Mating propensities and variations in enzyme activities in long-term cage populations of Drosophila melanogaster.

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ΤΗE PELAGONIAN NAPPE PILE IN NORTHERN GREECE AND FYROM. STRUCTURAL EVOLUTION DURING THE ALPINE OROGENY: A NEW APROACH

The geometry of kinematics and the deformation history of the Pelagonian nappe pile during the Alpine orogeny have been studied in Northern Greece and FYROM. Deformation was started in Middle-Late Jurassic time and was initially associated with ocean-floor subduction followed by ophiolites obduction, nappe stacking and duplication of the Pelagonian continent. The footwall Pelagonian segment from top to bottom was metamorphosed under greenschist to amphibolit facies conditions and a relative high pressure (T = 450o to 620o C and P = 12,5 to 8 kb). Blueschist facies metamorphic assemblages of Late Jurassic age are immediately developed between both hangingwall and footwall Pelagonian segments. Transgressive Late Jurassic-Early Cretaceous neritic limestones and clastic sediments on the top of the obducted ophiolites are maybe related to extension and basins formation simultaneously with the nappe stacking and metamorphism at the lower structural levels of the Pelagonian nappes. Contractional tectonics and nappe stacking continued during the Albian-Aptian time. Simultaneously retrogression and pressure decreasing taken place at the tectonic lower Pelagonian footwall segment. Low grade mylonitic shear zones, possible related to extension, are developed during Late Cretaceous time simultaneously with basins formation and sedimentation of neritic Late Cretaceous to Paleocene limestones and flysch. Intense shortening and imbrication under semi-ductile to brittle conditions occurred during Paleocene to Eocene time resulting the onset of the dome like formation of the footwall Pelagonian segment. The next stages of deformation from Oligocene to Quaternary are related to brittle extension and the final uplift and configuration of the Pelagonian nappe pile

The Mesohellenic trough and the Thrace Basin. Two Tertiary molassic Basins in Hellenides: do they really correlate?

Με βάση τη λιθοστρωματογραφία, την τεκτονική ανάλυση και τη γεωλογική χαρτο- γράφηση συγκρίθηκαν μεταξύ τους, οι μολασσικές λεκάνες της Θράκης (ThB) στη ΒΑ Ελλάδα (συμπεριλαμβάνονται οι Παλαιογενείς αποθέσεις της λεκάνης Αξιού) και της Μεσοελληνικής Αύλακας. Αμφότερες οι λεκάνες χαρακτηρίζονται από μια παχειά, μολασσικού-τύπου ιζηματογενή ακολουθία (3-5 km πάχος) Τριτογενούς ηλικίας, που καλύπτεται ασύμφωνα από Νεογενή και Τεταρτογενή ιζήματα. Η μολασσκή ιζηματογένεση αρχίζει σχεδόν ταυτόχρονα και στις δύο περιοχές κατά τη διάρκεια του Μέσου- Άνω Ηωκαίνου όμως σταματάει σε διαφορετικούς χρόνους, στο Μέσο-Άνω Μειόκαινο για τη ΜΗΤ και στο Άνω Ολιγόκαινο για τη ThB. Η ιζηματογένεση στη ThB συνοδεύτηκε επί πλέον από έναν ασβεσταλκαλικής και τοπικά σωσωνιτικής σύστασης μαγματισμό, Ηωκαινικής-Ολιγοκαινικής ηλικίας. Ερμηνεύσαμε τη ΜΗΤ ως μια πολυιστορική οριζόντιας μετατόπισης, piggy-back λεκάνη, που αποτέθηκε επάνω σε οφιόλιθους και στο Πελαγονικό κάλυμμα κατά την προς τα δυτικά τοποθέτησή τους πάνω στο κρύο πρίσμα επαύξησης των Ελληνίδων. Αντίθετα, η ThB αναπτύχθηκε ως μια Παλαιογενή λεκάνη, πάνω σε ρήγμα διαφυγής και στις γεωλογικές ενότητες των εσωτερικών Ελληνίδων, κατά τη διάρκεια της Ηωκαινικής-Ολιγοκαινικής έκτασης των Εσωτερικών Ελληνίδων. Ο σύγχρονος με την ιζηματογένεση μαγματισμός, πιθανόν, συνδέεται με τις ορογενετικές διαδικασίες υποβύθισης του ωκεανού της Πίνδου ή του Αξιού. Σε κάθε περίπτωση ΜΗΤ και ThB αναπτύχθηκαν κατά τη διάρκεια πλάγιας σύγκλισης της Απουλίας πλάκας και των Εσωτερικών Ελληνίδων.Based on lithostratigraphic and structural data, as well as geological mapping, the mollasic Thrace Basin (ThB) in NE Greece (including the Paleogene deposits of the Axios Basin) was compared with the Mesohellenic Trough (MHT) in NW Greece. Both basins are characterized by a thick sedimentary sequence of molassic-type strata (3-5km thickness) of Tertiary age, overlain unconformably by Miocene- Pliocene and Quaternary deposits. Molassic sedimentation started almost simultaneously in both areas during the Mid-Upper Eocene but it finished in different time, in the Mid-Upper Miocene for the MHT and the Upper Oligocene for the ThB, respectively. Sedimentation in ThB was also linked with an important calc-alkaline and locally shoshonitic magmatism of Eocene-Oligocene age. We interpreted the MHT as a polyhistory strike-slip and piggy-back basin, above westward-emplacing ophiolites and Pelagonian units on the cold Hellenic accretionary prism. In contrast to MHT, the ThB evolved as a Paleogene supra-detachment basin above the strongly extended during the Eocene-Oligocene Hellenic Hinterland. The syn-depositional magmatic products, linked possibly with subduction processes in Pindos or Axios ocean(s). In any case, MHT and ThB are related to inferred oblique convergence of the Apulia plate and the internal Hellenic units

