Naxos Research Articles

Evaluating Source Complexity in Blended Milk Cheese: Integrated Strontium Isotope and Multi-Elemental Approach to PDO Graviera Naxos.

Graviera Naxos, a renowned cheese with Protected Designation of Origin status, is crafted from a blend of cow, goat, and sheep milk. This study focused on assessing the Sr isotopic and multi-elemental composition of both the processed cheese and its ingredients, as well as the environmental context of Naxos Island, including samples of milk, water, soil, and feed. The objective was to delineate the geochemical signature of Graviera Naxos cheese and to explore the utility of Sr isotopes as indicators of geographic origin. The 87Sr/86Sr values for Graviera Naxos samples ranged from 0.70891 to 0.70952, indicating a relatively narrow range. However, the Sr isotopic signature of milk, heavily influenced by the feed, which originates from geologically distinct areas, does not always accurately reflect the local breeding environment. Multi-elemental analysis revealed variations in milk composition based on type and season; yet, no notable differences were found between raw and pasteurized milk. A mixing model evaluating the contributions of milk, sea salt, and rennet to the cheese's Sr isotopic signature suggested a significant average contribution of 73.1% from sea salt. This study highlights the complexities of linking dairy products with their geographical origins and emphasizes the need for sophisticated geochemical authentication methods.

A microbiome survey of contrasting potato terroirs using 16S rRNA long-read sequencing

Abstract Aims As a consequence of the increasing impact of climate change on crop production and food security worldwide, the need to explore agricultural systems in a sustainable manner is also intensified. The improvement of long-read metagenomics approaches might give valuable information not only on soil microbial communities, but also on their potential effects on plant phenotypes. Soil properties, climate conditions, and agricultural techniques are the main factors shaping microbial communities found in the soil and on the surface of the potatoes, influencing plant health and performance. The objective of this study was to decipher the bacterial communities in contrasting potato terroirs using long-read sequencing of the 16S rRNA gene. Methods To do so, 18 soil samples were taken from different potato fields in the island of Naxos (Island Terroir) and Northern Greece (Continental Terroir). Differences in soil properties and climatic conditions were also regarded to explore the possible motif of microbial structure and diversity in each region. Results Our results highlighted that contrasting potato terroirs strongly affected microbial community composition and diversity. A richer microbial composition in the island terroir was evident. A wide range of soil bacteria were identified, including Vicinamibacter, Neobacillus, Povalibacter, Microvirga, Thermoanaerobaculum, Arenimonas, and Rubrobacter, with different distribution patterns that resulted in characteristic microbial footprints. Conclusions In combination with soil analysis, microbial mapping might be a valuable tool, not only for gaining a deeper knowledge of their impact on potato production, but also for developing biomarkers that would uniquely define and characterize each potato habitat.

Murals and Graffiti in Ruins: What Does the Art from the Aliko Hotel on Naxos Tell Us?

This manuscript investigates the cultural and educational dimensions of murals and graffiti in the ruins of the Aliko Hotel on Naxos Island. Moving beyond their aesthetic value, these artworks are examined as conduits for complex sociocultural and educational discourses. Employing semiotic analysis, particularly informed by Roland Barthes’ conceptual framework, the study offers a multi-layered interpretation of the significance of street art. A systematic approach guided the empirical data collection, entailing the careful selection and categorisation of 76 photographs, eventually honed down to 21 key images for detailed analysis. This set, comprising 6 murals and 15 graffiti pieces, was subjected to meticulous examination to discern both dominant themes and motifs (‘studium’) and the elements evoking personal connections (‘punktum’), thereby facilitating emotional and intellectual engagement. The methodology of the study is tailored to uncover the collective narratives encapsulated within these visual forms, as well as the individual responses they provoke. It probes how personal interpretations are influenced by the viewers’ beliefs and backgrounds, thereby expanding the semiotic analysis to encompass both shared and individual meanings. This balanced analytical approach deepens the understanding of visual expressions as dynamic interactions between the artwork and its audience. It underscores the transformative role of street art in urban environments and its contribution to public art discourse. The impending demolition of the Hotel Aliko ruins underscores the ephemeral nature of street art. The murals and graffiti, as transient custodians of cultural and social narratives, accentuate the fragile nature of this cultural heritage. This critical moment underscores the importance of documenting and preserving such art forms and the stories they encapsulate, highlighting their significant role in shaping community identity and cultural education.

