Central Crete Research Articles

Preliminary results based on geochemical sedimentary constraints on the hydrocarbon potential and depositional environment of a Messinian sub-salt mixed siliciclastic-carbonate succession onshore Crete (Plouti section, eastern Mediterranean)

This study details new geochemical analysis from an outcrop in Crete to improve understanding of the hydrocarbon potential of the southern margin of the Hellenic Arc along the continental convergent zone of the central Mediterranean Ridge. Seventeen samples were collected from the Late Miocene sub-salt sedimentary succession of Plouti section in central Crete and were studied in terms of their organic geochemical features using Rock-Eval VI pyrolysis. Results of this investigation revealed intervals with sufficient organic material of good enough quality and quantity to be considered as potential source rocks. The obtained data generally present poor to fair and/or good in some cases hydrocarbon generation potential. The TOC values range from 0.03 to 1.99%, with an average fair (2.1 mg HC/g rock) hydrocarbon potential. A Type III kerogen was identified, indicating a terrestrial origin organic matter. T max and Production Index values suggest that the most promising parts of the section (organic-rich sediments) are immature with respect to oil generation and have not experienced high temperature during burial. Overall, the present study offers the opportunity to advance our understanding on the hydrocarbon potential onshore Crete and further investigate hydrocarbon prospectivity in the adjoining area, and particularly, the Greek part of the Mediterranean Ridge, a region with crucial economic and strategic importance.

New constraints from U–Pb dating of detrital zircons on the palaeogeographic origin of metasediments in the Talea Ori, central Crete

AbstractHigh-pressure low-temperature metamorphic sediments of the Phyllite–Quartzite unitsensu strictoand the Talea Ori group are investigated in the field, microstructurally and by U–Pb dating of detrital zircons to shed light on their palaeogeographic origin. Zircon age spectra with ages >450 Ma of the Phyllite–Quartzite unitsensu strictoindicate a palaeogeographic origin at the northern margin of East Gondwana. In contrast, the lower stratigraphic, siliciclastic formations of the Talea Ori group show a high number of well-rounded Cambrian to Early Carboniferous aged zircons and a Neoproterozoic zircon age spectrum with East Gondwana affinity. Based on the comparison of zircon age data, a possible distal sediment source is the Sakarya Zone at the southern active margin of Eurasia. To reconcile the zircon data with the geological observations we propose different alternative models, or a combination of these, including sediment transport from the Sakarya Zone and/or a westerly source towards the northern margin of Gondwana as well as terrane-displacement of the Sakarya Zone. Also, a palaeogeographic origin of the Talea Ori group at the southern active margin of Eurasia cannot be excluded. This alternative, however, would not be consistent with the usually assumed association of the Talea Ori group with the Plattenkalk unit characterized by a palaeogeographic origin at the northern margin of Gondwana.

The Thessalian and Cretan Name for ‘Bottle Gourd’

The Polish version of the article was published in “Roczniki Humanistyczne,” vol. 63 (2015), issue 3.
 In his work Deipnosophistae (IX 369b), Athenaeus discusses four Greek names for turnip, (Brassica campestris L., syn. Brassica rapa L.): βουνιάς, γογγυλίς, Laconian γάστρα and Boeotian ζεκελτίς. The three first names are clearly motivated by the Greek vocabulary. The fourth term remains obscure in terms of its etymology and word-formation. According to Athenaeus (IX 369b), two Greek writers, Amerias and Timachidas, refer to a dialectal (evidently Thessalian) term ζακελτίς f. ‘bottle gourd, calabash, Lagenaria siceraria (Molina) Standl.’. In his lexicon, Hesychius of Alexandria registers two related glosses: ζακελτίδες · κολοκύνται. ἢ γογγυλίδες (HAL ζ-24); ζακαυθίδες · κολοκύνται (HAL ζ-30). The former refers to the Thessalian lexis. The latter one (wrongly printed as ζακυνθίδες · κολοκύνται in M. Schmidt’s and K. Latte’s editions) demonstrates a shift of the liquid consonant λ [l] to [ṷ], which is a typical Cretan phenomenon, attested also in the Hesychian lexicon, see e.g. [1] αὐκάν · ἀλκήν. Κρῆτες (HAL α-8277); [2] αὐκυόνα · ἀλκυόνα. Κρῆτες (HAL α-8280); [3] αὕμα · ἅλμη, ὑπὸ Κρητῶν (HAL α-8324); [4] αὖσος · ἄλσος. Κρῆτες (HAL α-8347); [5] θεύγεσθαι · θέλγεσθαι. Κρῆτες (HAL θ-427). The same phonological process of the velarization of *λ [l] is also registered in epigraphic texts found in three towns of Central Crete (Gortyna, Leben, Phaistos). Thus, it seems that the Hesychian term ζακαυθίδες ‘bottle gourds’ (derived from the earlier *ζακαλθίδες) must be seen as a dialectal form typical of Central Cretan.

