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Remarkably well-preserved crustal sections from the Eastern Hellenides offer the chance to evaluate the regional geodynamic evolution of continental crust. Here, we identify and geodynamically interpret eclogite facies metamorphism in the Triassic–Jurassic volcano-sedimentary series of the West Circum Rhodope zone in the eastern Hellenides. Equilibrium phase diagrams and measured mineral compositions were used to inform reconstructions of geodynamic evolution during the early Alpine period. We newly define the existence of the Eohellenic HP belt, consisting of pre-Alpine basement, continental volcano-sedimentary formations, and a Jurassic magmatic arc. We suggest that the Eohellenic HP-Belt was subducted in the late Jurassic to early Cretaceous beneath the European plate margin. Detailed geodynamic reconstructions such as ours provide a robust anchor for future computational models of long-term crustal evolution in the Eastern Hellenides. [ABSTRACT FROM AUTHOR]

Assessing the hydrogeochemical evolution of groundwater is a challenging task, which is further exacerbated when considering the multiple geogenic and anthropogenic impacts that affect its quality and the hydraulic interactions between different aquifer bodies. This study combined hydrogeochemical modelling and data analysis to assess this complex hydrogeological regime. Before modelling, the groundwater samples were clustered using a multivariate statistical method (hierarchical cluster analysis (HCA)). Then, the Geochemist Workbench (GWB) software was applied to model the hydrogeochemical groundwater evolution, including the dominant ion exchange process, and to explain the changes in groundwater chemistry towards its flow. The input data consisted of five key parameters from seventy-seven sampling points collected in two periods (accounting for the start and the end of the irrigation period). A data analytical approach based on the optimal mixing ratios between the interacting groundwater systems and recharge inputs was also performed as part of the methodological approach. It revealed a progressively temporal-dependent behaviour of the aquifer system during the irrigation period, resulting in seasonal changes in the hydrodynamic conditions and depletion of the upper aquifer layers. Specifically, the aquifer system was confirmed to undergo cation exchange as the dominant geochemical process that increases calcium concentrations. The complex hydrogeological regime was further evaluated by assessing the mixing ratios of the different aquifer layers. Hence, the aquifer system (bulk samples) was mixed with the irrigation water by 71% and 97% and with the lateral recharge by 76% and 29% for the beginning and at the end of the irrigation period, respectively. Overall, the joint assessments were confirmed by the hydrogeochemical status of the end-members and the modelling approach and explained the sequential changes in groundwater chemistry due to the dominant ion-exchange process and the mixing of different water bodies. The proposed methodological approach proved that it could be used as an exploratory and preliminary method for capturing the temporal dynamics in complex groundwater systems and supporting groundwater resource management. [ABSTRACT FROM AUTHOR]

Aquifer overexploitation in coastal aquifers has led to seawater intrusion that causes severe salinization effects on the groundwater system. The most widespread method for assessing groundwater vulnerability to seawater intrusion, the dominant cause of salinization in coastal aquifers, is the GALDIT method, with numerous applications globally. The present study proposes a modified version of the GALDIT method (GALDIT-Ι) to evaluate the vulnerability of salinization, including its potential additional sources. Both methods have been applied to Rhodope coastal aquifer, an intensively cultivated agricultural area subject to multiple salinization sources. The basic modifications of the proposed GALDIT-I method include different weighting factors and modification of classes for critical parameters, the use of a different indicator (TDS) for the estimation of the Impact factor and, overall, the address of the concept of groundwater salinization instead of seawater intrusion only. The differences in the results of the two methods were significant, as the modified version exhibited a more finite and realistic vulnerability capture, according to the area's existing hydrogeological and hydrogeochemical knowledge. The original GALDIT method showed an area of nearly 80% as medium vulnerable with very limited spatial deviations. On the other hand, the proposed modified GALDIT method depicted high vulnerability hotspots away from the shoreline, indicating various salinity sources. The validation of the modified method showed that nearly 80% of the sampling points present very good to perfect match between the salinity assessment and the concentration of Cl−, indicating the successful validation of the method. Overall, the GALDIT-I method facilitated groundwater vulnerability assessment to salinization more accurately and exhibited a more discrete spatial assessment, thus, it could be regarded as a promising proactive tool for groundwater management and decision-making. [ABSTRACT FROM AUTHOR]

R. Gamzatov is a world-famous poet, whose work during his lifetime enjoyed a huge polarity, not only in Russia, but also far beyond its borders. He was a welcome guest in many foreign countries and republics of the Soviet Union, which he visited and absorbed their poetic, cultural, historical atmosphere. These visits inspired the poet for new creative achievements, enriched and expanded his work. As a result, whole cycles of works about different countries have been developed. One of these, that captivated the poet’s heart, was Bulgaria, to which he dedicated a number of works. R. Gamzatov warmly talks about his impressions of Bulgaria, friendly relations with figures of its literature, culture and society, and poetically recreates its multicolored image. The poet’s main attention is directed to the images of nature, glorifies the national character of the Bulgarians, moral and ethical principles, their commonality with the mentality of the Dagestan people.

Assessing the hydrogeochemical evolution of groundwater is a challenging task, which is further exacerbated when considering the multiple geogenic and anthropogenic impacts that affect its quality and the hydraulic interactions between different aquifer bodies. This study combined hydrogeochemical modelling and data analysis to assess this complex hydrogeological regime. Before modelling, the groundwater samples were clustered using a multivariate statistical method (hierarchical cluster analysis (HCA)). Then, the Geochemist Workbench (GWB) software was applied to model the hydrogeochemical groundwater evolution, including the dominant ion exchange process, and to explain the changes in groundwater chemistry towards its flow. The input data consisted of five key parameters from seventy-seven sampling points collected in two periods (accounting for the start and the end of the irrigation period). A data analytical approach based on the optimal mixing ratios between the interacting groundwater systems and recharge inputs was also performed as part of the methodological approach. It revealed a progressively temporal-dependent behaviour of the aquifer system during the irrigation period, resulting in seasonal changes in the hydrodynamic conditions and depletion of the upper aquifer layers. Specifically, the aquifer system was confirmed to undergo cation exchange as the dominant geochemical process that increases calcium concentrations. The complex hydrogeological regime was further evaluated by assessing the mixing ratios of the different aquifer layers. Hence, the aquifer system (bulk samples) was mixed with the irrigation water by 71% and 97% and with the lateral recharge by 76% and 29% for the beginning and at the end of the irrigation period, respectively. Overall, the joint assessments were confirmed by the hydrogeochemical status of the end-members and the modelling approach and explained the sequential changes in groundwater chemistry due to the dominant ion-exchange process and the mixing of different water bodies. The proposed methodological approach proved that it could be used as an exploratory and preliminary method for capturing the temporal dynamics in complex groundwater systems and supporting groundwater resource management.

Aquifer overexploitation in coastal aquifers has led to seawater intrusion that causes severe salinization effects on the groundwater system. The most widespread method for assessing groundwater vulnerability to seawater intrusion, the dominant cause of salinization in coastal aquifers, is the GALDIT method, with numerous applications globally. The present study proposes a modified version of the GALDIT method (GALDIT-Ι) to evaluate the vulnerability of salinization, including its potential additional sources. Both methods have been applied to Rhodope coastal aquifer, an intensively cultivated agricultural area subject to multiple salinization sources. The basic modifications of the proposed GALDIT-I method include different weighting factors and modification of classes for critical parameters, the use of a different indicator (TDS) for the estimation of the Impact factor and, overall, the address of the concept of groundwater salinization instead of seawater intrusion only. The differences in the results of the two methods were significant, as the modified version exhibited a more finite and realistic vulnerability capture, according to the area’s existing hydrogeological and hydrogeochemical knowledge. The original GALDIT method showed an area of nearly 80% as medium vulnerable with very limited spatial deviations. On the other hand, the proposed modified GALDIT method depicted high vulnerability hotspots away from the shoreline, indicating various salinity sources. The validation of the modified method showed that nearly 80% of the sampling points present very good to perfect match between the salinity assessment and the concentration of Cl−, indicating the successful validation of the method. Overall, the GALDIT-I method facilitated groundwater vulnerability assessment to salinization more accurately and exhibited a more discrete spatial assessment, thus, it could be regarded as a promising proactive tool for groundwater management and decision-making.