Disruption of a high‐pressure unit during exhumation: Example of the Cycladic Blueschist unit (Thera, Ios and Naxos islands, Greece)

AbstractReconstructing the original geometry of a high‐pressure tectonic unit is challenging but important to understand the mechanisms of mountain building. While a single nappe is subducted and exhumed, nappe‐internal thrusts may disrupt it into several subunits. The Middle‐CBU nappe of the Cycladic Blueschist Unit (Hellenide subduction orogen, Greece) shows evidence of such disruption along a Trans‐Cycladic‐Thrust (TCT), however, the timing of this thrusting is unknown. Here, we report multi‐petrological and geochronological data from the Middle‐CBU nappe from the Thera and Ios islands (Greece). Using Zr‐in‐rutile thermometry coupled with quartz‐in‐garnet elastic barometry, average P–T and phase equilibrium thermodynamic modelling, we show that garnet growth in Ios occurred during prograde metamorphism at 6.7 ± 1.4 kbar to 13.0 ± 1.6 kbar and 326 ± 20°C to 506 ± 13°C (2σ uncertainty) followed by early exhumation to 10.1 ± 0.6 kbar and 484 ± 14°C and a greenschist facies overprint at 5.7 ± 1.2 kbar and 416 ± 14°C. For Thera, we constrain peak HP conditions of 7.6 ± 1.8 kbar and 331 ± 18°C, followed by exhumation and equilibration at ~2 kbar and ~275°C using average P–T and phase equilibrium thermodynamic modelling. For Ios, Uranium‐Pb garnet geochronology provides ages of 55.7 ± 5.0 Ma (2σ uncertainties) for prograde and 40.1 ± 1.4 Ma for peak HP metamorphism. Combining our new P–T–t data from Thera and Ios islands with existing data from Naxos island, we conclude that the studied nappe segments represent remnants of a former coherent nappe. The P–T–t data define an Eocene subduction rate of 2.1 ± 1.0 km/Ma, which is distinctly slower than the current subduction rate of 40–45 km/Ma. After subduction, the exhumation of the Middle‐CBU nappe occurred during the Oligocene at different rates for different localities. The Middle‐CBU nappe of Naxos was exhumed at a rate of ~6 km/Ma, contrasting with the exhumation rate of ~3 km/Ma calculated for Ios. This result suggests that the Middle‐CBU nappe of Naxos rocks was thrust on the Ios one during the Oligocene. Using P–T–t data and assuming realistic subduction angles during the Eocene and the Oligocene, we present a 2D structural reconstruction of the Middle‐CBU nappe of these islands. This reconstruction helps to understand the mechanisms of subduction of a continental margin and its disruption during exhumation.

Linking Thermal Indices, Productivity, Phenotypic Traits, and Stressors for Assessing the Health of Centennial Traditional Olive Trees

Centennial olive trees, integral components of traditional Mediterranean agroecosystems, hold immense value as repositories of biodiversity and cultural heritage due to their physiological attributes and life history, making them crucial for the conservation of High Nature Value ancient olive orchards. However, they are increasingly confronted with physiological challenges exacerbated by various biotic and abiotic stressors jeopardizing their health and productivity, underscoring the urgency for ongoing monitoring and conservation measures to secure their long-term existence. To monitor these challenges, in recent years, the adoption of non-invasive techniques like infrared thermography (IRT) has become prevalent. In this study, we aimed to comprehensively assess the health state of traditional centennial olive trees, with a particular focus on their productivity. To achieve this, we monitored 44 centennial olive trees from a traditional olive grove on the island of Naxos, Greece, a representative location for Mediterranean olive groves, during the period from 2017 to 2020. We established connections between a set of trunk and canopy thermal and humidity indices, phenotypic traits, and the two most prevalent stressors affecting olive trees not only within the context of the island but also more broadly in similar Mediterranean environments worldwide: the olive leaf spot disease (OLS) and crop water stress, assessed through the crop water stress index (CWSI). To evaluate their interrelationships, we initially assessed intraspecific thermal and humidity pattern variations, and we developed linear and logistic regression models to gain insights into the factors influencing olive tree productivity, water stress, and the OLS presence. Results indicated that combining thermal and humidity indices can substantially explain olive tree productivity, water stress, and OLS, providing a valuable tool for assessing and monitoring the health and overall state of centennial olive trees, while offering a comprehensive approach to understanding the complex interactions shaping traditional olive grove dynamics. By identifying key indicators such as tree thermal patterns and water stress levels, olive growers and conservationists can make informed decisions to enhance the vitality and longevity of these culturally and ecologically significant trees.

