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岩石学报 2012
Karamaili strike-slipping fault and deformational sequence since Late Plaeozoic in the northern Xinjiang
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Abstract:
Large-scale strike-slip shearing is the primary style of continental deformation,so the development of the large-scale strike-slip fault indicates to a great extent the formation of continental crust with enough shear strength.As an important tectonic unit in the northern Xinjiang,Kalamaili tectonic belt used to be considered as a Paleozoic suture,though under dispute.The Karamaili strike-slip fault extends as an intermittent fault broken by late faulting on the remote sensing images.The fault is nearly perpendicular to the floor in the field with intensive and steep cleavages,as well as shown on the seismic profile.Flower structures are popularly revealed by cleavages in the geological section.The Carboniferous,Devonian strata and ophiolite were reconstructed strongly by shear faulting with phyllitization and mylonization.Subtension fracture in synpegmatite body and the direction of phacoidal siliceous sandstone indicate that the Karamaili strike-slip fault is a dextral shearing belt.Some evidences can used to infer that the Karamaili strike-slip fault was formed at the interval of 270~260Ma.We conclude that the Karamaili fault is a Late Paleozoic dextral strike-slip shearing fault.The Karamaili strike-slip shearing zone should be taken into consideration while it is considered to be a Late Paleozoic sutures in East Junggar basin.There are indications that there is a relative mature continent in northern Xinjiang since Permian due to large shearing zones dominate the tectonic evolution of an integrated continent.In the paper,different deformation sequence is also established on the basis of the intersected or cutting relationship of faults since Late Paleozoic.