We have combined new titanite, zircon, and apatite fission-track and apatite [U–Th–(Sm)]/He analyses with previously published U–Pb, Rb–Sr, and 40Ar/39Ar thermochronological data to reconstruct the Cenozoic thermal evolution of the Central Rhodope Metamorphic Complex (CRMC), exposed mainly in southern Bulgaria and to a lesser extent in northern Greece. Results reveal two phases of cooling. During the first phase, between ~ 37 and ~ 33 Ma, the CRMC experienced rapid cooling from partial melting at > 650 °C to ca 60 °C. Multiple generations of low-angle ductile-to-brittle fault zones accommodated the exhumation of the migmatitic core together with parts of its high-grade periphery. Oligocene volcanism and associated local elevation of the geothermal gradient is responsible for the resetting of some fission-track ages in the CRMC. The second cooling phase to temperatures of about 40 °C, between 24 and 13 Ma, is related to exhumation along high-angle normal faults in the southern part of the CRMC. [ABSTRACT FROM AUTHOR]

This article presents the preliminary results of the archaeological campaigns between 2009-2019 in the region of 'Tsarkvishte' (Church), south of the village of Dragoinovo, Parvomai municipality. In this period a full study of a three-nave basilica and the partial study of the building located south of it and part of the eastern enclosed wall of the complex has been undertaken. Although the excavations are not completed, they allow us to gain some idea of the specifics and reconstructions of the uncovered early Christian complex, which is interpreted as a monastery. Its foundation dates back to the end of the 4th - beginning of the 5th century and is accepted as part of the process of Christianisation of the mountain population of the Rhodopes, which in the sources is mentioned as 'Bessoi', and which determines the specifics of the complex. It lasted until the end of the 6th-beginning of the 7th century when it was destroyed during the Slavic-Avar invasions. [ABSTRACT FROM AUTHOR]

We focused on the Pirin–Pangeon–Thasos carbonate sequence of the Rhodope thrust system, combining Sr isotopes from marble with U–Pb dating of detrital zircons from interlayered schists with outcrop near the villages of Ilindentsi and Petrovo in Bulgaria. The youngest zircon age at Ilindentsi is 266 Ma, i.e. Middle Permian, while the youngest zircon at Petrovo yielded an age of 290 Ma, i.e. Early Permian. Strontium isotopes range from 0.707420 to 0.707653, and are consistent with a Middle Permian maximum depositional age. Middle Permian sedimentation of this carbonate platform most likely occurred along the Eurasian margin rather than the Gondwana margin. [ABSTRACT FROM AUTHOR]

Abstract: The core complexes of the North Aegean result from the gravity spreading of a thrust wedge, driven by the Hellenic slab rollback, since middle Eocene. The development of the Southern Rhodope Core Complex occurred in two stages: (i) core complex exhumation accommodated by the Kerdylion detachment and (ii) steep normal faulting controlling the deposition of Neogene sedimentary basins that segmented the core complex. Both stages have been controlled by a clockwise rotation of the detachment hanging wall. The bulk amount of extension along the Aegean coastline in Northern Greece reached 120 km. The transition between the two stages occurred in middle Miocene due to an increase in extensional displacement by a factor 5. This transition between two different modes of extension, from localized detachment (i.e., core complex mode) to distributed steep normal faulting (i.e., wide rift mode), occurred at Aegean scale as a result of an acceleration of slab rollback. The Neogene basins emplaced close to the detachment, where brittle upper crust was thin (around 7 km) but containing weak marble layers allowing the formation of ramp‐flat extensional systems with rollover‐type basin fill. Since Pliocene, the stretching direction changed, from NE‐SW to NS, due to the propagation of the North Anatolian Fault in the North Aegean domain. [ABSTRACT FROM AUTHOR]

The synmetamorphic nappe system of the Rhodope Metamorphic Complex has been deformed into dome-and-basin structures attributed to syn- to post-convergent exhumation. We document the deformation style and present new thermobarometric and geochronological constraints for the Kesebir-Kardamos dome in southern Bulgaria and northern Greece. The dome consists of a migmatitic core overlain by high-grade thrust sheets. Kinematic indicators indicate a continuum from ductile to brittle conditions during exhumation. Thermodynamic modeling applied to the high-grade, intermediate thrust sheets yielded peak conditions of 1.2 GPa and ca 730 °C. New U-Pb SHRIMP-II dating of zircons from rocks of the same unit revealed Late Jurassic-Early Cretaceous (145 Ma) as the time of metamorphic crystallization; some zircon rims yielded Eocene ages (53 and 44 Ma) interpreted as having been thermally reset owing to coeval granitoid magmatism. The high-grade rocks were covered by Lutetian-Priabonian marine sediments after exhumation. Slumps suggest that sedimentation took place in a tectonically active environment. Our new structural, petrological and geochronological results suggest that the major shear zone in the core of the Kesebir-Kardamos dome is equivalent to the Late Jurassic-Early Cretaceous Nestos Shear Zone. Post-Jurassic metamorphic ages recorded in the Rhodope most likely represent crustal rather than deep subduction geodynamic processes. [ABSTRACT FROM AUTHOR]

The Trikorfo area (Thassos Island, Rhodope massif, Northern Greece) represents a unique mineralogical locality with Mn-rich minerals including kyanite, andalusite, garnet and epidote. Their vivid colors and large crystal size make them good indicators of gem-quality materials, although crystals found up to now are too fractured to be considered as marketable gems. The dominant lithology is represented by a garnet−kyanite−biotite−hematite−plagioclase ± staurolite ± sillimanite paragneiss. Thermodynamic Perple_X modeling indicates conditions of ca. 630−710 °C and 7.8−10.4 kbars. Post-metamorphic metasomatic silicate and calc-silicate (Mn-rich)-minerals are found within (i) green-red horizons with a mineralogical zonation from diopside, hornblende, epidote and grossular, (ii) mica schists containing spessartine, kyanite, andalusite and piemontite, and (iii) weakly deformed quartz-feldspar coarse-grained veins with kyanite at the interface with the metamorphic gneiss. The transition towards brittle conditions is shown by Alpine-type tension gashes, including spessartine−epidote−clinochlore−hornblende-quartz veins, cross-cutting the metamorphic foliation. Kyanite is of particular interest because it is present in the metamorphic paragenesis and locally in metasomatic assemblages with a large variety of colors (zoned blue to green/yellow-transparent and orange). Element analyses and UV-near infrared spectroscopy analyses indicate that the variation in color is due to a combination of Ti4+−Fe2+, Fe3+ and Mn3+ substitutions with Al3+. Structural and mineralogical observations point to a two-stage evolution of the Trikorfo area, where post-metamorphic hydrothermal fluid circulation lead locally to metasomatic reactions from ductile to brittle conditions during Miocene exhumation of the high-grade host-rocks. The large variety of mineral compositions and assemblages points to a local control of the mineralogy and fO2 conditions during metasomatic reactions and interactions between hydrothermal active fluids and surrounding rocks.

Rhodope placozophagus nov. spec. from the western Gulf of Mexico that actively preys on placozoans is described. This white-translucent rhodopemorph was discovered on glass slides introduced in marine aquariums as part of an assemblage of small organisms including the vorticellids, ciliates, acoela, heliozoans and high populations of placozoans, which correlate with an abundance of this worm-like mollusk. When R. placozophagus comes into contact with placozoans, it immediately everts the anterior portion of the buccal bulb and sucks large portions of the disc-shape organism. The new species is likely to be a specialized predator since it was never observed chasing other microorganisms and especially because it can be reared for several generations while feeding exclusively on placozoans. It is known that the lipid granules called shiny spheres, located in the dorsal epithelium of Trichoplax , contain venoms and toxins that serve as an anti-predator defense. These properties can therefore be transmitted, at least transitorily, to a predator. Apart from one report of Riedl (1959) of Rhodope veranii preying on Trichoplax , no other predator-prey association has been described for placozoans. [ABSTRACT FROM AUTHOR]

The Rhodope Metamorphic Complex is a stack of allochthons assembled during obduction, subduction, and collision processes from Jurassic to Paleogene and overprinted by extensional detachment faults since Middle Eocene. In the study area, the following nappes occur in superposition (from base to top): an orthogneiss-dominated unit (Unit I), garnet-bearing schist with amphibolite and serpentinite lenses (Unit II), greenschist, phyllite, and calcschist with reported Jurassic microfossils (Unit III), and muscovite-rich orthogneiss (Unit IV). U-Pb dating of zircons from a K-feldspar augengneiss (Unit I) yielded a protolith age of ca. 300 Ma. Garnet-bearing metasediment from Unit II yielded an age spectrum with distinct populations between 310 and 250 Ma (detrital), ca. 150 Ma, and ca. 69 Ma (the last two of high-grade metamorphic origin). An orthogneiss from Unit IV yielded a wide spectrum of ages. The youngest population gives a concordia age of 581 ± 5 Ma, interpreted as the age of the granitic protolith. Unit I represents the Lower Allochthon (Byala Reka-Kechros Dome), Unit II the Upper Allochthon (Krumovitsa-Kimi Unit), Unit III the Uppermost Allochthon (Circum-Rhodope Belt), and Unit IV a still higher, far-travelled unit of unknown provenance. Telescoping of the entire Rhodope nappe stack to a thickness of only a few 100 m is due to Late Eocene north directed extensional shearing along the newly defined Kulidzhik Detachment which is part of a major detachment system along the northern border of the Rhodopes. Older top-to-the south mylonites in Unit I indicate that Tertiary extension evolved from asymmetric (top-to-the-south) to symmetric (top-to-the-south and top-to-the-north), bivergent unroofing. [ABSTRACT FROM AUTHOR]

