Evia Island Research Articles

Reproductive Biology of Pearl Oyster (Pinctada radiata, Leach 1814) Based on Microscopic and Macroscopic Assessment of Both Sexes in the Eastern Mediterranean (South Evia Island)

Reproductive Biology of Pearl Oyster (Pinctada radiata, Leach 1814) Based on Microscopic and Macroscopic Assessment of Both Sexes in the Eastern Mediterranean (South Evia Island)

Critical and Strategic Metal Resources of Greece

Greece has a large number of critical and strategic metal resources. The proven and indicated reserves of aluminum amount to 2.5 mt and their gross value €5.075 b. Those of chromium amount to 1.2 mt with gross value €4.320 b, while of cobalt are 129 th. t with gross value €3.348 b. The proven and indicated reserves of copper from Chalkidiki and Kilkis areas are approximately 3.04 mt and their gross value €24.776 b, while those of manganese are 2.25 mt with gross value €5.400 b. Molybdenum has been located in Pigi Kilkis with indicated reserves of about 7.7 th. t and gross value €326 m. Under mining are the vein type magnesite deposits of Gerakini Chalkidiki and North Evia. The total reserves (proven + indicated) of magnesite are 280 mt and their gross value €9.800 b. The most important lateritic Fe-Ni-bearing ores are those of Evia Island, Agios Ioannis Viotia, Lokrida Fthiotida, Mesopotamia and Ieropigi Kastoria. The proven and indicated reserves of nickel are 1.39 mt and their gross value €22.240 b. The Rizana/Lachanas porphyry-epithermal antimony deposit is considered the most important stibnite ore. The proven and indicated reserves of stibnite are at least 100 th. t with an average Sb content of 0.3 wt%. Copper, chromium, and cobalt present good prospects for mining. Platinum group metals (PGMs), with economic interest, are contained in the porphyry Cu deposits of Skouries Chalkidiki. Strymonikos Gulf, together with the neighboring coastal and submarine sands, is the most probable area for locating exploitable rare earth metals (REMs). There are excellent investment opportunities in the exploration and mining of Bi, Te, Ga, Ge, and In metals. The deposits of other critical and strategic metals of Greece should be adequately assessed.

Factors Controlling the Formation and Evolution of a Beach Zone in Front of a Coastal Cliff: The Case of the East Coast of Evia Island in the Aegean Sea, Eastern Mediterranean

The present study examines the recent evolution of a cliff coast along the Aegean Sea, considering its geotectonic context, oceanographic factors, sediment dynamics, and human impact. Initially, the formation of this coastal stretch was influenced by neotectonic faults, oriented both semi-parallel and diagonally relative to the present coastline orientation (NE–SW). Subsequently, the delivery of terrestrial sediment from ephemeral rivers and cliff erosion, along with nearshore wave-induced hydrodynamics have played a secondary role in shaping its current configuration, which includes a beach zone along the base of the cliff. This secondary phase of coastal evolution occurred over the past 4–5 thousand years, coinciding with a period of slow sea level rise (approximately 1 mm/year). Evidence such as uplifted notches and beachrock formations extending to around 5 m water depth suggests intervals of relative sea level stability, interrupted by episodic tectonic events. Anthropogenic interventions, related to both changes in coastal sediment budget and coastal engineering projects, have caused beach erosion, particularly in its central and northern sectors.

The 2022–2023 seismic sequence onshore South Evia, central Greece: evidence for activation of a left-lateral strike-slip fault and regional triggering of seismicity

On 29 November 2022, an earthquake of ML 5.0 (Mw 4.8) occurred onshore South Evia Island (central Greece) preceded by a ML 4.7 (Mw 4.6) event. The pattern of relocated aftershocks indicates the activation of a single, near-vertical fault segment, oriented NW-SE at shallow crustal depths (6–11 km). We suggest that both events ruptured a blind, left-lateral strike-slip fault, about 5 km southeast of village Almyropotamos. We observed that a clear foreshock activity (N=55 events) existed before the two moderate events. The impact of the static stress loading on neighboring fault planes diminishes after a distance of 7 km from the November 2022 epicenters, where the static stress falls below +0.1 bar. We further explore triggering relationships between the 29 November events and the late December 2022 moderate events (ML 4.9) that occurred about 60 km toward NW in the Psachna and Vlahia regions of central Evia. We present evidence of possible delayed dynamic triggering of the late December 2022 central Evia sequence, based on marked changes in seismicity rates and on measured peak ground velocities (PGVs) and peak dynamic strains, both exhibiting local maxima in their map distributions. The causes of the delayed triggering may be related to the well-known geothermal field in central/north Evia and the NW-SE strike of the seismic fault.

