准南逆冲褶皱带霍−玛−吐逆冲岩席发育力学机制与模拟实验  

Mechanics and analog modeling of the Huo-Ma-Tu thrust sheet in the southern Junggar Basin fold and thrust belt

作　　者：杨庚[1] 陈竹新[1] 鲁雪松[1] 张欲清 YANG Geng;CHEN Zhuxin;LU Xuesong;ZHANG Yuqing(Research Institute of Petroleum Exploration and Development,Beijing 100083,China)

机构地区：[1]中国石油勘探开发研究院,北京100083

出　　处：《地质力学学报》2025年第1期8-23,共16页Journal of Geomechanics

基　　金：中国石油天然气股份有限公司科技项目(2023ZZ0202,2023YQX10101)。

摘　　要：逆冲岩席发育的力学机制厘定是认识冲断带变形过程的基础与难点。文章以准南冲断带为研究实例,结合力学模型与物理模拟对逆冲岩席发育的力学机制进行探讨。依据地质调查、地震资料解释和钻井资料证实霍-玛-吐背斜核部和南翼发育有逆冲断层,断层向南延伸到第一排背斜之下,并形成广泛分布的霍-玛-吐逆冲席体,席体内部基本上无构造变形。霍-玛-吐构造带的钻井资料显示准南逆冲带前缘逆冲断层及滑脱断层均发育在流体压力系数较高的异常超压层中,说明该逆冲岩席属于强干变形席体、弱滑脱断层组合。根据玛纳斯构造带的钻井实测地层压力计算出逆冲断层的上下盘压力系数明显不同,且逆冲断层上盘的流体压力系数在逆冲断层处急剧降低,说明上盘逆冲岩席底部为弱滑脱层,有效分隔了上、下盘流体压力系统。文章依据地震剖面和钻井资料标定获得的霍-玛-吐逆冲岩席变形几何学特征,建立了后缘挤压下逆冲席体变形的简化力学模型,并计算出逆冲席体后缘水平挤压应力与垂直方向的重力比值与逆冲席体几何参数及断层摩擦系数和断坡角之间的数学关系式,分别给出了无流体超压的逆冲席体和含有流体超压滑脱层逆冲席体的数学关系式。为了验证力学模型可靠性,对准南逆冲带中的霍-玛-吐逆冲席体发育特征进行了物理模拟实验研究。结果证实该类型的刚性逆冲席体变形规律前缘逆冲断层发育样式符合地震剖面的构造解释认识,也佐证了简化的力学模型符合实际地质情况。实验结果表明逆冲席体底部大位移是多地段同时发生的小范围位移累积而成大位移,为认识造山带内推覆体或造山带前缘逆冲席体大规模远距离推覆问题提供了理论依据。[Objective]Understanding the mechanical development of thrust sheets is fundamental,yet challenging,to comprehensively understand the deformation processes of thrust belts.Various models explain the mechanics behind thrust sheet development,yet significant controversies persist.[Methods]This study takes a comprehensive approach,focusing on the southern Junggar Thrust Belt.We combine a variety of methods including surface geological surveys,seismic reflection profiles,and drilling data analysis with mechanical and physical modeling to thoroughly investigate this issue.[Results](1)Based on surface geological surveys,seismic data interpretation,and drilling data,we confirm that thrust faults have developed in the core and southern limb of the Huo-Ma-Tu anticline.These faults extend southward beneath the front of anticlines,forming the extensively distributed Huo-Ma-Tu thrust sheet,which exhibits none to weak internal structural deformation.(2)Drilling data from the Huo-Ma-Tu structural belt clearly show that the frontal thrust faults and detachment faults have developed in layers with abnormally high fluid pressure,indicating that the thrust sheet is a combination of strong deformation sheets and weak detachment faults.Analysis of in-situ formation pressure data suggests that the thrust faults within these overpressure layers can segregate fluid pressure coefficients between the hanging wall and the footwall.(3)Using the geometric deformation characteristics of the Huo-Ma-Tu thrust sheet obtained from seismic profiles and drilling data,a simplified mechanical model is established.This model calculates the mathematical relationship between the horizontal compressive stress-to-gravity ratio at the back of the thrust sheet,the geometric parameters of the thrust sheet,the fault friction coefficient,and the fault dip angle.Separate equations are provided for thrust sheets without fluid overpressure and those with fluid overpressure detachment layers.(4)A physical model of the development characteristics of the Huo-Ma-Tu

关 键 词：准南逆冲褶皱带 霍-玛-吐逆冲岩席 构造超压 力学模型 物理模拟实验 

分 类 号：P554[天文地球—构造地质学] P542[天文地球—地质学]