The Chalkidiki block is a major domain in the North Aegean that, contrary to other domains in the region, largely escaped thermal perturbations during Tertiary extension. As a result, the Chalkidiki block is an ideal candidate to glean information related to the timing of Mesozoic thermal events using appropriate geochronological techniques. We have undertaken a laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) study (U-Th-Pb on monazites and U-Pb on zircons) coupled with 40 Ar/ 39 Ar dating on nine samples from various structural levels within the thrust system of the Chalkidiki block. The eastern, and structurally lower part of the system revealed a complete isotopic reset of Carboniferous – Early Triassic monazites coeval with partial monazite destruction, REE-mobilisation and formation of apatite-allanite-epidote coronas at ~ 132 Ma, a reaction that is commonly observed in amphibolite-facies rocks. These coronas formed after crystallisation of garnet (i.e., at T > 580 °C) and, in all probability, either close to the peak-temperature conditions (~ 620 °C) on a prograde path or during retrogression between the peak-temperature and the low-temperature boundary of the amphibolite facies. Cooling of these rocks and arrival at mid-crustal levels occurred at 95–100 Ma. By contrast, the western, and structurally uppermost part of the system went through the same event by 120–125 Ma. Further structural considerations with respect to medium-temperature geochronology data imply that syn-metamorphic thrusting must have ceased by early Late Cretaceous. We emphasize that, with the sole exception of the Chalkidiki block, no pre-45 Ma medium-temperature geochronology data are preserved in other North Aegean domains, a feature that is clearly related to the extension-induced thermal perturbation of the region during the Tertiary. [ABSTRACT FROM AUTHOR]

Detrital heavy mineral and bulk rock geochemistry and a review of sandstone petrographic data have been used to investigate the post-collisional effusive magmatism that followed the closure of the Vardar Ocean and the generation of volcanic sediments in a complex and compositionally variable volcanic region. Available petrographic data gives evidence of contributions from three key source areas corresponding to the three main tectonic units: the structurally lower Gneiss–Migmatite Complex (Byala Reka-Kechros and Kesebir-Kardamos domes) and the upper Variegated (Kimi) Complex, both fringed by the low-to-medium-grade Mesozoic rocks of the Circum-Rhodope Belt. Besides the deposition of siliciclastic material, volcanic contributions from both, intermediate and acid products represent an important source of sediment in the area. Despite dominant intermediate to acid volcanic products, volcanic lithic fragments in sandstones (microlithic, lathwork and brown vitric textures) indicate main inputs from intermediate and basic-intermediate products generating questions on the interpretation of volcanic detritus in reconstruction of provenance. Detrital amphibole and pyroxene chemistry is used to characterise the supply of volcanic material as well as the dispersal mechanisms and understand the role played by each of the volcanic centers present in the area in the infill of the north-western Thrace basin. Amphibole chemistry reveals high compositional heterogeneity according to both compositional variability of the numerous volcanic centres active at the time of deposition and presence of metamorphic amphibole. 4 Al and Al T apfu values indicate that most of the amphiboles from the NERZ are not of volcanic origin and their presence can only be attributed to the numerous amphibolite facies metamorphic rocks abundantly documented in the area. Detrital amphibole compositions from the ZKVS indicate major contributions from the Iran Tepe and Zvedzel volcanoes. Analysed detrital clinopyroxenes from the NERZ are mostly diopside–augite, with no hedenbergite or Fe–augite detected. The 4 Al/ 6 Al ratio is comparable with compositions of volcanic pyroxenes from the Momchilgrad–Arda (ZKVS) region and products from the pre-caldera phase of the Borovitza. [ABSTRACT FROM AUTHOR]

In this study, we report the first discovery of microdiamond inclusions in kyanite–garnet schists from the Central Rhodope Mountains in Bulgaria. These inclusions occur in garnets from metapelites that are part of a meta-igneous and meta-sedimentary mélange hosted by Variscan (Hercynian) orthogneiss. Ultra-high-pressure (UHP) conditions are further supported by the presence of exsolved needles of quartz and rutile in the garnet and by geothermobarometry estimates that suggest peak metamorphic temperatures of 750–800 °C and pressures in excess of 4 GPa. The discovery of UHP conditions in the Central Rhodopes of Bulgaria compliments the well-documented evidence for such conditions in the southernmost (Greek) part of the Rhodope Massif. Dating of garnets from these UHP metapelites (Chepelare Shear Zone) using Sm–Nd geochronology indicates a Late Cretaceous age (70.5–92.7 Ma) for the UHP metamorphic event. This is significantly younger than previously reported ages and suggests that the UHP conditions are associated with the Late Mesozoic subduction of the Vardar Ocean northward beneath the Moesian platform (Europe). The present-day structure of the RM is the result of a series of subduction–exhumation events that span the Cenozoic, alongside subsequent post-orogenic extension and metamorphic core complex formation. [ABSTRACT FROM AUTHOR]

Characterization of various fluid parameters in magmatic-hydrothermal ore mineralizations is potentially essential for interpretation of the conditions of formation and therefore for mineral exploration. Fluid inclusions can provide a useful and promising tool in the research of the ore forming processes in these systems. This review focuses on the nature, composition and origin of magmatic-hydrothermal ore forming fluids involved in the formation of representative Tertiary ore deposits at the Rhodope metallogenic province in NE Greece. These deposits are spatially related to Tertiary magmatism in NE Greece. Case studies are presented here and include an intrusion-hosted sheeted vein system (Kavala), a Au-rich carbonate replacement and quartz-vein mineralization (Asimotrypes), mineralized veins in Eptadendro-Rachi and Thasos island (Kapsalina and Panagia), porphyry Cu-MoRe-Au deposits in Pagoni Rachi and Maronia and epithermal Au-Ag mineralizations in Perama and Loutros. Hydrothermal fluids rich in CO2together with elevated Au and Te content are common and occur at the Kavala intrusion hosted sheeted vein system, at the Asimotrypes Au-rich carbonate replacement mineralization and at the Panagia (Thasos) vein system. We classify all these ore mineralizations as intrusion-related gold systems (IRGS). Transport and precipitation of metals including Au and Te is favoured when CO2is Keywords: Fluid inclusions, metallogeny, Rhodope, intrusion related systems, porphyry systems, epithermal mineralizations present. Precipitation of the ore mineralization takes place due to the immiscibility of the carbonic and the aqueous fluids which have a magmatic origin with the contribution of meteoric water. Cooling of magmatic hydrothermal fluids and dilution with meteoric water is a common cause for ore mineral formation in the vein mineralizations of Eptadendro/ Rachi and Kapsalina Thasos. At the Pagoni Rachi and Maronia porphyry deposits, boiling and the high proportion of the vapour phase are the most essential fluid processes which affected ore formation. The epithermal veins overprinting the Pagoni Rachi and the Maronia porphyry systems and the HS-IS epithermal system in Perama Hill and the IS epithermal mineralization in Loutros are characterized by low to moderate temperatures and low to moderate salinities. Cooling and dilution of the ore fluids are the main process for gold precipitation. We conclude that the different fluid parameters and microthermometric data indicate a variety of fluid origin conditions and sources which can affect the strategy for exploration and prospecting for gold, rare and critical metals. [ABSTRACT FROM AUTHOR]

