天井山古隆起的“前世今生”:论古隆起的构造复原  

The “past and present” of the Tianjingshan palaeo-uplift:discussion on structural restoration of paleo-uplift

作　　者：何登发[1] 伍顺利 HE Dengfa;WU Shunli(School of Energy Resources,China University of Geosciences (Beijing),Beijing 100083,China)

机构地区：[1]中国地质大学(北京)能源学院,北京100083

出　　处：《地学前缘》2019年第1期86-101,共16页Earth Science Frontiers

基　　金：国家自然科学基金重点项目(41430316)

摘　　要：古隆起是地质历史时期地表的正向构造单元,是该时期地球内、外动力综合作用的结果;复原其构造-沉积面貌,将为探索地球演化历史及资源、能源矿产的赋存规律奠定重要基础。文中以龙门山北段的天井山古隆起为例,分析古隆起的地质结构及其演化、改造特征,探讨古隆起复原的思路、方法及意义。天井山古隆起早在20世纪80年代便被人们发现并提出,由于其所处地理位置特殊,天井山古隆起的地质结构及其在地质历史时期的形成与演化过程一直存在争议。基于天井山地区的地层与构造分布,文中建立其浅表地质结构模型,应用构造复原方法重建其形成与演化过程,恢复出天井山古隆起在不同地质历史时期的空间展布特征。研究认为,天井山古隆起发育震旦系、寒武系—志留系、泥盆系—石炭系、二叠系—三叠系和侏罗系—第四系等5套构造地层层序,沿构造走向划分为北、中、南3段。天井山古隆起北段总体表现为两背斜夹一向斜构造,中段表现为一紧闭的背斜构造,南段表现为一逐渐倾伏的背斜构造;天井山古隆起经历了寒武纪—志留纪幕式隆升、泥盆纪—石炭纪持续隆升、二叠纪—三叠纪整体埋藏与侏罗纪—现今为破坏改造等4个演化阶段;天井山古隆起在形成演化过程中,古隆起核部呈现出向南东迁移的特征。天井山古隆起为改造残余古隆起,反映了龙门山北段的多幕伸展-挤压构造事件的作用。Paleo-uplift is the positive structural unit on the Earth’s surface due to the interaction between the internal and exotic geodynamic processes.Its structural restoration is important for understanding the Earth’s evolutionary history as well as supporting energy exploration.In this paper,taking the Tianjingshan paleouplift as an example,we discussed the geological structure and formation and modification of paleo-uplift,and put forward a structural restoration methodology.Although the Tianjingshan paleo-uplift was discovered in the early 1980 s,its geological structure and formation and evolutionary history have been controversial owing to its distinctive geographic location.Based on stratigraphic and structural distribution data,we constructed the near-surface geological cross-section and reconstructed the formation and evolutionary history of the paleo-uplift using the structural restoration method.The Tianjingshan paleo-uplift developed several structural layers including the Sinian,the Cambrian to Silurian,the Devonian to Carboniferous,the Permian to Triassic,and the Jurassic to Quaternary.Along its strike,the paleo-uplift can be divided into the northern,central and southern segments,which consist of two anticlines intercalating with a syncline,a tight anticline,and a gradually overturned anticline,respectively.The Tianjingshan paleo-uplift underwent four-stage tectonic evolution,i.e.episodic uplifting during the Cambrian to Silurian,continual uplifting during the Devonian to Carboniferous,total burial during the Permian to Triassic,and modification and transformation during the Jurassic to Quaternary.The tectonic evolution resulted in a southeastward axial migration.The Tianjingshan paleo-uplift is a remnant uplift with extensive modification,demonstrating the effect of multi-phase extension and compression in the northern Longmenshan Mountains.

关 键 词：龙门山北段 天井山古隆起 地质结构 构造复原 伸展-聚敛旋回 

分 类 号：P618.130.2[天文地球—矿床学]