Seasonal Variation in the Thermoregulation Pattern of an Insular Agamid Lizard.

Ectotherms, including lizards, rely on behavioral thermoregulation to maintain their body temperature within an optimal range. The benign climate of islands is expected to favor the thermoregulation efficiency of reptiles throughout their activity period. In this study, we investigated the seasonal variation in thermoregulation in an insular population of the roughtail rock agama (Laudakia stellio) on Naxos Island, Greece. We measured body, operative, and preferred temperatures across three seasons (spring, summer, and autumn), and we evaluated the effectiveness of thermoregulation, using the Hertz index (E). Our results revealed that the effectiveness of thermoregulation was significantly influenced by seasonality. E was quite high in summer (0.97) and spring (0.92), and lowest in autumn (0.81). Accordingly, the quality of the thermal environment was significantly low during autumn, and maximum during summer. However, despite the environmental temperature fluctuations, lizards exhibited remarkable stability in body temperatures. They also adjusted their preferred temperatures seasonally and doubled the thermal niche breadth they occupied during summer, thus enhancing thermoregulation efficiency. Whether or not these adjustments are plastic or fixed local adaptations remains to be explored in further research across multiple years and seasons, including additional insular populations.

Some like it hotter: Differential thermal preferences among lizard color morphs

Temperature rules the lives of ectotherms. To perform basic biological functions, ectotherms must make behavioral adjustments to keep their body temperatures near a preferred temperature (Tpref). Many color polymorphic lizards are active thermoregulators and exhibit morph differences in traits related to thermoregulation, such as color, body size, and microhabitat use. The Aegean wall lizard, Podarcis erhardii, is a heliothermic lizard with orange, white, and yellow color morphs that differ in size, behavior, and microhabitat use. Here, we tested whether P. erhardii color morphs from the same population from Naxos island, Greece, differ in Tpref. We hypothesized that orange morphs would prefer lower temperatures than white and yellow morphs because orange morphs are often found on cooler substrates and in microhabitats with more vegetation cover. We obtained Tpref for 95 individuals using laboratory thermal gradient experiments of wild-caught lizards and found that orange morphs do, indeed, prefer cooler temperatures. Average orange morph Tpref was 2.85 °C lower than average white and yellow morph Tpref. Our results add support to the idea that P. erhardii color morphs have multivariate alternative phenotypes and present the possibility that thermally heterogeneous environments play a role in the maintenance of color polymorphism in this species.

Co-creating the future of heritage in-the-making: empirical evidence from community deliberation at Naxos Island, Greece

ABSTRACT Although participatory heritage has become a ‘buzzword’ of cultural policy, it remains a challenging field for related practice. Set at Naxos Island, Greece, the research presented in this article forms part of a bigger project exploring the values and meaning-making processes in rural landscape, currently at risk of neglect and over-tourism. Here, we test the usability of the Nominal Group Technique (NGT) as a tool for allowing citizens to deliberate and devise community desirable actions for the protection and invigoration of rural monuments. As we discuss, apart from enriching our participatory ‘toolbox’, NGT can offer some insight into bottom-up processes of valuing the past and producing its historicity. Furthermore, our workshop participants initiate a dialogue, wherein they advocate for ‘hands-on’ solutions, which although fit largely with standard heritage management practice, are rearranged in alternative hierarchies; an atypical organisation of actions that reflects community aspirations to preserve a yet unsettled type of heritage that is currently ‘in-the-making’. This supports our main theoretical argument that participatory approaches shall not be treated instrumentally but positioned as part of a wider prefigurative politics project to resist dominant conservative and positivist processes of heritagisation.

