【摘要】 论述了华北地区侏罗纪构造变形样式与岩浆活动序列,目的是试图提出一个侏罗纪构造阶段性演化历史的框架。将华北地区侏罗纪的沉积作用、构造变形和岩浆活动划分为3个阶段。早侏罗世早期大地构造显著特征是没有岩浆活动(205~191Ma的岩浆活动空隙),华北地区处于区域性隆升,这个时期应当是华北与华南板块碰撞和陆内俯冲作用(印支运动)的延续。早中侏罗世(190~175Ma)华北岩石圈处于弱伸展状态,表现为沿燕-辽构造带和郯庐断裂带两侧源于地幔的深成岩浆侵入、火山作用以及沿阴山—燕山构造带发育的正断层和裂谷作用,华北地块内部发生大面积整体沉降和含煤盆地的形成。这个时期大地构造仍可视作是印支运动的后效。中晚侏罗世(165±5Ma~136Ma)构造体制发生重大变革,以多向挤压引起的强烈陆内造山和板内变形为特征。这个阶段区分出了两幕主要挤压变形事件:早幕以上侏罗统巨厚磨拉石沉积之下的角度不整合面为标志,主要沿着鄂尔多斯西缘褶皱冲断带和阴山—燕山构造带发育,时代早于160Ma;晚幕以下白垩统底部的角度不整合面为标志,时代早于135Ma。在中晚侏罗世构造变革时期,两个纬向构造带:北缘的阴山—燕山构造带和南缘的秦岭—大别构造带,以及鄂尔多斯盆地西缘均发生强烈的冲断褶皱变形;华北地块本身遭受NE、NNE向逆冲断层、断层相关褶皱和左旋走滑断层等构造体系的改造,并在空间分布上出现变形分解。郯庐断裂带东侧胶辽地区一系列片麻状地壳重熔型花岗岩的侵入(时代160~150Ma)指示了中晚侏罗世重要的地壳增厚作用。华北侏罗纪变形样式、不同方向的构造体系和多向挤压是东亚周邻板块(北部西伯利亚板块、西部拉萨地块和东部古太平洋板块)从3个不同方向向亚洲大陆同时汇聚产生的远程效应的结果。正是中晚侏罗世强烈的板内挤压变形和地壳增厚作用才诱发了早白垩世(最早始于135Ma)时期岩石圈的巨量减薄和转型。更多还原

【Abstract】 This paper gives a synthetic view on Jurassic tectonics of North China, with an attempt to propose a framework for stepwise tectonic evolution history. Jurassic sedimentation, deformation and magmatism in North China have been divided into three stages. The earliest Jurassic is marked by a magmatism gap in 205~190 Ma and regional uplift, which are considered to be the continuation of the "Indosinian Movement" tectonic period characterized by continent-continent collision between the NCB and the SCB. Early to Middle Jurassic (190~170 Ma) was dominated by weak lithospheric extension expressed by mantle derived plutonism and volcanism along the Yanshan belt and alongside the Tan-Lu fault zone, normal faulting and graben formation along the Yinshan-Yanshan tectonic belt, depression and resumation of coal-bearing sedimentation in vast region of the NCB. Middle to Late Jurassic stage (from 165±5 Ma to 136 Ma) was dominated by intensive intraplate deformation resulting from multi-directed compressions. At least two major deformation events have been identified: one is marked by stratigraphic unconformity beneath thick Upper Jurassic molasic series in the foreland zones of the western Ordos thrust and fold belt and along the Yinshan-Yanshan belt and predated to 160 Ma; the other one is indicated by stratigraphic unconformity at the base of Lower Cretaceous and predated to 135 Ma. During this last stage, two latitudinal tectonic belts, the Yinshan-Yanshan one to north and the Qinling—Dabie one to south, and the western margin of the Ordos basin were all activated by thrusting; the NCB itself was deformed by NE to NNE-trending structural system involving thrusting, associated folding and sinistral strike-slip faulting, which were spatially partitioned. Foliated S-type granitic plutons aged 160~150 Ma were massively emplaced in the Jiao-Liao region east of the Tan-Lu fault zone and indicate important crustal thickening in the eastern part of North China. Jurassic deformation patterns, different tectonic systems and multi-directed contractions in North China recorded far-field effects of synchronous convergences, toward the east Asian continent, of three different plates, the Siberian in north, the paleo Pacific in east and the Lhasa Block in southwest. This Middle to Late Jurassic intraplate orogenesis and pervasive shortening deformation preceded lithospheric attenuation and thinning in East China, which most possibly started by the Earliest Cretaceous around 135 Ma.更多还原