Romain Rubi's thesis defense

Deep-water syn-rift sedimentary systems from Plio-Pleistocene outcrops and seismic lines of Gulf of Corinth deposits (Greece)

Romain Rubi's thesis defense, 2018


Syn-rift sedimentation is mainly controlled by normal-faults. However, the sedimentary architecture is more complex and present many heterogeneities generated by both gravity and hydrodynamic processes. Syn-rift sediments are primarily subaqueous and characterized from geophysics’ data. The syn-rift deposits when outcropping are mostly located in orogenic context and so poorly preserved and deformed. Nevertheless, the southern shore of the Gulf of Corinth (Greece) is uplifting the rift deposits and which allows to study well preserved syn-rift outcrops. Moreover, available seismic data allow to constrained and compare the present and past syn-rift deposits in the Gulf with the southern shore outcrops.
An integrated approach with field work and seismic data combined with a photogrammetric model documents an entire early syn-rift sedimentological deep-water profile from the delta to the basin.
Four different dynamics in Middle Pleistocene Gilbert-type bottomset deposits are documented to constrain the export of coarse-grained sediments, each bottomset typology is characterized by a specific range of facies, facies associations, geometries and integrated within the stratigraphic delta context. The associated pro-delta shows the formation of a mixed turbiditic and contouritic sedimentary system. The outcrop and seismic sedimentary architectures are mainly form by moats and drifts. The onshore sedimentary facies documented the processes involved in the rework and export of coarse-grained sediments in the moat. Simultaneously, the asymmetric drift is built by two sedimentary sequences: a bi-gradational contouritic and a finning-up turbiditic sequences. New interpretations of seismic data provide horizon, structural, morphosedimentary, and thickness maps, for the offshore Corinth Rift, at a 100 kyr time scales and confirm a mixed turbiditic and contouritic deep water system. These new elements reveal a major contouritic dominated event in the Gulf of Corinth at 0.4 Ma that implies to reconsider about the palaeo-geography of the Gulf and to propose an opening at the East and the West with the Mediterranean Sea.

Keywords :  Gilbert-delta, Bottomset, Prodelta, Turbidite, Contourite