印支运动以来南黄海盆地的构造变形与演化

Tectonic deformation and evolution of the South Yellow Sea basin since Indosinian movement

基于南黄海盆地历年来的地震资料解释成果和下扬子海陆对比,分析了南黄海盆地印支期以来的主要构造变形特征。认为其构造变形主要有3期:晚印支-早燕山期的前陆变形、燕山中期黄桥事件的转换变形和喜马拉雅晚期三垛事件的断坳变形。并控制前陆、断陷和坳陷3期盆地的形成。盆地演化经历了挤压褶断、碰撞造山,压、张脉动和走滑,拉张块断和反转,挤压收敛等发展过程。盆地构造变形机制主要受扬子和华北板块漂移碰撞、古太平洋板块活动特征和大型走滑断裂应力环境等影响。南黄海盆地构造变形具有规律性:平面上,以NE、NEE、近EW、NW向为主。从西往东,构造的走向为NEE向→近EW向→NW向;从北往南,构造变形具有强→弱→强特征和分带性,构造的走向为NEE向→近EW向。纵向上,海-陆相盆地活动展示了早期褶皱逆冲和晚期伸展断陷的"跷跷板"变形格局,并具有早期"北强南弱的不均衡对冲"和晚期"北深南浅断陷"的构造格局。海相盆地上构造层比海相下构造层冲断变形强。崂山隆起南部的高石稳定带为南北不均衡对冲的弱变形区和应力释放区,中-古生界受后期改造作用较弱,是油气勘探的有利地区。

Tectonic deformation of the South Yellow Sea basin since the Indosinian tectonic movement is studied in this paper based on the seismic data over the past years and the correlation between the sea and land areas of the Lower Yangtze platform.There are three stages of tectonic deformation in the South Yellow Sea since the Indosinian.The first stage from late Indosinian to early Yanshanian is dominated by foreland deformation including both the uplifting and subsidence under an intensive compression environment.The second stage which is called the Huangqiao Event in the middle Yanshanian,is dominated by transform deformation,suggesting a change of stress field from extrusion to extension.In the third stage or the Sanduo Event in the late Himalayan,however,the deformation was changed from the late Cretaceous-Paleogene stretching rifting to the Neogene-Quaternary depression.During the process,it controlled 3 stages basin formation from a foreland to fault and depression basin.In conclusion,since the Indosinian,the South Yellow Sea basin has experienced deformations of compressional folding and faulting,collisional mountain-building,compressional and tensional pulsation,strike-slipping,block extension and inversion,compression and convergence.Structures in NE,NEE,nearly EW and NW directions coexist.From west to east,they change directions from NEE to near EW to NW,while from north to south they change from NEE to near EW in a zonal pattern from strong to weak to strong.Vertically,the marine and terrestrial basins alternate in a＂seesaw＂pattern with fold thrusts in early stage,which is stronger in north and weaker in south and extension rifts in later stage,which is stronger in north and weaker in south.In marine basins,stronger thrusting deformation is more popupar in upper structural layer than that in the lower layer.The tectonic deformation mechanism in the South Yellow Sea basin is mainly affected by the drift collision between the Yangtze and North China blocks,and the stress environment of large-scale strikeslip faults owing to activities of the Paleo-Pacific plate.The southern part of the Laoshan uplift is a weak deformation zone as well as a stress release zone,and the Meso-Paleozoic reform is weak in later stage.It is believed,therefore,a favorable area for oil and gas exploration.