Βιοστρωματογραφική και παλαιοπεριβαλλοντική ανάλυση στα πλαίσια της γεωδυναμικής εξέλιξης της λεκάνης της Θράκης

• Main Authors: Kostopoulou, Sofia, Κωστοπούλου, Σοφία
• Format: Doctoral or Postdoctoral Thesis
• Language: Greek
• Published: National and Kapodistrian University of Athens 2016
• Subjects: Όριο Ηωκαίνου-Ολιγοκαίνου; Πλαγκτονικά τρηματοφόρα; Βενθονικά τρηματοφόρα; Λεκάνη της Θράκης; Λήμνος; Eocene-Oligocene boundary; Planktonic foraminifera; Benthic foraminifera; Thrace basin; Lemnos; Φυσικές Επιστήμες; Γεωεπιστήμες και Επιστήμες Περιβάλλοντος; Natural Sciences; Earth and Related Environmental Sciences
• Online Access: http://hdl.handle.net/10442/hedi/40123; https://doi.org/10.12681/eadd/40123

The paleoenviromental conditions during the sedimentation in Lemnos Island (Northeast Aegean Sea) are studied based on qualitative analysis of calcareous nannoplankton and quantitative analysis of planktonic and benthic foraminifera. The samples were collected from the geological sections (Ifestia section, Panagia section, Kaspaka section and Kaminia section) according to the sedimentary facies that occur in the region. The biostratigraphic analysis of calcareous nannoplankton and planktonic foraminifera recommend that the sedimentation in Lemnos Island took place on the time interval Upper Eocene/Lower Oligocene (Priabonian/Rupelian). The Eocene/Oligocene boundary (E/O) is clearly seen into the lower part of turbiditic system (Ifestia section). It was the first time that planktonic foraminifera of this age interval were studied and analyzed in detail in Lemnos Island. The species Dipsidripella liqianyui, Catapsydrax unicavus, Globigerina officionalis, Paragloborotalia nana, Chiloguembelina cubensis, Dentoglobigerina sp., Turborotalia sp. and Turborotalia cerroazulensis were indentified, while D. liqianyui adding new data on the biogeographical distribution in global basis. According to benthic foraminifera analysis the P/B% ratio in conjunction with the model of the van der Zwaan et al. (1990) and the qualitative analysis of foraminifera showed clear shallowing-upward trend of the study area for upper Eocene-lower Oligocene epoch. At the upper Eocene the presence of Globobulimina confirmed dysoxic intervals, while the presence of paragloborotaliids, globigerinids and chiloguembelinids may suggest a gradual cooling event since the upper Eocene. The Eocene-Oligocene boundary is characterized by well-oxygenated bottom waters, while the high presence of C. unicavus certifies a strong cooling event in the early Oligocene (biozone O1) probably linked to global cold Oi1 event at 33.7 Ma. Finally, during the lower Oligocene there are well oxygenated bottom waters which are intermittently interrupted by low oxygenated ...