Temporally Constant Quaternary Uplift Rates and Their Relationship With Extensional Upper‐Plate Faults in South Crete (Greece), Constrained With36Cl Cosmogenic Exposure Dating

AbstractPreserved sets of marine terraces and palaeoshorelines above subduction zones provide an opportunity to explore the long‐term deformation that occurs as a result of upper‐plate extension. We investigate uplifted palaeoshorelines along the South Central Crete Fault and over its western tip, located above the Hellenic Subduction Zone, in order to derive uplift rates and examine the role that known extensional faults contribute to observed coastal uplift. We have mapped palaeoshorelines and successfully dated four Late‐Quaternary wave‐cut platforms using in situ36Cl exposure dating. These absolute ages are used to guide a correlation of palaeoshorelines with Quaternary sea level highstands from 76.5 to ~900 ka; the results of which suggest that uplift rates vary along fault strikes but have been constant for up to 600 ka in places. Correlation of palaeoshorelines across the South Central Crete Fault results in a throw‐rate of 0.41 mm/year and, assuming repetition of 1.1‐m slip events, a fault‐specific earthquake recurrence interval of approximately 2,700 years. Elastic‐half‐space modeling implies that coastal uplift is related to offshore upper‐plate extensional faults. These faults may be responsible for perturbing the uplift rate signals in the south central Crete area. Our findings suggest that where uplifted marine terraces are used to make inferences about the mechanisms responsible for uplift throughout the Hellenic Subduction Zone, and other subduction zones worldwide, the impact of upper‐plate extensional faults over multiple seismic cycles should also be considered.

Feeding Ecology and Prey Selection by Wintering Long-Eared Owls Asio otus in Mediterranean Agrosystems

The diet composition and dietary patterns of the Long-eared Owl Asiootus were studied in Mediterranean agrosystems in central Crete (Greece) over the winters of 2009–2015. Overall, 2,819 prey items were recovered from 1,207 pellets, belonging to six taxa of mammals, 22 taxa of birds and four taxa of insects. Small mammals were the most common prey species, accounting for 75.8% by frequency and 79.7% by biomass, followed by birds (23.2% and 20.1%); the latter being rather an island component compared to continental regions. The House Mouse Mus musculus was the most important prey species in the owl's diet (56.3%) ahead of the Wood Mouse apodemus sylvaticus (9.51%) and the Black Rat Rattus rattus (7.9%). The species proved to be a significant rodent predator in olive groves and vineyards during winter months, selecting Wood Mouse and young Black Rat more than expected. Long-eared Owl feeding ecology studies could lead to improved land management and agricultural practices in the rural landscapes of the Mediterranean.

A ductile extensional shear zone at the contact area between HP-LT metamorphic units in the Talea Ori, central Crete, Greece: deformation during early stages of exhumation from peak metamorphic conditions

