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Geochemistry and evolution of the fanos granite,N. Greece 总被引：1，自引：0，他引：1
Summary The Fanos granite, a Jurassic pluton composed of high silica fine- to coarse-grained leucogranites, is associated with and intrudes the Mesozoic Guevgueli ophiolitic complex. Discriminant diagrams indicate a collision related plate tectonic environment for the rocks studied. They are peraluminous with calc-alkaline affinities. Major and trace element behaviour suggest a fractional crystallization process for the evolution of the Fanos granite. Petrographic calculations, based on major elements, require 32% crystal accumulation mainly of plagioclase, K-feldspar and biotite for a direct model, while for a two-step model 21% and 14% crystal cumulate is required for the first and the second step respectively.
With 6 Figures 相似文献
Geochemie und Entwicklungsgeschichte des Fanos-Granites, N-Griechenland
Zusammenfassung Der jurassische Fanos-Granit ist ein fein- bis grobkörniger Leukogranit mit hohem Silikatanteil. Er ist mit dem mesozoischen Ophiolithkomplex von Guevgueli, mit dem er in instrusivem Kontakt steht, verknüpft.Diskriminierungsdiagramme weisen darauf hin, dab die untersuchten Gesteine im Zuge kollisions-tektonischer Prozesse gebildet wurden. Die untersuchten peraluminösen Gesteine folgen einem kalkalkalischen Trend. Die Haupt- und Spurenelementverteilungen belegen eine fraktionierte Kristallisation des Fanos-Granites. Einfache Mischungsmodell-Berechnungen, die mittels der Hauptelemente erstellt wurden, ergeben eine 32 %ige Kristallakkumulation von vorwiegend Plagioklas, Kalifeldspat und Biotit. Eine Zweistufenmodell-Berechnung ergab eine 21- beziehungsweise 14 %ige Kristallakkumulation für die erste und zweite Stufe.
With 6 Figures 相似文献
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Diego Perugini Giampiero Poli George Christofides George Eleftheriadis Antonis Koroneos Triantafyllos Soldatos 《Geological Journal》2004,39(1):63-80
Two distinct groups of subduction‐related (orogenic) granitoid rocks, one Jurassic and the other Tertiary, occur in the area between the Vardar (Axios) Zone and the Rhodope Massif in northern Greece. The two groups of granitoids differ in many respects. The first group shows evolved geochemical characters, it is not associated with mafic facies, and evidence of magmatic interaction between mantle‐ and crustal‐derived melts is lacking. The second group has less evolved geochemical characters, it is associated with larger amount of mafic facies, and magmatic interaction processes between mantle‐derived and crustal melts are ubiquitous as evidenced by mafic microgranular enclaves and synplutonic dykes showing different enrichment in K2O, Ti, and incompatible elements. This kind of magmatism can be attributed to the complex geodynamic evolution of the area. In particular, we suggest that two successive subduction events related to the closure of the Vardar and the Pindos oceans, respectively, occurred in the investigated area from Late Jurassic to Tertiary. We relate the genesis of Jurassic granitoids to the first subduction event, whereas Tertiary granitoids are associated with the second subduction. Fluids released by the two subducted slabs induced metasomatic processes generating a ‘leopard skin’ mantle wedge able to produce mafic melts ranging from typical calc‐alkaline to ultra‐potassic. Such melts interacted in various amounts with crustal calc‐alkaline anatectic melts to generate the wide spectrum of Tertiary granitoids occurring in the study area. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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Ioannis K. Georgiadis Antonios Koroneos Ananias Tsirambides Michael Stamatakis 《Central European Journal of Geosciences》2012,4(3):465-477
Modern sand samples were collected from the Vertiskos Unit of the Serbomacedonian Massif, northern Greece, and were examined for their texture and mineralogical composition. They were collected from active channels and torrents. The textural study demonstrated that these modern sands are moderately to very-poorly sorted, often polymodal in grain size distribution, texturally and mineralogically immature to submature, and consist of coarse-grained gravelly sands to slightly-gravelly muddy sands. The dominant composition is quartzofeldspathic. All samples contain detrital minerals of metamorphic origin, mainly amphibole and garnet, in addition to minor amounts of pyroxene and detrital calcite. These sediments were deposited rapidly and close to their source, the metamorphic basement of the Vertiskos Unit. The mineral constituents of the samples indicate that the Vertiskos Unit is undergoing rapid physical weathering due to the temperate and seasonal climate. The results of this study suggest that these modern sands constitute one sedimentary petrologic province comprised of primarily of amphibole-garnet. 相似文献
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G. Christofides D. Perugini A. Koroneos T. Soldatos G. Poli G. Eleftheriadis A. Del Moro A.M. Neiva 《Lithos》2007,95(3-4):243-266
Orogenic granitoids often display mineralogical and geochemical features suggesting that open-system magmatic processes played a key role in their evolution. This is testified by the presence of enclaves of more mafic magmas dispersed into the granitoid mass, the occurrence of strong disequilibrium textures in mineralogical phases, and/or extreme geochemical and isotopic variability.
In this contribution, intrusive rocks constituting the Sithonia Plutonic Complex (Northern Greece) are studied on the basis of mineral chemistry, whole-rock major, trace element geochemistry, and Sr and Nd isotopic composition. Sithonia rocks can be divided into a basic group bearing macroscopic (mafic enclaves), microscopic (disequilibrium textures), geochemical, and isotopic evidence of magma interaction, and an acid group in which most geochemical and isotopic features are consistent with a magma mixing process, but macroscopic and microscopic features are lacking.
