A Large-Scale Palaeozoic Dextral Ductile Strike-Slip Zone:the Aqqikkudug-Weiya Zone along the Northern Margin of the Central Tianshan Belt,Xinjiang,NW China |
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| Authors: | SHU Liangshu CHARVET Jacques GUO Lingzhi LU Huafuand LAURENT-CHARVET Sebastien |
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| Institution: | SHU Liangshu,CHARVET Jacques,GUO Lingzhi,LU Huafuand LAURENT-CHARVET Sebastien Department of Earth Sciences and State Key Lab of Metallization,Nanjing University,Nanjing,P.R. of China Departement des Sciences de la Terre,URM,Universite d'Orleans,Orleans,France |
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| Abstract: | The nearly E-W-trending Aqqikkudug-Weiya zone, more than 1000
km long and about 30 km wide, is an important segment in the Central Asian tectonic
framework. It is distributed along the northern margin of the Central Tianshan belt in
Xinjiang, NW China and is composed of mylonitized Early Palaeozoic greywacke, volcanic
rocks, ophiolitic blocks as a mélange complex, HP/LT-type bleuschist blocks and
mylonitized Neoproterozoic schist, gneiss and orthogneiss. Nearly vertical mylonitic
foliation and sub-horizontal stretching lineation define its strike-slip feature; various
kinematic indicators, such as asymmetric folds, non-coaxial asymmetric macro- to
micro-structures and C-axis fabrics of quartz grains of mylonites, suggest that it is a
dextral strike-slip ductile shear zone oriented in a nearly E-W direction characterized by
"flower" strusture with thrusting or extruding across the zone toward the two
sides and upright folds with gently plunging hinges. The Aqqikkudug-Weiya zone experienced
at least two stages of ductile shear tectonic evolution Early Palaeozoic north vergent
thrusting ductile shear and Late Carboniferous-Early Permian strike-slip deformation. The
strike-slip ductile shear likely took place during Late Palaeozoic time, dated at 269(5 Ma
by the40Ar/39Ar analysis on neo-muscovites. The strike-slip deformation was followed by
the Hercynian violent S-type granitic magmatism. Geodynamical analysis suggests that the
large-scale dextral strike-slip ductile shearing is likely the result of intracontinental
adjustment deformation after the collision of the Siberian continental plate towards the
northern margin of the Tarim continental plate during the Late Carboniferous. The
Himalayan tectonism locally deformed the zone, marked by final uplift, brittle layer-slip
and step-type thrust faults, transcurrent faults and E-W-elongated Mesozoic-Cenozoic
basins. |
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| Keywords: | ductile thrusting dextral strike-slipping kinematic analysis Aqqikkudug-Weiya zone Tianshan Palaeozoic erogenic belt |
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