Supervisors info:
Γεώργιος Αναστασάκης, Καθηγητής, Τμήμα Γεωλογίας και Γεωπεριβάλλοντος, Εθνικό και Καποδιστριακό Πανεπιστήμιο Αθηνών
Summary:
Previous studies argued that during prolonged periods of low sea level stands, Megara Basin (NW Saronikos Gulf, Greece) becomes an isolated basin that produces thick beds of fine-grained aragonite until the reconnection with the open sea is re-established again.
The purpose of this thesis is to examine the conditions under which this carbonate factory flourished after the end of the LGM within Western Saronikos and determine the changes that went through till its termination.
Based on the results of this thesis, by the end of the LGM, Megara Basin was indeed an isolated aragonite-dominated marine basin, with no indications of river discharges. This hypothesis is supported by both the measured MS of all the retrieved cores and the terrigenous mineralogy of SAR39 that verify the absence of significant terrigenous input previous to Holocene. Moreover, bulk carbonate mineralogy and XRD estimates support the idea that Megara Basin was relatively shallow and supersaturated with respect to CaCO3, though it never experienced typical hypersaline conditions (e.g. forming gypsum)
Also, the data, which were derived from the marine sediment core SAR39 point to the brief “cold” HS1 Event that disrupted aragonite deposition to a minor level without however destroying the carbonate factory, followed shortly after by the warmer Bølling-Allerød interstadial that accelerated aragonite precipitation, reaching (80-90%). Finally, distribution of the carbonate minerals along the basin points out that reconnection of western Saronikos Gulf with the open sea was in fact delayed, not being reestablished before SL reached ~-82m.
