CAJ | 학술논문

本文从岩浆弧的火成岩构造组合、主要地质特征和弧地壳成熟度几个方面，讨论洋陆转换作用及其过程。表征洋俯冲环境的火成岩构造组合主要有英云闪长岩—奥长花岗岩—花岗闪长岩（TTG）组合，高镁安山岩组合，镁安山岩组合，Adakite 组合（即高锶低钇中酸性岩）与富铌弧玄武岩组合等。基于火成岩构造组合的配置，讨论了4种可能的洋俯冲壳的壳幔结构：（1）热的年轻的俯冲洋壳与上覆冷的幔楔岩石圈；（2）冷的老的俯冲洋壳与冷的幔楔岩石圈；（3）冷的老的洋壳与热的幔楔软流圈；（4）热的年轻的俯冲洋壳与上覆幔楔软流圈。讨论了弧岩浆前锋作为结构标志以及空间组成极性的构造意义；讨论了弧火山作用的时间极性与弧成熟度及其地壳厚度之间的正相关关系，提出岩浆弧地壳双层结构的模型，下地壳主要为玄武质的基性麻粒岩和角闪岩，上地壳为长英质的 TTG 片麻岩，相当于大陆壳形成的第一阶段，即新生陆壳。岩浆弧及其洋—陆过渡性的弧地壳是洋俯冲作用形成的洋陆转换带（或增生造山带）的最重要的记录。
본문종암장호적화성암구조조합、주요지질특정화호지각성숙도궤개방면，토론양륙전환작용급기과정。표정양부충배경적화성암구조조합주요유영운섬장암—오장화강암—화강섬장암（TTG）조합，고미안산암조합，미안산암조합，Adakite 조합（즉고송저을중산성암）여부니호현무암조합등。기우화성암구조조합적배치，토론료4충가능적양부충각적각만결구：（1）열적년경적부충양각여상복랭적만설암석권；（2）랭적로적부충양각여랭적만설암석권；（3）랭적로적양각여열적만설연류권；（4）열적년경적부충양각여상복만설연류권。토론료호암장전봉작위결구표지이급공간조성겁성적구조의의；토론료호화산작용적시간겁성여호성숙도급기지각후도지간적정상관관계，제출암장호지각쌍층결구적모형，하지각주요위현무질적기성마립암화각섬암，상지각위장영질적 TTG 편마암，상당우대륙각형성적제일계단，즉신생륙각。암장호급기양—륙과도성적호지각시양부충작용형성적양륙전환대（혹증생조산대）적최중요적기록。
This paper discusses the ocean—continent transition of the magmatic arc and its processes in terms of the igneous petrotectonic assemblage,the geologic characteristics,and the arc maturity.The major igneous petrotectonic assemblages characterized the oceanic subduction may be tonalite—trondhjemite—granodiorite (TTG),high-Mg andesitic,Mg andesitic,adakitic and Nb-enriched arc basaltic assemblages.Based on the disposition of the petrotectonic assemblages,four possible models of oceanic subducted crust—mantle structure are discussed:(1 )the warm young subducted oceanic crust and the above-situated cool mantle-wedge lithosphere;(2)both the cool older subducted oceanic crust and the mantle-wedge lithosphere;(3)the cool older subducted oceanic crust and the above-situated warm mantle-wedge asthenosphere;(4)both the warm oceanic crust and the mantle-wedge asthenosphere.The tectonic indications of the arc magmatic front as the structure markers and the special compositional polarity are also discussed.A model of two-layered arc crust is suggested,the lower arc crust may be composed of the mafic granulites and amphibolites,and the upper crust consists of the felsic TTG gneisses. The petrologic structure of the arc crust may have a typical transitional character between the ocean crust and the continental crust or may be regarded as the first stage of the continental crust,the juvenile continental crust.The magmatic arc and the transitional character of the arc crust are regarded as the most important record for the ocean—continent transitional belts (or the accretional orogenic belts)derived by the oceanic subduction.