The tectono-stratigraphic sequences of the Kuqa foreland fold-thrust belt in the northern Tarim basin, northwest China, can be divided into the Mesozoic sub-salt sequence, the Paleocene-Eocene salt sequence and the Ol...The tectono-stratigraphic sequences of the Kuqa foreland fold-thrust belt in the northern Tarim basin, northwest China, can be divided into the Mesozoic sub-salt sequence, the Paleocene-Eocene salt sequence and the Oligocene-Quaternary supra-salt sequence. The salt sequence is composed mainly of light grey halite, gypsum, marl and brown elastics. A variety of salt-related structures have developed in the Kuqa foreland fold belt, in which the most fascinating structures are salt nappe complex. Based on field observation, seismic interpretation and drilling data, a large-scale salt nappe complex has been identified. It trends approximately east-west for over 200 km and occurs along the west Qiulitag Mountains. Its thrusting displacement is over 30 km. The salt nappe complex appears as an arcuate zone projecting southwestwards along the leading edge of the Kuqa foreland fold belt. The major thrust fault is developed along the Paleocene-Eocene salt beds. The allochthonous nappes comprise large north-dipping faulting monoclines which are made up of Paleocene-Pliocene sediments. Geological analysis and cross-section restoration revealed that the salt nappes were mainly formed at the late Himalayan stage (c.a. 1.64 Ma BP) and have been active until the present day. Because of inhomogeneous thrusting, a great difference may exist in thrust displacement, thrust occurrence, superimposition of allochthonous and autochthonous sequences and the development of the salt-related structures, which indicates the segmentation along the salt nappes. Regional compression, gravitational gliding and spreading controlled the formation and evolution of the salt nappe complex in the Kuqa foreland fold belt.展开更多
The Tianshan orogenic belt has a W-shape, composed of the V-shape Southern Tianshan and Northern Tianshan with different orogenic models .The Southern Tianshan broke off from the Sinian, forming a passive continenta...The Tianshan orogenic belt has a W-shape, composed of the V-shape Southern Tianshan and Northern Tianshan with different orogenic models .The Southern Tianshan broke off from the Sinian, forming a passive continental margin and ocean, and closed during Silurian and Devoaian. It belongs to the Wilson cycle orogenic model. The net duration is about 400 My.The Northern Tianshan began back-arc spreading during Devonian, forming the Devonian-Carboniferous marginal sea, and dosed during Late Carboaiferous. It belongs to the non-Wilson cycle orogeulc model or back-arc orogenic model. The duration is about 100 My .Deformation of the foreland fold-thrust belt occurred in two stages: in the early stage, folds and thrusts were formed by wedge-thrusting and lateral compression, while in the later stage, folds, gravitational normal faults and reveal faults were formed by the uplift of the Tianshan range and by gravity-gliding.展开更多
基金This research received financial supports from the National Natural Science Foundation of China(grant 40172076)the National Major Fundamental Research and Development Project(grant G1999043305)the National Key Project of the Ninth Five—Year Plan(grant 99—1111)
文摘The tectono-stratigraphic sequences of the Kuqa foreland fold-thrust belt in the northern Tarim basin, northwest China, can be divided into the Mesozoic sub-salt sequence, the Paleocene-Eocene salt sequence and the Oligocene-Quaternary supra-salt sequence. The salt sequence is composed mainly of light grey halite, gypsum, marl and brown elastics. A variety of salt-related structures have developed in the Kuqa foreland fold belt, in which the most fascinating structures are salt nappe complex. Based on field observation, seismic interpretation and drilling data, a large-scale salt nappe complex has been identified. It trends approximately east-west for over 200 km and occurs along the west Qiulitag Mountains. Its thrusting displacement is over 30 km. The salt nappe complex appears as an arcuate zone projecting southwestwards along the leading edge of the Kuqa foreland fold belt. The major thrust fault is developed along the Paleocene-Eocene salt beds. The allochthonous nappes comprise large north-dipping faulting monoclines which are made up of Paleocene-Pliocene sediments. Geological analysis and cross-section restoration revealed that the salt nappes were mainly formed at the late Himalayan stage (c.a. 1.64 Ma BP) and have been active until the present day. Because of inhomogeneous thrusting, a great difference may exist in thrust displacement, thrust occurrence, superimposition of allochthonous and autochthonous sequences and the development of the salt-related structures, which indicates the segmentation along the salt nappes. Regional compression, gravitational gliding and spreading controlled the formation and evolution of the salt nappe complex in the Kuqa foreland fold belt.
文摘The Tianshan orogenic belt has a W-shape, composed of the V-shape Southern Tianshan and Northern Tianshan with different orogenic models .The Southern Tianshan broke off from the Sinian, forming a passive continental margin and ocean, and closed during Silurian and Devoaian. It belongs to the Wilson cycle orogenic model. The net duration is about 400 My.The Northern Tianshan began back-arc spreading during Devonian, forming the Devonian-Carboniferous marginal sea, and dosed during Late Carboaiferous. It belongs to the non-Wilson cycle orogeulc model or back-arc orogenic model. The duration is about 100 My .Deformation of the foreland fold-thrust belt occurred in two stages: in the early stage, folds and thrusts were formed by wedge-thrusting and lateral compression, while in the later stage, folds, gravitational normal faults and reveal faults were formed by the uplift of the Tianshan range and by gravity-gliding.
