαναεπεξεργασμένες αποθέσεις υφαλοκρηπίδας. Η έντονη εξωτερική τεκτονική δραστηριότητα στη Ιόνιο λεκάνη κατά τη διάρκεια του Κρητιδικού, με συνθετικά και αντιθετικά ρήγματα που παράγουν ενεργά περιθώρια πλατφόρμας και ασύμμετρες λεκάνες. ...
Microfacies analysis, facies zones and age determination: In Kastos Island based on lithological ... more Microfacies analysis, facies zones and age determination: In Kastos Island based on lithological and sedimentological characteristics, the following depositional environments have been recognized: deep sea and deep shelf, toe of slope-to-slope and open marine to restricted. Calciturbidites and basin evolution: 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 event beds in the studied section shows a lognormal statistical distribution, typical of turbidite successions. Limestone microfacies suggest deep-water deposits and reworked shelf deposits. The intense extensional tectonic activity in the Ionian basin during the Early Cretaceous, with synthetic and antithetic faults, produced active platform margins and asymmetrical grabens. The Early Cretaceous to early Eocene depositional history i...
The studied area is situated in northwestern Greece and corresponds to the northern end of the Pr... more The studied area is situated in northwestern Greece and corresponds to the northern end of the Pre-Apulian Zone, in contact with the Apulian platform to the west and the Ionian Basin to the east. The proposed model is based on fieldwork, measured deformation structures, and age determination of the studied deposits. Until now, the known Pre-Apulian platform or Pre-Apulian zone represents the margins of the Apulian platform to the Ionian Basin and was formed due to the normal faults’ activity during the Mesozoic to Cenozoic Eras. Soft sediment deformation (SSD) structures are widespread within the upper Paleocene to lower Miocene limestones/marly limestones that are exposed in both Paxoi and Anti-Paxoi Islands, mostly along their eastern coasts, across sections of 2–3 km long and up to 60 m high. SSD structures, with a vertical thickness up to 10 m, have been observed in limestones and were formed during or immediately after deposition, during the first stage of sediment consolidatio...
In order to decipher the paleo-depositional environments, during the Late Jurassic to Early Eocen... more In order to decipher the paleo-depositional environments, during the Late Jurassic to Early Eocene syn-rift stage, at the margins of the Ionian basin, two different areas with exposed long sequences have been selected, Kastos Island (external margin) and Araxos peninsula (internal margin), and were examined by means of microfacies analysis and biostratigraphy. On Kastos Island, based on lithological and sedimentological features, the following depositional environments have been recognized: an open marine/restricted environment prevailed during the Early Jurassic (“Pantokrator” limestones), changing upwards into deep-sea and slope environments during the Late Jurassic and Early Cretaceous (Vigla limestones). The Upper Cretaceous (Senonian limestones) is characterized by a slope environment, whereas during the Paleogene, deep-sea and toe of slope conditions prevailed. In Araxos peninsula, Lower Cretaceous deposits (“Vigla” limestones) were accumulated in a deep-sea environment; Upper...
Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of... more Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of diagenetic minerals than their host limestone and interbedded shale. The goal of this study was to test the possible presence of a high-temperature mineralising system in the Ionian basin of western Greece. Upper Cretaceous chert nodules were sampled at Araxos, where rocks are highly faulted and uplifted by salt diapirism, and on Kastos Island, on the flanks of a regional anticline. Chert concretions have microporosity produced by recrystallisation of opal to quartz and fractures produced in the brittle chert during basin inversion. Diagenetic mineral textures were interpreted from backscattered electron images, and minerals were identified from their chemistry. Diagenetic minerals in pores and veins include sedimentary apatite (francolite), dolomite, Fe-chlorite, Fe oxide-hydroxide mixtures, sphalerite, barite and calcite. Sphalerite is restricted to Araxos, suggesting that inferred ba...
Siliceous concretions (nodules), from two different geological settings—the Apulian platform marg... more Siliceous concretions (nodules), from two different geological settings—the Apulian platform margins in Kefalonia island, and the Ionian Basin in Ithaca, Atokos, and Kastos islands—have been studied both in the field and in the laboratory. Nodule cuttings are mainly characterized by the development of a core, around which a ring (rim) has been formed. Mineralogical study, using X-ray powder diffraction (XRPD) analysis, showed that the rim is usually richer in moganite than the core. Homogeneous concretions, without discernible inner core and outer ring, were observed generally in both settings. Mineralogical analysis of the selected siliceous concretions from Kefalonia island showed the presence mostly of quartz and moganite, while calcite either was absent or participated in a few samples in minor/trace abundances. Moganite was generally abundant in all the samples from Kefalonia island. Concretions from the Ionian Basin showed a variation in the quartz, moganite, and calcite conte...
