从深部背景看燕山陆内造山作用的主因  

The dominant factors of the Yanshan intracontinental orogeny seen from its deep background

作　　者：邵济安[1] SHAO Ji’an(The Key Laboratory of Orogenic Belts and Crustal Evolution,Ministry of Education,School of Earth and Space Sciences,Peking University,Beijing,100871)

机构地区：[1]北京大学造山带与地壳演化教育部重点实验室,地球与空间科学学院,北京100871

出　　处：《地质学报》2020年第8期2190-2199,共10页Acta Geologica Sinica

基　　金：中国地质调查项目(编号121201102000150009)资助成果。

摘　　要：中生代华北燕山造山带是陆内造山作用的典型,但长期来对造山作用的动力学机制存在多种分歧观点。本文尝试将岩石圈不同深度的构造整合在一起,探索陆内造山作用的主因。本文拟从燕山带中生代构造运动的基本特征入手,选择集宁-承德基底岩石圈断裂带作为先存构造薄弱带,结合不同深度层次的地质作用:①地表的断陷盆地及其火山-沉积岩建造;②断块构造的差异隆升;③固态流变和地热活动;④幔源或者壳幔混溶的火山岩,论证先存构造薄弱带的活化现象。在此基础上,通过幔源熔-流体的交代作用讨论了岩石圈强度的弱化,结合岩石圈结构的层析成像研究,得到初步结论:地幔底辟体上涌是华北克拉通中生代构造活化的重要背景。不排除不同板块间相互作用的影响。最后,从与国外典型的陆内造山带的对比中,进一步认识到:深部地幔物质上涌和上部岩石圈物质的均衡调整,是陆内造山与陆缘造山的本质区别。The Mesozoic Yanshan orogenic belt in the North China is typical of intracontinental orogeny, but there are divergent views on the dynamic mechanism of its orogeny. In this article an attempt is made to explore the key factors in the intracontinental orogeny by comprehensively investigating the structures at different depths of the lithosphere to discover the main characteristics of the Mesozoic tectonic movement in the Yanshan belt. At first, with the Jining-Chengde basement lithospheric fault belt as an example, activation of the preexisting weak structure belts is studied in terms of geological actions at different depth levels:(1) the surface faulted basins and their volcanic-sedimentary formations,(2) the different swells of block structures,(3) the rheological deformation and thermal activity,(4) the mantle-derived or crust-mantle miscible volcanism. Secondly, weakening of the lithosphere is investigated through the mantle-derived fusion-fluid metasomatism. Finally, by taking into account the tomographic imaging of the lithospheric structures, it can be concluded that(1) the upwelling of mantle diapir is the most important background of Mesozoic intracontinental orogeny in the North China Craton, and(2) that the effects of interaction between adjacent plates should not be excluded. Finally, from comparison with other typical intracontinental orogenic beltsabroad, it is further recognized that deep mantle material upwelling and isostatic adjustment of upper lithosphere materialsare essential differences of the intracontinental orogeny from the continental margin orogeny.

关 键 词：燕山 陆内造山带 先存构造薄弱带活化 岩石圈弱化 地幔底辟体的上涌 

分 类 号：P542[天文地球—构造地质学]