Methana Research Articles

Compositional variation of mafic calc-alkaline lavas at the submarine Pausanias Volcanic Field, western South Aegean Volcanic Arc: Implications for magma formation and ascent

The calc-alkaline lavas of the submarine Pausanias Volcanic Field and the neighboring Methana peninsula represent the largest volcanic edifices of the western South Aegean Volcanic Arc (SAVA) in the Mediterranean Sea and erupted on 30–35 km thick continental crust. We report the first whole rock major and trace elements together with Sr-Nd-Pb isotope ratios for basaltic to andesitic lavas from the submarine Pausanias Volcanic Field consisting of six smaller, volcanic structures. The mafic lavas have the most primitive compositions of the SAVA with MgO of up to 9 wt% and Ni concentrations >100 ppm. The incompatible trace element abundance patterns of the Pausanias and Methana lavas overlap and have typical island arc patterns, but Pausanias lavas display a larger geochemical heterogeneity on a smaller spatial scale compared to those from Methana. The Pausanias lavas resemble those from Methana in Sr, Nd, and Pb isotopes reflecting higher sediment subduction in the western SAVA than in the central arc at Santorini. The variability of incompatible element concentrations at relatively constant isotope compositions suggests variable degrees of partial melting of a peridotite-sediment mélange diapir in the mantle wedge. The Pausanias magmas formed from a less depleted mantle source compared to the central SAVA and their ascent in an extensional basin supported relatively rapid ascent without the extensive stagnation in the crust observed in the Methana magmas. The compositional differences between Pausanias and Methana imply differences in their composition and/or transport in the mantle wedge and the crust, allowing highly variable melts to reach the surface within a spatial distance of few kilometers. • Small scale mantle heterogeneity recorded at the Pausanias Volcanic Field. • Melting of sediment-rich mélange diapirs contribute to Pausanias lavas. • At Pausanias, extension allows melts to ascend more direct through the crust compared to Methana.

Phytoplankton community structure changes during autumn and spring in response to environmental variables in Methana, Saronikos Gulf, Greece

Phytoplankton community was investigated during two contrasting periods using offshore plankton samples in the volcanic area of Methana peninsula (Saronikos Gulf): the first at early autumn (warm period, September 2016) and the second one at early spring (cold period, March 2017). In order to investigate the phytoplankton community structure in the complex geo-biochemical conditions of the area, samples were collected from stations near the CO2 hydrothermal vents, at the hydrothermal sulfur and radioactive springs and at a fishery nearby Methana town. Three major phytoplankton groups, Bacillariophyceae, Dinophyceae, and Prymnesiophyceae, were studied, using inverted microscopy. In early autumn, Dinophyceae were dominant in the majority of the stations with cell concentrations of Prorocentrum spp. up to ~ 35.5 × 103 cells l-1. In early spring, the dominant class was Bacillariophyceae with dominant genus Nitzschia/Pseudo-nitzschia presenting cell concentrations up to ~ 33.9 × 103 cells l-1. Furthermore, Prymnesiophyceae appeared in both spring and autumn samples with small fluctuations. Total phytoplankton cell concentrations followed a seasonal trend, presenting slightly lower values in the hydrothermal-effected area in comparison with the broader Saronikos Gulf, confirming the prevalence of oligotrophic conditions. Seasonal variation was very strong, revealing an association with water temperature and nutrient content. Those environmental variables proved to have a strong effect that was reflected in the phytoplankton community structure.

The islands of the Saronic Gulf: connections & cultural histories

This article reviews a decade of publications and rescue excavations on the islands of Aegina, Poros and Salamis, and on the island-like Methana peninsula. Considerable amounts of new data have come to light that demonstrate how, from prehistory through to more recent times, the islands of the Saronic Gulf have been plugged in to networks with one another, with their neighbouring mainlands and with the wider Aegean. Moreover, a not insignificant number of publications has recently become available that synthesize many years of archaeological discoveries into cultural histories, telling the stories of each island and of the whole archipelago.