We report on an extensional ductile shear zone in central Crete at the contact area between the high-pressure low-temperature (HP-LT) metamorphic Phyllite-Quartzite unit sensu stricto (PQ s.str.) and the Talea Ori group (Plattenkalk unit). Mapping and microscopic analysis along the 20 km long contact reveal extensional shear bands, shear band cleavages (C′-type) and associated quartz veins in both units, occurring over a width of up to a kilometer. The shear offset along the shear bands is systematically perpendicular to the contact with the hanging block (PQ s.str.) being downfaulted. Abundant discordant quartz veins are associated to shear band boundaries, asymmetric boudinage and foliation boudinage, forming m-wide vein networks. These mesoscopic deformation structures together with related microstructures such as strain shadows, growth rims of albite porphyroblasts and stylolites indicate dissolution–precipitation creep as main deformation mechanism accompanied by vein formation. Temperatures during deformation are indicated to be close to peak metamorphic temperatures (≥ 300–350 °C) by the growth rims of albite porphyroblasts and micas present in the shear band cleavages, which are consistent with quartz vein microstructures showing subgrains and sutured high angle grain boundaries. Peak metamorphic temperatures inferred by the degree of graphitization of carbonaceous material are similar in the hanging wall and the footwall of the shear zone, which is consistent with fast and nearly adiabatic exhumation. Our study demonstrates the importance of ductile shear zones with high strain rate dissolution–precipitation creep and vein formation in HP-LT metamorphic rocks for the early exhumation history.

New data on the Dogger - Cenomanian stratigraphy of Tripolitza series in Central Crete

Tripolitza series represents the eastern part of the Gavrovo - Tripolitza platform. It outcrops in central and southeastern Peloponnesus, Crete and the Aegean islands. Its stratigraphie column starts with a volcano-sedimentary, clastic sequences (the Tyros beds), of Late Paleozoic to Late Triassic age, followed by a carbonate series of Late Triassic to Late Eocene age and a tertiary flysch. On account of intense dolomitisation as well as of rarity of fossils, the stratigraphy of Tripolitza series is not so well known as the Gavrovo series. Recent investigation attempts to complete the puzzle of Tripolitza's stratigraphie column and to reconstruct the paleogeographic sedimentation conditions. In this paper, we study some stratigraphie sections, which are taken in different places in northern – central Crete(Fig.l). New data about the stratigraphy and the sedimentation conditions of the Tripolitza series during Late Dogger to Cenomanian, complete older ones and provide information about the paleogeographic evolution of the platform. Late Dogger is determinated by Pfenderina salernitana. It is overlain by a carbonate series containing Cladocoropsis mirabilis and Macroporella sellii, dating Early Malm. Early Malm (Oxfordian - Early Kimmeridgian) is characterized by the presence of Cladocoropsis mirabilis, Kurnubia palastiniensis, Neokilianina rahonensis, Parurgonina caelinensis. Late Malm (Late Kimmeridgian - Portlandian) is characterized by Clypeina jurassica and Kurnubia palastiniensis. Early Cretaceous (Valanginian - Barremian) is determinated by Salpingoporella katzeri and Orbitolinopsis capuensis. Early Aptian is determinated by Palorbitolina lenticularis, Salpingoporella dinarica, Debarina hahounerensis, Pseudocyclammina hedbergi. Late(?) Aptian comprises Sabaudia minuta, Cuneolina hensoni, Cuneolina laurentii, Glomospira urgoniana. Albian is characterized by the disappearence of Cuneolina hensoni and Cuneolina laurentii, while Praechrysalidina infracretacea and Cretacicladus minervini are present. Late Albian is determined by the presence of "Coskinolina" bronnimanni. Early Cenomanian is not determinated by characteristic microfossils. Upper Cenomanian is overlain in comformity with upper Albian - lower Cenomanian carbonates. It is characterized by Chrysalidina gradata, Pseudorhapydionina dubia, Pseudorhapydionina laurinensis, Nummoloculina heimi, Broeckina balcanica, Nezzazata gyra, Biconcava bentori, Trochospira anvimelechi. Sedimentation took place in a peritidal environment. We observe alternations of subtidal and intratidal to supratidal conditions of sedimentation. Comparison between the carbonate microfacies of different sections representing synchronous deposits on different places of the platform, show lateral differentiation of depositional environments, from subtidal to supratidal, even supported short and local emersive episodes, (compare lower Aptian deposits of Profitis Ilias and Pinakianou sections, upper Albian deposits of Kythia and Karouzanos sections in present paper, as well as upper Cenomanian deposits of Karouzanos section in this paper, Louloudaki section (ZAMBETAKIS-LEKKAS et al. 1995 and Vitina section ZAMBETAKIS et al. 1988, Varassova section BERNIER & FLEURY 1980, Gavrovo mountain I.G.R.S. & I.F.P. 1966)(Fig.2). Similar sedimentation characterize the perimediterranean platforms during this period (SARTONI & CRESCENTI 1962, DE CASTRO 1962, FARINACCI & RADOICIC 1964, GUSIC 1969, GUSIC, NIKLER & SOKAC 1971, VELIC 1977, CHIOCCHINI et. al.1979, LUPERTO SINNI & MASSE 1993).

