摘要
阿尔金断裂是青藏高原的西北边界，分隔了塔里木与柴达木盆地，是新生代中亚大陆内一条重要的走滑断裂带，目前已成为中、外地学界瞩目的研究热点。作者阐明了在该项研究中应解决的３个科学问题，并提出了研究思路：（１）关于断裂形成时代的研究，目前存在３种不同认识。其一，认为早古生代阿尔金断裂就已存在，强调自早古生代以来断裂的多期活动；其二，认为断裂从华力西—印支期就开始活动；其三，作者根据柴达木盆地中由于阿尔金断裂左行走滑而引起的“反Ｓ型”同沉积构造的雏型从始新世晚期才开始出现，因而认为阿尔金断裂从始新世晚期才开始出现，解决这一问题需要查明断裂带内出露的不同时代的地层岩块究竟属于原地岩块还是异地岩块？同时应对断裂本身进行变形年代学研究；（２）断裂运动学特征的研究。这关系到断裂两侧原有构造带、地块和原型盆地的构造复位问题，作者认为通过断裂旁侧牵引构造形成的过程来研究断裂运动学演化的特征是一重要途径；（３）断裂对中国西北大陆构造的影响。这３个科学问题的解决，对于重新认识中国西北大陆构造的格架，对于中国西北地区找油勘探的战略部署都有重要意义。
The Altun fault is an important Cenozoic strike slip fault zone in Mid Asia,which defines the northwest boundary of Qinghai Tibet Plateau and separates the Tarim and Qaidam basins.It becomes a controversial point of research on the tectonic framework of western China or Mid Asia.Three scientific problems and the thought for further study on above fault are proposed.Dating the fault activities,there were three controversies on the ages of fault activities:(1) The fault zone was thought of as a multiple activity fault since the Early Paleozoic based on the existence of fault rocks of weakly metamorphosed Lower Paleozoic rocks and ophiolitic melange;(2)The fault activities started in Variscan Indosinian;(3)Depending on the fact that the synsedimentary structures with reverse S type in the Qaidam Basin appeared in the Late Eocene,which were caused by the sinistral strike slip of the Altun fault,the authors suggest that the activities of the Altun fault has acted since Late Eocene. To make this problem clear we should research which situation do the fault blocks in different ages belong to,autochthonous or allochthonous?and the deformation chronology for the fault zone.The kinematic research of the fault zone may be related to the reconstruction of the original tectonic zones, cratons and prototype basins on both sides of the Altun zone.The authors believe that it is one of important ways to research the process of drag structures for the kinematics evolution of the fault zone and determine the uplifting and erosion history of the Altun Mountain.The Altun fault influenced the tectonic framework of northwestern China.In the case of Cenozoic,the sinistral displacement of the Altun fault from Late Eocene would inevitably displace the original tectonic zones,cratons and prototype basins.The authors suggest following sequences of correspondence:the Variscan Indosinian tectonomagmatic zone in west Kunlun Mountain with the Variscan Indosinian tectonomagmatic zone in Qimantage Burhanbudai in east Kunlun Mountain;the south Tarim Basin(block)with the the Qaidam Basin(block);the Qilian Mountain with the middle Tarim where the north Qilian Mountain correlates to the Manjiaer depression,middle Qilian to mid Tarim uplift,north Tarim block with the Alex block.The relative displacement is up to 600～750km.The solution of these three scientific problems as mentioned above is of great significance to recognize the continental tectonic framework of northwestern China and to make the strategic plans of oil exploration in that region.This point should be paid more attention.
出处
《现代地质》
CAS
CSCD
北大核心
1998年第3期295-301,共7页
Geoscience
基金
国家自然科学基金
关键词
阿尔金断裂
变形年代学
运动学
大陆构造
断层
Altun fault, deformation geochronology,kinematics,northwestern China, continental tectonics