Copernicus Sentinel-1 MT-InSAR, GNSS and Seismic Monitoring of Deformation Patterns and Trends at the Methana Volcano, Greece

The Methana volcano in Greece belongs to the western part of the Hellenic Volcanic Arc, where the African and Eurasian tectonic plates converge at a rate of approximately 3 cm/year. While volcanic hazard in Methana is considered low, the neotectonic basin constituting the Saronic Gulf area is seismically active and there is evidence of local geothermal activity. Monitoring is therefore crucial to characterize any activity at the volcano that could impact the local population. This study aims to detect surface deformation in the whole Methana peninsula based on a long stack of 99 Sentinel-1 C-band Synthetic Aperture Radar (SAR) images in interferometric wide swath mode acquired in March 2015–August 2019. A Multi-Temporal Interferometric SAR (MT-InSAR) processing approach is exploited using the Interferometric Point Target Analysis (IPTA) method, involving the extraction of a network of targets including both Persistent Scatterers (PS) and Distributed Scatterers (DS) to augment the monitoring capability across the varied land cover of the peninsula. Satellite geodetic data from 2006–2019 Global Positioning System (GPS) benchmark surveying are used to calibrate and validate the MT-InSAR results. Deformation monitoring records from permanent Global Navigation Satellite System (GNSS) stations, two of which were installed within the peninsula in 2004 (METH) and 2019 (MTNA), are also exploited for interpretation of the regional deformation scenario. Geological, topographic, and 2006–2019 seismological data enable better understanding of the ground deformation observed. Line-of-sight displacement velocities of the over 4700 PS and 6200 DS within the peninsula are from −18.1 to +7.5 mm/year. The MT-InSAR data suggest a complex displacement pattern across the volcano edifice, including local-scale land surface processes. In Methana town, ground stability is found on volcanoclasts and limestone for the majority of the urban area footprint while some deformation is observed in the suburban zones. At the Mavri Petra andesitic dome, time series of the exceptionally dense PS/DS network across blocks of agglomerate and cinder reveal seasonal fluctuation (5 mm amplitude) overlapping the long-term stable trend. Given the steepness of the slopes along the eastern flank of the volcano, displacement patterns may indicate mass movements. The GNSS, seismological and MT-InSAR analyses lead to a first account of deformation processes and their temporal evolution over the last years for Methana, thus providing initial information to feed into the volcano baseline hazard assessment and monitoring system.

The Methana Volcano – Geothermal Resource, Greece, and its relationship to regional tectonics

Geophysical methods of analysis were applied, in order to investigate the deep structure and the geothermal potential of the Methana Volcano (NE Peloponnesus, Greece). The study is based on a re-evaluation and reinterpretation of legacy magnetotelluric (MT) data with modern analysis methods, as well as 3-D inversion of aeromagnetic data constrained by in situ measurements of magnetic susceptibility. Magmatic systems are located in regions of active tectonic processes that often play a controlling role. The MT method is effective in delineating low resistivity functional elements of volcanic systems, such as magma chambers, vents, thermal fluid reservoirs and thermal fluid circulation conduits, the latter two of which are typically associated with active faults. The aeromagnetic data can assist in mapping the configuration, hence emplacement modes of volcanic rocks at depth. Accordingly, the joint interpretation of these lines of evidence, together with structural and geochemical information, is expected to allow insight into the influence of contemporary tectonics on the inception and evolution of the volcano. The contemporary stress field is mainly extensional, NNE-SSW oriented and overall homogeneous; in the area of Methana it allows for the formation of WNW-ESE north-easterly dipping normal faults, W-E faults consistent with the synthetic (dextral) R-shear direction of Riedel's shear theory and NW-SE faults consistent with the antithetic (sinistral) R′-shear direction; all such features have been mapped on Methana Peninsula. The magnetotelluric data imaged a significant geothermal reservoir developing around an intersection of the three active fault zones (normal, R and R′) at depths of 1–1.5 km below the centre of the peninsula, as well as elongate epiphenomenal conductivity anomalies associated with the circulation of thermal fluids along all three fault zones. The 3-D magnetic susceptibility model strongly suggests that the intrusion and emplacement of magmas were guided by the same active fault zones, with particular reference to the R and R′ shears whose influence is imprinted on the configuration of volcanic rocks at depth. The joint interpretation of all lines of evidence indicates that magmatism and volcanism at Methana are almost completely controlled by tectonic activity in a manner analogous to the situation of the large Santorini Volcanic Complex. It also indicates that the reservoir is replenished through the weak permeable zone created by the intersection of the R and R′ shears, which is very probably collocated with the main vent of intrusive magmatic activity and may connect with a shallow magma chamber at depths greater than 4.5 km. The apparently common origin and similarities/differences in the circulation paths of thermal fluids may amply explain both the individual characteristics and similarities/differences in the chemical composition of thermal spring discharges, which have been reported by hitherto geochemical investigations.