In the Chalkidiki Peninsula of northern Greece a thrust complex made of a basement (Vertiskos Unit), a cover (Circum–Rhodope belt) and arc/back-arc units (Chortiatis Magmatic Suite and eastern Vardar Ophiolites) is exposed in the Chalkidiki Peninsula of northern Greece. The complex forms the western part of the Rhodope Metamorphic Province and lies on the hanging-wall of the Kerdylion Detachment, the structure responsible for the exhumation of the Southern Rhodope Core Complex and the most prominent and visible ductile structure related to the Tertiary Aegean extension. The Chalkidiki thrust complex arguably preserves a complete record of Cretaceous deformation and related fabrics. In this contribution we describe the geometry of foliation, stretching lineation and shear sense(s) on a regional scale. The regional foliation strikes NW–SE and displays different patterns in the three studied units: (i) dominantly dipping at low angle in the Vertiskos Unit, (ii) affected by upright folding in the Circum–Rhodope belt and (iii) systematically steeply dipping to the NE in the Chortiatis Magmatic Suite. Stretching lineation trend dominantly SW–NE in the three mentioned units. On the basis of new mapping, neglecting local perturbations and deformation related to Tertiary extension, we infer the regional kinematics of Cretaceous syn-metamorphic thrusting and subsequent exhumation of the metamorphic units. Thrusting took place toward the SW (in present-day coordination) and the related fabrics are recorded throughout the metamorphic pile. On the contrary, exhumation-related fabrics are related to shear toward the NE and are preferentially recorded in the uppermost part of the metamorphic pile suggesting that extension was more localised and of less finite intensity compared to thrusting. [ABSTRACT FROM AUTHOR]

The South Rhodope Core Complex (SRCC) of Northern Greece is probably the most studied metamorphic core complex of the Rhodope Massif, and yet its geological evolution has not yet been fully unravelled, especially the later stages of its thermotectonic evolution. We applied the fission-track method on apatite and zircon and the [U-Th-(Sm)]/He method on apatite in order to reconstruct the low-temperature thermal history. The main detachments responsible for the unroofing of the core complex are the Kerdilion and the Strymon Valley detachments. The Kerdilion detachment initiated the exhumation of the SRCC at the latest at 42 Ma and controlled it until about 24 Ma. Between 24 and 12 Ma, the Strymon Valley detachment accommodated the exhumation. Since 12 Ma brittle normal faults, some of them cutting the Strymon Valley detachment were responsible for the final cooling of the basement rocks in the studied area and the formation of syn-tectonic sedimentary basins. Activity along these brittle normal faults lasted until 6 Ma or probably even until today, as indicated by recent seismic activity in the area. [ABSTRACT FROM AUTHOR]

In the Thrace region of NE Greece, the crystallization and post-solidification cooling below 600 °C of the intrusive suite of the Circum-Rhodope Belt arc-related Evros ophiolite span from 176.4 ± 0.93 to 163.5 ± 3.85 Ma. In the underlying Rhodope high-grade metamorphic basement, (ultra-) high-pressure metamafic rocks are cross-cut by orthogneisses with granitoid protoliths and crystallization ages between 160 ± 0.69 and 154 ± 1.5 Ma. This new U–Pb LA–ICP-MS zircon geochronological data provides evidence that the timing of the evolution of the Evros ophiolite coincides, within analytical error, with granitoid magmatism in the underlying high-grade basement. One of the dated metagranitoid rocks cross-cuts amphibolitized eclogite, indicating that the high-pressure conditions have a maximum age of 160 Ma postdating one of the proposed ages of ultra-high pressure conditions in the Rhodope Massif. The currently earliest recognised Rhodope high/ultra-high pressure metamorphic event is therefore related to the subduction setting which formed the Evros ophiolite. Based on these new temporal constraints and the regional tectonic–geochronologic framework, we discuss and update the geodynamic context connected to the Jurassic subduction–collisional setting at the Rhodope continental margin of Eurasia. [ABSTRACT FROM AUTHOR]

We present textural, chemical and U-Th-Pb-age data on monazites from garnet--kyanite (Grt-Ky) metapelites, from the Chepelare Shear Zone (Bulgaria) and the Nestos Shear Zone (Greece), in the Central Rhodope. Samples from both locations have experienced two stages of high temperature metamorphism during Alpine times. The first event involved mid-Mesozoic granulite facies dehydration melting. The second event involved mid-Cenozoic lower-grade fluid-assisted partial melting. The latter is well expressed in adjacent felsic rocks but had limited impact on the Grt-Ky metapelites. Most samples display evidence for strong ductile shearing in the presence of fluids. Monazite is present in the highly foliated matrix and as inclusions in garnet and kyanite. Unlike the inclusions, matrix monazites display features of fluid-assisted dissolution--recrystallization. Y-poor domains with U-Th-Pb ages of between ca. 115 and 165 Ma represent the largest part of the grains. Y-rich domains with mid-Cenozoic ages occur as rims, or as small satellite grains surrounding the Mesozoic grains. The Cenozoic monazite domains crystallized at the expense of the Mesozoic ones and simultaneously incorporated Y provided by the fluid-assisted resorption of garnet. An age of ca. 36 Ma is obtained for the samples of both shear zones, interpreted as dating the main episode of monazite growth during the Cenozoic. Similar ages exist for the crystallization of leucosomes and pegmatites in the adjacent migmatitic gneisses, indicating that the fluids responsible for the precipitation of the Cenozoic monazites were probably released during the crystallization of nearby anatectic melts. Together with associated rutile and biotite, many newly grown monazites show a preferred orientation paralleling the matrix foliation. This supports the hypothesis of dynamic dissolution--precipitation as an efficient mean to promote renewed monazite crystallization during ductile deformation of the host rock at ca. 36 Ma. [ABSTRACT FROM AUTHOR]

The metamorphosed thrust stack of the Rhodopes comprises a level with ophiolites (Middle Allochthon) underlain and overlain by continent-derived allochthons. The Upper Allochthon represents the European margin, but the origin of the Lower Allochthon remains controversial, with suggestions that it may be derived from an inferred microcontinent (Drama) or from the margin of Adria. Trace element compositions and Sr and Nd isotope ratios of metagabbroic amphibolites and enclosed meta-plagiogranites from the Satovcha Ophiolite, Middle Allochthon, show that they are cogenetic and represent suprasubduction zone ophiolites. U-Pb dating using laser ablation sector field inductively coupled plasma mass spectrometry of zircons from two meta-plagiogranites and a metagabbro yielded identical Jurassic ages (160 ± 1 Ma, 160.6 ± 1.8 Ma, and 160 ± 1 Ma, respectively), similar to ophiolites in the eastern Vardar Zone bordering the Rhodopes to the SW. The trace element patterns also closely resemble those of the Vardar ophiolites. The association with Late Jurassic arc-type granitoids is another feature that applies both to eastern Vardar and Satovcha. This strongly suggests that the Middle Allochthon comprises the metamorphosed northeastward continuation of the Vardar Zone. The Jurassic age of the Satovcha Ophiolite contradicts the hypothesis of Early Jurassic suturing between Europe (Upper Allochthon) and the assumed Drama microcontinent (Lower Allochthon) but is in line with the 'maximum allochthony hypothesis,' i.e., the assumption that the Lower Allochthon represents Adria and that the 'root' of the Vardar-derived thrust sheets is at the NE boundary of the Rhodopes. [ABSTRACT FROM AUTHOR]

The whole-rock chemistry of eclogites, partially amphibolitized eclogites, and dyke amphibolites from the metamorphic Kechros complex in the eastern Rhodope Mountains preserves evidence of the geodynamic framework for the origin of their protoliths. Major and trace-element concentrations define two distinct protolith groups for the eclogites. The low-Fe-Ti (LFT) eclogites have low-TiO content (<0.67 wt%), negative high field strength element anomalies, and variable enrichments in large ion lithophile elements (LILE). The rare earth element (REE) patterns are characterized by strong light-REE (LREE) enrichment and heavy-REE (HREE) depletion. The high-Fe-Ti (HFT) eclogites have small to moderate LILE enrichment and lack Nb anomalies. The REE patterns of the HFT eclogites are characterized by LREE depletion and relatively flat MREE-HREE patterns. The rock compositions and petrographic features of the LFT eclogites resemble gabbros formed in a continental rift environment with minor to moderate contamination of a mantle-derived mafic magma by continental crust, whereas the HFT eclogites resemble mafic rocks formed in extensional oceanic environments. We interpret the HFT suite to represent a later stage in an evolution from continental rift to open ocean, following the origin of the LFT suite. Dyke amphibolite compositions, except for probable SiO loss associated with metamorphic dehydration reactions, appear to represent liquid compositions quenched in conduits through the lower crust. MELTS modeling shows that dyke amphibolite compositions can be related to each other by fractional crystallization under strongly oxidizing conditions at ~0.5 GPa pressure, and all can be derived from a low-degree melt of modified fertile peridotite from around 1.7 GPa. Cumulates crystallized from the parental liquids of the amphibolites under oxidizing conditions may have yielded the protoliths of the HFT suite. [ABSTRACT FROM AUTHOR]

