Γεωχημικά χαρακτηριστικά γρανιτικών μαγμάτων από τήξη πετρωμάτων του ηπειρωτικού φλοιού

Γεωργία Παπαδοπούλου

Γεωχημικά χαρακτηριστικά γρανιτικών μαγμάτων από τήξη πετρωμάτων του ηπειρωτικού φλοιού

Γεωργία Παπαδοπούλου

Περίληψη

Η γένεση γρανιτικών μαγμάτων αποτελεί μια πολύπλοκη διαδικασία ιδιαίτερης γεωλογικής και γεωδυναμικής σημασίας. Βασίζεται στη μερική τήξη ιζηματογενών, μεταμορφωμένων και πυριγενών πετρωμάτων, τόσο ηπειρωτικής όσο και ωκεάνιας προέλευσης. Η παρούσα διπλωματική εργασία εστίαζει στη μελέτη πετρωμάτων του ηπειρωτικού φλοιού και πως η σύσταση τους σε συνδυασμό με τη θερμοκρασία και τη πίεση επηρεάζει τα τήγματα που θα δημιουργηθούν από τη τήξη τους. Αρχικά παραθέτονται οι βασικοί παράμετροι που επιδρούν στη διαδικασία της μερικής τήξης και οι τύποι των γρανιτών που θα προκύψουν από τα εξεταζόμενα αρχικά υλικά. Επίσης παρουσιάζεται η πειραματική μελέτη δεδομένων για τη θερμοκρασία, τη πίεση και τη σύσταση των πετρωμάτων πηγών και των αντίστοιχων τηγμάτων τους, καθώς και τα διαγράμματα που κατασκευάστηκαν σύμφωνα με αυτά. Τέλος αναφέρονται τα συμπεράσματα που εξάγονται από τα διαγράμματα, για τη μεταβολή της χημικής σύστασης από τη πηγή στο παραχθέν τήγμα. Λέξεις-κλειδιά: Γρανιτικά μάγματα, μερική τήξη, ηπειρωτικός φλοιός, θερμοκρασία, πίεση, χημική σύσταση

The generation of granitic magmas is a complex process, of particular geological and geodynamic significance. It’s based on the process of partial melting of sedimentary, metamorphic and igneous rocks, both of continental and oceanic origin. This present thesis focuses on the study of sedimentary and metamorphic rocks from the continental crust and how their composition in combination with temperature and pressure affects the granitic melts that will be produced. At first are listed the primary parameters that influence the procedure of partial melting and the types of the granites that will be generated by the different starting materials. The experimental study of data for temperature, pressure and chemical composition, and the diagrams that are made according to those data, are presented. Lastly the conclusions from the mentioned above diagrams, for the variation of the chemical composition from the source to the produced melt, are being discussed. Keywords: Granitic magmas, partial melting, continental crust, temperature, pressure, chemical composition

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Αναφορές

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