Chemical Evolution of Calc-alkaline Magmas during the Ascent through Continental Crust: Constraints from Methana, Aegean Arc

AbstractQuaternary calc-alkaline andesitic to dacitic lavas effusively erupted on top of about 30 km thick accreted continental crust at Methana peninsula in the western Aegean arc. We present new data of major and trace element concentrations as well as of Sr–Nd–Pb isotope ratios along with mineral compositions of Methana lavas and their mafic enclaves. The enclaves imply a parental basaltic magma and fractional crystallization processes with relatively little crustal assimilation in the deep part of the Methana magma system. The composition of amphibole in some mafic enclaves and lavas indicates deeper crystallization at ∼25 km depth close to the Moho compared with the evolved lavas that formed at <15 km depth. The presence of amphibole and low Ca contents in olivine suggest high water contents of ∼4 wt% in the primitive magmas at Methana. The compositions of andesitic and dacitic lavas reflect fractional crystallization, assimilation of sedimentary material, and magma mixing in the upper 15 km of the crust. The Methana magmas have fO2 of FMQ + 1 to FMQ + 2 (where FMQ is the fayalite–magnetite–quartz buffer) at temperatures of 1200 to 750 °C and the fO2 does not vary systematically from mafic to felsic compositions, suggesting that the mantle wedge was oxidized by sediment subduction. Amphibole is an important fractionating phase in the more evolved Methana magmas and causes significant changes in incompatible element ratios. Although xenocrysts and mineral compositions indicate magma mixing, the major and trace element variation implies only limited mixing between dacitic and basaltic melts.

Gamma spectroscopy studies of the underwater hydrothermal vent field of the Methana Peninsula

A preliminary study of natural radioactivity was conducted on the thermal spas in Methana Peninsula. To carry out this research, a collection of 17 water samples were taken from thermal springs around and underwater of the volcanogenic Peninsula at depths ranging 0–5 m. The Methana peninsula belongs to the Hellenic Volcanic Arc and is characterized by hydrothermal vent activity. A NaI(Tl) scintillator (AMESOS) was used to carry out gamma–ray counting of the samples to deduce the activity concentrations of the natural radionuclides of the 238U and 232Th decay series, as well as 40K in spa waters. Results are expected to provide information on the geological setting of the Methana peninsula. The impact of naturally occurring radioisotopes to human health has also been assessed in terms of the radiation dose risk corresponding to the measured activities.

Creating a Story Map Using Geographic Information Systems to Explore Geomorphology and History of Methana Peninsula

Story maps are used as an interactive tool for communication and information dissemination. A web-based application using story mapping technology is presented to explore the Methana peninsula. This volcanic area is characterized by specific volcanic geoforms, unique flora and rich history. The story map combines maps, narrative texts and multimedia content. The spatial data produce thematic maps created by a Geographic Information System on geological data, historical monuments, biodiversity and hiking paths. The purpose is to highlight the distinguishing characteristics of the Methana peninsula, to enable users to interact with maps, texts and images and to inform professional and non-professional users about the particular aspects of volcanic areas.

Extreme isotopic variation documents extensional tectonics in arc magmas from Methana, Greece

New Sr-Nd-Hf-Pb isotope data for volcanic rocks from the peninsula of Methana (South Aegean Active Volcanic Arc, Greece) show a wide variation, and more ‘enriched’ isotopic signatures (e.g. elevated 87Sr/86Sr at 0.705–0.709) than those of other active Aegean volcanic centres, all located on thinner crust. The data set is best explained by polybaric AFC processes, with contaminants similar to country rocks and xenoliths, showing moderately high 87Sr/86Sr ratios, and with isotopically more evolved lower crust, similar to the pre-Alpine Ios basement. Pb isotope ratios show some minor influence of assimilation of fluid-altered volcanic cumulates. Intermediate lava domes with mafic enclaves were formed during periods of compression, whereas an extensional period saw the deposition of explosive products of bimodal composition, with the more felsic deposits showing the most pronounced influence of crustal assimilation. The latter likely represent stalled magmas from an earlier compressional period, which were remobilised and flushed out by ascending mafic magmas during extension. Recognition of these volcanological, geochemical and isotopic characteristics of deposits associated with extensional tectonics in a modern arc will enable us to use these criteria to infer paleo-tectonics from older volcanic deposits.

