龙门山冲断带北段前山带构造分带性及山前带变形特征  

Tectonic Zonation of Front Range and Deformation Features of Foreland in Northern Longmen Mountain Thrust Zone

作　　者：孙晓猛[1] 杜继宇[1] 单玄龙[1] 程日辉[1] 王英德[1] 许强伟[1] 田景雄[1] 

机构地区：[1]吉林大学地球科学学院,长春130026

出　　处：《吉林大学学报（地球科学版）》2010年第6期1323-1332,共10页Journal of Jilin University：Earth Science Edition

基　　金：国土资源部油气资源战略研究中心项目(2009GYXQ14);国家'973'计划项目(2009CB219305)

摘　　要：龙门山冲断带构造分带性是龙门山构造研究中的核心内容和关键科学问题。在野外实测地质大剖面以及路线地质调查的基础上,根据冲断带不同部位构造样式的不同,将龙门山冲断带北段前山带划分出3个构造亚带,即唐王寨—仰天窝飞来峰-滑覆体构造亚带、楼子坝—雁门坝—马角坝叠瓦冲断亚带、矿山梁—天井山—二廊庙冲断背斜亚带。各亚带具有不同构造变形特征:飞来峰-滑覆体构造亚带具有'推覆加滑覆'的构造叠加和演变特征;叠瓦冲断亚带中冲断构造十分发育,从北西至南东方向,不同系、同一系中不同组、同一组中不同段的地层依次由老向新逆冲,组成典型的叠瓦状构造样式,逆冲断裂向西呈铲式倾斜,并收敛于逆冲断裂系底板断层之上。构造岩片中褶皱构造十分发育,以断层传播褶皱为主,其轴迹走向和轴面产状与叠瓦冲断亚带中各条断层的总体产状几乎相同,均倒向前陆方向。冲断背斜亚带具有双重构造特点,在浅层表现为近直立的短轴背斜,构造样式以断层转折褶皱为主,深层由多个逆冲岩片叠置而成。下寺—金子山—厚坝山前带浅部层次中冲断稀少、规模较小、变形微弱,主要表现为向南东倾斜的单斜构造,深部层次发育有大型隐伏逆冲断裂。从前山带和山前带总体上具有变形强度向前陆方向有规律递减、卷入构造的地层逐渐变新、变形层次逐渐变浅的趋势,反映了冲断构造具有前展式特征。冲断构造是晚三叠世与新生代两期构造变形的产物:晚三叠世构造变形强烈,是龙门山前陆冲断带的主要形成期;新生代变形较弱,叠加和改造了晚三叠世的构造变形。The tectonic zonation of Longmen Mountain thrust zone is the key problem in the study of Longmen Mountain structure.According to the field measured geologic section and the geological survey as well as the different structural types of the different part within the thrust zone,the northern front range of Longmen Mountain thrust zone is divided into three tectonic sub-belts,Tangwangzhai-Yangtianwo klippe and gliding nappe tectonic subbelt,Louziba-Yanmenba-Majiaoba imbricate thrust subbelt and Kuangshanliang-Tianjingshan-Erlangmiao thrust and anticline subbelt,namely.Each has the different tectonically deformation.The klippe and gliding nappe tectonic subbelt is characterized by structural superimposition and tectonic evolution of nappe and addition gliding nappe.The thrust structure of the imbricate thrust subbelt is well developed,different systems,different formation in the same system as well as the different member in the same formation in the imbricate thrust subbelt thrusts from northwest to southeast,from older to younger in turn and forms the typical imbricate structural type.The thrust faults take on listric inclination westward and converge above the basal thrust plane of the thrust zone.There well developed fault-propagation folds in the structural rock fragments.These folds have almost the same axial strike and axial-plane occurrence as those faults in the imbricate thrust zone,and all fall toward foreland.The thrust anticline subbelt has the dual feature,on the one hand,it shows as brachyanticline on the surface or the near surface,on the other hand,thrust sheets are distributed in the deep crust of earth.In Xiasi-Jinzishan-Houba foreland,the thrusts are of scarcity,small scale and weak deformation in the shallow which mainly shows that monoclinal structure dipps toward southeast.Whereas,buried thrust faults has been well developed in the depth.Thrust zone has the tendency of regular decreasing gradually in its deformation strength,the involved strata gradually becoming new and the deformation levels

关 键 词：龙门山 冲断带 前山带 山前带 构造分带 构造特征 构造地质学 

分 类 号：P641.8[天文地球—地质矿产勘探]