Variscan basic dykes in the Pelagonian (Northern Greece and south FYROM): Geodynamic significance based on petrological, geochemical and geochronological studies

Dolerite dykes intruding Variscan plutonites were studied in terms of mineralogy, petrology, geochemistry and geochronology. The main mineral constituents were studied and the sequence of crystallization has been derived. The geochemical characteristic indicate mantle origin of the dolerites and magma sources different from the hosting granitoids. From SHRIMP analyses of five spots on four different zircon crystals, resulted a 292.0±4.1 Ma age that is interpreted as the time of crystallization of the dolerite. The hosting granitoids are probably the result of mixing between two possible end-members: enriched mantle and acid metaigneous or lower crustal metasediments. The Variscan age of the dolerites, in combination with the geochemical characteristics, indicated that the enriched mantle basaltic material should be the source of the dolerite veins. These mantle-derived basaltic melts may represent the underplated material, which probably provided the necessary thermal input to the dehydration melting in the lower crust. The dolerites should have intruded the newly formed batholiths before or at the first stages of their uplift, recording the last events of the Variscan subduction. © 2005 Elsevier GmbH. All rights reserved

Occurrence of primary almandine-spessartine-rich garnet and zinnwaldite phenocrysts in a Neogene rhyolite on the island of Chios, Aegean Sea, Greece

Primary almandine and spessartine-rich garnet and zinnwaldite phenocrysts occur along with feldspar (plagioclase and sanidine) phenocrysts, in the rhyolite of Profitis Ilias, which is located on the SE coast of the island of Chios, Greece. The distinctive mineralogical composition of this rhyolite is described. Although formed in the back-arc tectonic environment of the Aegean volcanic arc, the Profitis Ilias rhyolite shows significant trace element compositional differences when compared with typical arc or back-arc volcanic rocks of the area. It shows extreme depletion in Sr and Ba and enrichment in Nb and Mn, and has much more affinity with A-type granites and particularly Li-mica granites. Apparently, both zinnwaldite and spessartine-rich garnet can be generated as primary phases from a granite melt enriched in volatile constituents at low P-T. This granite melt could be the residual product of an un-exposed, earlier formed, typical back-arc granite of the area, enriched in volatile constituents from a subcrustal source above the active mantle of the eastern Aegean area. The extensive and deep faulting in the broad eastern Aegean lithosphere section would have facilitated the rapid ascent of that volatile-enriched granite melt, the parent of the Profitis Ilias rhyolite

A mineralogical petrographic and geochemical study of samples from wells in the geothermal field of Milos Island (Greece)

This paper presents a study of hydrothermal alteration on Milos island, Greece. Examination of cores and cuttings from the two drill sites, obtained from a depth of about 1100 m in Milos geothermal field, showed that the hydrothermal minerals occurring in the rock include: K-feldspar, albite, chlorite, talc, diopside, epidote, muscovite, tremolite, kaolinite, montmorillonite, alunite, anhydrite, gypsum, calcite, and opaque minerals. The chemical composition of the minerals (104 analyses) was determined with Electron Probe Microanalysis. The composition of the hydrothermal fluid was determined and correlated with the mineralogy. Isotopic ratios of C and O for one calcite sample taken from 341 m depth were determined and used for geochemical calculations. A number of reactions feasible at the P-T conditions of the geothermal field are given to establish the chemical evolution of the hydrothermal fluid. The distribution of the hydrothermal minerals indicates the dilution of the K-, Na-, Cl-rich hydrothermal fluid of the deep reservoir by a Ca-, Mg-rich cold water at a shallower level. © 1991

Crystal chemistry, structure analyses and phase transition experiment on an omphacite from eclogitic metagabbro from Syros island, Greece

Pyroxene samples, from the Greek island of Syros, taken from a blueschist-eclogite facies Mg-rich metagabbro, were investigated by chemical and XRD analyses and Mössbauer spectroscopy. Single-crystal XRD and microprobe analysis showed that the natural sample is a typical omphacite of intermediate composition in the Ca-Na pyroxene solid solutions. The space group P2/n was confirmed and the cations Mg, Al and Ca, Na were found to be ordered in the M1 and M2 positions, respectively. Mössbauer spectroscopy showed that there is both ferrous and ferric iron in the structure, with the ratio 1.38:1. The M2 sites are fully occupied by Ca and Na, thus the iron (Fe2+ and Fe3+) can substitute only for Mg and Al in the M1 sites. Partial disorder was attained by annealing the sample at 850 °C, 20 kbar for 7 days, as confirmed by decrease of intensity of reflections affected by the C-type extinction. © Springer-Verlag 2007

