基于断层滑动矢量应力反演的燕山中段中侏罗世–早白垩世构造应力场序列  

Paleotectonic Stress Field and its Evolution in Central Part of the Intraplate Yanshan Orogenic Belt during Middle Jurassic and Early Cretaceous: Constrains of Stress Inversion of Fault Slip Vectors

作　　者：林逸[1] 张长厚[1,2] 李程明[1] 史小龙[1] 

机构地区：[1]中国地质大学(北京)地球科学与资源学院,北京100083 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083

出　　处：《大地构造与成矿学》2015年第2期187-207,共21页Geotectonica et Metallogenia

基　　金：中国地质调查局地质调查工作项目(编号:121201112073;12120113059700);国家自然科学基金(批准号:90814002;40672150;40739906)资助

摘　　要：燕山板内造山带中段承德一带地层记录齐全且构造变形复杂。该区域主要构造形迹及其运动学特征已经得到了比较系统的研究，但有关形成这些构造形迹的古构造应力场及其演变过程的研究鲜有报道。本文根据断层滑动矢量应力反演理论和方法，通过露头与区域尺度断层运动学数据的搜集与处理，结合研究区域构造层划分特征及主要岩石地层单位的年代学资料，对研究区中侏罗世–早白垩世的构造应力场演变过程进行了研究。经过对擦痕数据进行应力反演并综合分析，共划分出3期5阶段应力场：中侏罗世下花园组沉积之后–髫髻山组火山活动之前的NNW向挤压（D1）（〈173~165 Ma）；晚侏罗世土城子组沉积中–晚期 N-S 向挤压（D2-1）（〈152~139 Ma）；早白垩世初土城子组沉积期末 NNE-NE 向挤压（D2-2）（〈139~135 Ma）；以及早白垩世张家口组火山喷发之后垂向挤压主导的多向伸展（D3-1）和 NW-NNW 向弱挤压（D3-2）（〈125 Ma之后）。其中，中–晚侏罗世至早白垩世初以挤压为主，最大主压应力方向发生了大〈60°的顺时针旋转，且土城子组沉积作用发生于此挤压作用为主的构造背景之下。早白垩世以伸展为主，并有弱挤压作用出现。同时，研究区内未发现与中侏罗世以来古太平洋板块或伊佐奈岐（Izanagi）板块俯冲作用相关的近 W-E 向或 NW-SE 向挤压应力场的存在，可能与克拉通内部变形不均匀有关。The Mesozoic structural deformation and sedimentation as well as the volcanism in the Chengde area, central part of intraplate Yanshan orogenic belt, have been systematically investigated in the last two decades. The paleostress fields leading to these complicated tectonic deformations remain unrevealed. Paleostress inversion of fault slip vectors, combining with the newly defined structural levels and the latest age dating results on the key lithostratigraphic units, is employed to establish the paleostress fields in the Chengde area during Middle Jurassic and Early Cretaceous. Three generations including five phases of paleostress fields have been identified in this study. The first generation is believed to be the Middle Jurassic NNW compression （D1） after the sedimentation of the Xiahuayuan Formation and previous to that of the Tiaojishan Formation volcanism （~173 Ma–165 Ma）; The second generation includes two phases, the Late Jurassic and earliest Cretaceous N-S compression （D2-1） during and after the sedimentation of the Tuchengzi Formation（~152 Ma–139 Ma） followed by the NNE compression （D2-2） post to the Tuchengzi Formation and predate the Zhangjiakou Formation （~139 Ma–135 Ma）. The third generation of paleostress field is inferred to be later than 125 Ma and characterized by a widespread multidirectional extension （D3-1） induced from vertical compression, followed by a leading and weak NW-NNW compression （D3-2）. It is inferred that the contraction regime dominated in the Chengde area during the Middle Jurassic and the early Early Cretaceous, with the maximum principal stress axes （σ1） rotated ca 60° clockwise from NNW to NNE, and the sedimentation of the Tuchengzi Formation occurred in this compressive tectonic setting. Extension regime characterized the Early Cretaceous in the central Yanshan belt, even a weak compression once occurred during this period. There is no nearly W-E or NW-SE compressional stress field previously inferred as far-field response to th

关 键 词：燕山中段 中生代 擦痕 应力反演 构造应力场 

分 类 号：P542[天文地球—构造地质学]