地学前缘
地學前緣
지학전연
2000年
4期
411-419
,共9页
变质核杂岩%韧性拆离体系%火山岩台地%伸展断陷%拆沉作用
變質覈雜巖%韌性拆離體繫%火山巖檯地%伸展斷陷%拆沉作用
변질핵잡암%인성탁리체계%화산암태지%신전단함%탁침작용
metamorphic core complex%ductile detachment system%volcanic platform%extensional faulted depression%delamination
文中讨论了松辽盆地北部中央基底隆起变质核杂岩和徐家围子伸展断陷的构造特征、成因和演化，重点讨论了下列问题：(1) 中央基底隆起变质核杂岩具有科迪勒拉变质核杂岩的许多特征；(2) 识别出组成中央基底隆起变质核杂岩的多层次、低角度韧性拆离体系，它们是使中地壳的中深变质岩层抽拉至上地壳的主要原因；(3)穹窿状火山岩台地于晚侏罗世(145.7±6.2) Ma形成，受顶部拆离断层控制的伸展断陷于早白垩世(133～120 Ma)形成，而邻近顶部拆离断层的糜棱岩年龄为(126.7±1.54) Ma。这表明变质核杂岩的形成始于晚侏罗世。早白垩世递进的伸展构造与变质核杂岩较深部的部分上拱至地表相伴生，推测该变质核杂岩的上拱和剥露、火山岩台地和伸展断陷盆地的形成可能是由伊泽奈奇和亚洲板块陆陆碰撞后的地幔拆沉作用、地幔的岩浆底侵作用以及伸展垮塌作用联合造成的。
文中討論瞭鬆遼盆地北部中央基底隆起變質覈雜巖和徐傢圍子伸展斷陷的構造特徵、成因和縯化，重點討論瞭下列問題：(1) 中央基底隆起變質覈雜巖具有科迪勒拉變質覈雜巖的許多特徵；(2) 識彆齣組成中央基底隆起變質覈雜巖的多層次、低角度韌性拆離體繫，它們是使中地殼的中深變質巖層抽拉至上地殼的主要原因；(3)穹窿狀火山巖檯地于晚侏囉世(145.7±6.2) Ma形成，受頂部拆離斷層控製的伸展斷陷于早白堊世(133～120 Ma)形成，而鄰近頂部拆離斷層的糜稜巖年齡為(126.7±1.54) Ma。這錶明變質覈雜巖的形成始于晚侏囉世。早白堊世遞進的伸展構造與變質覈雜巖較深部的部分上拱至地錶相伴生，推測該變質覈雜巖的上拱和剝露、火山巖檯地和伸展斷陷盆地的形成可能是由伊澤奈奇和亞洲闆塊陸陸踫撞後的地幔拆沉作用、地幔的巖漿底侵作用以及伸展垮塌作用聯閤造成的。
문중토론료송료분지북부중앙기저륭기변질핵잡암화서가위자신전단함적구조특정、성인화연화，중점토론료하렬문제：(1) 중앙기저륭기변질핵잡암구유과적륵랍변질핵잡암적허다특정；(2) 식별출조성중앙기저륭기변질핵잡암적다층차、저각도인성탁리체계，타문시사중지각적중심변질암층추랍지상지각적주요원인；(3)궁륭상화산암태지우만주라세(145.7±6.2) Ma형성，수정부탁리단층공제적신전단함우조백성세(133～120 Ma)형성，이린근정부탁리단층적미릉암년령위(126.7±1.54) Ma。저표명변질핵잡암적형성시우만주라세。조백성세체진적신전구조여변질핵잡암교심부적부분상공지지표상반생，추측해변질핵잡암적상공화박로、화산암태지화신전단함분지적형성가능시유이택내기화아주판괴륙륙팽당후적지만탁침작용、지만적암장저침작용이급신전과탑작용연합조성적。
The structural characteristics, origin and evolution of the metamorphic core complex of the central basement uplift and Xujiaweizi faulted depression in northern Songliao basin are discussed and several points have been emphasized as follows: (1) The central basement uplift metamorphic core complex displays many of the structural characteristics of Cordillerian metamorphic core complex; (2) Multi-layered low-angle ductile detachment systems which consist of the central basement uplift are recognized, and they have been the main factors enabling middle grade metamorphic rocks to be brought from middle crust to upper crust;(3) The volcanic dome-shaped platform were formed during the Late Jurassic (145.7±6.2)Ma, the extensional faulted depressions controlled by top-detachment fault were formed the Early Cretaceous (133～120 Ma), while the age of mylonites near top-detachment fault in Well Fang deep-3 is (126.7±1.54)Ma. These imply doming and exhumation of the central basement uplift were also generated since the Late Jurassic. Progressive extension tectonics was associated with upwarping of the deeper parts of this core complex to the surface during the Early Cretaceous. It is suggested that doming and exhumation of this core complex, formation of extensional faulted depression, are driven by mantle delamination, magmatic underplating of mantle and extensional collapse following the continental collision of Izanazi plate and Asia plate.