Coccolithophore community response along a natural CO2 gradient off Methana (SW Saronikos Gulf, Greece, NE Mediterranean).

A natural pH gradient caused by marine CO2 seeps off the Methana peninsula (Saronikos Gulf, eastern Peloponnese peninsula) was used as a natural laboratory to assess potential effects of ocean acidification on coccolithophores. Coccolithophore communities were therefore investigated in plankton samples collected during September 2011, September 2016 and March 2017. The recorded cell concentrations were up to ~50 x103 cells/l, with a high Shannon index of up to 2.8, along a pH gradient from 7.61 to 8.18, with values being occasionally <7. Numerous holococcolithophore species represented 60–90% of the surface water assemblages in most samples during September samplings. Emiliania huxleyi was present only in low relative abundances in September samples, but it dominated in March assemblages. Neither malformed nor corroded coccolithophores were documented. Changes in the community structure can possibly be related to increased temperatures, while the overall trend associates low pH values with high cell densities. Our preliminary results indicate that in long-termed acidified, warm and stratified conditions, the study of the total coccolithophore assemblage may prove useful to recognize the intercommunity variability, which favors the increment of lightly calcified species such as holococcolithophores.

Bathy-morphological setting of the Submarine Pausanias Volcanic Field, South Aegean Active Volcanic Arc

ABSTRACTHigh-resolution swath-bathymetry has been acquired during recent surveys in Saronikos Gulf, near the densely populated city of Athens. This paper presents the first detailed bathymetric map, at a scale of 1:12,000, of the active Submarine Pausanias Volcanic Field located offshore NW Methana Peninsula in Saronikos Gulf, Aegean Sea (Main Map). Rugged morphology characterizes the volcanic field that includes mainly cone-shaped features. Six volcanic outcrops, covering an area of about 12 km2, have been morpho-bathymetrically outlined, and their sub-bottom character has been described by the integration of 2D seismic reflection profiles. Two groups of outcrops have been distinguished. An older group comprising more complex, erosional-shaped outcrops, and a younger group consisting of sub-conical outcrops. Both groups have been morphologically correlated to their onshore equivalents in the adjacent peninsula of Methana. Despite the active tectonic regime of the region, no evidence of mass transport-related features have been observed.

The active submarine NW termination of the South Aegean Active Volcanic Arc: The Submarine Pausanias Volcanic Field

Methana peninsula shows the longest recorded volcanic history at the western end of the South Aegean Active Volcanic Arc, including volcanic products from the Upper Pliocene to recent times. The volcanic rocks comprise widespread dacite domes and andesite lava flows from several small volcanic centers and are only imprecisely dated. In this paper, the integrated analysis of swath bathymetry, side scan sonar data, and high resolution seismic reflection profiles correlated with core samples, has allowed detailed mapping, characterization and precise chronological identification of the Pausanias submarine volcanic field activity offshore northern Methana. Six volcanic cones or domes are recognized, typically 1–3 km in diameter, some elongated NE–SW and some with a small central crater. On their flanks, the acoustically reflective volcanic rocks pass laterally into incoherent transparent seismic facies interpreted as volcaniclastic deposits, possibly including hyaloclastites, that interfinger with the regional basin sediments. A sea-bottom hummocky field, is interpreted as volcanic avalanche and appears to be the submarine continuation of the volcaniclastic apron of northern Methana peninsula. A robust chronostratigraphic framework has been established, based on the recognition of shoreline progradational units and their connection with Quaternary eustatic sea level cycles. Relative dating of the different phases of submarine volcanic activity during the Upper Quaternary has been achieved by correlating the imaged volcaniclastic flows, interlayered within the chronostratigraphically dated sediments. Dating by stratigraphic position, relative to 2D imaged eustatic sea level clinoform wedges appears to be more precise than radiometric methods on land. Three main submarine Volcanic Events (VE) are recognized: VE3 at ~450 ka, a less precisely dated interval at 200–130 ka (VE2), and VE1 at ~14 ka. Based on chronostratigraphic constraints, subsidence rates of 0.16 (±0.008) m/ka in-between Marine Isotopic Stages 6 and 12 and 0.19 (±0.009) m/ka in-between Marine Isotopic Stages 12 and 16 were estimated for the marine basin north of Methana. The morphological similarity to the onshore volcanoes of Methana Peninsula implies that magmatic constructive processes were dominant, regardless of whether in air or in water. The Upper Quaternary submarine volcanic rocks of Methana differ from those known from stratovolcanoes elsewhere in the Mediterranean, (e.g. Kos-Nisyros, Stromboli) and in other volcanic arcs (e.g., Montserrat, St Vincent), in the submarine development of domes or small cones, the paucity of volcano flank failure deposits and the lack of explosive events. Pausanias volcanic products date the onset of NE–SW faulting as well as the following tectonic phase of E-W striking faults, possibly related to basin inversion, caused by a major rifting phase that also affected most of the South Aegean Arc and the adjacent Gulfs of Corinth and Argolikos.