Otoliths from the lower Pliocene of the section Prassies (Rethymnon, ΝW - Crete). Systematics - Paleoecology

This paper concerns the study of Otoliths coming from the sediments of the L. Pliocene of the region Kefales of the community Prassies at the northern part of Rethymnon (NW- Central Crete), 10 km from it and the places of sampling are along the road Rethymnon- Amari to the village Prassies. These sediments are yellowish with a visible inclination and sedimentary structures overlying in unconformity on the alpic substrate. The sediments of the studied area consist of Miocene, Plio-Pleistocene and Holocene formations. Holocene appears with littoral deposits (sand, gravels and alluvian deposits) 20 m. The Plio - Pleistocene formations –marine deposits- consisting of brawn marls without fossils (upper members), of marls with macrofossils (intermediate members) and white marls and clays with Algae and Pectinidae, Ostreidae, some Gastropods and Echinoids (lower members). Total height 150 m. The Miocene has a total thickness of 200 m. The studied Otoliths belong to the orders: 1. Iniomi (Myctophiformes): Diaphus splendidus (PROCHAZKA 1893), Diaphus sp., Diaphus holti TANING, 1918, Diaphus kokeni (PROCHAZKA 1893), Ceratoskopelus madarensis (LOWE 1839), Myctophidarum edwardsi (SAUVAGE 1873), 2. Anacanthini (Gadiformes): Bregmaceros albyi (SAUVAGE 1880), Macrurus novus BASSOLI, 3. Percomorphi (Perciformes): Gobius vicinalis KOKEN., Gobius sp. The studied Otoliths, mentioned for the first time in Greece, give important results on the biogeography and paleogeography and contribute to our knowledge about this fossilized group.

Home Range and Habitat Selection of Long-Eared Owls (Asio Otus) in Mediterranean Agricultural Landscapes (Crete, Greece)

The Long-eared Owl (Asio otus) in Crete (Greece) is a common agricultural species affected by the recent changes in agro-forestry systems. Concrete studies of habitat selection are needed in order to improve our knowledge of its foraging behaviour in managed rural landscapes. In the present study, we analysed the home range size and habitat selection of 11 Long-eared Owls inside olive groves in the plain of central Crete using radio tracking data and remote sensing images. Six nominal scale and 11 landscape scale predictors were used for habitat selection analysis, using a maximum entropy approach. Home range size ranged between 337 and 969 ha while a 52% of home range overlap was observed suggesting that Long-eared Owls do not defend hunting territories. At the nominal scale, distance to potential roosts (trees) was the most important contributor to model performance, followed by vegetation heterogeneity. Furthermore, local heterogeneity of greenness was a better predictor than simply greenness at the presence location. At the landscape scale the amount of habitat openness significantly improved model performance. Incorporating landscape heterogeneity improved habitat selection prediction compared to using only discrete land cover classification. Results of our study pinpoint that although Long-eared Owls exhibit a wide range of habitat tolerance, they prefer mixed habitat conditions avoiding particularly open areas or dense olive plantations. The research has implications in the face of new reforms of European Common Agricultural policy which emphasised the importance of landscape structure in preserving biodiversity in agricultural areas of Europe.