Wildfire and African dust aerosol oxidative potential, exposure and dose in the human respiratory tract

Exposure to wildfire smoke and dust can severely affect air quality and health. Although particulate matter (PM) levels and exposure are well-established metrics linking to health outcomes, they do not consider differences in particle toxicity or deposition location in the respiratory tract (RT). Usage of the oxidative potential (OP) exposure may further shape our understanding on how different pollution events impact health. Towards this goal, we estimate the aerosol deposition rates, OP and resulting OP deposition rates in the RT for a typical adult Caucasian male residing in Athens, Greece. We focus on a period when African dust (1–3 of August 2021) and severe wildfires at the northern part of the Attika peninsula and the Evia island, Greece (4–18 of August 2021) affected air quality in Athens. During these periods, the aerosol levels increased twofold leading to exceedances of the World Health Organization (WHO) [15(5) μg m−3] PM10 (PM2.5) air quality standard by almost 100 %. We show that the OP exposure is 1.5-times larger during the wildfire smoke events than during the dust intrusion, even if the latter was present in higher mass loads – because wildfire smoke has a higher specific OP than dust. This result carries two important implications: OP exposure should be synergistically used with other metrics - such as PM levels - to efficiently link aerosol exposure with the resulting health effects, and, certain sources of air pollution (in our case, exposure to biomass burning smoke) may need to be preferentially controlled, whenever possible, owing to their disproportionate contribution to OP exposure and ability to penetrate deeper into the human RT.

Comparative Spectral Analysis of Octopus vulgaris Cuvier, 1797, Jellyfish and Seawater from Aegean Sea, Evia, Greece

Research was conducted using the Fourier Transform Infrared (FTIR) spectral spectroscopy method on octopus, jellyfish, and seawater from the Aegean Sea, Chalkida, Evia Island, Greece. Our analyses of two peaks at 896 and 933 cm-1 indicate their presence in the octopus. These peaks are expressed in Martian minerals and meteorites. The results suggest that the octopus is adaptable to conditions on another planet. Our data provide a basis for speculating that it is an organism from Mars or another planet with similar characteristics. However, the spectral characteristics of the jellyfish and seawater do not correspond to the spectral characteristics of Martian minerals and meteorites. Studies have been conducted also on the microbial flora on the skin of octopus of the species Octopus vulgaris Cuvier, 1797, captured in the Aegean Sea near Chalkida, Greece, on the island of Euboea (Evia). The aim was to assess their role as carriers of pathogenic microorganisms. Bacteria from the families Micrococcaceae and Enterobacteriaceae have been isolated, as well as Aeromonas hydrophilia ssp. hydrophilia, Enterococcus caseiflavus, and Candida lusitaniae. Staphylococci prevail, with the highest quantity being Staphylococcus simulans (107.67 + 10.21 CFU cm-2 on the head and 67.33 + 6.02 CFUcm-2 on the tentacles), followed by Staphylococcus piscifermentans (14.33+1.69 CFU cm-2 on the head and 37.33+1.25 CFU cm-2 on the tentacles) and Staphylococcus hyicus (3.67+1.25 CFU cm-2 on the head and 14.67 + 3.39 CFU cm-2 on the tentacles). Among the Gram-negative bacteria, Aeromonas hydrophilia ssp. hydrophilia piscifermentans predominated, found only on the head of octopuses at 9.67+2.05 CFU cm-2, followed by Klebsiella pneumoniae ssp. ozaenae, also isolated solely from the head (4.00+1.63 CFU cm-2). Escherichia coli was the least prevalent, but it was detected both on the head (2.67+0.47 CFU cm-2) and the tentacles of the studied animals (1.67+0.47 CFU cm-2). Enterococci and fungi were isolated in small quantities from the octopuses' heads and tentacles. The isolated bacteria demonstrated in vitro resistance to most of the tested antibiotics. They were only sensitive to broad-spectrum agents such as amphenicols, tetracyclines, aminoglycoside-aminocyclitols (excluding kanamycin), and quinolones. Staphylococci also showed sensitivity to some penicillins (ampicillin, amoxicillin). However, lincosamides (clindamycin) were ineffective in vitro against the studied bacteria. Potentiated sulfonamides exhibited high activity against the Gram-negative bacteria but not against Gram-positive ones.Aeromonas hydrophila is known to be pathogenic to marine inhabitants, including octopuses. S. simulans, E. coli, and K. pneumoniae are conditionally pathogenic to animals and humans. Their presence on the surface of the studied octopuses, especially E. coli, could indicate seawater fecal contamination and possibly other pathogenic species. The current results also reveal the distribution of multidrug-resistant bacterial strains, even among bacteria that are representatives of the normal microflora of octopuses.

