Geomorphic evolution of the upper reaches of the drainage basin of Acheloos river
| Jazyk: | angličtina |
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| Rok vydání: | 2001 |
| Předmět: | |
| Zdroj: | Δελτίο της Ελληνικής Γεωλογικής Εταιρείας; Τόμ. 34 Αρ. 1 (2001): 9o διεθνές Συνέδριο της ΕΓΕ; 397-404 Bulletin of the Geological Society of Greece; Vol. 34 No. 1 (2001): 9th International Conference of the Geological Society of Greece; 397-404 |
| ISSN: | 0438-9557 2529-1718 |
| Popis: | Στην παρούσα εργασία παρουσιάζεται ένα μέρος των αποτελεσμάτων της αδημοσίευτης διδακτορικής διατριβής με τον αντίστοιχο τίτλο, όπου ερευνάται η λεκάνη απορροής του άνω ρου του Αχελώου ποταμού (ανάντη της τεχνητής λίμνης των Κρεμαστών). Από τη γεωμορφολογική ανάλυση, η οποία δίνει στοιχεία σχετικά με το παλαιοπεριβάλλον της περιοχής και της γεωμορφολογικής της εξέλιξης, προέκυψε ότι η αποστράγγιση του υδρογραφικού δικτύου του άνω ρου του Αχελώου δεν είναι ομαλή και ότι αυτό βρίσκεται σε ασταθή δυναμική κατάσταση ισορροπίας, με μεγαλύτερη αστάθεια στο δυτικό τμήμα. Αυτό οφείλεται στην αναγέννηση του υδρογραφικού δικτύου λόγω νεοτεκτονικών κινήσεων (ανύψωση της περιοχής), με μεγαλύτερη ταχύτητα ανύψωσης του δυτικού τμήματος (όρος Γάβροβο). The scope of this study work is to give an insight into the dynamic processes which shape the relief in the drainage basin of the upper reaches the Acheloos river, so that the geomorphological and geodynamical evolution of the region in the past can be approached, together with a possible prediction. For this reason, the relationships between the relief and the endogenic and exogenic factors are sought. The investigated area is made up of geological formations that belong to the zones: "Ionian" (inner Ionian zone), "Gavrovo", "Pindos" and "Hyperpindos". There are also younger rocks (postalpine formations), together with some volcanic rocks. The main stream segment of Acheloos river was formed in the Upper-Middle Miocene, after the deposition of the flysch of "Gavrovo" and the tectonism of the zone. The structures were cut to a large extent by trace-slip faults, striking ENE-WSW, during the Middle-Upper Miocene. At the same time (Lower Miocene - Plio-Quaternary), in NW-Greece, is observed a horizontal clockwise rotation (45°). Finally, the region shows an expanding movement from North to South. Due to the above tectonic activity, the drainage basin shows a monoclinic structure with a westward displacement of the drainage pattern. The displacement increases from North to South. The displacement of the drainage pattern is also favoured by the presence of erodible rocks in the western part (flysch of "Gavrovo") and the general eastward dip of the strata. Neotectonic activity controls the river up to date, as it is inferred from the orientation of the stream segments, which follow the tectonic structure (lithological boundaries, faults, thrusts). The drainage pattern appears to be in an early mature stage. According to the quantitative geomorphological analysis data, the drainage pattern (mainly the west part of it) is in an unstable dynamic status. During Plio-Quaternary there were a few rejuvenating episodes, due to tectonic and climate changes. The present rejuvenated stage, which is more obvious in the southwestern part of the investigated area, is supported by morphotectonic data. Among them, the most remarkable are: a)the steep slopes (30-60 %), b)the negative deviation of "cummulative" area compared to ideal values, c)the slope flexions, which separate the new lower level from the old higher one. |
| Databáze: | OpenAIRE |
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