Орнамент и содержание: сюжет и смысл «Поцелуя» Густава Климта

The article examines the most famous work of the Austrian artist Gustav Klimt — The Kiss. It analyses the insufficiency of the existing, most common both in academic and popular culture interpretations of this painting as an abstract image of lovers, a kind of “yin and yang” or the struggle and unity of the male and female opposites. For the first time in Russian research, evidence of a specific plot of The Kiss is provided. Based on the artist’s career, then-contemporary literature, the context of the creation of the painting, and its figurative and symbolic content, the plot of the painting is identified as the meeting of Ariadne and Dionysus on the island of Naxos. This, in turn, reveals the semantic content of The Kiss not as an abstract “icon of love” or the image of gender relations, as universally perceived, but broadly — as a symbol of the fullness of life in general, correlating, on the one hand, with the programs of R. Wagner and F. Nietzsche, and on the other hand, with the aspiration of Art Nouveau to the ultimate modernity. As a whole, The Kiss reconciles the conditional avant-garde of modernity with strict academicism, being a capacious and emotionally charged variation on a classic theme, performed in the current artistic language. At the same time, in the context of the artist’s own path, The Kiss, due to the reversal of the plot about Theseus and the Minotaur, which was put on the poster of the first Secession exhibition, becomes a sign of overcoming the crisis of 1905 associated with the failure of the artist’s Faculty paintings and the break with the Secession.

GIS-Based Virtual Field Trip as a Tool for Remote Education

Geoscience courses, such as geology and geomorphology, require not only classroom lessons and laboratory exercises, but field trips as well. However, the COVID-19 restrictions did not allow the execution of most planned field trips, and an alternative needed to be developed. The use of virtual field trips is one such alternative. Through this research, we evaluate the usefulness of virtual field trips as tools for preparatory activities before an actual field trip takes place in the same area, and their contribution in providing a better understanding of geomorphological processes and landscape evolution. We performed a virtual navigation on the island of Naxos, Cyclades (Aegean Sea, Greece) for a series of virtual field trips, which took place during webinars in the framework of Erasmus+ CIVIS. The virtual field trip was also presented to the third-year students of the Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, in the framework of the obligatory course of Geomorphology. Upon completion, all participating students were asked to fill in a questionnaire in order to evaluate the contribution of virtual field trips to their education regarding geomorphology and state their opinion as to whether they can supplement and/or substitute actual field trips. According to the results, virtual field trips can aid, but not substitute, the actual field trip. Most students mentioned that they would attend another virtual field trip in the future, both as an alternative to classroom lessons and as a means of preparation for an actual field trip, but not in order replace the actual one. Virtual field trips can significantly support the realization of actual ones, by introducing the necessary tectonic, geological and geomorphological background of a particular study area and offering more time for practical activities or field methodologies during the actual field trip.

Morph-specific differences in escape behavior in a color polymorphic lizard

Variation in color morph behavior is an important factor in the maintenance of color polymorphism. Alternative anti-predator behaviors are often associated with morphological traits such as coloration, possibly because predator-mediated viability selection favors certain combinations of anti-predator behavior and color. The Aegean wall lizard, Podarcis erhardii, is color polymorphic and populations can have up to three monochromatic morphs: orange, yellow, and white. We investigated whether escape behaviors differ among coexisting color morphs, and if morph behaviors are repeatable across different populations with the same predator species. Specifically, we assessed color morph flight initiation distance (FID), distance to the nearest refuge (DNR), and distance to chosen refuge (DR) in two populations of Aegean wall lizards from Naxos island. We also analyzed the type of refugia color morphs selected and their re-emergence behavior following a standardized approach. We found that orange morphs have different escape behaviors from white and yellow morphs, and these differences are consistent in both populations we sampled. Orange morphs have shorter FIDs, DNRs, and DRs; select different refuge types; and re-emerge less often after being approached compared to white and yellow morphs. Observed differences in color morph escape behaviors support the idea that morphs have evolved alternative behavioral strategies that may play a role in population-level morph maintenance and loss.Significance statementColor polymorphic species often differ in behaviors related to reproduction, but differences in other behaviors are relatively underexplored. In this study, we use an experimental approach in two natural populations of color populations of color polymorphic lizards to determine that color morphs have diverged in their escape behaviors. By conducting our experiments in two different populations with similar predator regimes, we show for the first time that behavioral differences among intra-specific color morphs are repeatable across populations, suggesting that alternative behavioral strategies have evolved in this species. Using this experimental approach, we demonstrate that the brightest orange morph stays closer to refuge than other morphs, uses a different refuge type (vegetation) more often than other morphs (wall crevices), and take much longer to emerge from refuge after a simulated predation event than other morphs. Thus, selective pressures from visual predators may differ between morphs and play a role in the evolution and maintenance of color polymorphisms in these types of systems. Our study species, Podarcis erhardii, belongs to a highly color polymorphic genus (19/23 spp. are color polymorphic) that contains the same three color morphs, thus we believe our results may be relevant to more than just P. erhardii.

