底辟构造启动及其沉积建造形成机制探讨——来自物理模拟的启示  

Diapiric Initiation and Formation Mechanism——Insights from Analogue Modelling

作　　者：何文刚 沈传波[3] 吴磊[4] 李生红[1] 赵远雯 HE Wengang;SHEN Chuanbo;WU Lei;LI Shenghong;ZHAO Yuanwen(College of Engineering and Technology,Zunyi Normal University,Zunyi 563006,Guizhou,China;Instituto Dom Luiz,Faculdde de Ciencias,University de Lisboa,Lisboa 1749-016,Portugal;Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education,China University of Geosciences,Wuhan 430074,Hubei,China;School of Earth Sciences,Zhejiang University,Hangzhou 310058,Zhejiang,China)

机构地区：[1]遵义师范学院土木工程系,贵州遵义563006 [2]里斯本大学科学院地质系,葡萄牙里斯本1749-016 [3]中国地质大学(武汉)构造与油气资源教育部重点实验室,湖北武汉430074 [4]浙江大学地球科学学院,浙江杭州310058

出　　处：《大地构造与成矿学》2023年第5期1069-1084,共16页Geotectonica et Metallogenia

基　　金：国家留学基金委博士后研究项目(CSC:20190820019);贵州省科技厅项目(黔科合基础-ZK[2022]一般571);黔科合支撑([2018]2778号);黔教合项目(KY[2022]014号);遵义师范学院大创项目(S202210664030)联合资助。

摘　　要：底辟构造因与造山带和盆地的变形演化过程以及油气资源分布关系密切而备受关注,到目前为止,有关底辟构造的形成环境、变形样式以及成因机制研究,已取得了许多重要的成果和认识,但对于盐岩或者泥岩底辟的启动及其沉积建造形成机制的模拟探讨仍然十分不足。本研究利用物理模拟技术,建立差异的初始地貌、塑性层之上覆盖层厚度、沉积速率以及基底与侧向摩擦力差异4组基底硅胶与其上覆石英砂组合模型,对底辟的初始启动条件及其沉积建造的形成机制进行了模拟分析和探讨。结果表明,地貌差异是盐丘或泥丘构造产生的初始必要条件,即在伸展、挤压环境以及由构造作用所形成的薄弱带等均有利于底辟构造的快速启动;而在底辟沉积建造过程中,快速的沉积加载、塑性层之上沉积层的初始厚度越大,以及具有较大的侧向与基底摩擦力,则会抑制早期底辟的发育;而缓慢的沉积作用、塑性层之上初始沉积层厚度越薄以及减小侧向与基底摩擦力,则会促进早期底辟的生长。同时在底辟沉积建造的中后期,随着沉积速率的加载,底辟会快速的生长变形。综合模拟结果和实际的底辟沉积建造过程表明,底辟沉积建造是地貌、沉积速率、地层温度、地层压力和底辟塑性流体埋深等综合作用的结果,正如北海盆地盐底辟和安达曼海弧后盆地泥底辟的沉积建造过程,在形成机制上与模拟结果具有较大的相似性。Diapir structure has received considerable attention and extensively studied because it is closely related to the deformation and evolution process of orogeny,as well as the distribution of oil and gas resources.Many significant achievements and understandings on the formation environment,deformation styles,and deformation mechanism of diapir structures have been obtained thus far.However,there have been very few studies on the formation mechanism of salt or mud diapir initiation and its downbuilding.To better understand the starting mechanism of diapir structure and downbuilding,nine groups of four series models with sand and silicone layers were designed using initial geomorphology,the thickness of the covering layer above the ductile layer,sedimentary rate,and basal and lateral friction.According to the findings,the difference in geomorphology is the initial necessary condition for forming a salt-or mud-dome structure.The extension,compression environment,and weak zone formed by tectonic activity all contribute to the diapir structure’s rapid start.Early diapir development will be hampered by diapir downbuilding,rapid deposition loading,the initial thickness of the covering layer above the ductile layer,and significant basal and lateral friction.Slow deposition rate,thin initial thickness of the covering layer above the ductile layer,and reduced basal and lateral friction,conversely,will promote the growth of early diapirs.Simultaneously,diapirs will grow and deform rapidly with the loading of the high deposition rate in the middle and late stages of diapir downbuilding.Comprehensive analysis of the physical modeling results and natural deformation of the diapiric structure shows that diapir downbuilding results from the combined effects of geomorphology,deposition rate,formation temperature,pressure,and diapir fluid depth.Further,the formation mechanisms of salt diapir downbuilding in the North Sea Basin and mud diapir downbuilding in the Andaman back-arc basin are similar to the analogue modelling experime

关 键 词：底辟沉积建造 初始地貌沉积速率 覆盖层厚度控制 基底与侧向摩擦力 物理模拟 

分 类 号：P554[天文地球—构造地质学]