Publication Date:
2019-08-05
Description:
On Syros, high‐pressure metamorphism affects a lithological pile that is composed of,
from base to top: (1) the Komito‐Vari granitic basement, (2) a margin sedimentary
sequence that is predominantly made of marbles and schists (the Pyrgos and Kastri units),
and (3) the Kambos metaophiolitic mélange. The tectonic history occurred in three main
stages. During the first stage, in the mid‐Eocene, the Kambos oceanic unit was thrust
southward on top of the sedimentary pile. Top‐to‐the‐south‐southwest ductile senses of
shear are synchronous with prograde high‐pressure metamorphism and associated with
this thrusting event. The second stage corresponds to a top‐to‐the‐northeast ductile shear
that affects the whole metamorphic pile and is synchronous with the metamorphic
retrogression from eclogite to greenschist facies. However, the Kambos oceanic unit
remained partly undeformed, as shown by significant volumes containing undeformed
lawsonite pseudomorphs. No major extensional detachment related to this exhumation
event outcrops on the island. The localized semibrittle to brittle deformation of the third
stage is associated with the postmetamorphic development of (1) a ramp‐flat extensional
system at the island scale, whose southward minimum displacement is estimated at
approximately 7 km, and (2) two sets of steeply dipping strike‐slip faults with a normal
component, trending either east–west or around north–south, indicating that the mean
stretching and shortening directions are trending NNE–SSW and ESE–WNW, respectively.
This sequence of major tectonic events and their relationship to metamorphism are
interpreted within the framework of the subduction of the Pindos Ocean and then of the
Adria continental passive margin.
Type:
Article
,
PeerReviewed
Format:
text
Permalink