DIVERSITY AND ABUNDANCE TRENDS OF BENTHIC FORAMINIFERA FROM THE SOUTHERN PART OF THE IRAKLION BASIN, CENTRAL CRETE

Benthic foraminiferai fossil assemblages of the Roufas Section, southern Iraklion Basin, central Crete, were analyzed for the first time. Taxonomic and quantitative analyses were made in order to obtain paleoenvironmental (physical as well biological) information. A data set has been subjected to R- and Q-mode cluster analyses in order to demonstrate the linkage between taxa distribution and paleoenvironmental gradients. Our results suggest that oxygenation and trophic conditions of the near-surface sediments are the most important factors that control the community structure of the benthic foraminiferai fauna. The application of the oxygen transfer function - based on the use of benthic foraminiferai taxa from oxyphilic habitats - to the benthic faunas of the Roufas Section, allows the reconstruction of the oxygen contents of the bottom waters. Apart from the middle part of the section, no severe disturbances are recorded, pointing to the fact that we are dealing with an overall rather well ventilated water column during most of the part of the sequence.

Historical intermediate-depth earthquakes in the southern Aegean Sea Benioff zone: modeling their anomalous macroseismic patterns with stochastic ground-motion simulations

We model the macroseismic damage distribution of four important intermediate-depth earthquakes of the southern Aegean Sea subduction zone, namely the destructive 1926 M = 7.7 Rhodes and 1935 M = 6.9 Crete earthquakes, the unique 1956 M = 6.9 Amorgos aftershock (recently proposed to be triggered by a shallow event), and the more recent 2002 M = 5.9 Milos earthquake, which all exhibit spatially anomalous macroseismic patterns. Macroseismic data for these events are collected from published macroseismic databases and compared with the spatial distribution of seismic motions obtained from stochastic simulation, converted to macroseismic intensity (Modified Mercalli scale, IMM). For this conversion, we present an updated correlation between macroseismic intensities and peak measures of seismic motions (PGA and PGV) for the intermediate-depth earthquakes of the southern Aegean Sea. Input model parameters for the simulations, such as fault dimensions, stress parameters, and attenuation parameters (e.g. back-arc/along anelastic attenuation) are adopted from previous work performed in the area. Site-effects on the observed seismic motions are approximated using generic transfer functions proposed for the broader Aegean Sea area on the basis of VS30 values from topographic slope proxies. The results are in very good agreement with the observed anomalous damage patterns, for which the largest intensities are often observed at distances > 100 km from the earthquake epicenters. We also consider two additional “prediction” but realistic intermediate-depth earthquake scenarios, and model their macroseismic distributions, to assess their expected damage impact in the broader southern Aegean area. The results suggest that intermediate-depth events, especially north of central Crete, have a prominent effect on a wide area of the outer Hellenic arc, with a very important impact on modern urban centers along northern Crete coasts (e.g. city of Heraklion), in excellent agreement with the available historical information.

Geological and seismological evidence for NW-SE crustal extension at the southern margin of Heraklion basin, Crete.

In this paper we present new geological and seismological data on the orientation of crustal extension in central Crete (SE Heraklion basin) following the occurrence of two shallow seismic sequences: a) the May 2005 Assimi M=4.1 earthquake sequence and b) the 2013 Houdetsi-Tefeli sequence (3.2≤Mw≤3.6). Emphasis is given to the results of the geological field work, stress analysis, source inversion, aftershock relocations and mapping of earthquake-induced environmental effects. For the first time we find seismological evidence for N-S strike-slip motions along shallow fault planes in central Crete (Amourgeles fault). Our results indicate that while crustal extension dominates there is a combination of active fault kinematics, ranging from normal faulting along the northern edge of Messara basin (south-dipping Plakiotissa fault) to strike-slip faulting inside the SE part Heraklion basin (Houdetsi-Tefeli). The combination of active fault motions accommodates a NW-SE extension of the upper crust.

Engaging Local Communities in Heritage Decision-Making: The Case of Gonies, Crete, Greece

This article presents a community project developed through the Three Peak Sanctuaries of Central Crete archaeological project in the village of Gonies in Crete, Greece. We propose that archaeological research should include community projects and involve locals in decision-making. We examine the limitations put on such community programs by state institutions and networks of power. We argue that archaeologists should be involved as experts through engaged long-term ethnographic research that precedes any archaeological or heritage investigation and enables them to understand the position of their research within instituted networks of power and knowledge. We make a case for local engagement that can alter the course of research towards more ethical and sustainable forms. And finally, we discuss the development of public outreach programs in collaboration with the communities themselves.

