灵山岛早白垩世构造应力解析及区域地质意义

Study on Early Cretaceous Stress Fields and Geological Significance of Lingshan Island

通过对灵山岛野外地质考察及总结前人资料,并利用节理、岩墙和褶皱等应力感应构造的测量分析,得出研究区早白垩世可能存在四期构造作用:莱阳期NW向伸展形成近海盆地,莱阳期末期NW向挤压反转作用,青山期NW向伸展裂谷作用和早白垩世末期NW向挤压反转。灵山岛早白垩世两期伸展作用可能是分别对华北地区增厚地壳或岩石圈重力垮塌和岩石圈拆沉的响应,而两期挤压反转作用可能是研究区由伊泽奈崎板块NW向俯冲消减向太平洋板块NW向俯冲过渡的结果。

Four periods of structural stress fields can be recognized during Early Creraceous in Lingshan Island and adjacent areas based on field geological investigation and summary of the previous data, which is derived from the occurrence data of the stress response structures, i.e., tectonic stress period of extension in the direction of NW X-type shear jointing, dykes and folds. They are the formed the offshore basins during the Laiyang stage, followed extrusion in the direction of NW in the late Laiyang stage, during the Qingshan stage further extension in the direction of NW turned the offshore basins into rift basins, and followed basin inversion in the direction of NW in the late Early Cretaceous. It is concluded that the two extensional phases in Early Cretaceous were dynamically associated with either gravity collapse or lithospheric delamination of the thicked crust or lithosphere in North China and the NW-SE extrusion records the effect by the transmission of the NW-directed subduction of Izanaqi plate to the NW-directed subduction of paleo Pacific plate towards the bottom of the Asian continent.