The Vertiskos Unit of northern Greece is an elongated basement belt with a complex poly-metamorphic history. It extends from Greece (Chalkidiki peninsula), to the south, up to Serbia, in the north, and arguably represents the westernmost part of the Rhodope Metamorphic Province (northern Greece to southern Bulgaria). The Vertiskos Unit experienced a medium pressure lower amphibolite-facies metamorphic overprint during the Alpine Orogeny. The available medium-temperature geochronology implies that it remained at temperature of approximately 300°C (or slightly higher) during Lower Cretaceous. In order to constrain its post-Lower Cretaceous thermal history, until near-surface exposure, we applied apatite fission track analysis. The central ages obtained range from 68.5 ± 3.8 to 46.6 ± 3.6 Ma (uppermost Cretaceous to Middle Eocene) and mean track lengths between 13 and 13.5 µm. We applied two inverse thermal modeling approaches using either each sample independently (high degree of freedom in the thermal history, better data fit) or all samples together interpreting them as a vertical profile (simpler thermal history, worse data fit). Irrespective of the modeling approach, we conclude that the bulk thermal history of the Vertiskos Unit crosses the high-temperature limit of the apatite partial annealing zone by the uppermost Cretaceous and reaches near-surface conditions as early as lower/middle Eocene. These results contrast with the thermal history of the other domains of the Rhodope Metamorphic Province further east (namely the Southern Rhodope Core Complex and the Northern Rhodope Complex) and establish the Vertiskos basement complex as the oldest exhumed coherent basement fragment of the Rhodope Metamorphic Province and Greece. [ABSTRACT FROM AUTHOR]

The Sr-Nd isotopic ratios of selected post-collisional, calc-alkaline, I-type granitoids from the Pangeon pluton, intruding the lower tectonic unit (LTU) in the Southern Rhodope in the Miocene, support the existence of two types of granitoids (PTG porphyritic tonalite granodiorite and MGG biotite granodiorite to two-mica granite) unrelated by crystal fractionation and likely derived by partial melting of the same source under different P-T conditions. The Sr-Nd isotopic ratios of mafic enclaves in the granitoids as well as metamorphic rocks from the LTU have also been determined. At 22 Ma, the IRSrrange between 0.706850 and 0.708381, whereas the εNd(22)range from –3.86 to –1.05, with no relationship to granitoid types. The relationships between Sr and Nd isotopes as well as these isotopes and SiO2provide evidence of contamination of mafic melts by interaction with crust during magma differentiation. Both partial melting and AFC processes (r = 0.2) may account for compositional variations in the Pangeon magmas. The mafic enclaves display IRSrfrom 0.706189 to 0.707139, and εNd(22)from –2.29 to –1.94, similar to the granitoids, supporting the hypothesis of a common origin. Amphibolites inferred to be subduction-enriched metabasalts under-plated crust during old subduction can represent the source of the Pangeon melts. The TDMof the Pangeon granitoids is in the range 0.7–1.1 Ga for the inferred extraction age of the LILE-enriched subcontinental lithospheric mantle source. The upper crustal geochemical signatures and the relatively small isotopic composition of the Pangeon granitoids make these rocks similar to the coeval eastern-Mediterranean lamproites emplaced within the same geodynamic setting; this prompts similar melt sources. Lastly, the Pangeon granitoids display geochemical characteristics, isotopic ratios, and TDMalso similar to other Tertiary magmatic rocks from the Southern Rhodope and Biga peninsula, western Anatolia, suggesting a similar tectonic environment and co-magmatic evolution throughout the area. [ABSTRACT FROM AUTHOR]

Salix appendiculata is a typical Central European willow species. Its geographical distribution in the Balkan Peninsula is scattered and its occurrence in some Balkan countries is not yet clarified. The occurrence of the taxon in Greece is confirmed in this study. Leaf morphology of the Greek populations shows that they belong to S. appendiculata var. latifolia (A. Kerner) Rech. f. Finally, the ecological preferences of the taxon at the easternmost extent of its distribution are described with reference to bibliographic data. [ABSTRACT FROM AUTHOR]

The Rhodope Domain in NE Greece is comprised of different tectonometamorphic complexes involved in the Alpine collisional history between the Eurasian and African plates. The Kechros Complex represents the lowermost tectonic unit in East Rhodope, and contains a metamorphic suite of Na–Al-rich leucocratic rocks (i.e., alkali feldspar granites, alkali syenites and syenites) within the Virsini antigorite serpentinite. Based on the calculated P–T pseudosection and superimposed isopleths for a meta-syenite, we have determined a peak pressure and temperature of 1.55±0.03GPa and 550±25°C, suggesting HP metamorphism for leucocratic rocks enclosed in the Virsini serpentinized peridotites. The retrograde conditions suggest a prolonged exhumation history, with equilibration conditions first at P 1.1±0.03GPa and T 580±20°C and then at P 0.55±0.04GPa and T 430±30°C. The P–T conditions suggest an early rapid uplift event followed by a late-stage exhumation period, characterized by rapid cooling at relatively isobaric conditions. Similar metamorphic signatures are also recorded in continental rocks of the Kechros complex (i.e., orthogneisses, metapelites), suggesting that crustal and mantle rocks underwent a common Alpine tectonometamorphic evolution. The exact ages of HP metamorphism in the Kechros Complex are not well constrained, however, a Rb–Sr age of 37Ma from a neighboring orthogneiss records a stage of exhumation that may be contemporaneous with the Eocene HP metamorphism (49–55Ma; i.e., recorded in the Nestos Shear Zone of Central Rhodope). We interpret this to be the result of the eventual closure of the Axios/Vardar Ocean and subsequent subduction of the Apulian continental crust (a promontory of the Africa continent) under the southern margin of the European continent in the late Cretaceous and early Tertiary. [ABSTRACT FROM AUTHOR]

We investigated rutile needles with a clear shape preferred orientation in garnet from (ultra) high-pressure metapelites from the Kimi Complex of the Greek Rhodope by electron microprobe, electron backscatter diffraction and TEM techniques. A definite though complex crystallographic orientation relationship between the garnet host and rutile was identified in that Rt[001] is either parallel to Grt<111> or describes cones with opening angle 27.6° around Grt<111>. Each Rt[001] small circle representing a cone on the pole figure displays six maxima in the density plots. This evidence together with microchemical observations in TEM, when compared to various possible mechanisms of formation, corroborates a precipitate origin. A review of exchange vectors for Ti substitution in garnet indicates that rutile formation from garnet cannot occur in a closed system. It requires that components are exchanged between the garnet interior and the rock matrix by solid-state diffusion, a process we refer to as 'open-system precipitation' (OSP). The kinetically most feasible reaction of this type will dominate the overall process. The perhaps most efficient reaction involves internal oxidation of Fe to Fe and transfer from the dodecahedral to the octahedral site just vacated by $$ {\text{Ti}}^{ 4+ }: 6\,{\text{M}}^{ 2+ }_{ 3} {\text{TiAl}}\left[ {{\text{AlSi}}_{ 2} } \right]{\text{O}}_{ 1 2} + 6\,{\text{M}}^{ 2+ }_{ 2, 5} {\text{TiAlSi}}_{ 3} {\text{O}}_{ 1 2} = 10\,{\text{M}}^{ 2+ }_{ 3.0} {\text{Al}}_{ 1. 8} {\text{Fe}}_{0. 2} {\text{Si}}_{ 3} {\text{O}}_{ 1 2} + {\text{M}}^{2+} + 2 {\text{e}}^{-} + 1 2\,{\text{TiO}}_{ 2} . $$ OSP is likely to occur at conditions where the transition of natural systems to open-system behaviour becomes apparent, as in the granulite and high-temperature eclogite facies. [ABSTRACT FROM AUTHOR]

In the Central Rhodopes of southern Bulgaria, an eclogite-bearing rock sheet belonging to the Middle Allochthon (Starcevo Unit) is over- and underlain by eclogite-free, amphibolite-facies rock units along low-angle shear zones, the Borovica Shear Zone at the top and the Starcevo-Ardino Shear Zone at the base. The age of these shear zones is determined by U-Pb zircon dating of pre-, syn- and posttectonic magmatic rocks, mostly pegmatite veins, using LA-SF-ICP-MS. Zircons from pre- to syntectonic pegmatites within the Borovica Shear Zone yielded ages of ca. 45-43 Ma, indicating that the shear zone was active at that time, and zircons from a pretectonic pegmatite and a posttectonic granitoid body within the Starcevo-Ardino Shear Zone yielded ages of ca. 45 and ca. 36 Ma, respectively, giving a time frame for the activity of that shear zone which probably rather postdated the activity of the Borovica Shear Zone. By combining the ages with the kinematics of the shear zones and the metamorphic history of the rock units, the following scenario is sketched: Soon after the Starcevo Unit reached peak pressure (eclogite facies), it was exhumed to a mid-crustal level by top-to-the-north-west, extensional unroofing along the Borovica Shear Zone, in a kinematic framework of orogen-parallel extension. Beginning at ca. 40 Ma, the partly exhumed Starcevo Unit was underthrust from the south-west by continental crust of the foreland (Apulia), forming the Lower Allochthon of the Rhodopes, along the Starcevo-Ardino Shear Zone. These results underline the significance of orogen-parallel extension for the exhumation of high-pressure rocks. With respect to regional geology of the Hellenides and the Aegean, it is found that the tectonic architecture of the Rhodopes is essentially of Tertiary age. Cretaceous syn-metamorphic shear zones do exist but are largely restricted to higher levels of the nappe stack (Upper Allochthon). The Rhodopes do not represent an older essentially Mesozoic core of the Hellenides but are formed by the internal, higher-metamorphic portions of the same major nappe systems as occur in the Hellenides. [ABSTRACT FROM AUTHOR]