Introduction

Introduction

DISTRIBUTION OF RARE EARTH ELEMENTS IN METAMORPHIC ROCKS OF PLATTENKALK GROUP AT CENTRAL CRETE, GREECE

Within the metamorphic rocks of the Plattenkalk Group, in an occurrence at Tallaia Mountains, central Crete, light rare earth elements Cerium and Lanthanum are found. The studied rare earths are seen in an epidote group mineral, allanite. Scanning Electron Microscopy of the samples showed clearly the crystals of allanite (prekinematic crystals) and their grain size. Mineral processing was conducted for the size fractions: (<10 μm), (10-212 μm) and (212-1000 μm), according to the magnetic properties and grain size of allanite. After magnetic separation of the fraction (<10 μm) and (212-1000 μm) rare earths Ce and La were observed to have higher concentrations in the magnetic products. In conclusion, (according to the microscopic and mineral processing data) the optimum grain size for the beneficiation of allanite is the size fraction (10-212 μm).

The tectonometamorphic and magmatic evolution of the Uppermost Unit in central Crete (Melambes area): constraints on a Late Cretaceous magmatic arc in the Internal Hellenides (Greece)

Crete consists of a nappe pile that formed during Alpine subduction and collision. The lower nappes belong to the External Hellenides, whereas the uppermost nappe is ascribed to the Pelagonian Zone of the Internal Hellenides. The Uppermost Unit consists of several subunits including the Asterousia Crystalline Complex (ACC), which comprises metasedimentary rocks, (meta)granitoids and serpentinite, the protolith age and the tectonometamorphic evolution of which are largely unknown. In the present study, we present new structural, microfabric and geochronological data from the Uppermost Unit in the Melambes area (central Crete). 206Pb/238U zircon ages (LA-ICP-MS and ID-TIMS) indicate granitic and dioritic intrusions between 71.9±0.6 and 76.9±0.3Ma. Identical ages have previously been obtained from comparable intrusions in eastern Crete and on Anafi. The composition and geochemical signature suggest an extended magmatic arc along the southern active margin of the Pelagonian-Lycian Block. Post-intrusive shearing transformed granite into orthogneiss, whereas diorite remained free from foliation, because of the lower amount of mechanically weak phases. Deformation microfabrics suggest top-to-the SE shearing under amphibolite facies conditions of the ACC and at greenschist facies conditions of rocks at the base of the ACC referred to as Akoumianos Greenschist. The Akoumianos Greenschist is considered as the northern part of the Pindos realm that was subducted underneath the Pelagonian-Lycian active margin. Based on our new and on published data, the following orogenic stages are suggested to have contributed to the evolution of the Hellenides during the Late Cretaceous to Eocene: (1) pre-middle Campanian collision and subduction of the Pindos lithosphere underneath the southern margin of the Pelagonian-Lycian terrane led to obduction and offscraping of serpentinized ocean floor and stacking of the ACC during amphibolite facies top-to-the SE thrusting, (2) formation of a Campanian magmatic arc along the Pelagonian-Lycian active margin; (3) Maastrichtian collision and stacking of the magmatic arc during top-to-the SE mylonitic shearing; (4) Palaeocene top-to-the SE greenschist-facies shearing of the ACC on top of the Akoumianos Greenschist; (5) Late Eocene thrusting of the Uppermost Unit on top of the Arvi and Pindos units. Thus, top-to the SE was the dominant shear sense in the southern Aegean from at least the mid-Late Cretaceous until the Eocene.

Contrasting Histories in Early Bronze Age Aegean: Uniformity, Regionalism and the Resilience of Societies in the Northeast Peloponnese and Central Crete

Late Early Bronze Age (EB IIB–III, 2500–2000 bc) evidence from the northeast Peloponnese and central Crete present two coeval sequences of events with very different societal outcomes. By drawing on resilience theory and the model of adaptive cycles, this article explores when and why the paths of mainland Greece and Crete diverged around 2200 bc, leading to an eventually destabilizing change on the mainland and a more sustainable one on Crete. It is argued that the two EB II societal structures were more similar than current discourse generally allows. However, during some hundred years leading up to the end of the EB II period, an increased societal uniformity and a decrease of social arenas on northeast Peloponnese may in the end have circumscribed the Early Helladic communities’ room to manoeuvre. Conversely, through strong regionalism and greater multiplicity of social arenas, Early Minoan societies seem to have retained a greater level of socio-economic variability that enabled proactiveness and sustained expansion through ideological change.