Evidence for melting of subducting carbonate-rich sediments in the western Aegean Arc

Subduction of sediments affects the composition of the Earth's mantle and the formation of melts in subduction zones. The sediment thickness of ~8 km along the Hellenic Trench is the largest observed globally and significant volumes of these sediments are subducted. Magmas erupting in the Aegean Arc reflect sediment subduction but they also assimilated sediments during ascent, making distinction of the two processes difficult. In this study, we present geochemical data from olivines in lavas and enclaves from the peninsula of Methana in the western Aegean Arc. The olivines have high forsterite (Fo) contents of 90–92% and contain Cr-spinel with Cr# >60 originating from a primitive melt in equilibrium with a highly depleted mantle wedge. The high δ18OVSMOW of ~6.5‰ of the olivines imply input of up to 6.5% sediment component into the mantle wedge. Incompatible element and radiogenic isotope ratios suggest that the sediment component is added as a carbonate-rich melt. Low Ni contents and small rounded sulphide inclusions in the Fo-rich olivines indicate the formation of an immiscible sulphide liquid during olivine crystallization. The input of carbonate-rich sediment reduced the mantle and the co-existing primitive melts, and possibly added S leading to sulphide saturation. This study shows that olivine crystals and their inclusions provide important insights into the mantle wedge, sediment subduction and its effects on the primary magma composition and can indeed be used to distinguish between a mantle and crustal origin of the sediment signature.

Hydrothermally-altered dacite terrains in the Methana peninsula Greece: Relevance to Mars

Dacitic rocks, often indicative of crustal recycling on Earth, have been identified in some regions on Mars, as have possible hydrothermally/aqueously-altered dacites. To enable more robust identification of unaltered and altered dacites on Mars and other planetary bodies, we undertook a spectroscopic-structural-compositional study of altered and unaltered dacites from a dacitic volcanic region in Methana, Greece. Dacites erupted in this region range from fresh to pervasively hydrothermally altered, resulting in friable, Si-enriched products, as well as fumarolic deposition of Si and S-rich precipitates. Spectrally, fresh dacites are unremarkable in the 0.35–2.5µm region with low, generally flat, reflectance and few, if any, absorption bands. Dacite infrared spectra exhibit Si-O absorption features in the 8–10µm region (which are characteristic of Si-bearing rocks, in general). With increasing alteration, reflectance over the 0.35–2.5µm range increases, absorption bands in the 1.4 and 1.9µm region, associated with H2O/OH, and in the 2.2–2.3µm region, associated with SiOH, become deeper, Fe3+-associated absorption bands in the 0.43 and 0.9µm region appear, and the Christiansen feature near 8µm moves to shorter wavelengths. Silica-rich coatings appear to be spectrally indistinguishable from Si-rich alteration. Alteration-formed sulfates may be detectable by the presence of diagnostic absorption features in the 0.35–2.5µm region. Spectral similarities between different poorly crystalline high-Si phases make it difficult to uniquely determine the processes that formed high-Si surfaces that have been identified on Mars. However, the samples described here show a variety of spectral features that correspond to variable amounts of alteration. We find a similar range of spectral features, likely due to similar phases, on Mars, perhaps indicating a similar range of alteration environments. Comparison of laboratory spectra to Mars observational data also suggests that the major Si-rich regions likely consist of assemblages that more mineralogically complex than those included in this study.

