塔里木盆地北缘温宿凸起压扭隆升的证据

Transpressional uplift of Wensu Uplift in northern Tarim Basin,NW China:evidence from seismic profiles

温宿凸起是塔里木盆地北缘极为重要的近东西向构造带。前人研究认为,温宿凸起以逆冲变形为主。但是,这一认识既与地震剖面上背冲的2个方向断层同等发育矛盾,又与主干断层产状突变矛盾。基于高分辨率二维地震剖面的精细地质解释,提出塔里木北缘温宿凸起的构造变形以走滑为主,而非前人认为的以逆冲为主。主要证据是:(1)在地震剖面上,表现为2个正花状构造的变形特征;(2)形成花状构造的主干断层(沙井子断裂与古木别兹断裂)在东段向南强烈逆掩,在西段则向北强烈逆掩,顺断层走向产状多变;(3)温宿凸起的前中生界为古老的震旦系—寒武系,向南、向北分别逆冲于阿瓦提凹陷与乌什凹陷中—新生界之上。走滑构造变形发生于加里东中期(晚奥陶世末)、加里东晚期(志留纪末)、海西早期(早—中泥盆世末)、海西晚期(晚二叠世)、印支—燕山期(三叠纪末期和晚白垩世)和喜马拉雅期(古近纪、新近纪和第四纪)。该走滑构造带的厘定表明,古生代时期塔里木盆地北缘可能并非统一的构造—沉积环境,温宿凸起为一重要的构造—沉积分隔带。

The Wensu Uplift is an important structural belt in the northern Tarim Basin,NW China,always regarded as a thrust belt.However,this recognition is not only incompatible with the facts that synthetic and antithetic faults are equally developed in thrusting systems on the seismic profiles,but also contradictory with the changeable thrust directions of the main faults.Based on the high⁃resolution seismic profiles,strike⁃slip deformation happened in the Wensu Uplift.It is because:(1)Two large flower structures are developed on seismic profiles;(2)The main strike⁃slip faults named as the Shajingzi and Gumubiezi faults,which are the main faults of two large flower structures mentioned above,thrust violently southward in the eastern section and northward in the western section,respectively;(3)The pre⁃Mesozoic units in the Wensu Uplift are ancient Sinian-Cambrian strata,which thrust southward and northward over the Mesozoic-Cenozoic strata in the Awati and Wushi sags,respectively.The strike⁃slip activities happened during the middle Caledonian(the latest Ordovician),the late Caledonian(the latest Silurian),the early Hercynian(the latest Early-Middle Devonian),the late Hercynian(Late Permian),Indosinian⁃Yanshan(the latest Triassic and Late Cretaceous)and Himalayan period(Paleogene,Neogene and Quaternary).These results indicate that the Paleozoic is not a uniform tectonic-sedimentary environment in the northern Tarim Basin because of the Wensu Uplift barrier.