The Rhodope Domain in NE Greece consists of different tectonometamorphic complexes involved in the Alpine collisional history between the Eurasian and African plates. In the Kechros Complex, which is the lowermost tectonic unit in the East Rhodope, a lense of kyanite eclogite occurs within orthogneiss and common eclogites are found between serpentinized peridotite and underlying pelitic gneisses. In kyanite eclogite, the high-pressure (HP) mineral assemblage is Grt + Omp (Jd) + Ky + Ph + Qz + Rt + (indirectly inferred Tlc + Law); a Na-rich tremolite and zoisite formed at or near peak metamorphic conditions. In common eclogites, the HP mineral assemblage is Grt + Omp (Jd29-41) + Rt and, with less certainty, Amp (Gln-rich + Brs + Wnc + Hbl) ± Czo. The inclusions in garnet are glaucophane, actinolite, barroisite, hornblende, omphacite, clinozoisite, titanite, rutile and rarely paragonite and albite. In kyanite eclogite, peak P- T conditions are constrained at 2.2 GPa and 615°C using garnet-omphacite-phengite geothermobarometry and very similar values of 585 ± 32°C and 2.17 ± 0.11 GPa with the average P- T method, by which conditions of formation could also be narrowed down for the common eclogite (619 ± 53°C and 1.69 ± 0.17 GPa) and for a retrogressed eclogite (534 ± 36°C and 0.77 ± 0.11 GPa). Ages for the HP metamorphism in the Kechros Complex are not yet available. A Rb-Sr white mica age of 37 Ma from orthogneiss records a stage of the exhumation. The HP event may be coeval with the Eocene HP metamorphism (49-55 Ma) recorded in the Nestos Shear Zone in Central Rhodope and in the Attic-Cycladic crystalline belt, where it is interpreted as the result of subduction and final closure of the Axios/Vardar ocean and subsequent subduction of the Apulian continental crust (a promontory of the Africa continent) under the southern margin of the European continent in the late Cretaceous and early Tertiary. [ABSTRACT FROM AUTHOR]

Virtual Water is a recently introduced and widely recognized concept that is considered important for attaining regional and global water security. It refers to the water needed for the production of an agricultural or industrial product and it is contained in the product not in real but in virtual sense. The practical importance of the virtual water concept is mainly twofold, as virtual water trade can act as a tool to achieve water security and efficient water use, while water footprints can act as links between consumption patterns and the impacts on water. This paper applies the virtual water concept at regional level using the Prefectures of Xanthi and Rhodope as case studies. The ensuing results are juxtaposed and commented. [ABSTRACT FROM AUTHOR]

Abstract: In the central Rhodope mountains of Greece a carbonate-bearing metaperidotite lens ∼200×500m in size crops out as part of the high- to ultrahigh-pressure metamorphic Upper Sidironero Complex ∼500m SE of the Gorgona Village, north of Xanthi town. It is composed primarily of coarse grained (3–20mm in size) olivine and orthopyroxene, medium grained clinohumite and medium to fine grained tremolite, chlorite, dolomite, magnesite, talc, antigorite and various spinel phases. Whole-rock chemistry, mineral textures and compositions, and phase diagram calculations show that the metaperidotite was subjected to a prograde HP metamorphism, isofacial with the surrounding migmatitic gneisses, metapelites and amphibolites. The prograde character of metamorphism is demonstrated by inclusions of talc, antigorite, chlorite, dolomite, magnesite and Ti-clinohumite in ferrit-chromite, olivine, and orthopyroxene, as well as of olivine in orthopyroxene, and by the typical change in composition of zoned spinel minerals from ferrit-chromite in the core to chromian spinel at the rim. The prograde path is characterized by successive growth of amphibole, Ti-clinohumite, olivine and orthopyroxene, followed by the breakdown of Ti-clinohumite to olivine+Mg-ilmenite and of chlorite to olivine+spinel, probably during exhumation. The construction of a partial petrogenetic P–T grid in the system CaO–MgO–Al2O3–SiO2–CO2–H2O (CMASCH) for Ca-poor ultramafic bulk compositions has proven highly useful for the reconstruction of the metamorphic evolution and a P–T path, indicating that the use of univariant reactions in mixed volatile systems is highly warranted. The P–T path is clearly constrained to pressures below 1.5–1.7GPa by the absence of clinopyroxene. These pressures are slightly lower than those recorded in the closely associated Jurassic eclogites and much lower than those recorded in the diamond-bearing gneisses 5km to the south in the same tectonic unit. The carbonate-bearing metaperidotite from Gorgona probably represents a fragment of the hydrated mantle wedge. This is indicated by the REE compositions which differ from those of ophiolitic peridotites and resemble those of spinel or garnet peridotites of sub-continental origin. The ultramafic slice was incorporated tectonically into the subduction channel, most likely by tectonic erosion in the Early Jurassic, but did not experience ultrahigh-pressure metamorphism like the nearby metapelites that exhumed along the same subduction channel. [Copyright &y& Elsevier]

Abstract: The Rhodope Metamorphic Province in Bulgaria and Northern Greece has been affected by significant extensional tectonics since the Middle to Late Eocene. An important fault system active in the Eocene and Early Oligocene includes the Ribnovo Fault on the eastern side of the Mesta Basin in Bulgaria and the Vertiskos–Kerdilion Fault in Greece. Together with several minor normal fault relicts identified during this study, these represent an originally west-southwest-dipping, low-angle (at least at the end of faulting) normal fault with greenschist-facies mylonites in the footwall and cataclasites along the fault plane, the Mesta–Kerdilion Detachment, exposed over ca. 150km along strike and about 50km parallel to the slip direction. During the intrusion of several plutons in the Pirin Mountains at ca. 32Ma, the footwall of the fault was uplifted to form a large anticline parallel to fault strike, and the fault was offset by a system of antithetic, northeast-dipping normal faults along the northeastern flank of this anticline (Dobrotino and Breznitsa faults). The Mesta–Kerdilion Detachment was later, in the Miocene, again crosscut and offset by the southwest-dipping Strimon Valley Detachment which accommodated important, core complex-like exhumation to the South, strongly diminishing and finally ceasing towards north. This rotational activity of the Strimon Valley Detachment represents the onset of the extension that led to opening of the Aegean Basin. The Mesta–Kerdilion Detachment can be viewed as a precursor of this, but with slightly different kinematics (i.e. not involving significant vertical-axis rotation) and separated in time from the following events by a phase of relative tectonic quiescence in the Late Oligocene. [Copyright &y& Elsevier]

The occurrence of ultra high pressure (UHP) and high pressure (HP) relicts associated with oceanic material suggests the presence of a suture zone within the Rhodope Massif. Characterisation of the accreted igneous terranes and their relationship with the UHP/eclogite occurrences provide new constraints on the location of this suture. Single-zircon evaporation and sensitive high-resolution ion microprobe dating of orthogneiss protoliths define two groups of intrusion ages: Permo-Carboniferous and Late Jurassic–Early Cretaceous. Structurally, the Late Jurassic gneissic complex overthrust a unit with Permo-Carboniferous orthogneisses. A “melange zone” marked by mylonites, eclogites, amphibolites, and UHP micaschists separates these two units. We interpret these observations in terms of two distinct igneous terranes, the Thracia (Permo-Carboniferous) and Rhodope (Late Jurassic) terranes, separated by the Nestos suture, and assembled during the closure of an oceanic basin of the Tethys. Geochemically, the Late-Jurassic rocks are akin to subduction magmatism, possibly the same subduction that caused the UHP metamorphism of metasediments within the “melange zone”. Observed UHP–HP relicts are restricted to the tectonic contact zone, suggesting that a single subduction/collison event can explain the occurrences of UHP relicts and eclogites in the Central Rhodope, and that subducted rocks are exhumed only within the Nestos suture. [ABSTRACT FROM AUTHOR]

