摘要
博格达山北缘褶皱冲断带以横向分段、纵向分层、多期构造变形叠加、先存构造发育为主要特征,发育有中侏罗统西山窑组和下侏罗统八道湾组两套滑脱层,为探究这两套滑脱层内聚力强度差异及先存构造对冲断带新生代构造变形的影响,研究采用离散元数值模拟方法,在布设先存构造的基础上设计了无滑脱层模型和不同内聚力强度组合的双滑脱层模型共5组数值模拟实验.实验结果表明:双滑脱层内聚力强度相同时,上滑脱层在应力传播中占据优势;双滑脱层内聚力强度不同时,应力会优先沿弱内聚力滑脱层传递,且当下滑脱层内聚力较弱时,上滑脱层可能不发挥作用.通过对比实验结果与实际地质剖面,认为先存构造控制了冲断带构造变形的总体样式,而两套滑脱层共同控制了冲断带纵向上的变形解耦,上部滑脱层内聚力弱于下部滑脱层是影响研究区新生代构造变形的关键性因素.
The fold-thrust belt of the northern Bogda Mountain is characterized by horizontal segmentation,vertical stratification,overlap of multi-phase structure deformation and rich pre-existing structures.Two décollements,the Xishangyao Formation of Upper Jurassic and the Badaowan Formation of Lower Jurassic,are developed in this area.In order to investigate the influence of the difference in cohesion strength between the two décollements and the pre-existing structures on the structure deformation in Cenozoic,this study designed five experiments including a model without décollement and four double-décollement models with different cohesion strength combinations adopted the discrete element method,on the basis of laying out pre-existing structures.The experimental results show that when the cohesion strengths of the double-décollement are the same,the upper décollement has the advantage in stress propagation;when the cohesion strengths of the double-décollement are different,the stress will preferentially transmits along the weaker cohesion décollement,and when the cohesion strength of the lower décollement is weaker,the upper décollement may not play a role.By comparing the experimental results with actual geological profile,it is concluded that the pre-existing structures control the structure deformation style of the thrust belt.However,the two décollements jointly control the tectonic decoupling in the vertical of the fold-thrust belt,and that the cohesion strength of the upper décollement weaker than that of the lower décollement,which is a key factor affecting the Cenozoic structure deformation in the study area.
作者
屈梦雪
程晓敢
田禾丰
陈汉林
于洪洲
陈昌锦
孙思瑶
Qu Mengxue;Cheng Xiaogan;Tian Hefeng;Chen Hanlin;Yu Hongzhou;Chen Changjin;Sun Siyao(School of Earth Sciences,Zhejiang University,Hangzhou 310027,China;Structure Research Center of Oil&Gas Bearing Basin of Ministry of Education,Hangzhou 310027,China;Shengli Oil Field Exploration and Development Research Institute,SINOPEC,Dongying 257015,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2023年第4期1366-1378,共13页
Earth Science
基金
国家重点研发计划(No.2019YFC0605501)
国家自然科学基金(No.41720104003).
关键词
博格达山北缘
褶皱冲断带
离散元数值模拟
双滑脱层
内聚力强度
先存构造
构造地质学
northern Bogda Mountain
fold-thrust belt
discrete element method
double-décollement
cohesion strength
preexisting structure
structural geology