Origin of the Rubian carbonate-hosted magnesite deposit, Galicia, NW Spain: mineralogical, REE, fluid inclusion and isotope evidence)

The Rubian magnesite deposit (West Asturian—Leonese Zone, Iberian Variscan belt) is hosted by a 100-m-thick folded and metamorphosed Lower Cambrian carbonate/siliciclastic metasedimentary sequence—the Cándana Limestone Formation. It comprises upper (20-m thickness) and lower (17-m thickness) lens-shaped ore bodies separated by 55 m of slates and micaceous schists. The main (lower) magnesite ore body comprises a package of magnesite beds with dolomite-rich intercalations, sandwiched between slates and micaceous schists. In the upper ore body, the magnesite beds are thinner (centimetre scale mainly) and occur between slate beds. Mafic dolerite dykes intrude the mineralisation. The mineralisation passes eastwards into sequence of bedded dolostone (Buxan) and laminated to banded calcitic marble (Mao). These show significant Variscan extensional shearing or fold-related deformation, whereas neither Rubian dolomite nor magnesite show evidence of tectonic disturbance. This suggests that the dolomitisation and magnesite formation postdate the main Variscan deformation. In addition, the morphology of magnesite crystals and primary fluid inclusions indicate that magnesite is a neoformed hydrothermal mineral. Magnesite contains irregularly distributed dolomite inclusions (<50 μm) and these are interpreted as relics of a metasomatically replaced dolostone precursor. The total rare earth element (REE) contents of magnesite are verysimilar to those of Buxan dolostone but are depleted in light rare earth elements (LREE); heavy rare earth element concentrations are comparable. However, magnesite REE chondrite normalised profiles lack any characteristic anomaly indicative of marine environment. Compared with Mao calcite, magnesite is distinct in terms of both REE concentrations and patterns. Fluid inclusion studies show that the mineralising fluids were MgCl2–NaCl–CaCl2–H2O aqueous brines exhibiting highly variable salinities (3.3 to 29.5 wt.% salts). This may be the result of a combination of fluid mixing, migration of pulses of variable-salinity brines and/or local dissolution and replacement processes of the host dolostone. Fluid inclusion data and comparison with other N Iberian dolostone-hosted metasomatic deposits suggest that Rubian magnesite probably formed at temperatures between 160 and 200°C. This corresponds, at hydrostatic pressure (500 bar), to a depth of formation of ∼5 km. Mineralisation- related Rubian dolomite yields δ18O values (δ18O: 12.0–15.4‰, mean: 14.4±1.1‰) depleted by around 5‰ compared with barren Buxan dolomite (δ18O: 17.1– 20.2‰, mean: 19.4±1.0‰). This was interpreted to reflect an influx of 18O-depleted waters accompanied by a temperature increase in a fluid-dominated system. Overlapping calculated δ18Ofluid values (∼+5‰ at 200°C) for fluids in equilibrium with Rubian dolomite and magnesite show that they were formed by the same hydrothermal system at different temperatures. In terms of δ13C values, Rubian dolomite (δ13C: −1.4 to 1.9‰, mean: 0.4±1.3‰) and magnesite (δ13C: −2.3 to 2.4‰, mean: 0.60±1.0‰) generally exhibit more negative δ13C values compared with Buxan dolomite (δ13C: −0.2 to 1.9‰, mean: 0.8± 0.6‰) and Mao calcite (δ13C: −0.3 to 1.5‰, mean: 0.6± 0.6‰), indicating progressive odification to lower δ13C values through interaction with hydrothermal fluids. 87Sr/86Sr ratios, calculated at 290 Ma, vary from 0.70849 to 0.70976 for the Mao calcite and from 0.70538 to 0.70880 for the Buxan dolostone. The 87Sr/86Sr ratios in Rubian magnesite are more radiogenic and range from 0.71123 to 0.71494. The combined δ18O–δ13C and 87Sr/86Sr data indicate that the magnesite-related fluids were modified basinal brines that have reacted and equilibrated with intercalated siliciclastic rocks. Magnesite formation is genetically linked to regional hydrothermal dolomitisation associated with lithospheric delamination, late-Variscan high heat flow and extensional tectonics in the NW Iberian Belt. A comparison with genetic models for the Puebla de Lillo talc deposits suggests that the formation of hydrothermal replacive magnesite at Rubian resulted from a metasomatic column with magnesite forming at higher fluid/rock ratios than dolomite. In this study, magnesite generation took place via the local reaction of hydrothermal dolostone with the same hydrothermal fluids in very high permeability zones at high fluid/rock ratios (e.g. faults). It was also possibly aided by additional heat from intrusive dykes or sub-cropping igneous bodies. This would locally raise isotherms enabling a transition from the dolomite stability field to that of magnesite

