冀东-辽西太古宙火成岩岩石组合和动力学意义  

Lithological Assemblages of Archean Meta-Igneous Rocks in Eastern Hebei-Western Liaoning Provinces of North China Craton,and Their Geodynamic Implications

作　　者：刘树文[1] 王伟[2] 白翔[3] 郭荣荣 付敬浩 郭博然 胡方泱 王茂江 

机构地区：[1]北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室,北京100871 [2]中国地质大学地球科学与资源学院地质过程与矿产资源国家重点实验室,北京100083 [3]中国地震局地质研究所活动构造与火山重点实验室,北京100294 [4]东北大学资源与土木工程学院深部金属矿山安全开采教育部重点实验室,辽宁沈阳110819 [5]北京矿产地质研究院,北京100012

出　　处：《地球科学》2018年第1期44-56,共13页Earth Science

基　　金：国家自然科学基金重点项目(No.41530207);国家自然科学基金面上项目(No.41472165)

摘　　要：冀东-辽西地区是华北克拉通北部出露面积最大的太古宙变质基底区.经过岩石组合填图和综合研究,将其太古宙变质火成岩分为2.64~2.60Ga MORB型拉斑玄武质火山岩、2.61~2.52Ga拉斑玄武质-钙碱性变质火山岩、2.52~2.50Ga浅变质钙碱性火山岩组合和2.54~2.50Ga英云闪长质-奥长花岗质-花岗闪长质片麻岩、2.54~2.51Ga闪长质-石英闪长质-英云闪长质-奥长花岗质-花岗闪长质片麻岩、2.54~2.51Ga紫苏花岗闪长质-紫苏花岗质岩石、2.57~2.52Ga闪长质-石英二长闪长质-花岗闪长质-二长花岗质片麻岩和2.53~2.51Ga弱片麻状到块状二长花岗质-正长花岗质深成侵入体岩石组合.这些岩石组合从东北部的辽西阜新到西南部的遵化马兰峪地区呈现出条带状时-空分布特征.变质作用研究揭示了青龙-上营-洒河桥-马兰峪为高压麻粒岩带,记录了ITD型PTt轨迹,与NNW-NW向SSE-SE方向逆冲推覆构造相伴生;而三屯营-太平寨高温麻粒岩带,记录了IBC型PTt轨迹,与锦州-兴城-安子岭-界岭口-太平寨-三屯营伸展-底劈构造带相伴生.综合分析表明冀东-辽西太古宙晚期的构造-岩浆活动形成于热造山带型俯冲-弧后伸展到碰撞隆升的侧向增生动力学过程.The eastern Hebei-western Liaoning provinces are the largest exposure regions of Archean basement rocks in the northern part of North China Craton.Comprehensive studies including detailed mapping of lithological assemblages reveal that the Archean basement rocks in the study regions can be subdivided into eight different assemblages,i.e.,2.64-2.60 GaMORB-type metabasaltic rocks;2.61-2.52 Ga metamorphosed tholeiitic to calc-alkaline volcanic rocks;2.52-2.50 Ga calcalkaline volcanic rocks with low metamorphic grade;2.54-2.50 Ga tonalitic-trondhjemitic-granodioritic gneisses;2.54-2.51 Ga dioritic-quartz dioritic-tonalitic-trondhjemitic-granodioritic gneisses;2.54-2.51 Ga enderbites and charnockites;2.57-2.52 Ga dioritic-quartz monzodioritic-granodioritic-monzogranitic gneisses;and 2.53-2.51 Ga weakly gneissic to massive monzogranitic to syenogranitic plutonic rocks.The above lithological assemblages show apparently banded spatial distribution patterns from Fuxin area of western Liaoning in the northeast to the Malanyu area of Zunhua in the southwest.Metamorphic studies indicate that high pressure granulites outcropped in the Qinglong-Shangying-Saheqiao areas record typical isothermal decompression（ITD）-type metamorphic P-T-t paths,which are associated with the thrusting structures from NNW-NW to SSE-SE.In contrast,isobaric cooling（IBC）-type metamorphic P-T-t paths are recorded by the high-temperature granulites from Santunying-Taipingzhai areas,which were accompanied by extensional diapiric structures in the Jinzhou-XingchengAnziling-Jiehekou-Taipingzhai-Santunying regions.Accordingly,it is suggested that the Late Archean tectonothermal events in the eastern Hebei-western Liaoning provinces could have been generated under a typical Archean hot orogenic belt,evolving from subduction and back-arc extension to the final collision.

关 键 词：冀东-辽西 太古代变质基底区 火成岩组合分带性 地壳侧向增生 热俯冲-碰撞造山带 岩石学 

分 类 号：P588[天文地球—岩石学]