What the Fire Has Left Behind: Views and Perspectives of Resin Tappers in Central Greece

Resin tapping has long been an important traditional economic activity in less advantaged areas that serves as a source for income to local populations as well as an important management tool intricately linked with ecosystem services. In Greece, the majority of the remaining resin tappers are located in communities close to Pinus halepensis stands in the northern part of Evia Island. However, on 3 August 2021, a wildfire burned more than 50,000 Ha in the region, bringing the remaining resin tappers to a standstill. This paper aims to examine the views of 89 resin tappers in N. Evia and their perspectives on their profession as expressed during personal interviews. According to the participants’ replies, resin production is expected to bounce back to pre-fire levels in 40 years. A considerable portion of those interviewed (39.3%) were forced to work in other professions near their communities during the period that followed the fire. They were very dissatisfied by the fire management and initial mitigation actions, and fairly satisfied by the ecosystem recovery works that followed. However, they have high expectations for employment in a seven-year long government-funded support program which will allow them to continue living in their communities, and in this context they are willing to make a professional shift to forest operations work. In this context, the role of state authorities is expected to be crucial. The provision of vocational training and financial incentives could be decisive in preventing them from transitioning to alternative production sectors.

New boundaries: Redefining the geographical range of a threatened fish through environmental DNA survey

AbstractAccurate data on the distribution and population status of threatened fish species are fundamental for effective conservation planning and management. In this work, in order to reassess the distribution of the globally threatened Evia barbel, Barbus euboicus, we undertook an environmental DNA (eDNA) survey coupled with conventional electrofishing, focusing on major river basins in Evia Island in proximity to its known occurrence in a single Evian basin (Manikiatiko stream). For comparison purposes, we conducted eDNA sampling in several locations in the geographically closest continental river basin, the Sperchios basin (Central Greece) which hosts the closely related Barbus sperchiensis. Our results expand the known range of the Evia barbel on Evia adding four new river basins, apart from its type locality (Manikiatiko stream (EV3)). In a single Evian River, where the species had never been located before, there was also a positive eDNA signal for Barbus sperchiensis within the same basin. The research confirms the occurrence of Evia barbel in a wider geographical area, highlighting however the sensitive conservation status of the species due to its still very narrow geographical distribution. The biogeographical implications of our study, as well as potential conservation interventions, are discussed.

Floating Solar Systems with Application to Nearshore Sites in the Greek Sea Region

The increased availability of solar energy potential, especially in southern latitudes as in the Mediterranean Sea and the Aegean Sea regions, constitutes a strong motivation for the design and development of floating offshore solar energy platforms suitable for deployment and operation in the sea environment. In this work, a boundary element method is applied to the hydrodynamic analysis of pontoon-type floating structures carrying photovoltaic panels on the deck. Results are used to estimate the responses of the above floating structures, which are then exploited to calculate the effects of waves and motions on the energy performance of photovoltaics arranged on deck (FPVs). Using as an example a 100 kWp floating module located in the nearshore area of the Pagasitikos Gulf and Evia Island in the central Greece region, the time series of environmental parameters concerning wave, wind and solar data are used, in conjunction with the hydrodynamic responses of the floating structure, to illustrate the effects of waves on the floating PV performance. The results indicate significant variations in energy production due to the dynamic angle of solar incidence generated from the floating module’s responses depending on the sea state that should be taken into account in the design process. Additionally, it is shown that the particular concept could be a promising and economically viable alternative of marine renewables contributing to the European Green Deal policies.