As Lower Cretaceous “Vigla” shales have been suggested as one of the main source rocks for the Io... more As Lower Cretaceous “Vigla” shales have been suggested as one of the main source rocks for the Ionian Basin in Greece, a geochemical analysis was performed for “Vigla” shales in Kastos Island and the Araxos peninsula, far from the already studied areas. Results, based on Rock-Eval VI analysis, sample fractionation, and biomarkers analysis, showed that the studied rocks could be of low production capacity, are type II/III of kerogen, and can produce liquid and gas hydrocarbons for Kastos Island. Organic matter (total organic carbon-TOC 0.02–3.45%) of the studied samples is thermally immature, in the early stages of diagenesis, and was accumulated in an anoxic environment. Additionally, the geochemical analyses confirmed the combination of marine and terrestrial origin of the organic matter. On the other hand, TOC (0.01–0.72%) from the Araxos peninsula shows fair oil potential and type IV kerogen. The results based on the Odd–Even Predominance, OEP (27–31), OEP (2), and OEP (1), value...
The new approach on depositional conditions of the Messinian evaporites in Zakynthos Island indic... more The new approach on depositional conditions of the Messinian evaporites in Zakynthos Island indicates that the evaporites in the Kalamaki and Ag. Sostis areas were redeposited during the Early Pliocene. They accumulated either as turbiditic evaporites or as slumped blocks, as a response to Kalamaki thrust activity. Thrust activity developed a narrow and restricted Kalamaki foreland basin with the uplifted orogenic wedge consisting of Messinian evaporites. These evaporites eroded and redeposited in the foreland basin as submarine fans with turbiditic currents or slumped blocks (olistholiths) that consist of Messinian evaporites. These conditions occurred just before the inundation of the Mediterranean, during or prior to the Early Pliocene (Zanclean). Following the re-sedimentation of the Messinian evaporites, the inundation of the Mediterranean produced the “Lago Mare” fine-grained sediments that rest unconformably over the resedimented evaporites. The “Trubi” limestones were deposi...
Kefalonia Island is situated in western Greece and geologically corresponds to the Apulian Platfo... more Kefalonia Island is situated in western Greece and geologically corresponds to the Apulian Platform Margins (APM), with the Apulian Platform lying to the west and the Ionian Basin to the east. The studied deposits, with a thickness up to 164.5, extend along the 650 m long Agia Efimia bay, ranging from the Middle Paleocene (Selandian) to the uppermost Eocene (Priabonian), during the latest part of the rift stage. Fieldwork measurements of soft-sediment deformation structures (SSDS), paleocurrent directions, the size and abundance of siliceous concretions (SC) and siliceous beds (SB), and shale horizons were correlated with the age of selected samples, and thus, the relation of the tectonic regime with the depositional conditions was presented. As SSDS could represent an indicator of tectonic activity and instability of the basin floor instability, the size and the abundance of the SSDS whereas used to identify the parameters that produced the basin floor instability like the intensit...
Μικροφασική ανάλυση, φασικές ζώνες και προσδιορισμός ηλικιών: Στο νησί του Κάστου με βάση λιθολογ... more Μικροφασική ανάλυση, φασικές ζώνες και προσδιορισμός ηλικιών: Στο νησί του Κάστου με βάση λιθολογικά και ιζηματολογικά χαρακτηριστικά, έχουν αναγνωριστεί τα ακόλουθα περιβάλλοντα απόθεσης: βαθιάς θάλασσας και περιβάλλον με βαθιά υφαλοκρηπίδα, η βάση της κατωφέρειας προς κατωφέρεια και ανοιχτή θαλάσσια προς περιορισμένη λεκάνη. Ασβεστοτουρβιδίτες και εξέλιξη λεκάνης: Οι ασβεστοτουρβιδίτες περιλαμβάνουν τις υποδιαιρέσεις της Bouma από το Τa έως το Te και είναι οργανωμένοι σε κύκλους που σχηματίζουν καναλοειδείς αποθέσεις με υψηλό ποσοστό συγχώνευσης τους (amalgamation). Η στατιστική ανάλυση επιβεβαιώνει την παρουσία της σειράς της ακολουθίας των υποδιαιρέσεων της Bouma. Η μικροφασική ανάλυση των ασβεστολίθων παρουσιάζει αποθέσεις βαθιάς θάλασσας και επαναεπεξεργασμένες αποθέσεις υφαλοκρηπίδας. Η έντονη εξωτερική τεκτονική δραστηριότητα στη Ιόνιο λεκάνη κατά τη διάρκεια του Κρητιδικού, με συνθετικά και αντιθετικά ρήγματα που παράγουν ενεργά περιθώρια πλατφόρμας και ασύμμετρες λεκάνες. ...
