Discussion: "Unraveling the provenance of Eocene-Oligocene sandstones of the Thrace Basin, North-east Greece"

The petrographic analysis of Caracciolo et al.(2011)suggests that the Greek part of the Thrace Basin was affected by the epimetamorphic and ophiolite units of the Circum-Rhodope Belt. This influence is less likely on the southern part of the basin (Lemnos) where the role of the outer arc ridge as a contributor of sediments into the fore-arc basin appears to be of great importance. Supporting evidence comes from palaeocurrent data that indicates a northward palaeoflow direction, the relative successive landward migration of the basin depocentre to the north-east, higher ophiolite influence to the south, the active influence of the outer arc ridge as displayed by the pure ophiolitic layers, and stratigraphic architecture that indicates an ophiolitic source rock coming from ophiolite units, i.e. on Lesvos Island (Maravelis et al., 2007; Maravelis & Zelilidis, 2010a, 2011). The Greek part of the Thrace Basin (Lemnos and Rhodope) comprises a fore-arc basin of the ‘contracted’ type, constructed as an effect of the subduction of the African Plate beneath the Eurasian Plate and is influenced mainly by two major sediment inputs (Maravelis & Zelilidis, 2010a). The southern part is significantly affected by the accretionary prism and associated ophiolitic units, i.e. on Lesvos Island (Maravelis et al., 2007; Maravelis & Zelilidis, 2010a), while the northern part reflects a Circum-Rhodope Belt influence (Maravelis & Zelilidis, 2010a; Caracciolo et al., 2011) (Fig. 1). Several hypotheses and conclusions presented by Caracciolo et al. (2011) do not reflect the actual sedimentary record seen throughout the Palaeogene in the Greek Thrace Basin. In particular, the important influence of the outer arc ridge as major sediment input is not considered. This basin is a complex system of depocentres extending across Greek, Bulgarian and Turkish domains, and an additional multi-faceted approach is required to advance our understanding of its development. Such research should involve age-equivalent rocks within these countries, and be supported by a wide range of data and analytical techniques, such as high frequency sequence stratigraphy, sedimentology, palaeoflow analysis, petrography and geochemistry

Reassessing Depositional Conditions of the Pre-Apulian Zone Based on Synsedimentary Deformation Structures during Upper Paleocene to Lower Miocene Carbonate Sedimentation, from Paxoi and Anti-Paxoi Islands, Northwestern End of Greece

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 consolidation. SSD structures are cross-cut by normal faults, indicating their development during the rift stage. There are at least five different SSD horizons, and most of them present either an eastward or a westward progradation. These SSD structures are classified into four (4) different types of deformations: (1) thick synclines and anticlines, formed due to strong synsedimentary deformation; (2) strong and thick SSD structures that produced erosional contacts both with the underlying and the overlying undeformed horizons; (3) thin slumps, having sharp contacts with the underlying undeformed horizons and erosional contacts with the overlying undeformed horizons; and (4) thin slump horizons passing laterally to undeformed deposits in the same horizon. The studied SSD structures and their age of development introduce active margins between the Apulian platform and the Ionian Basin that have been influenced by normal fault activity. These normal faults have been active since the Ionian Basin changed gradually to a foreland basin, and after the tectonic regime changed from extension to compression, during the early to middle Eocene. It seems that compression in the studied Apulian platform margins arrived later and after the lower Miocene, and after the development of the SSD structures. The confinement of the lower Miocene deposits, both northwards and southwards (in Anti-Paxoi Island), indicates the presence of active transfer faults, with flower structure geometry, that were formed during sedimentation, producing highs and troughs. The present open anticline geometry of Paxoi Island indicates that the Island represents the forebulge area of the middle Miocene Ionian Foreland due to Ionian Thrust activity

The implication of transfer faults in foreland basin evolution: application on Pindos foreland basin, West Peloponnesus, Greece

Pindos foreland basin in west Peloponnesus (Tritea, Hrisovitsi and Finikounda sub-basins) during Late Eocene to Early Oligocene was an underfilled foreland basin. The basin's geometry was affected by the presence of internal thrusting and transfer faults, causing changes in depth and width. Due to internal thrusting, the foreland basin changed through time from a uniform to non-uniform configuration, whereas transfer faults have an intensive impact on depositional environments within the basin. Internal thrusting (Gavrovo, internal and middle Ionian thrusts) activated synchronously with the major Pindos Thrust, creating intrabasinal highs that influenced palaeocurrent directions. The transfer faults cross-cut the intrabasinal highs and produced low relief areas that act as pathways for sediment distribution. The sediments are thicker and sandstone-rich on the downthrown sides of the transfer faults. In these areas, sandstone reservoirs could be produced. Such tectonically active areas constitute promise for oil and gas reservoirs and traps

Microfacies and Depositional Conditions of Jurassic to Eocene Carbonates: Implication on Ionian Basin Evolution

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 Cretaceous ones (Senonian limestones) were deposited in slope or toe of slope conditions. Paleocene limestones correspond to a deep-sea environment. In Araxos peninsula, changes occurred during the Cretaceous, whereas on Kastos Island, they occurred during the Paleocene/Eocene, related to different stages of tectonic activity in the Ionian basin from east to west

The Lower Cretaceous “Vigla” Shales Potentiality to Be Source Rocks in the Ionian Basin, Greece