The Formation of Magnesite Ores by Reactivation of Dunite Channels as a Key to Their Spatial Association to Chromite Ores in Ophiolites: An Example from Northern Evia, Greece

Ophiolite magnesite deposits are among the main sources of magnesite, a raw material critical for the EU. The present work focuses on magnesite occurrences at Kymasi (Evia Island, Greece), in close spatial association with chromitite within the same peridotite massif, and on the relationship between ultramafic rocks and late magnesite veins. Chromitite lenses are hosted within dunite, in contact with a partially serpentinized peridotite cut by magnesite veins. Close to the veins, the peridotite shows evidence of carbonation (forming dolomitized peridotite) and brecciation (forming a serpentinite–magnesite hydraulic breccia, in contact with the magnesite veins). Spinel mineral chemistry proved to be crucial for understanding the relationships between different lithologies. Spinels within partially serpentinized peridotite (Cr# 0.55–0.62) are similar to spinels within dolomitized peridotite (Cr# 0.58–0.66). Spinels within serpentinite–magnesite hydraulic breccia (Cr# 0.83–0.86) are comparable to spinels within dunite and chromitite (Cr# 0.79–0.84). This suggests that older weak zones, such as dunite channels, were reactivated as fluid pathways for the precipitation of magnesite. Magnesite stable isotope composition, moreover, points towards a meteoric origin of the oxygen, and to an organic source of carbon. The acquired data suggest the following evolution of Kymasi ultramafic rocks: (i) percolation of Cr-bearing melts in a supra-subduction mantle wedge within dunite channels; (ii) obduction of the ophiolitic sequence and peridotite serpentinization; (iii) uplift and erosion of mantle rocks to a shallow crustal level; (iv) percolation of carbon-rich meteoric waters rich at shallow depth, reactivating the dunite channels as preferential weak zones; and (v) precipitation of magnesite in veins and partial brecciation and carbonation of the peridotite host rock.

Soil Loss Potential Assessment for Natural and Post-Fire Conditions in Evia Island, Greece

A devastating forest fire in August 2021 burned about 517 km2 of the northern part of Evia Island, affecting vegetation, soil properties, sediment delivery and the hydrological response of the catchments. This study focuses on the estimation of the annual soil loss in the study area under natural (pre-fire) and post-fire conditions. The assessment of the soil loss potential was conducted with the application of the Universal Soil Loss Equation (USLE), which is an empirical equation and an efficient way to predict soil loss. The USLE factors include rainfall erosivity (R), soil erodibility (K), the slope and slope length factor (LS), the cover management factor (C) and the erosion control practice factor (P). The USLE quantified the annual soil erosion (in t/ha/year) for both pre- and post-wildfire conditions, and the study area has been classified into various soil loss categories and soil erosion intensity types. The results showed that the annual soil loss before the forest fires ranged from 0 to 1747 t/ha, with a mean value of 253 t/ha, while after the fire the soil loss significantly increased (the highest annual soil loss was estimated at 3255 t/ha and the mean value was 543 t/ha). These values demonstrate a significant post-fire change in mean annual soil loss that corresponds to an increase of 114% compared to the pre-fire natural condition. The area that is undergoing high erosion rates after the extreme wildfire event increased by approximately 7%, while the area of moderate rates increased by 2%. The calculated maximum potential of soil erosion, before and after the 2021 extreme wildfire event, has been visualized on spatial distribution maps of the average annual soil loss for the study area. The present study underlines the significant post-fire increase in soil loss as part of the identification of the more vulnerable to erosion areas that demand higher priority regarding the protective/control measures.