CRUSTAL MOVEMENTS ALONG THE NW HELLENIC VOLCANIC ARC FROM DGPS MEASUREMENTS

The north-western part of the Hellenic Volcanic Arc was studied by Differential GPS measurements in an attempt to investigate the regional deformation of the area. The GPS network involving stations in Athens, Aegina Island, Methana Peninsula and Soussaki was established in February 2006 and since then it was reoccupied twice. The GPS measurements were primarily referred to Worldfixed reference frame (ITRF2000) and then to Europe and Athens as well. The observed velocities for the overall three-year spanning period according to Athens station showed rates at the order of 7-10 mm/yr, while the directions of the displacements tend towards NNW to NNE. The results of the horizontal velocities with respect to Europe indicate rates of SW directions, exhibiting higher magnitudes (25-26±2mm/yr) in the western and southern part of the Saronikos Gulf than in its central part (20±7 mm/yr). The horizontal velocities with respect to ITRF2000 showed consistent SE directions with higher rates in Aegina (12±7 mm/yr) than in Soussaki and Methana (9±3 mm/yr). A kinematic interpretation based on velocity and strain rates is finally attempted on the basis of the regional tectonics in the Saronikos Gulf.

The impact of natural and anthropogenic factors on groundwater quality in an active volcanic/geothermal system under semi-arid climatic conditions: The case study of Methana peninsula (Greece)

A comprehensive hydrogeochemical study of the cold and thermal groundwaters of the presently quiescent volcanic system at Methana was undertaken that involved collecting 71 natural water samples. Methana is a peninsula in Peloponnesus, Greece whose arid climate and hydrological situation is similar to that of the nearby small islands of the Aegean Sea. Similarly, the chemical and isotopic compositions of its water are dominated by the mixing of seawater with meteoric water both through direct intrusion and meteoric recharge. However, the simple mixing trends at Methana are modified by water–rock interaction processes, enhanced by the dissolution of endogenous CO2, which lead to strong enrichments in alkalinity, Ca, Ba, Fe and Mn. The thermal waters show very high salinity that is sometimes close to that of seawater [total dissolved solids (TDS)=8.5–40g/l]. Although the cold groundwaters sometimes also show elevated TDS values (up to 6.3g/l), their overall quality is acceptable due to the trace metal and nitrate contents mostly being below acceptable limits. While the saltiest groundwaters are not acceptable for human consumption, they are used for irrigation without exerting toxic effects on plants, which is probably due to the high permeability of the soils not supporting salt accumulation and salinity-resistant crops being cultivated.

The effect of changing regional tectonics on an arc volcano: Methana, Greece

The peninsula of Methana has the longest recorded volcanic history of any volcanic centre in the South Aegean Arc. Regional fault patterns in the arc changed during the Pliocene–Quaternary, with E–W-striking listric faulting increasingly important through the Quaternary, as recorded in well-dated sedimentary basins. This study investigates how the geochemistry and eruptive style of volcanic products is influenced by regional tectonics. The volcanic stratigraphy of Methana was refined using radiometric dating, lithogeochemistry and field observations that included recording deformational structures and enclave abundance. Small N–S-striking Pliocene domes and a central volcano of uncertain type (phase A) were eroded to produce a widespread volcaniclastic apron (phase B). In the early Quaternary, an explosive central volcano with flank eruptions of andesite developed (phase C). Dacite domes and small andesitic stratovolcanoes formed throughout the mid and late Quaternary (phases D–H).Basaltic andesite and andesite of phase C are the least evolved rocks, characterised by high TiO2. Rocks that have experienced important assimilation and fractional crystallisation in the crust have a high abundance of enclaves, Th, U and alkalies (Na, K). Ni and Cr are abundant in phase A andesites, due to crystallisation and entrainment of olivine and pyroxene, whereas phase H andesites have the highest relative abundance of Ba, Rb and Sr from crystallisation and entrainment of hornblende and biotite.Pliocene domes of phase A were emplaced on N–S-striking listric faults during regional E–W extension. Onset of NE–SW faulting, arguably crustal scale and strike slip in character, led to the eruption of the least evolved rocks of phase C. Thereafter, E–W-striking faults controlled the location of volcanism. Volcanism in phases F and G was particularly voluminous and was synchronous with the onset of steep normal faulting in the Gulf of Corinth, 150km west of Methana. These steep faults cross-cut older, lower angle, listric faults. It is times of changes in regional fault patterns, as in phases C, F and G, that have the greatest influence on the eruptive style and abundance of volcanic products.