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), valued for samples AG1, AG2, AG5, and AG6, indicated an anoxic deposition environment. As the Ionian Basin was sub-divided into three sub-basins (internal, middle, and external) during its syn-rift evolution, different depositional conditions were developed from one sub-basin to the other, with different sedimentary thicknesses within the same sub-basin or among different sub-basins and with different amounts of TOC. The fact that there is a great difference in geochemical indices between the two studied areas during the same period suggests that probable different depositional conditions could exist. It seems that the richness in Kastos Island could be related to the neighboring Apulian Platform, whereas the poorness in the Araxos peninsula could be related to the Gavrovo platform, or the differences could be related to restrictions produced regions. The comparison with previous studies indicates that different quality and quantity of organic matter could be accumulated either within the same sub-basin or from one sub-basin to the other

The Lower Cretaceous “Vigla” Shales Potentiality to Be Source Rocks in the Ionian Basin, Greece

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), valued for samples AG1, AG2, AG5, and AG6, indicated an anoxic deposition environment. As the Ionian Basin was sub-divided into three sub-basins (internal, middle, and external) during its syn-rift evolution, different depositional conditions were developed from one sub-basin to the other, with different sedimentary thicknesses within the same sub-basin or among different sub-basins and with different amounts of TOC. The fact that there is a great difference in geochemical indices between the two studied areas during the same period suggests that probable different depositional conditions could exist. It seems that the richness in Kastos Island could be related to the neighboring Apulian Platform, whereas the poorness in the Araxos peninsula could be related to the Gavrovo platform, or the differences could be related to restrictions produced regions. The comparison with previous studies indicates that different quality and quantity of organic matter could be accumulated either within the same sub-basin or from one sub-basin to the other

The Knowledge and Application of Sedimentary Conditions of Shallow Marine and Tidal Waters of Ionian Islands, Greece: Implications for Therapeutic Use

This study delves into the sedimentation mechanisms governing mud deposits in shallow marine and tidal environments, with a particular focus on elucidating the versatile therapeutic applications of these muds. This research provides valuable insights for optimizing the selection of mud as a cosmetic resource that can positively influence human health and well-being by utilizing a comprehensive analysis involving CaCO3, TOC, grain size, and statistical parameters across six outcrops situated on the Kefalonia and Corfu islands. The research reveals that the CaCO3 content of mud deposits on both islands is comparable. Despite the average value (26.71%) significantly exceeding the recommended value (10%) for optimal plasticity, no discernible impact on the mechanical behavior and plasticity of the clay was observed, rendering it a neutral quality criterion. Notably, the TOC content is higher on Corfu Island, suggesting its potential superiority for mud therapy. However, all samples exhibit a TOC content (<0.77%) considerably below the threshold required (2–5%) for material maturation in mud therapy. Consequently, an enrichment of samples with organic matter is imperative. The application of statistical parameters, analyzed through graphical methods, facilitated the creation of various bivariate diagrams, offering insights into the prevailing environmental conditions during deposition. Linear and multigroup discriminant analyses categorize two sediment types: a unimodal type, characterized by mud grain-size dominance, deposited in a shallow water environment, and a bi-modal type, featuring mud and sand content, deposited in a tidal-affected environment. This classification underscores the potential of shallow marine muds (Kefalonia Island) for therapeutic use, given their optimal grain size. In contrast, the tidal mud (Corfu Island), while also suitable for mud therapy, necessitates processing as a cosmetic product to minimize sand content, as coarser fractions may induce skin irritations or injuries

Re-Evaluation of the Ionian Basin Evolution during the Late Cretaceous to Eocene (Aetoloakarnania Area, Western Greece)

Field investigation, Microfacies analysis, and biostratigraphy have been carried out in the central parts of the Ionian Basin (Aetoloakarnania area, Western Greece) in order to decipher the depositional environments that developed during the accumulation of the Upper Cretaceous to Eocene carbonate succession. Three different Standard Microfacies types (SMF) have been observed, corresponding to two different depositional environments (Facies Zones or FZ) of a platform progradation. The three SMF types which occur in the study area during the Upper Cretaceous to Eocene are: 1. SMF 3 that includes mudstone/wackestone with planktic foraminifera and radiolaria, corresponding to toe-of-slope (FZ: 3), 2. SMF 4, which can be classified as polymict clast-supported microbreccia, indicating a toe-of-slope-slope environment (FZ: 4) and 3. SMF 5 which is characterized by allochthonous bioclastic breccia and components deriving from adjacent platforms and which reflects a slope environment. Microfacies analysis provided evidence of a change in the origin of sedimentary components and biota showing the transition from toe-of-slope to slope, as well as a change in organism distribution

Re-Evaluation of the Ionian Basin Evolution during the Late Cretaceous to Eocene (Aetoloakarnania Area, Western Greece)

Field investigation, Microfacies analysis, and biostratigraphy have been carried out in the central parts of the Ionian Basin (Aetoloakarnania area, Western Greece) in order to decipher the depositional environments that developed during the accumulation of the Upper Cretaceous to Eocene carbonate succession. Three different Standard Microfacies types (SMF) have been observed, corresponding to two different depositional environments (Facies Zones or FZ) of a platform progradation. The three SMF types which occur in the study area during the Upper Cretaceous to Eocene are: 1. SMF 3 that includes mudstone/wackestone with planktic foraminifera and radiolaria, corresponding to toe-of-slope (FZ: 3), 2. SMF 4, which can be classified as polymict clast-supported microbreccia, indicating a toe-of-slope-slope environment (FZ: 4) and 3. SMF 5 which is characterized by allochthonous bioclastic breccia and components deriving from adjacent platforms and which reflects a slope environment. Microfacies analysis provided evidence of a change in the origin of sedimentary components and biota showing the transition from toe-of-slope to slope, as well as a change in organism distribution