燕山造山带侏罗-白垩纪岩浆活动与构造序列的关系初探  

A preliminary discussion on the relationship between Jurassic-Early Cretaceous magmatism and tectonic sequences in Yanshan Orogen

作　　者：汪洋[1] 邓晋福[1] 姬广义[2] 

机构地区：[1]中国地质大学地球科学与资源学院岩石教研室,北京100083 [2]北京市地质研究所,北京100011

出　　处：《北京地质》2001年第4期1-7,共7页Beijing Geology

基　　金：国家自然科学基金 ( No.4 0 1 0 4 0 0 3) ;中国博士后科学基金 ;国土资源部国际合作与科技司科技发展计划"华南地区岩石圈三维结构及其演化" ( 2 0 0 0 1 0 1 0 2 0 6;"华北地区岩石圈三维结构及其演化"资助 ( 2 0 0 0 1 0 1 0 2 0 2 );中国地质调查局 K1

摘　　要：根据地质接触关系和同位素年龄资料 ,划分出燕山造山带从早侏罗世到早白垩世时期的五个岩浆活动阶段 ,并讨论了其与构造变形序列的关系。第一阶段的代表是早侏罗世玄武岩 (和安粗岩 ) ;而第二阶段以中侏罗世中性火山岩和闪长岩 -石英二长岩 /花岗闪长岩 -花岗岩侵入岩组合为标志 ;第三阶段表现为晚侏罗世酸性火山岩和闪长岩 -石英二长岩 -正长岩 -花岗岩侵入岩组合的活动。早白垩世时期发育有两次岩浆活动阶段 ,较早的阶段 (第四阶段 )以安粗岩和流纹岩以及闪长岩 -石英二长岩 -正长岩 -碱性正长岩 -花岗岩侵入岩组合为标志 ,而后一个阶段(第五阶段 )以 1 2 0 Ma以后发育的小规模火山岩和花岗岩 -碱性花岗岩组合为标志。其中 ,第二、三岩浆活动阶段分别早于燕山造山带在中、晚侏罗世末的两次主造山幕发生的时代 ,所以燕山地区主造山幕的 P-T-t演化为逆时针轨迹。同时 ,第五阶段岩浆活动对应于造山后崩塌阶段。本文归纳的燕山造山带侏罗 -白垩纪造山过程演化模式为 :玄武岩底侵、地壳物质熔融形成安粗岩和流纹岩岩浆→地壳被加热并弱化→推覆构造发育、地壳增厚→造山后崩塌和碱性花岗岩形成。In this paper we propose a framework of magmatic event sequence from the Early Jurassic to Early Cretaceous in Yanshan Orogen, North China; and discuss the relationship between the magmatism and the deformation sequences. Five stages of magmatism were identified by the aid of geological contact relation and the isotope ages of igneous rocks.The Early Jurassic basalt and/or latite represented the first magmatic stage; and the second one is represented by the intermediate volcanic rocks and diorite-quartz monzonite/granodiorite-granite assemblage in Middle Jurassic; but the acid volcanic rocks and diorite-quartz monzonite-syenite-granite assemblage were developed in the third stage during Late Jurassic. In the Early Cretaceous,two stages of magmatism were developed, the earlier stage(fourth) stands by latite and rhyolite in strata and diorite-quartz monzonite-syenite-alkaline syenite-granite assemblage; and the later one(fifth) is represented by small scale volcanic activities and alkaline granite-granite assemblage after 120 Ma.The second and third stages of magmatism occurred before the main orogenic episodes in the end of mid-Jurassic and late-Jurassic,respectively;therefore,the main orogenic episodes have counterclockwise(CCW)P-T-t path.Meanwhile,the fifth stage of magmatism corresponds to the post-orogenic collapse episode. We proposed a general model for the orogenic evolution in Yanshan belt,i.e.basaltic underplating and formation of latite or rhyolite magma→crustal heating and weakening→thrust developing and crustal thickening→post-orogenic collapse and alkaline granite activity.

关 键 词：岩浆活动 构造序列 燕山造山带 侏罗-白垩纪 火山岩 同位素年龄 

分 类 号：P542.2[天文地球—构造地质学] P588.1[天文地球—地质学]