Chemodiversity is closely linked to genetic and environmental diversity: Insights into the endangered populations of the local endemic plant Sideritis euboea Heldr. of Evia Island (Greece)

Sideritis euboea is a perennial medicinal, local endemic species to mountainous areas of Central and Southern Evia Island (Greece) with isolated populations threatened with extinction. In this context, a genetic and phytochemical survey has been performed to evaluate the present status of S. euboea inter- and intra-population diversity in three mountainous areas (Dirfis, Xerovouni, Ochi) of Evia, while its occurrence data have been used to define the species-specific climate requirements and to simulate the habitat suitability. Our analysis revealed differences between the populations concerning their polymorphism and genetic homogenity, resulting in a clear clustering of the main three populations based on PCA analysis. An admixture of individuals was identified between distant populations, indicating a possible gene flow between them. The phytochemical analysis revealed significant differences concerning their content in species-specific polyphenolic metabolites, especially isoscutellarein and hypolaetin derivatives; based on the PCA analysis of the cumulative polyphenolic groups’ pattern, two populations were the more distinctive, while different functional groups of metabolites could result to more clear clustering. The ecological profile analysis revealed that the more diverse S. euboea populations in terms of genetics and cumulative polyphenolics are found under comparatively wetter conditions with lower annual temperature and higher annual precipitation. The findings herein support the distinct climate in the habitats of the main populations of S. euboea from the three mountains, suggesting that all three populations should be considered as distinct units for conservation management with Mt. Ochi’s population firstly prioritized.

Climatic reconstruction at the early Miocene La Rinconada mine (Ribesalbes-Alcora Basin, eastern Spain) based on Coexistence Approach, CLAMP and LMA analysis

The early Miocene La Rinconada mine from eastern Iberian Peninsula contains a rich megafloral assemblage with abundant leaf fossils from a single stratigraphic level of the sedimentary succession. This has provided a good opportunity to undertake detailed comparative quantitative palaeoclimate reconstruction using different approaches, namely the Coexistence Approach (CA), Climate Leaf Analysis Multivariate Programme (CLAMP) and Leaf Margin Analysis (LMA). Considering the results of all techniques used, the palaeoclimate estimates are the following: mean annual temperature (MAT) CA = 10–16.5 °C/CLAMP = 11.48 °C, warmest month mean temperature (WMMT) CA = 25–26.4 °C/CLAMP = 23.31 °C, coldest month mean temperature (CMMT) CA = 4.3–4.8 °C/CLAMP = 0.84 °C, mean annual precipitation (MAP) CA = 1217–1297 mm, mean precipitation of the wettest month (MPWet) CA = 116–164 mm and mean precipitation of the warmest month (MPWarm) CA = 118–131 mm. Temperature and precipitation values obtained through CLAMP, LMA and CA indicate the occurrence of a wet and warm climate the whole year around with marked seasonality for rainfall and temperature but without a summer-dry regime. The climatic values obtained in the La Rinconada mine are in well accordance with other Burdigalian and late Burdigalian–early Langhian sites from the Iberian Peninsula (e.g. S 141 Borehole) and Central-Southern Europe (e.g. Holedeč, Čermníky, Přívlaky, Bílina Delta, Manisa-Soma, Spanokhorion and the Evia Island), suggesting the absence of a clear latitudinal gradient in temperature and precipitation for this period in Europe. This climate is consistent with the plant communities described in the area from taxonomic studies and IPR analysis.

Microstructural and textural modification of columnar calcite under increasing shear strain (Evia Island, Greece)

We studied the microstructural and textural modification of columnar calcite naturally deformed at increasing shear strain. The studied marbles were sampled from different structural levels of the Basal Unit of the Cycladic Massif on Evia Island, Greece. The marbles have experienced high pressure metamorphism at peak temperatures around 350 °C. The long axes of the columnar calcite grains and their c-axes were originally oriented normal to the foliation and were subsequently rotated during exhumation. The obliquity of the long axes of relict calcite grains with respect to the foliation was used to infer shear strain. Electron backscatter diffraction (EBSD) analysis was used to characterize the marble microstructure as well as the crystallographic preferred orientations (CPO) and misorientations in calcite. Recrystallization of calcite was active from very low shear strains (0.1) and mylonitization (∼60% area fraction of recrystallized grains) took place at shear strains >∼4. Subgrain rotation was the dominant recrystallization mechanism in calcite in all samples. Differential stress and strain rate did not show any systematic variation with increasing shear strain. A shear strain of up to ∼4 was not enough to produce a strong CPO in calcite.

