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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。
Based on the geological contact and isotopic age data, five stages of the Yanshan orogenic belt from Early Jurassic to Early Cretaceous are divided and their relationship with tectonic deformation sequences is discussed. The representative of the first stage is the Early Jurassic basalts (He’an rock), while the second stage is marked by the combination of Middle Jurassic neutral volcanic rocks and diorite-quartz diorite / granodiorite-granite intrusive rocks In the third stage, the activity of late Jurassic acidic volcanic rocks and diorite-quartz monzonite-syenite-granite intrusive rock assemblages. During the Early Cretaceous period, there were two stages of magmatic activity. In the earlier stage (the fourth stage), amphiboles and rhyolite and diorite-quartz monzonite-syenite-alkali syenite-granite The combination of intrusive rocks is a hallmark, while the latter (Phase V) is marked by a combination of small-scale volcanic and granite-alkaline granite developed after 120 Ma. Among them, the second and third stages of magmatism were earlier than those of the Yanshan orogenic belt at the end of the middle and late Jurassic, respectively. Therefore, the P-T-t evolution of the main orogenic mountain curtain in the Yanshan area evolved into a counter-clockwise trajectory. Meanwhile, the fifth stage magmatism corresponds to the post-orogenic post-collapse stage. The evolutionary models of the Jurassic-Cretaceous orogenic processes in the Yanshan orogenic belt summarized in this paper are: basaltic underplating, crustal material melting to form amphibolite and rhyolite magma → the crust is heated and weakened → the nappe structure is developed, the crust thickens → the orogenic After collapse and alkaline granite formation.