IODP - expedition 381, site 79A : insights into the palaeoceanography of the Corinth gulf in the upper Quaternary from the study of foraminifera assemblages

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Αγγελοπούλου, Δήμητρα

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The Corinth Gulf is considered one of the high degree of important natural laboratories for the natural scientists. The Corinthian Gulf is an asymmetrical tectonic rift. High tectonic activity and complex geomorphological evolution indicatea highly active deformation of the area, highlighting the geological importance of the region. This is the main reason why International Ocean Discovery Program (IODP) proposed the study of Corinth Gulf. As the basin has subsided, fluctuating global sea level and its absolute position relative to sea level, has affected the depositional environment. This appears from the basin sediments which record this spatial and temporal advancement. The principal objective of International Ocean Discovery Program (IODP) Expedition 381 was to retrieve a record of early continental rifting and basin development from the rift, in the Corinth gulf, central Greece. During this expedition three different sites (Site M0078, M0079, M0080) in the Corinth Gulf were drilled, cored and logged. The main finding of this study was that the Corinthian Gulf presented periods of connection with the open sea and its isolation from it during the Quaternary period. In the present master thesis, 175 sediment samples were studied from the M0079 core in 125µm and 63µm fractions to examine the presence of planktonic and benthic foraminifera. These sediment samples are located between0.23and148.43mbsf (meters below seafloor). This interval corresponds to the Subunits SU1 and SU2, as these determined from the scientific sedimentological group of the expedition. SU1 extends from 0.23 to 32.02 mbsf and it most probably corresponds to Marine Isotopic Stage (MIS) 1. In this unit foraminifera are abundant though the number of benthic specimen is significant higher than that of the planktonics. This suggests that SU1 corresponds to a marine phase. SU2 extends from 32.59 to 148.43 mbsf and most probably it corresponds to MIS 2, 3 and 4.SU2 is characterized in general by absence or low numbers of foraminiferal specimen suggesting that SU2 corresponds to an isolated phase. This isolated phase is interrupted by short marine phase intervals where planktonic and benthic foraminifera are abundant. The deposition of these short intervals could be related to temporal rises of sea level due to eustatic –isostatic factors or to tectonic driven mechanisms.



IODP, Quaternary, Foraminifera, Palaeoceanography, Corinth gulf, Expedition 381, Site 79A