CONTRIBUTION TO THE FLORA OF THE SOUTH AEGEAN VOLCANIC ARC: THE METHANA PENINSULA (SARONIC GULF, GREECE)

The Methana Peninsula (Saronic Gulf, Greece) constitutes the youngest and northwestern part of the South Aegean Volcanic Arc. The flora of the Methana Peninsula consists of 620 taxa, 101 of which are under some protection status, while 35 are Greek endemics and 380 are reported here for the first time. The study area has the highest percentage of endemism in the Saronic Gulf. Additionally, for some endemic taxa, their known distribution is expanded. These include Crocus sieberi subsp. atticus and Ophrys oestrifera subsp. leptomera, reported for the first time for the phytogeographical region of the Peloponnese; Campanula andrewsii subsp. hirsutula and Colchicum psaridis, reported for the first time for the North Peloponnese; and Trigonella rechingeri, reported for the first time from the Greek mainland. The floristic affinities between the study area and the large islands of the Saronic Gulf are examined by the application of Sørensen’s index to investigate the relationships between them.

Fluid geochemistry of the Methana Peninsula and Loutraki geothermal area, Greece

A geochemical survey on the thermal fluids released by the volcanic/geothermal system of Methana Peninsula and Loutraki area was undertaken. The Loutraki area is found in the southern part of Athens and the Methana volcano in the north-eastern part of Peloponnesus, which is characterized by high salinity waters. Chemical and isotopic contents were used for the investigation of the origin of thermal water, for the estimation of the mixing process between meteoric, magmatic and sea water involved in the deep geothermal systems and for the evaluation of the deep aquifer temperature. The chemical and isotopic data of the thermal Cl-rich water springs of Methana suggest that they are fed by thermal water mixed with local groundwater and seawater respectively. The parent hydrothermal liquid is a mixture of local groundwater (∼ 43%), seawater (∼ 34%) and arc-type magmatic water (∼ 23%). The chemical and isotopic data of the thermal HCO 3-rich water springs of Loutraki samples indicate a purely meteoric origin. Assessments from chemical and isotopic geothermometer applied on the thermal waters springs suggest the probable existence of a deep geothermal reservoir of middle enthalpy (150 °C) a Methana and low enthalpy (80 °C) in Loutraki area. However, the contribution of marine solutions to the geothermal fluids of Methana and Loutraki area is one of the main cases for the disturbance of the chemical and isotopic geothermometers rendering these calculated temperatures questionable.

Researching Ekina ta Khronia [Times Past] in a Rural Greek Community

This contribution addresses recent reconsiderations of the work of ethnographers working with regional archaeological surveys in Greece. It discusses the relationship of oral histories to historical documents as representations of the past, in the context of long-term ethnographic and archaeological research on the peninsula of Methana in the Peloponnese. It investigates the historicity of oral stories as genuine rememberings of life in the past, arguing that while recent studies have focused on how people remember, there is also value in exploring what they remember and the sorts of pasts represented. Recent publications emphasizing that the classical past and its monuments represent crucial cultural and symbolic capital resources for Greeks, present largely the views of the urbanized middle classes and intellectuals engaging with non-Greeks in presenting Greece's specialness in an increasingly culturally homogenized world. Methanites, excluded from such privileged positions and traditionally denigrated by Greeks closer to the centres of power, see their past(s) in a very different way. The pasts of this marginalized rural community incorporate many of the details of traditional agriculture commented upon unfavourably by critics of village ethnographies that were conducted in the context of regional survey.