科研之友
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摘要
The Neoproterozic-related structures have provided important insights into the tectonic history of the Egyptian Eastern Desert as well as the Arabian-Nubian Shield (ANS). The Gabal Abu Houdeid (GAH) area is in the extreme northern portion of the Hamisana shear zone (HSZ), one of the major high-strain zones in the ANS. The Neoproterozoic rocks exposed around GAH include ophiolitic ultramafic-mafic rocks, island-arc metasediments, metavolcanic rocks, intrusive syn-tectonic granodiorites, post-tectonic gabbros, and granites. The analysis of large-scale structures and fault kinematic data in terms of ductile and brittle deformation indicates that the sequence of folding and faulting events was constrained by available litho-tectonic units. Four deformational events are distinguished in the Neoproterozic rocks. Event D1 a pure compression stress regime with sigma 1 stress axis trending NNW-SSE to N-S represents an early shortening event associated with the Pan-African thrusting, during which intra-oceanic arcs and plateaus were accreted. Event D2 characterized by structures developed under ENE-WSW compressional regime (shortening event) and considered as the early stage of the second episode of collision within the Pan-African orogeny. Event D3 transpressional deformation associated with E-W contraction and N-S extension. It is the main event that controlled the deformation along the HSZ during the late stages of the collision between the East and West Gondwana in terms of escape tectonics. The D4 event is interpreted as a post-orogenic extensional event manifested by E-W dextral strike-slip and dip-slip normal faults striking NNW-SSE to N-S and E-W, which began to occur after the emplacement of post-tectonic granites.
- 出版日期2015-7