Environmental monitoring of soil pollution in urban areas (a case study from Heraklion city, Central Crete, Greece)

Main scope of the present study is to combine topographic and geological data, magnetic susceptibility and thermomagnetic analysis in order to investigate the magnetic properties of the near surface soils in possible polluted urban areas. For this purpose, a power plant with a dense traffic net around it, located in the NW section of Heraklion city in Crete was selected to be the study area. Surface soil samples have been collected from the area under investigation and they were analyzed in order to estimate the spatial distribution of the magnetic susceptibility. Loci of high values of the magnetic susceptibility within the study area gave rise to further proceed to thermomagnetic analysis of the selected samples. GIS techniques were used for mapping the magnetic measurements on the various topographic and geological features of the area. The digital elevation model was created by the digitization of the topographic map contours (1:5000 scale maps). The combination of the above techniques indicate high values of the magnetic susceptibility especially in the northeastern part of the investigated area, possibly related to pollution due to the presence of heavy metals.

CONTRIBUTION TO THE LATE NEOGENE STRATIGRAPHY OF THE ANCIENT GORTYS AREA (SOUTHERN CENTRAL CRETE, GREECE)

Most of the basal Neogene sediments of Crete Island (South Aegean Sea) were unconformably deposited during synsedimentary extensional tectonics and subsequent transgression on the basement. This work mainly focuses on the marine stratigraphy of south central Crete and specifically on the sedimentary deposits of the Gortys subbasin-area located in the basin of Messara. Four selected profiles north of Gortys ancient ruins (Heraklion Province) are lithostratigraphically presented. Profiles Gortys-1 and -2 (combined to one: 1+2) represent the basal Neogene deposits (older strata-commence of sedimentation) and are interpreted as of fluviatile to lagoonal origin, while profiles Gortys-4 and - 4a are considered the younger, marine development of the Gortys subbasin. Between profiles –4 and –4a are developed evaporites of the Messinian Salinity Crisis (MSC). Profiles are biostratigraphically studied and correlated on the basis of either identified macrofossils or calcareous and siliceous nannofossils. The recorded assemblages range in age from Serravallian-Tortonian to Messinian and Zanclean respectively. The good preservation and abundance of the fossil phytoplankton establishes a well-constrained biostratigraphic framework, which will further contribute to the understanding of the evolution of the Messara sedimentary basin.

Exploring the role of within-island ecogeographical factors: insights from the genetic diversity of Cretan trap-door spiders (Cyrtocarenum cunicularium, Ctenizidae : Araneae)

Crete (Aegean Sea, Greece), like other Mediterranean islands, has a complex palaeogeographical history, including several cycles of fragmentation into palaeoislands and subsequent reconnection. Here, we use the Cretan trap-door spider Cyrtocarenum cunicularium as a model organism to explore the importance of within-island evolutionary processes, such as palaeogeographic events and climatic changes. We assessed the phylogeny, population clustering and historical demography of 61 specimens with mitochondrial (COI) and nuclear (H3) markers. We investigated the isolation-by-distance and spatial diffusion processes that have shaped their past and current distribution and estimated the effect of niche divergence, using species distribution modelling. Two genetic lineages have continuously been distributed in the west and east part of Crete during the last 2million years. Their genetic structure is concordant with Crete’s fragmentation into palaeoislands during the Pliocene and additionally affected by the sea-level oscillations and climatic changes due to the Pleistocenic glacial cycles. In central Crete, some evidence of genetic admixture between them was found, which needs to be further explored. According to species distribution modelling, the niche of each lineage corresponds to different environmental parameters, while isolation-by-distance was also detected. The divergence between the ‘West’ and ‘East’ lineages was promoted by palaeogeographical factors but seems to be maintained by the species’ poor dispersal abilities and the local ecological adaptation of each lineage. The case of the Cretan C. cunicularium highlights the additive effect of ecogeographical and behavioural factors in shaping insular biodiversity.