Abstract: Single and multiphase inclusions in garnet porphyroblasts from the diamond-bearing pelitic gneisses were studied by means of combined Raman Spectroscopy and Electron Scanning Microscopy (SEM/EDX). They are either randomly distributed or with preferred orientation within the garnet host and their dimensions vary from less than 5 up to 60μm. In the single-phase inclusions quartz, rutile, kyanite and graphite dominate. Biotite, zircon, apatite, monazite and allanite are also common. Two types of multiphase inclusions were recognized, hydrous silicate (Type I) and silicate–carbonate (Type II) ones. The carbon-bearing multiphase inclusions predominantly consist of Mg-siderite+graphite+CO2 +muscovite+quartz formed by a high density carboniferous fluid rich in Fe, Mg, Si and less Ca, Mn, Al and K trapped in the growing garnet in a prograde stage of metamorphism at high-pressure (HP) conditions. The carbon-free multiphase inclusions predominantly consist of biotite+quartz+rutile±kyanite+muscovite formed through decompression-dehydration/melting reactions of pre-existing phengite. Single and multiphase inclusions are characterized by polygonal to negative crystal shape formed by dissolution-reprecipitation mechanism between the garnet host and the inclusions during the long lasting cooling period (>100Ma) of the Kimi Complex. [Copyright &y& Elsevier]

Abstract: The monazite Th–Pb chronometer is widely used in a variety of geological contexts but may be affected by interaction with fluids. In the central part of the Rhodope Massif (Greece, Bulgaria), synfolial pegmatite veins were emplaced within two major synmetamorphic shear zones. In the Chepelare shear zone (CZS), which displays no evidence of post-metamorphic fluid flow, consistent monazite Th–Pb ages of ∼36 Ma are interpreted as dating vein emplacement. Higher in the metamorphic pile, zircon and monazite give U–Th–Pb ages of ∼42 Ma for vein emplacement. In the Nestos Shear Zone (NSZ) pegmatites show evidence of post-emplacement interaction with fluids during greenschist facies ductile deformation. Evidence for this includes the precipitation of calcite in microscale tension gashes within feldspar porphyroclasts, and the oxygen isotope disequilibrium between quartz and feldspar. Aqueous carbonic fluids deriving from carbonate lithologies in the footwall of the NSZ are identifiable in the pegmatites by the high δ 18O value of quartz (up to 21.8‰) and the presence of calcium in calcite veinlets. In these samples, some of the monazite grains show large intragrain scattering of Th–Pb age spanning up to ∼12 Ma, with intergrain scattering reaching ∼16 Ma (from ∼39 to ∼55 Ma). Within individual grains, age domains correlate with chemical heterogeneities, and some show a characteristic Ca-excess. These chemical and isotopic alterations are interpreted to be caused by interaction with fluids derived from carbonate lithologies. Complementary U–Pb data on zircons from the NSZ pegmatites yield mostly Mesozoic ages related to an older metamorphic cycle, and an age of ∼48 Ma for one grain with typical magmatic zoning. The Th–Pb ages of 49.3±1.6 to 54.9±1.7 Ma probably relate to the emplacement of the pegmatites. The spread of younger Th–Pb ages (from 38.6±1.1 to 46.2±1.6 Ma) probably reflects the period of fluid circulation during progressive cooling to greenschist facies conditions, or variable perturbations of the monazite isotope system during fluid-assisted greenschist facies deformation. This is consistent with 39Ar–40Ar mica ages of ∼32 to 34 Ma, interpreted as a tighter constraint for the timing of the greenschist facies metamorphism. This study illustrates the capacity of monazite to record distinct events in a single rock and highlights the need for identifying the potential involvement of fluids in order to interpret monazite ages. [Copyright &y& Elsevier]

Abstract: The region located between the Carpathian–Balkan and Aegean arcs, the Moesian Platform and Bulgarian Rhodope, is generally assumed to have been stably attached to the East European craton during the Cenozoic evolution of these arcs. The kinematic evolution of this region is, however, poorly constrained by paleomagnetic analysis. In this paper we provide new paleomagnetic data (800 volcanic and sedimentary samples from 12 localities) showing no significant post-Eocene rotation of the Moesian platform and Rhodope with respect to Eurasia, therefore confirming the stability of this region. We compare this result to a provided review of paleomagnetic data from the South Carpathians (Tisza block) and the Aegean region. The Tisza block underwent 68.4±16.7° of middle Miocene (∼15–10 Ma) clockwise rotation with respect to the Moesian Platform, in line with previous rotation estimates based on structural geology. The stability of the Moesian platform during middle Miocene eastward emplacement of the Tisza block into the Carpathian back-arc supports dextral shear along the Southern Carpathians recorded by 13–6 Ma clockwise strike-slip related rotations in foreland deposits. The new reference direction for the Moesian platform and Rhodope allows accurate quantification of the rotation difference with the west Aegean domain at 38.0±7.2° occurring between 15 and 8 Ma. To accommodate this rotation, we propose that the pivot point of the west-Aegean rotation was located approximately in the middle of the rotating domain rather than at the northern tip as previously proposed. This new scenario predicts less extension southeast of the pivot point, in good agreement with estimates from Aegean structural geology. Northwest of the pivot point, the model requires contraction or extrusion that can be accommodated by the coeval motion of the Tisza Block around the northwestern edge of the Moesian platform. [Copyright &y& Elsevier]

Abstract: Zircons from an eclogite and a diamond-bearing metapelite near the Kimi village (north-eastern Rhodope Metamorphic Complex, Greece) have been investigated by Micro Raman Spectroscopy, SEM, SHRIMP and LA-ICPMS to define their inclusion mineralogy, ages and trace element contents. In addition, the host rocks metamorphic evolution was reconstructed and linked to the zircon growth domains. The eclogite contains relicts of a high pressure stage (ca. 700 °C and >17.5 kbar) characterised by matrix omphacite with Jd40–35. This assemblage was overprinted by a lower pressure, higher temperature metamorphic event (ca. 820 °C and 15.5–17.5 kbar), as indicated by the presence of clinopyroxene (Jd35–20) and plagioclase. Biotite and pargasitic amphibole represent a later stage, probably related to an influx of fluids. Zircons separated from the eclogite contain magmatic relicts indicating Permian crystallization of a quartz-bearing gabbroic protolith. Inclusions diagnostic of the high temperature, post-eclogitic overprint are found in metamorphic zircon domain Z2 which ages spread over a long period (160–95 Ma). Based on zircon textures, zoning and chemistry, we suggest that the high-temperature peak occurred at or before ca. 160 Ma and the zircons were disturbed by a later event possibly at around 115 Ma. Small metamorphic zircon overgrowths with a different composition yield an age of 79±3 Ma, which is related to a distinct amphibolite-facies metamorphic event. The metapelitic host rock consists of a mesosome with garnet, mica and kyanite, and a quartz- and plagioclase-bearing leucosome, which formed at granulite-facies conditions. Based on previously reported micro-diamond inclusions in garnet, the mesosome is assumed to have experienced UHP conditions. Nevertheless, (U)HP mineral inclusions were not found in the zircons separated from the diamond-bearing metapelite. Inclusions of melt, kyanite and high-Ti biotite in a first metamorphic zircon domain suggest that zircon formation occurred during pervasive granulite-facies metamorphism. An age of 171±1 Ma measured on this zircon domain constrains the high-temperature metamorphic event. A second, inclusion-free metamorphic domain yielded an age of 160±1 Ma that is related to decompression and melt crystallization. The similar age data obtained from the samples indicate that both rock types recorded a high-T metamorphic overprint at granulite-facies conditions at ca. 170–160 Ma. This age implies that any high pressure or even ultra-high pressure metamorphism in the Kimi Complex occurred before that time. Our findings define new constraints for the geodynamic evolution for the Alpine orogenic cycle within the northernmost Greek part of the Rhodope Metamorphic Complex. It is proposed that the rocks of the Kimi Complex belong to a suture zone squeezed between two continental blocks and result from a Paleo-ocean basin, which should be located further north of the Jurassic Vardar Ocean. [Copyright &y& Elsevier]

Summary: The Aggitis karst system developed in the marbles of the Rhodope massif. The conditions of the development of its karst drainage network are determined from the geological and geomorphologic settings by means of a microstructural analysis, following Eraso’s method. This analysis shows that the karst conduit network intensely developed in the western part of the mountain Falakro where the majority of the open fractures oriented in the same direction as the hydraulic gradient, while the two directions are perpendicular in its eastern part drained by the spring of Drama. The behaviour of the system was analysed by means of hydrodynamic and water geochemical techniques. Despite the extension of the cave system and of the favourable development conditions of conduits, the functioning appears complex, with a significant storage, and a slow infiltration as well as an easy drainage. On the contrary the Drama karst system, characterised by a low variability in its hydrological and geochemical characteristics does not show any karst functioning. In the Aggitis karst system the initial groundwater flow conditions in combination with the aperture planes of which the directions are in agreement with the hydraulic gradient, favoured the rapid development of a drainage network system. The recharge from a large surface catchment area on non-karstic rocks, through swallow holes in a wide polje contributed to increase the groundwater flow through the karst part of the system, facilitating the development of the conduits. [Copyright &y& Elsevier]