Microfacies analysis, facies zones and age determination: In Kastos Island based on lithological ... more Microfacies analysis, facies zones and age determination: In Kastos Island based on lithological and sedimentological characteristics, the following depositional environments have been recognized: deep sea and deep shelf, toe of slope-to-slope and open marine to restricted. Calciturbidites and basin evolution: 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 event beds in the studied section shows a lognormal statistical distribution, typical of turbidite successions. Limestone microfacies suggest deep-water deposits and reworked shelf deposits. The intense extensional tectonic activity in the Ionian basin during the Early Cretaceous, with synthetic and antithetic faults, produced active platform margins and asymmetrical grabens. The Early Cretaceous to early Eocene depositional history i...
The studied area is situated in northwestern Greece and corresponds to the northern end of the Pr... more The studied area is situated in northwestern Greece and corresponds to the northern end of the Pre-Apulian Zone, in contact with the Apulian platform to the west and the Ionian Basin to the east. The proposed model is based on fieldwork, measured deformation structures, and age determination of the studied deposits. Until now, the known Pre-Apulian platform or Pre-Apulian zone represents the margins of the Apulian platform to the Ionian Basin and was formed due to the normal faults’ activity during the Mesozoic to Cenozoic Eras. Soft sediment deformation (SSD) structures are widespread within the upper Paleocene to lower Miocene limestones/marly limestones that are exposed in both Paxoi and Anti-Paxoi Islands, mostly along their eastern coasts, across sections of 2–3 km long and up to 60 m high. SSD structures, with a vertical thickness up to 10 m, have been observed in limestones and were formed during or immediately after deposition, during the first stage of sediment consolidatio...
In order to decipher the paleo-depositional environments, during the Late Jurassic to Early Eocen... more In order to decipher the paleo-depositional environments, during the Late Jurassic to Early Eocene syn-rift stage, at the margins of the Ionian basin, two different areas with exposed long sequences have been selected, Kastos Island (external margin) and Araxos peninsula (internal margin), and were examined by means of microfacies analysis and biostratigraphy. On Kastos Island, based on lithological and sedimentological features, the following depositional environments have been recognized: an open marine/restricted environment prevailed during the Early Jurassic (“Pantokrator” limestones), changing upwards into deep-sea and slope environments during the Late Jurassic and Early Cretaceous (Vigla limestones). The Upper Cretaceous (Senonian limestones) is characterized by a slope environment, whereas during the Paleogene, deep-sea and toe of slope conditions prevailed. In Araxos peninsula, Lower Cretaceous deposits (“Vigla” limestones) were accumulated in a deep-sea environment; Upper...
Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of... more Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of diagenetic minerals than their host limestone and interbedded shale. The goal of this study was to test the possible presence of a high-temperature mineralising system in the Ionian basin of western Greece. Upper Cretaceous chert nodules were sampled at Araxos, where rocks are highly faulted and uplifted by salt diapirism, and on Kastos Island, on the flanks of a regional anticline. Chert concretions have microporosity produced by recrystallisation of opal to quartz and fractures produced in the brittle chert during basin inversion. Diagenetic mineral textures were interpreted from backscattered electron images, and minerals were identified from their chemistry. Diagenetic minerals in pores and veins include sedimentary apatite (francolite), dolomite, Fe-chlorite, Fe oxide-hydroxide mixtures, sphalerite, barite and calcite. Sphalerite is restricted to Araxos, suggesting that inferred ba...
Siliceous concretions (nodules), from two different geological settings—the Apulian platform marg... more Siliceous concretions (nodules), from two different geological settings—the Apulian platform margins in Kefalonia island, and the Ionian Basin in Ithaca, Atokos, and Kastos islands—have been studied both in the field and in the laboratory. Nodule cuttings are mainly characterized by the development of a core, around which a ring (rim) has been formed. Mineralogical study, using X-ray powder diffraction (XRPD) analysis, showed that the rim is usually richer in moganite than the core. Homogeneous concretions, without discernible inner core and outer ring, were observed generally in both settings. Mineralogical analysis of the selected siliceous concretions from Kefalonia island showed the presence mostly of quartz and moganite, while calcite either was absent or participated in a few samples in minor/trace abundances. Moganite was generally abundant in all the samples from Kefalonia island. Concretions from the Ionian Basin showed a variation in the quartz, moganite, and calcite conte...
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