Multiple Rodingitization Stages in Alkaline, Tholeiitic, and Calc-Alkaline Basaltic Dikes Intruding Exhumed Serpentinized Tethyan Mantle from Evia Island, Greece

Abstract In Pagondas and Kimi areas, central Evia Island, Greece, variably serpentinized ultramafic rocks of an ophiolitic origin are crosscut by rodingite dikes. Based on their protoliths, these rodingites are distinguished into the following: (i) rodingites of island arc tholeiitic dolerites, (ii) rodingites of Mg-rich tholeiitic gabbros, (iii) rodingites of alkaline basalts, and (iv) rodingites of calc-alkaline basalts. Rodingitization evolved in three successive phases (namely, stages 1, 2, and 3) of increasing metasomatic degree that occurred during the exhumation of the mantle wedge serpentinites. Thermodynamic modeling suggests that stage 1 was developed at ~5 kbar and 450-550°C, whereas at stage 2 and stage 3, gradually decreasing P-T conditions prevailed. Stage 1 affected the protoliths of all rodingite types and was characterized by the crystallization of grossular, diopside, chlorite, and prehnite leading to Ca and LOI enrichments. The observed Si and REE depletions are assigned to the dissolution of primary clinopyroxene and amphibole. Stage 2 mainly affected the rodingites that were derived from alkaline and calc-alkaline basalts, promoting the growth of andradite, vesuvianite, and chlorite at the expense of stage 1 rodingitization mineral phases. At this stage, the marginal zones of rodingite dikes from alkaline and calc-alkaline basalts experienced remarkable Mg and REE enrichments. Stage 3 corresponds to derodingitization and restricted carbonation processes of the previously formed rodingites, which are associated with Fe enrichments. During this stage, significant trace elements including REEs were transferred from the marginal zones to the inner cores of rodingite dikes that were derived from metasomatism of calc-alkaline basalts. Calcite δ18Ο-δ13C isotopic data suggest that carbonation processes were developed at shallow depths below the Tethyan ocean floor, through mixing of seawater and serpentinization-derived fluids. Such multiple stages of rodingitization processes that affected four different lithotypes, as well as the unusual case of alkaline basalts’ rodingitization, would render the Evia rodingites as an important and very rare example of metasomatism.

A Google Earth Engine code to estimate properties of vegetation phenology in fire affected areas – A case study in North Evia wildfire event on August 2021

The present work aims to demonstrate the application of a previously published methodology concerning the properties of NDVI time series in fire-affected areas. Our work has been motivated by the devastating fire events in the northern part of Evia island, during August 2021, that destroyed more than 400 km2 of forest and agricultural land. The fire had a strong impact on the environment and the local communities, depriving them of their main income sources. Within this paper, a Google Earth Engine tool was developed, to facilitate access, processing and estimation of properties of remotely sensed NDVI time series in distinct zones, that corresponds to the fire-affected area, whereas the second one delineates a zone of equal area and with the same land cover characteristics to the burned land as described by the CORINE Level 1 and Level 3 nomenclature. Landsat 8 NDVI times series, at a spatial resolution of 30 m, with a 32-day time step, was used to construct a time series from January 2014 to September 2021 and assess structural phenological differences in the two predefined zones. Results fully support our previous findings concerning the differences in the NDVI time series of the two examined zones that is of considerably lower standard deviation values in the fire-affected areas.

Comparing High Accuracy t-LiDAR and UAV-SfM Derived Point Clouds for Geomorphological Change Detection

Analysis of two small semi-mountainous catchments in central Evia island, Greece, highlights the advantages of Unmanned Aerial Vehicle (UAV) and Terrestrial Laser Scanning (TLS) based change detection methods. We use point clouds derived by both methods in two sites (S1 & S2), to analyse the effects of a recent wildfire on soil erosion. Results indicate that topsoil’s movements in the order of a few centimetres, occurring within a few months, can be estimated. Erosion at S2 is precisely delineated by both methods, yielding a mean value of 1.5 cm within four months. At S1, UAV-derived point clouds’ comparison quantifies annual soil erosion more accurately, showing a maximum annual erosion rate of 48 cm. UAV-derived point clouds appear to be more accurate for channel erosion display and measurement, while the slope wash is more precisely estimated using TLS. Analysis of Point Cloud time series is a reliable and fast process for soil erosion assessment, especially in rapidly changing environments with difficult access for direct measurement methods. This study will contribute to proper georesource management by defining the best-suited methodology for soil erosion assessment after a wildfire in Mediterranean environments.