Historical Evolution of the Narrative Theme of Ariadne’s Abandonment in European Painting

The story of abandonment of Ariadne, a Cretan princess, especially connected with two other mythological characters, Theseus and Dionysus, has drawn the attention of painters and sculptors throughout history. Ariadne, Mino’s daughter, fell in love with Theseus, but Theseus abandoned her, and she was finally found by Dionysus in Naxos Island. Quite a few paintings have emerged in various styles from this theme, i.e. Ariadne’s abandonment by Theseus, Ariadne’s solitariness, and her meeting with Dionysus. This narrative has been portrayed by painters from different perspectives, and the works of paintings available on this theme in antiquity, the Renaissance and Baroque, and the eighteenth and nineteenth centuries AD have undergone fundamental evolution and change in terms of form, structure, and narrative style. This paper is aimed at providing a descriptive and analytical account of European works of paintings about Ariadne’s abandonment and identifying and understanding the structural and narrative changes of European works of paintings about this abandonment throughout history (from ancient Greece to the twentieth century). Importantly, each artist has seen and portrayed this narrative according to his/her style and lived experience from a specific period. The works analyzed in this study belong to historical periods and artistic styles of Renaissance, Baroque, and the eighteenth, nineteenth and twentieth centuries. The theme of abandoned Ariadne narrative makes its contextual and iconographic analysis possible with regard to the historical changes and the artists’ desire in each era to select and interpret this legend. In the historical world of myths, Ariadne was left alone in her way to Athens in Naxos Island, but the depiction of this narrative in painting at different times and in different works has opened a new symbolic aspect of it and given it a new interpretation. There are more than five hundred images of this theme available from classical Greece to modern art. Three well-known and recurring scenes of this story can be examined. The first is the scene where Ariadne falls asleep and is abandoned by Theseus by Athena’s guidance and decree. The second is the scene where Dionysus finds Ariadne Naxos Island in great sadness and appeases her. It is in this scene that they hold a feast and celebrate their wedding. The third scene portrays Ariadne left alone after waking up, while gazing upon Theseus’s ship moving away at sea. Examining these works indicates that the frequency, repetition and attention to the importance of each of these scenes change in different periods. Ancient Greek paintings often portray the first scene. During the Renaissance and Baroque, it is the second scene that is often portrayed, while the third scene draws the painter’s attention from the late eighteenth century, and particularly the nineteenth century. Using library resources and qualitative and descriptive-analytical method, this study aimed to analyze the paintings pertaining to Ariadne’s abandonment in the historical course from antiquity to the beginning of the twentieth century and to present a reading of them. The results suggest the evolution of this narrative theme throughout the history of painting.

Evidence of Coastal Changes in the West Coast of Naxos Island, Cyclades, Greece

Coastal lagoons and dunes are of great ecological importance, not only for providing habitats for rare flora and fauna, but also for protecting coastal areas from rising sea levels and storms, etc. Even though these features are unique for sustainable development and are extremely important to the natural environment and economy, they are one of the most vulnerable and threatened ecosystems due to their small size. The western coasts of Naxos (central Aegean Sea) represent an example of such phenomena, with various wetlands bordered by low-lying sand dunes. The aim of our study is to assess the vulnerability and pressures of the western coasts of Naxos Isl. by taking into consideration both natural and anthropogenic factors. We used a variety of approaches for the environmental and geomorphological study of the coastal zone to achieve this goal, including: (a) study of aerial photography from 1960 until today, (b) systematic seasonal aerial monitoring by drone, since 2015, (c) use of DGPS for the mapping of the coastal zone and for obtaining detailed topographic sections, and (d) dune mapping. Our findings reveal the vulnerability of the western coasts of Naxos due to sea level rise, tectonic subsidence, and a variety of anthropogenic pressures, such as uncontrolled parking, vegetation uprooting, sand extractions, and heavy touristic traffic. Therefore, the protection of the sand dunes, their restoration where they have been eroded, the definition of a zone of control, and restriction of human activities must be a key priority.

