Back-thrusting response of continental collision: Early Cretaceous NW-directed thrusting in the Changle-Nan’ao belt (Southeast China)
Résumé
The SE coastal area of the South China Block (SCB) is generally interpreted as a
Cretaceous active continental margin due to subduction of the Paleo-Pacific plate
beneath the Eurasian plate. There, the NE-SW striking Changle-Nan’ao belt was
previously considered as a major strike-slip fault zone with a large displacement
accommodating the northward subduction of the Paleo-Pacific plate. Our new field
and laboratory investigations document a NW-directed ductile thrust zone that placed
gneiss upon Early Cretaceous foliated volcanic rocks. Structural analyses and
Anisotropy of Magnetic Susceptibility results indicate that the ductile fabrics in both
units are represented by a NE-SW striking foliation and a NW-SE stretching lineation
with top-to-the-NW shear sense. This deformation occurred at ca. 130-105 Ma, before
the deposition of undeformed (ca. 104 Ma) volcanic rocks, and the intrusion of ca. 90
Ma isotropic plutons. This continent-ward structure is tentatively interpreted as a
back-thrust resulting of the collision of the West Philippines microcontinent with the
SCB rather than an effect of a simple oceanic subduction.
Origine | Fichiers produits par l'(les) auteur(s) |
---|
Loading...