 |
| Titel |
Receiver function images of the Hellenic subduction zone and comparison to microseismicity |
| VerfasserIn |
F. Sodoudi, A. Brüstle, T. Meier, R. Kind, W. Friederich, EGELADOS Working Group |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1869-9510
|
| Digitales Dokument |
URL |
| Erschienen |
In: Solid Earth ; 6, no. 1 ; Nr. 6, no. 1 (2015-02-04), S.135-151 |
| Datensatznummer |
250115392
|
| Publikation (Nr.) |
 copernicus.org/se-6-135-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| New combined P receiver functions and seismicity data obtained from the
EGELADOS network employing 65 seismological stations within the Aegean
constrained new information on the geometry of the Hellenic subduction zone.
The dense network and large data set enabled us to estimate the Moho depth of
the continental Aegean plate across the whole area. Presence of a negative
contrast at the Moho boundary indicating the serpentinized mantle wedge
above the subducting African plate was seen along the entire forearc.
Furthermore, low seismicity was observed within the serpentinized mantle
wedge. We found a relatively thick continental crust (30–43 km) with a
maximum thickness of about 48 km beneath the Peloponnese Peninsula, whereas
a thinner crust of about 27–30 km was observed beneath western Turkey. The
crust of the overriding plate is thinning beneath the southern and central
Aegean and reaches 23–27 km. Unusual low Vp / Vs ratios were estimated beneath
the central Aegean, which most likely represent indications on the
pronounced felsic character of the extended continental Aegean crust.
Moreover, P receiver functions imaged the subducted African Moho as a strong
converted phase down to a depth of about 100 km. However, the converted Moho
phase appears to be weak for the deeper parts of the African plate
suggesting nearly complete phase transitions of crustal material into denser
phases. We show the subducting African crust along eight profiles covering the
whole southern and central Aegean. Seismicity of the western Hellenic
subduction zone was taken from the relocated EHB-ISC catalogue, whereas for
the eastern Hellenic subduction zone, we used the catalogues of manually
picked hypocentre locations of temporary networks within the Aegean.
Accurate hypocentre locations reveal a significant change in the dip angle
of the Wadati–Benioff zone (WBZ) from west (~ 25°)
to the eastern part (~ 35°) of the Hellenic
subduction zone. Furthermore, a zone of high deformation can be
characterized by a vertical offset of about 40 km of the WBZ beneath the
eastern Cretan Sea. This deformation zone may separate a shallower N-ward
dipping slab in the west from a steeper NW-ward dipping slab in the east. In
contrast to hypocentre locations, we found very weak evidence for the
presence of the slab at larger depths in the P receiver functions, which may
result from the strong appearance of the Moho multiples as well as
eclogitization of the oceanic crust. The presence of the top of a strong low-velocity zone at about 60 km depth in the central Aegean may be
related to the asthenosphere below the Aegean continental lithosphere and
above the subducting slab. Thus, the Aegean mantle lithosphere seems to be
30–40 km thick, which means that its thickness increased again since the
removal of the mantle lithosphere about 15 to 35 Ma ago. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|