Development of a Tourism Carrying Capacity Index (TCCI) for sustainable management of coastal areas in Mediterranean islands – Case study Naxos, Greece

Mediterranean Region is nowadays deemed to be a ‘hot spot’ in various respects, including climate change, environment and biodiversity, urbanization and mass tourism, to name a few. This holds true in the case of Mediterranean islands in particular, i.e. places that are globally acknowledged as appealing mass tourism destinations; while at the same time are confronted with severe threats, more intensely presented in islands' overcrowded coastal zones. In fact, intensified Climate Change incidents and related threats, coupled with the escalating – beyond carrying capacity limits – coastal urbanization and mass tourism development, represent currently key policy concerns in Mediterranean islands. These also raise, in a strict and urgent way, the necessity to sketch more sustainable and resilient future pathways, especially in their coastal counterparts. Towards this end, this paper attempts to outline the Tourism Carrying Capacity (TCC) approach as a means for assessing and steadily monitoring tourism development trajectory in coastal areas of the Mediterranean islands. More particularly, by using the Pressure-State-Response (PSR) framework as a foundation, it develops and implements a Tourism Carrying Capacity Index (TCCI) that focuses primarily on environmental and manmade dimensions; incorporates mostly tourism-specific variables; and is capable of providing guidance towards planning more sustainable tourism future pathways in coastal areas. TCCI application, demonstrated for the Island of Naxos, Greece, unveils its power as an easy to handle decision-making tool for serving coastal tourism sustainability assessment and monitoring; but also its replicability potential and barriers to implementation.

THE EMERY OF NAXOS: A MULTIDISCIPLINARY STUDY OF THE EFFECTS OF MINING AT A LOCAL AND NATIONAL CONTEXT

The aim of this paper is to present the fluctuations of emery mining, from Ancient times to the present day, in the island of Naxos, Greece. Many Aegean islands were characterised in Antiquity by intense mining and quarrying activities, and many such activities continue even today. Emery is along with marble, the distinctive industrial mineral of the Cyclades, even now that production has largely ceased. This is an analysis of how emery came to be in Naxos, and how its existence and its exploitation by the local population shaped the society, the economy and the folklore of the local mining communities. In addition, since such mineral wealth is a matter not only of local but of national importance as well, the significance of emery export in Greek national economy will be discussed, along with how the changing international industrial and financial reality affected mining and thus the life of the locals. While presently profitable emery mining is rather unlikely, it is still possible for the insular community and economy to benefit from the establishment of a thematic geopark, based on the existing mines and the old mining infrastructure.

Sourcing macrolithics: Mineralogical, geochemical and provenance investigation of stone artefacts from Neolithic Avgi, north‐west Greece

AbstractThe provenance of the lithic raw materials employed in the production of macrolithic artefacts at Neolithic Avgi (Middle–Late Neolithic, c.5700–4500 cal bce) in Kastoria, north‐western Greece, is studied. Mineralogical, petrographic and geochemical analysis was conducted on selected samples of the archaeological material, supported by geological fieldwork and outcrop sampling. The majority of the macrolithic stone artefacts was manufactured by local raw materials, originating from either the neighbouring ophiolites at Maniakoi or the alluvial sediments of the Aliakmon River and its tributaries. A minor amount of artefacts was produced from ‘exotic’ rocks, such as marble, malachite and amber. The study of two marble artefacts indicates that the raw material is from the island of Naxos in Aegean, although the neighbouring island of Paros is not excluded, suggesting the participation of the Neolithic community of Avgi in social and/or exchange networks.

Spectroscopy and Microscopy of Corundum from Primary Deposits Found in Greece

Corundum primary deposits in Greece occur in four locations: Paranesti in Drama and Gorgona in Xanthi, both belonging to the wider Rhodope Massif, as well as, Ikaria island and Kinidaros in Naxos island, both belonging to Attic-Cycladic Massif. Eight samples were examined with spectroscopic methods (FTIR, UV-Vis, EDXRF) in order to better characterize these four primary deposits: two pink sapphires from Paranesti, a pink and a blue sapphire from Gorgona, two blue sapphires from Ikaria and three blue sapphires from Kinidaros. Under the microscope, all samples present characteristics linked to post-crystallization deformation, decreasing their gem quality. The FTIR absorption spectra of all samples present in different relative intensities, bands of boehmite, diaspore, goethite, mica and/or chlorite inclusions and CO2 in fluid inclusions. Boehmite and diaspore inclusions are most likely epigenetic. In the UV-Vis spectra, the pink color of the samples is linked with Cr3+ absorptions and the blue color with absorptions due to Fe2+-Ti4+ intervalence charge transfer. EDXRF analyses in the studied samples show relatively high titanium and iron concentrations that are related with mineral inclusions. Gallium is slightly variable in samples from different regions; also, different colored samples from Gorgona present diverse gallium content.