Génesis del yacimiento de magnesita de Rubián (Lugo): nueva interpretación basada en datos petrológicos y geoquímicos

The Rubian sparry magnesite (Galicia, NW Spain) is hosted in Lower Cambrian carbonate rocks (Caliza de Cándana Fm.) included in a strongly deformed and faulted thick succession of siliciclastic and carbonate rocks. The magnesite shows massive and banded fabrics. δ18 O SMOW values range from 13,32‰ to 17,22‰ whilst δ13C PDB values range from -2,32‰ to 2,37‰. Radiogenic strontium isotopes from magnesite exceed 0.711435, considerably higher than those commonly reported for Cambrian marine carbonates. Similarly, REE patterns do not show any sort of anomaly indicative of marine environment. Fluid inclusions can be interpreted as a result of NaCI-CaCI2(±MgCI2) mineralising brines, probably by mixing of two CaCI2 -rich fluids of contrasted salinity, and allow to conclude that magnesite formed at a minimum temperature of 170±15QC. Accordingly, a hydrothermal/metasomatic replacement of preexisting dolostone is proposed as a more reliable process to explain the origin of the sparry magnesite of Rubian, which is in contrast with previous interpretations that supported a syn-diagenetic model for the formation of the deposit

Kinematics of the Southern Rhodope Core Complex (North Greece)

The Southern Rhodope Core Complex is a wide metamorphic dome exhumed in the northern Aegean as a result of large-scale extension from mid-Eocene to mid-Miocene times. Its roughly triangular shape is bordered on the SW by the Jurassic and Cretaceous metamorphic units of the Serbo-Macedonian in the Chalkidiki peninsula and on the N by the eclogite bearing gneisses of the Sideroneron massif. The main foliation of metamorphic rocks is flat lying up to 100 km core complex width. Most rocks display a stretching lineation trending NEâ SW. The Kerdylion detachment zone located at the SW controlled the exhumation of the core complex from middle Eocene to mid-Oligocene. From late Oligocene to mid-Miocene exhumation is located inside the dome and is accompanied by the emplacement of the synkinematic plutons of Vrondou and Symvolon. Since late Miocene times, extensional basin sediments are deposited on top of the exhumed metamorphic and plutonic rocks and controlled by steep normal faults and flat-ramp-type structures. Evidence from Thassos Island is used to illustrate the sequence of deformation from stacking by thrusting of the metamorphic pile to ductile extension and finally to development of extensional Plio-Pleistocene sedimentary basin. Paleomagnetic data indicate that the core complex exhumation is controlled by a 30� dextral rotation of the Chalkidiki block. Extensional displacements are restored using a pole of rotation deduced from the curvature of stretching lineation trends at core complex scale. It is argued that the Rhodope Core Complex has recorded at least 120 km of extension in the North Aegean, since the last 40 My