Υγρομαγματικά κοιτάσματα χρωμίτη στρωματόμορφου τύπου = Stratiform chromite deposits.

Γεώργιος Παναγιώτης Παναγιωτίδης


Η παρούσα διπλωματική πτυχιακή εργασία αφορά την μελέτη των υγρομαγματικών κοιτασμάτων χρωμίτη στρωματόμορφου τύπου που υπάρχουν σε όλο τον κόσμο. Πρόκειται για κοιτάσματα, τα οποία συναντώνται μόνο σε ενδοπλακικές κρατονικές περιοχές και οφείλουν την ύπαρξη τους σε διεισδύσεις βασικών και υπερβασικών μαγμάτων. Τα κύρια χαρακτηριστικά των κοιτασμάτων αυτών είναι η στρωματοειδής ανάπτυξη σε αλλεπάλληλα στρώματα και οι εξαιρετικά υψηλή περιεκτικότητα σε χρωμίτη, με σημαντικές ποσότητες σε ορυκτά της ομάδας της πλατίνας. Τα σημαντικότερα κοιτάσματα στρωματόμορφου τύπου είναι το Bushveld Complex, το Stillwater Complex και το Great Dyke. Τα πετρώματα στα οποία συνήθως φιλοξενείται ο χρωμίτης, είναι ο χαρτσβουργίτης και ο αστριούχος πυροξενίτης. Ο χρωμίτης, σε τέτοιου είδους κοιτάσματα, μπορεί να έχει 3 μορφές: α) Διάσπαρτος, β) Ταινιωτός και γ) Συμπαγής. Σημαντικό ρόλο, στον καθορισμό της ποιότητας ενός στρωματόμορφου κοιτάσματος, παίζει η περιεκτικότητα σε Fe, δηλαδή ο λόγος Cr/Fe.
Λέξεις κλειδιά: Bushveld, Χρωμίτης, Στρωματόμορφος

This diploma thesis focuses on the study of the stratiform chromite deposits globally. These deposits that can only be found in intraplate craton areas and owe their existence in intrusions of mafic - ultramafic magma. The main features of these deposits are the stratiform growth of successive layers and that they are incredibly rich in chromite, with significant quantities of Platinum Group Elements. The most important stratiform deposits in the world are the Bushveld Complex, the Stillwater Complex and the Great Dyke. The chromite is primarily hosted by harzburgite and feldspathic pyroxenite. There are 3 types of chromite that can be found in stratiform deposits: a) Disseminated, b) Schlieren and c) Massive. The ratio of Cr/Fe is of great importance for the quality of the deposit.
Key words: Bushveld, Chromite, Stratiform

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