The tectonic evolution of the Rhodope massif involves Mid-Cretaceous contractional deformation and protracted Oligocene and Miocene extension. We present structural, kinematic and strain data on the Kesebir–Kardamos dome in eastern Rhodope, which document early Tertiary extension. The dome consists of three superposed crustal units bounded by a low-angle NNE-dipping detachment on its northern flank in Bulgaria. The detachment separates footwall gneiss and migmatite in a lower unit from intermediate metamorphic and overlying upper sedimentary units in the hanging wall. The high-grade metamorphic rocks of the footwall have recorded isothermal decompression. Direct juxtaposition of the sedimentary unit onto footwall rocks is due to local extensional omission of the intermediate unit. Structural analysis and deformational/metamorphic relationships give evidence for several events. The earliest event corresponds to top-to-the SSE ductile shearing within the intermediate unit, interpreted as reflecting Mid-Late Cretaceous crustal thickening and nappe stacking. Late Cretaceous–Palaeocene/Eocene late-tectonic to post-tectonic granitoids that intruded into the intermediate unit between 70 and 53 Ma constrain at least pre-latest Late Cretaceous age for the crustal-stacking event. Subsequent extension-related deformation caused pervasive mylonitisation of the footwall, with top-to-the NNE ductile, then brittle shear. Ductile flow was dominated by non-coaxial deformation, indicated by quartz c-axis fabrics, but was nearly coaxial in the dome core. Latest events relate to brittle faulting that accommodated extension at shallow crustal levels on high-angle normal faults and additional movement along strike-slip faults. Radiometric and stratigraphic constraints bracket the ductile, then brittle, extensional events at the Kesebir–Kardamos dome between 55 and 35 Ma. Extension began in Paleocene–early Eocene time and displacement on the detachment led to unroofing of the intermediate unit, which supplied material for the syn-detachment deposits in supra-detachment basin. Subsequent cooling and exhumation of the footwall unit from beneath the detachment occurred between 42 and 37 Ma as indicated by mica cooling ages in footwall rocks, and extension proceeded at brittle levels with high-angle faulting constrained at 35 Ma by the age of hydrothermal adularia crystallized in open spaces created along the faults. This was followed by Late Eocene–Oligocene post-detachment overlap successions and volcanic activity. Crustal extension described herein is contemporaneous with the closure of the Vardar Ocean to the southwest. It has accommodated an earlier hinterland-directed unroofing of the Rhodope nappe complex, and may be pre-cursor of, and/or make a transition to the Aegean back-arc extension that further contributed to its exhumation during the Late Miocene. This study underlines the importance of crustal extension at the scale of the Rhodope massif, in particular, in the eastern Rhodope region, as it recognizes an early Tertiary extension that should be considered in future tectonic models of the Rhodope and north Aegean regions. [ABSTRACT FROM AUTHOR]

This article presents the findings of the first major visitor survey conducted at the Central Rhodope Mountain Complex, situated in northern Greece. The study area is one of a number of sites planned to become National Parks under a recent initiative of the Greek government. We used a logistic regression method to define significant predictors of visitors’ awareness and attitude toward park designation, as well as their willingness to pay a conditional entrance fee. Study findings demonstrated that the probability of being aware of the park designation initiative is higher for visitors who obtained information from travel agencies or media to make their destination choice, compared to visitors who resorted to word-of-mouth recommendations. Knowledge and attitudes toward animals living in the study area revealed a limited influence on visitors’ dispositions toward park designation. The results of this study call for action to implement education programs for National Park users. These programs should aim at rendering the environmental characteristics of the Central Rhodope Mountain Complex to be significant predictors of visitors’ dispositions toward the study area. This would favor its uniqueness as a destination, as well as contribute to its long-term economic sustainability. [ABSTRACT FROM AUTHOR]

Abstract: Orthogneisses of late-Hercynian protolith age crop out in the Central Rhodope high-grade metamorphic complex, which is part of the Alpine orogen in south-eastern Europe. They compose a tectonic unit bordered by late-Alpine extensional shear zones. These rocks reflect Eocene amphibolite facies migmatization (&#60;750 °C/0.9–0.5 GPa). The low-temperature melting favored zircon inheritance and disturbed mainly the LILE protolith compositions. Despite the intense Alpine metamorphic overprint, the major elements, HFSE and REE reflect the initial composition of the Hercynian protolith. A geochemical data set summarizing 200 whole rock analyses testifies to a calc-alkaline magma differentiation producing a compositional range of tonalite and/or granodiorite to granite and leucocratic granite. Geochemical compositions combined with published isotope and age data suggest dominant I-type protoliths and mixed magma sources including crustal and mantle material, and distinguish between older granitoids of volcanic-arc affinity and probably younger ones of late or post-collision origin. [Copyright &y& Elsevier]

Structural analysis of low-grade rocks highlights the allochthonous character of Mesozoic schists in southeastern Rhodope, Bulgaria. The deformation can be related to the Late Jurassic–Early Cretaceous thrusting and Tertiary detachment faulting. Petrologic and geochemical data show a volcanic arc origin of the greenschists and basaltic rocks. These results are interpreted as representing an island arc-accretionary complex related to the southward subduction of the Meliata–Maliac Ocean under the supra-subduction back-arc Vardar ocean/island arc system. This arc-trench system collided with the Rhodope in Late Jurassic times. To cite this article: N.G. Bonev, G.M. Stampfli, C. R. Geoscience 335 (2003). [Copyright &y& Elsevier]

U–Pb ion microprobe (SHRIMP) dating of zircon domains assisted by cathodoluminescence imaging was carried out on (1) a garnet-rich mafic rock and (2) a cross-cutting pegmatoid from the area of Kimi, East Rhodope. Quartz exsolution lamellae in cpx of the garnet-rich mafic rock point to a precursor supersilicic cpx implying pressures >2.5 GPa. This indicates UHP conditions for the studied geotectonic unit and is in line with the (rare) presence of radial cracks around quartz inclusions in garnet, which suggest the former presence of coesite. Bleb-shaped cpx inclusions in garnet may be interpreted as primary inclusions during garnet growth. However, based on their shape and general orientation, the possibility that they represent exsolutions from a precursor majoritic garnet, in an advanced state of recrystallization (coalescing initial needles) remains open and needs further investigation. If the latter is proven true, it implies minimum pressures of 4 GPa.The oscillatory zoned domains of the zircon crystals from the garnet-rich mafic rock yield a weighted mean age at 117.4±1.9 Ma (Early Cretaceous) for the magmatic crystallization of the protolith. The zircon domains characterized by clearly fainted oscillatory zoning and/or U-rich embayments of the same zircon crystals are interpreted as metamorphic domains. They yield a weighted mean age of metamorphism at 73.5±3.4 Ma (Late Cretaceous). Different degrees of Pb loss resulted in discordant ages scattering between the magmatic and metamorphic age. The euhedral oscillatory zoned zircons of the cross-cutting pegmatoid yield a weighted mean age of 61.9±1.9 Ma for the time of emplacement and crystallization of retrograde metamorphic fluids into the middle-upper crust. Two scenarios are considered as possible for the interpretation of the SHRIMP-results and the petrological observations: (1) the protolith was an ultra high pressure melt (probably a grt±cpx cumulate) crystallizing in the mantle at Early Cretaceous times, partly exhumed into the lithosphere by mantle upwelling, and then transferred to a subduction zone and metamorphosed under eclogite-facies conditions in the Late Cretaceous; (2) the protolith was a cumulate within a gabbroic melt crystallizing at high crustal levels in the Early Cretaceous and subsequently metamorphosed under UHP conditions in the Late Cretaceous. Retrograde stages of metamorphism (ca. 500 °C, 0.5 GPa) occurred at 61.9±1.9 Ma.The petrological findings, which provide evidence for UHP conditions for these rocks of the Kimi Unit, combined with the SHRIMP-results, reveal different conditions of rock formation at different times for the Rhodope zone. The existence of a subduction zone in the Late Cretaceous shows that the Rhodope was not metamorphosed as a single geotectonic element but consists of different terranes subducted and exhumed at different times. [Copyright &y& Elsevier]