Factors controlling granitic cavernous weathering forms in a Mediterranean island: the case of Naxos island, Aegean Sea, Greece

Factors controlling granitic cavernous weathering forms in a Mediterranean island: the case of Naxos island, Aegean Sea, Greece

Quo vadis Zeus : is there a Zas shear zone on Naxos Island, Aegean Sea, Greece? A review of metamorphic history and new kinematic data

Detecting zones of considerable early-orogenic displacement in rather monotonous rock sequences which have undergone a late and pervasive tectonometamorphic overprint is challenging. It has been proposed that the alleged Zas shear zone in the passive margin sequence of the Cycladic Blueschist Unit on Naxos Island, Greece, separates amphibolite facies, non-high-pressure rocks (Koronos Unit) below the shear zone from Eocene high-pressure rocks (Zas Unit) above the shear zone. We review existing pressure–temperature data from the Koronos Unit and present new kinematic data from the anticipated Zas shear zone to evaluate the tectonic significance of this recently proposed structure. This has implications for unravelling the subduction history of rock units from tectonometamorphic datasets. Common to all pressure–temperature data from the Koronos Unit is a well-defined amphibolite facies equilibration stage at 8–11 kbar and 600–700°C, followed by initial near-isothermal to slightly prograde decompression and subsequent pronounced cooling. This segment of the high-temperature pressure–temperature loop is associated with top-to-the-NNE extensional deformation in the footwall of the Miocene Naxos–Paros detachment. Little is known about the metamorphism preceding the amphibolite facies overprint in the Koronos Unit. Our review shows that it is likely that the rocks experienced a prior high-pressure metamorphic overprint that is typical of rocks of the Cycladic Blueschist Unit. Our kinematic data show that the Zas shear zone contains variably deformed rocks with dominantly top-to-the-NNE shear sense indicators that developed under greenschist facies metamorphism in the footwall of the Naxos–Paros detachment. No significant offset can be detected across the Zas shear zone and the geology on either side of it does not support large-scale movement across the shear zone. We discuss a model in which the Zas shear zone is considered to be a minor zone of deformed schist near the biotite-in isograd of Miocene high-temperature metamorphism. We conclude that there is no need to tectonically subdivide the passive margin sequence of the Cycladic Blueschist Unit on Naxos.

Differences in decompression of a high-pressure unit: A case study from the Cycladic Blueschist Unit on Naxos Island, Greece

Determining the tectonic evolution and thermal structure of a tectonic unit that experiences a subduction-related pressure temperature (P-T) loop is challenging. Within a single unit, P-T conditions can vary from top to bottom which can only be revealed by detailed petrological work. We present micropetrological data from the middle section of the Cycladic Blueschist Unit (CBU) in Naxos, Greece, which indicates a different P-T loop than that for the top of the sequence. Using Zr-in-rutile and Ti-in-biotite thermometry coupled with quartz-in-garnet elastic barometry and phase equilibrium thermodynamic modeling, we identify a prograde path from 15.4 ± 0.8 kbar to 19.9 ± 0.6 kbar and from 496 ± 16 °C to 572 ± 7 °C (2σ uncertainty), equilibration during decompression at 8.3 ± 1.5 kbar and 519 ± 12 °C followed by near-isobaric heating to 9.2 ± 0.8 kbar and 550 ± 10 °C (or even 584 ± 19 °C), and a final greenschist-facies equilibration stage at 3.8 ± 0.3 kbar and 520 ± 4 °C. We compare these P-T estimates with published data from the top and also the bottom of the CBU section and find that the bottom half of the CBU on Naxos records higher peak high-pressure (HP) of about 4 kbar than the top of the unit, defining the thickness of the CBU section on Naxos to about 15 km in the Eocene. We determine that crustal thickening of up to ~15% occurs in the upper half of the CBU section during exhumation of the HP rocks in an extrusion wedge in a convergence setting. At about 30 Ma, the bottom half of the CBU was finally thrust onto the radiogenic Cycladic basement. Subsequently this bottom half of the CBU section underwent isobaric heating of 9–96 °C between c. 32–28 and 23–21 Ma. Isobaric heating occurred below the upper CBU section that thickened during decompression and commenced when HP metamorphism in the Cyclades ended. This suggests that thermal relaxation following tectonic accretion in the Cyclades controlled heating of the evolving Cycladic orogen during a tectonically quiescent period before lithospheric extension commenced by 23–20.5 Ma.