Analogue and Seismic Modelling of the Kuche Fold and Thrust Belt (North Tarim, China)
The Kuqa foreland fold and thrust belt developed at the
contact between the uplifted basement block of the Tien Shan and the Tarim
basin in foreland setting, since early Oligocene. It is mainly controlled by
two major decollement levels. Thin skin deformation and Mesozoic thrust sheet
develop above the Triassic coal measures. The Paleogene and Neogene foreland
synclines developed detached above the stacked thrust sheets through the Eocene
salt layer. Analogue models are used to analyse the relative importance of the
kinematic boundary conditions and the rheological behaviour of the main decollement levels. The experiments demonstrate that the geometry of the belt depends
on the two decollement with a frictional behaviour at Triassic level and a
thick viscous Eocene salt layer pinching to the South along the Qilitag fodl
belt and to the North close to the Tien Shan boundary. The geometry of the salt
layer plays an important role in the structural style, controlling the shape
and propagation of the foreland synclines. The backstop geometry is the second
major element, controlling the dip of the stacked thrust sheets. Inverted
basement block associated to a basement short cut emplaced during the late
stage of evolution are both needed to generate the overall geometry of the
Mesozoic units. Based on the analogue models, the geometry of the thrust sheet
and foreland syncline is used to perform a synthetic seismic experiment. The
recovered seismic data demonstrate that the thrust sheet length is not imaged.
These results shed a new light on the Kuqa fold and thrust belt exploration
potential.
AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California