A two-step Mixing plus Fractional Crystallization (MFC) process is considered responsible for the evolution of the basic group. The first step explains the chemical variation in the mafic enclave group: a basic magma, represented by the least evolved enclaves, interacted with an acid magma, represented by the most evolved granitoid rocks, to give the most evolved enclaves. The second step explains the geochemical variations of the remaining rocks of the basic group: most evolved enclaves interacted with the same acid magma to give the spectrum of rock compositions with intermediate geochemical signatures. A convection–diffusion process is envisaged to explain the geochemical and isotopic variability and the lack of macroscopic and petrographic evidence of magma interaction in the acid group.
The mafic magma is presumably the result of melting of a mantle, repeatedly metasomatized and enriched in LILE due to subduction events, whereas the acid magma is considered the product of partial melting of lower crustal rocks of intermediate to basaltic composition.
It is shown that Sithonia Plutonic Complex offers the opportunity to investigate in detail the complex interplay between geochemistry and magma dynamics during magma interaction processes between mantle and crustal derived magmas. 相似文献
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Ioannis K. Georgiadis Antonios Koroneos Lamprini Papadopoulou Nikolaos Kantiranis Alexios E. Tamparopoulos Ananias Tsirambides 《Mineralogy and Petrology》2014,108(2):187-206
Garnet single crystals of several millimeters in diameter were collected from the uppermost horizon of a soil profile developing immediately on the gneissic rocks of the Vertiskos Unit of the Serbomacedonian Massif in northern Greece. The garnets were analyzed for major elements by EDS analyzer mounted on a scanning electron microscope, and the obtained data were utilized to determine their source rocks. Bivariate diagrams, spider diagrams as well as statistical analysis were used in order to correlate and compare the garnet composition of the basement rocks of the Vertiskos Unit with the existing reference data. This case study demonstrates the difficulty in assigning a source rock to sediment, using only the chemical compositional of detrital garnet. Direct linking of the detrital garnets and the outcropping rocks is not always possible despite well documented outcrop lithologies. This is largely due to a complex metamorphic evolution that leads to overlapping compositions between garnets originating from different lithologies that have undergone similar metamorphic processes and alteration effects. 相似文献
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Argyrios Papadopoulos Georgios Christofides Antonios Koroneos Stylianos Stoulos 《Central European Journal of Geosciences》2014,6(2):229-242
This study aims to evaluate the activity concentrations of 238U, 226Ra, 232Th, 228Th and 40K along the beaches of Sithonia Peninsula which are adjacent to the rock-types of the Sithonia Plutonic Complex. These range from 6–673, 5–767, 5–1750, 6–1760 and 185–875 Bq/kg respectively. The (% wt.) heavy magnetic (HM) fraction (epidote, allanite, hornblende, biotite and garnet), the heavy non-magnetic (HNM) fraction (monazite, zircon, titanite and apatite) and the total heavy (TH) fraction, were correlated with the concentrations of the measured radionuclides in the bulk samples. The HNM fraction seems to control the activity concentrations of 238U in all samples, while the HM fraction, at least for the heavy mineral rich samples bearing high amounts of epidote crystals with allanite cores, controls their 232Th content. The measured radionuclides in beach sands were normalized to the respective values measured in the granitic rocks, which are their most probable parent rocks, in order to provide data on their enrichment or depletion. The annual effective dose varies from 0.013 to 0.688 mSv y?1 for local people working on the beach, while for tourists the annual external effective dose ranges between 0.003 and 0.165 mSv y?1. 相似文献
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I.?BaziotisEmail authorView author&#;s OrcID profile P.?D.?Asimow T.?Ntaflos J.?W.?Boyce F.?M.?McCubbin A.?Koroneos D.?Perugini S.?Flude M.?Storey Y.?S.?Liu S.?Klemme J.?Berndt 《Contributions to Mineralogy and Petrology》2017,172(7):58
Composite mantle xenoliths from the Cima Volcanic Field (CA, USA) contain glassy veins that cross-cut lithologic layering and preserve evidence of lithospheric melt infiltration events. Compositions and textures of minerals and glasses from these veins have the potential to place constraints on the rates and extents of reaction during infiltration. We studied glass-bearing regions of two previously undescribed composite xenoliths, including optical petrography and chemical analysis for major and trace elements by electron probe microanalysis and laser-ablation inductively coupled plasma mass spectrometry. The petrogenetic history of each vein involves melt intrusion, cooling accompanied by both wall-rock reaction and crystallization, quench of melt to a glass, and possibly later modifications. Exotic secondary olivine crystals in the veins display concentric phosphorus (P)-rich zoning, P-rich glass inclusions, and zoning of rapidly diffusing elements (e.g., Li) that we interpret as records of rapid disequilibrium events and cooling rates on the order of 10 °C/h. Nevertheless, thermodynamic modeling of the diversity of glass compositions recorded in one of the samples demonstrates extensive reaction with Mg-rich olivine from the matrix before final quench. Our results serve as a case study of methods for interpreting the rates and processes of lithospheric melt-rock reactions in many continental and oceanic environments. 相似文献
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