Lithospheric structure of the Aegean obtained from P and S receiver
functions
Freie Universität Berlin, Germany, (2005)Zusammenfassung
Aegean is one of the most tectonically complex areas worldwide. Because
of its position in the back arc area of the active subduction of
the African plate beneath the Eurasian plate as well as occurrence
of two successive stages of extension within Aegean since Oligocene
times, it belongs to the most interesting areas and has been the
focus of many studies. In this thesis a joint P and S receiver function
analysis is used to estimate the crustal and upper mantle structure
in the whole Aegean Sea, mainland Greece and the island of Crete.
To reach this goal, combined P and S receiver functions of teleseismic
events are computed, which are recorded by a total number of 65 temporary
and permanent stations including GEOFON, National Observatory of
Athens, Cyclades-network, Mediterranean network and the Seisfaultgreece
experiment. These combined data show a more dense coverage in the
southern and central Aegean Sea where no information from P receiver
functions can be obtained without OBS stations. The receiver function
images reliably demonstrate the subducting oceanic African lithosphere
up to northern Greece, where the slab is not marked by earthquakes.
The results lead also to an average depth of 40 km for the subducted
oceanic Moho beneath southern Crete, western Peleponnesus and southeast
of Rhodes, which significantly increases down to the volcanic arc
to a depth of 160 km. The oceanic Moho can be reliably followed further
north to depth of 220 km beneath northern Greece. The new information
on the oceanic and continental lithosphere deduced from the new technique
of S receiver function clearly reveals the lithosphere-asthenosphere
boundary beneath each part of the area. This boundary is estimated
about 150 km beneath mainland Greece, which presents the continental
Aegean lithosphere (Eurasian lithosphere) and shows a thickening
from 100 km beneath southern Crete to about 225 km under volcanic
arc of the subduction zone. This thickening of the LAB towards the
Aegean Sea is associated with the subduction of the oceanic African
lithosphere beneath the Aegean plate. Moreover, detailed informations
about the crustal thickness variation are inferred from this study.
In Crete, the Aegean Moho varies from 25 km in the east to 33 km
in the west. In the Cretan Sea a thin crust of approximately 20 km
is observed, which thickens up to 30 km at the volcanic arc. A thicker
crust of about 35 km beneath two volcanic islands in the Aegean (SANT,
MILO) are also observed. In the northern Aegean Sea the crustal thickness
is ranging between 25-28 km, whereas beneath western Greece a significantly
crustal thickening resulted in a Moho depth of 32-38 km. The estimations
in the Peleponnesus show a crustal thickness of 25-28 km. urn:nbn:de:kobv:b103-05152
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