A multi-analytical study of the crystal structure of unusual Ti-Zr-Cr-rich Andradite from the Maronia skarn, Rhodope massif, western Thrace, Greece

Unusual Ti-Cr-Zr-rich garnet crystals from high-temperature melilitic skarn of the Maronia area, western Thrace, Greece, were investigated by electron-microprobe analysis, powder and single-crystal X-ray diffraction, IR, Raman and Mössbauer spectroscopy. Chemical data showed that the garnets contain up to 8 wt.% TiO2, 8 wt.% Cr2O3 and 4 wt.% ZrO2, representing a solid solution of andradite (Ca3Fe3+2 Si3O12 ≈46 mol%), uvarovite (Ca3 Cr2Si3O12 ≈23 mol%), grossular (Ca3Al2Si3O12 ≈10 mol%), schorlomite (Ca3Ti2[Si,(Fe3+, Al3+)2]O12 ≈15 mol%), and kimzeyite (Ca3Zr2 [Si,Al2]3 O12 ≈6 mol%). The Mössbauer analysis showed that the total Fe is ferric, preferentially located at the octahedral site and to a smaller extent at the tetrahedral site. Single-crystal XRD analysis, Raman and IR spectroscopy verified substitution of Si mainly by Al3+, Fe3+ and Ti4+. Cr3+ and Zr4+ are found at the octahedral site along with Fe3+, Al3+ and Ti4+. The measured H2O content is 0.20 wt.%. The analytical data suggest that the structural formula of the Maronia garnet can be given as: (Ca2.99Mg0.03) ∑=3.02 (Fe3+0.67Cr0.54Al0.33 Ti0.29Zr0.15)∑=1.98 (Si2.42Ti0.24Fe0.18Al0.14) ∑=2.98O12OH0.11. Ti-rich garnets are not common and their crystal chemistry is still under investigation. The present work presents new evidence that will enable the elucidation of the structural chemistry of Ti- and Cr-rich garnets. © Springer-Verlag 2008

The Acheulian site at Rodafnidia, Lisvori, on Lesbos, Greece: 2010–2012

Rodafnidia is an Acheulian site on Lesbos Island, in the north-east Aegean Sea. This chapter presents the model that guided Paleolithic investigations on the island, the history of research, and the results of the 2012 expedition of systematic work in the field, which consisted of surface survey and excavation. The typology and technology of lithic artifacts from the surface and the uppermost Unit 1, as well as the first cluster of luminescence dates, firmly place the early component of the site in the Middle Pleistocene. The Acheulian industry derives from fluvio-lacustrine deposits at a locale with abundant fresh-water and lithic resources. Situated in the north-east Mediterranean Basin, an area where research on early hominin prehistory is intensifying, Rodafnidia holds the potential to contribute to Eurasian Lower Paleolithic archaeology and fill the gap in our understanding of early hominin presence and activity where Asia meets Europe. © 2016, Springer Science+Business Media Dordrecht

Correction of the structure of a new sesquiterpene from Cistus creticus ssp. creticus

In an attempt to identify the structure of a sesquiterpene from Cistus creticus ssp. creticus proposed in the literature as 1,1,4a,6-tetramethyl-5- methylene-1,2,3,4,4α,5,8,8α-octahydronaphthalene, the synthesis of its cis isomer 2 was carried out in 11 steps and 9.5% yield. Comparison of the spectra of 2 and those reported earlier for the synthetic irons isomer 1 with the spectral profile of the isolated natural product indicated that the latter was not compatible with either 1 or 2. The correct structure was assigned, by detailed spectroscopic analysis of the natural product, as 6-isopropenyl-4,4a- dimethyl-1,2,3,4,4a,5,6,7-octahydronaphthalene (3)