Περίληψη:
The Kerkyra-Kefalonia valley system is the northwestern extension of the
Hellenic are-trench system, representing the collision zone of the
Apulian Platform and the Hellenides. The system is distinguished by two
different physiographic regions: the northern part, U-shaped, and
oriented NNW-SSE, with relatively gentle slopes and a wide floor; and
the southern part, oriented NE-SW, V-shaped, and with much steeper side
walls and a narrow floor. Both parts are formed tectonically, with the
former coinciding with a collision zone, and the latter being the
morphometric expression of the Kefalonia strike-slip fault. Sediments
recovered in the piston cores from the region consist of fine-grained
material, deposited by a variety of sedimentation processes such as:
gravity-driven mass movements, associated with seismic activity (i.e.,
slumping, sliding, debris flows, grain flows,
turbidites-seismoturbidites); and, to a lesser extent, by hemipelagic
deposition, Measured near-bed currents and their associated shear
stresses indicate resuspension of the material, mainly within the
northern part of the valley. Sub-bottom acoustic (seismic) profiling
data reveal various sedimentary provinces, related to different
mechanisms of sediment accumulation: (i) the i:astern margin of the
Apulian Platform with hemipelagic sedimentation, together with possible
advection of suspensates from; the Adriatic, in response localised to
seabed erosion; (ii) the western Hellenic margin, with down-slope
episodic sliding and slumping, induced primarily by earthquake activity,
together with an input from hemipelagic settling; (iii) the collision
zone, coinciding with the northern part of the Kerkyra-Kefalonia valley
system, with deposition mostly from resuspension, the occurrence of
local mass gravity flows and the advection of some material from the
north; and (iv) the Kefalonia strike-slip fault region, where mass
gravity flows are the dominant mechanisms, related to erosion/deposition
from resuspension. Overall sedimentation within the tectonically-active
Kerkyra-Kefalonia valley system is characterised by the coupling of the
mass gravity-driven flows, which are the predominant mechanisms, with
the near-bed current regime related with resuspension phenomena and the
advection of suspensates. These latter mechanisms is likely more
pronounced during the winter period, when dense water masses formed in
the Adriatic inflowing into the Ionian Sea. (C) 1999 Elsevier Science
B.V. All rights reserved.
Συγγραφείς:
Poulos, SE
Lykousis, V
Collins, MB
Rohling, EJ and
Pattiaratchi, CB
