摘要
构造变形与地表过程相互影响,但前人研究主要关注构造变形如何塑造地貌,而对地表过程如何影响构造变形尚有待研究。研究区塔西南褶皱冲断带主要经历了三叠纪末和新生代两期逆冲变形过程。在这两期变形过程中,剥蚀作用和沉积作用共同对变形施加影响,形成了山前逆冲断层突破地表、盆地内断层远距离传播的现今构造样式。因此,本研究以塔西南褶皱冲断带地质模型为基础,开展剥蚀和同沉积这两个地表过程对褶皱冲断带变形影响的构造物理模拟实验研究,结合塔西南地区的实际地质条件,在双滑脱层条件下,设计了3组实验模型,包括未施加剥蚀和同沉积的参照模型A、同时施加差异剥蚀和同沉积的模型B、同时施加剥蚀夷平和同沉积的模型C。在第一期变形结束后,三组模型变形样式相似,在没有上覆沉积物的负载作用时,变形均未向盆地内部远距离传播。在第二期变形结束后,模型A山前与盆地内部构造以及地形坡角差异不大,变形前锋最远可达106 cm;模型B在山前和盆地内部的地形坡度为14°以及4°,变形前锋最远可达96 cm;模型C在山前和盆地内部的地形坡度为20°以及5°,变形前锋最远可达89 cm。实验结果表明:1)早期剥蚀作用会降低逆冲楔体的地形坡度,从而在褶皱冲断带根部形成逆冲断层突破上滑脱层直至显露出地表的构造形态,并在一定程度上抑制了变形向盆地方向传递,最终形成冲断带根部更大的地形坡度;2)后期同沉积作用会抑制深部断层向浅部地表突破,促使上部韧性滑脱层产生良好的滑脱效果,导致变形远距离地向前陆方向扩展,形成更宽的山前褶皱冲断带,最终形成冲断带根部较小的地形坡度。
Tectonic deformation and surface processes interact with each other.Several analogue modeling studies have been conducted during the past decades with the aim to investigate the effects of tectonic deformation on landforms;whereas how surface processes affect tectonic deformation has been rarely addressed.The study area of the fold-and-thrust belt in SW Tarim Basin mainly experienced two stages of thrust deformation in the Late Triassic and Cenozoic.During these two stages of denudation and syn-tectonic sedimentation jointly affected the deformation,forming the current structural style of foreland thrust fault breaking through the surface and long-distance propagation of faults in the hinterland.In this study,based on the geological model of the fold-and-thrust belt,we use analogue modeling to analyze the effects of denudation and syn-tectonic sedimentation on the structural evolution of the fold-and-thrust belt.Combined with the natural geological conditions in SW Tarim Basin,three groups of experimental models with double décollements were designed,including the reference model A(without denudation and syn-tectonic deposition),the model B(differential denudation and syn-tectonic sedimentation),and the model C(denudating to a planation and syn-tectonic sedimentation).After the first stage of deformation,the deformation styles of the three groups of models are similar.Without the load of overlying sediments,the deformation has not propagated far into the hinterland.After the second stage of deformation,there is little difference in the structure and surface slope between foreland and hinterland of model A,and the maximum deformation front can reach 106 cm;The surface slope of model B in the foreland and hinterland are 14°and 4°,and the deformation front can reach 96 cm;The surface slope of model C in the foreland and hinterland are 20°and 5°,and the deformation front can reach 89 cm.The results suggest that:(1)Previous denudation will decrease the surface slope,and to a certain extent,restrain deformation propagation into the hinterland,produce the structural style in which the thrust faults break through the upper décollement to emerge onto the surface at the root of the fold thrust belt,and form a higher surface slope at the second stage of deformation;(2)Syn-tectonic sedimentation will promote the detaching role of the upper décollement,prevent the deep faults from breaking through to the surface,force the deformation to propagate basinward in a long distance and thus produce a broader foreland fold-and-thrust belt,and form a lower surface slope at the second stage of deformation.
作者
洪晨
张亮
林秀斌
孙迪
陈汉林
陈才
程晓敢
章凤奇
HONG Chen;ZHANG Liang;LIN Xiubin;SUN Di;CHEN Hanlin;CHEN Cai;CHENG Xiaogan;ZHANG Fengqi(Key Laboratory of Geoscience Big Data and Deep Resource of Zhejiang Province,School of Earth Sciences,Zhejiang University,Hangzhou 310027,Zhejiang;Research Center for Structures in Oil-and Gas-Bearing Basins,Ministry of Education,Hangzhou 310027,Zhejiang;Research Institute of Exploration&Development,PetroChina Tarim Oilfield Company,Korla 841000,Xinjiang)
出处
《第四纪研究》
CAS
CSCD
北大核心
2022年第3期692-703,共12页
Quaternary Sciences
基金
科技部第二次青藏高原综合科学考察研究项目(批准号:2019QZKK0708)
国家自然科学基金项目(批准号:41720104003和41972217)
中央高校基本科研业务经费项目(批准号:2019FZA3008、2019QNA3013和2021XZZX005)共同资助。
关键词
物理模拟
褶皱冲断带
多期构造叠加
剥蚀
同沉积
塔里木西南地区
analogue modeling
fold-and-thrust belt
multistage tectonic superposition
denudation
syn-tectonic sedimentation
southwest Tarim Basin
