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Ορυκτολογική μελέτη σκαπόλιθου στην επαφή γνεύσιου-μαρμάρου στην ολυμπιάδα χαλκιδικής. = Mineralogical study of scapolite from gneiss-marble contact in olympiada, NE Chalkidiki.
Περίληψη
In this study, the mineralogical composition of scapolite that occurs at the gneiss-marble contact in the area of Olympiada, NE Chalkidiki, is investigated. The biotite-gneiss and the marble belong to the Kerdyllia unit of the Serbomacedonian Massif. Scapolite occurs at the contact of these rocks as a result of metasomatic processes and is found with diopside, calcite, amphibole (magnesio- and ferrohornblende), titanite, allanite, quartz, plagioclase and K-feldspar. The fluid phase that produced scapolite contained Na and Si, whereas it was rich in CO2 and poor in H2O. It is considered that scapolite which occurs in contact to calcite was formed at approximately 700oC while scapolite in contact with diopside was formed at lower temperatures, approximately 550-600oC. The fluids that took place in the formation of scapolite derived from the major magmatic bodies that are located in the study area, i.e. the Stratoni granodiorite and the porphyries occurring in the area of Skouries.
Σε αυτή την εργασία μελετάται η ορυκτολογική σύσταση σκαπόλιθου που εμφανίζεται στην επαφή γνευσίου και μαρμάρου στην περιοχή της Ολυμπιάδας, στη Β.Α. Χαλκιδική.Ο βιοτιτικός γνεύσιος και το μάρμαρο ανήκουν στην ενότητα Κερδυλλίων της Σερβομακεδονικής Μάζας.Ο σκαπόλιθος δημιουργείται στην επαφή των δύο αυτών πετρωμάτων από μετασωματικές διεργασίες και βρίσκεται σε παραγένεση με διοψίδιο, ασβεστίτη, αμφίβολο (μαγνησιο- και σιδηροκεροστίλβη), τιτανίτη, αλλανίτη, χαλαζία, πλαγιόκλαστο και Κ-άστριο. Η ρευστή φάση που έδωσε τον σκαπόλιθο περιείχε Na και Si και ήταν πλούσια σε CO2 και φτωχή σε H2O. Θεωρείται ότι ο σκαπόλιθος που βρίσκεται δίπλα στον ασβεστίτη σχηματίστηκε περίπου στους 700οC, ενώ ο σκαπόλιθος που είναι σε επαφή με τον πυρόξενο, δημιουργήθηκε σε χαμηλότερες θερμοκρασίες, περίπου 550-600οC. Τα ρευστά διαλύματα που πήραν μέρος στο σχηματισμό του σκαπόλιθου θεωρείται ότι προήλθαν από τους κύριους πυριγενείς όγκους που υπάρχουν στην περιοχή μελέτης, τον γρανοδιορίτη του Στρατωνίου και τους πορφύρες της περιοχής των Σκουριών.
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