Calcite pseudomorphs after aragonite: A tool to unravel the structural history of high-pressure marbles (Evia Island, Greece)

Calcite pseudomorphs after aragonite were recorded throughout the high-pressure marbles of the Basal Unit (Evia Island, Greece). The pseudomorphs form a columnar microstructure oriented normal to the foliation, which developed at peak metamorphic conditions within the stability field of aragonite. Modification of the columnar microstructure by bending of the long axis of the calcite pseudomorph and dynamic recrystallization, was mainly dependent on the intensity of subsequent, exhumation-related deformation. We used the degree of preservation or modification of the columnar microstructure observed in shear zones, to distinguish between the subduction- and exhumation-related nature of the studied shear zones. The degree of modification of the columnar microstructure was also used as a tool to investigate variations in strain intensity, recrystallization mechanism and kinematics during the exhumation of the high-pressure marbles. Combined field and microstructural data suggest that subduction-related ductile deformation preceded the growth of the columnar microstructure and was associated with internal imbrication by SE-directed thrusting. The ductile stage of the exhumation was characterized by strain localization at the middle and upper structural levels of the Basal Unit, and E-directed thrusting (i.e., northeast in pre-Neogene configuration). Final exhumation of the Basal Unit was achieved by top-to-the-E ductile to brittle thrusting, which was accompanied by syn-orogenic extension at the upper crustal levels.

Assessment of Neotectonic Landscape Deformation in Evia Island, Greece, Using GIS-Based Multi-Criteria Analysis

This study deals with the assessment and mapping of neotectonic landscape deformation in the northern part of the Evia Island (Central Greece). Multi-Criteria Decision Analysis (MCDA) utilizing Analytic Hierarchy Process (AHP) and Weighted Linear Combination (WLC) procedures were conducted for the calculation of the Neotectonic Landscape Deformation Index (NLDI). The study is based on the combination of morphotectonic, geomorphological and geological parameters. The GIS-based spatial MCDA led to the classification of the study area into five classes of neotectonic deformation (from very low to very high) and to a neotectonic deformation map. The results were compared with the outputs of a relative tectonic activity classification approach based on quantitative geomorphic analysis at a regional scale, including site-specific field observations. Areas of high and very high deformation are related to the major active faults of Dirfis, Kandili and Gregolimano–Telethrio. Other minor active normal faults of medium to high seismic risk level, affecting the northern and northeastern parts of the island, are also associated with areas of intense landscape neotectonic deformation.

Μorphometric Analysis for the Assessment of Relative Tectonic Activity in Evia Island, Greece

The aim of this study is to evaluate the relative tectonic activity in the north part of the Evia Island, located in Central Greece, and to investigate the contribution of neotectonic processes in the development of the fluvial landscape. Five morphometric parameters, including Drainage Basin Slope (Sb), Hypsometric Integral (Hi), Asymmetry Factor (Af), Relief Ratio (Rh), and Melton’s Ruggedness Number (M), were estimated for a total of 189 drainage basins. The catchments were classified into two groups, according to the estimated values of each morphometric parameter, and maps showing their spatial distribution were produced. The combination of the calculated morphometric parameters led to a new single integrated Index of relative tectonic activity (named Irta). Following this indexing, the basins were characterized as of low, moderate, or high relative tectonic activity. The quantitative analysis showed that the development of the present drainage systems and the geometry of the basins of the study area have been influenced by the tectonic uplift caused by the activity of two NW-SE trending offshore active normal fault systems: the north Gulf of Evia fault zone (Kandili-Telethrion) and the Aegean Sea fault zone (Dirfis), respectively. The spatial distribution of the values of the new integrated index Irta showed significant differences among the drainage basins that reflect differences in relative tectonic activity related to their location with regard to the normal fault systems of the study area.