龙门山前陆褶皱冲断带的平衡剖面分析  

Balanced Cross-section Analysis of the Fold—Thrust Belt of the Longmen Mountains

作　　者：陈竹新[1] 贾东[1] 张惬[1] 魏国齐[2] 李本亮[2] 魏东涛[1] 沈扬[1] 

机构地区：[1]南京大学地球科学系,210093 [2]中国石油天然气股份有限公司勘探开发研究院,北京100083

出　　处：《地质学报》2005年第1期38-45,共8页Acta Geologica Sinica

基　　金：国家自然科学基金项目 (编号 40 3 72 0 91);中国石油天然气集团公司创新基金项目;国家"十五"重点科技攻关项目 (编号2 0 0 1BA60 5 A-0 6-0 1)资助的成果

摘　　要：对龙门山前陆褶皱冲断带形成的正反转构造过程有过许多分析 ,但明显缺乏直接的证据和定量的分析。本文在地层资料分析的基础上 ,借助平衡剖面分析验证龙门山形成的正反转构造过程 :志留纪至中三叠世受多条倾向北西的同沉积断裂控制 ;晚三叠世以来遭受北西—南东向挤压、抬升和剥蚀 ,形成逆冲推覆构造。在晚三叠世和新生代的两期板块碰撞的影响下 ,龙门山产生了两期褶皱冲断作用 ,但在南、北两段表现出显著不同的变形过程。龙门山北段表现为复杂的逆冲推覆构造 ,能明确划分出两期构造变形 ,晚三叠世的变形强烈 ,缩短率达 31.7% ;而新生代的变形较弱 ,缩短率仅为 10 .5 %。南段则表现出基底卷入的叠瓦状冲断的特点 ,主要体现新生代的构造变形 ,晚三叠世的构造变形基本上被改造 ,南段整体缩短率达 2 6 .2 %。There are lots of discussions about the positive inversion process of the fold—thrust belt of the Longmen Mountains, but there are no direct evidences and quantitative analysis. Based on the analysis of strata and balanced cross-sections, writers discuss the positive inversion process of Longmen Mountains, which had been controlled by several NW trending syn-depositional normal faults from Silurian to Middle Triassic, and suffered NW—SE directional compression, uplift, thrust and denudation since Late Triassic. At least two major tectonic events of Late Triassic and early Cenozoic ages have occurred and formed two phases of the foreland fold—thrust belt, and had significantly different effects on the northern and the southern Longmen Mountains. The northern Longmen Mountains is composed of several southeastward thrusting nappes and thin-skinned imbricates of Cambrian—Triassic rocks, which deformed intensively during the Late Triassic events and got the 31.7% rate of shortening, while weakly since the early Cenozoic and got the 10.5% rate of shortening. However, the southern Longmen Mountains presents the basement-involved thrust structures that wholly represent the deformation features formed since early Cenozoic instead of during the Late Triassic, and made the 26.2% total rate of shortening.

关 键 词：前陆褶皱冲断带 龙门山 平衡剖面 构造变形 晚三叠世 新生代 逆冲推覆构造 中三叠世 志留纪 缺乏 

分 类 号：P542[天文地球—构造地质学] Q915[天文地球—地质学]