渤海湾盆地中新生代构造演化与构造样式

通过火成岩岩石地球化学分析，渤海湾地区中新生代岩浆活动大致可分为5期，由此将渤海湾盆地中新代构造演化划分为5个阶段：①印支期岩性组合为正长花岗岩和二长花岗岩，以伸展构造环境为主；②燕山早期岩性组合为埃达克岩和高锶花岗岩，以挤压造山构造环境为主；③燕山晚期岩性组合为酸性-偏碱性岩，如A型花岗岩、辉长岩、正长岩以及拉斑质钙碱性玄武岩等，以伸展和岩石圈减薄构造环境为主；④沙三-东营期岩性组合以碱性玄武岩为主，此时岩石圈减薄作用减弱，渤海湾拉分盆地正式形成；⑤馆陶期之后，火成岩为碱性玄武岩，构造活动处于相对平静期，渤海湾地区处于整体坳陷阶段。结合地震资料解释认为：印支期以伸展构造样式为主；燕山早期以收缩构造样式为主；燕山晚期-喜山早期以负反转构造样式为主；沙三-东营期以扭动构造样式为主；馆陶-明化镇期后由于盆地处于整体坳陷阶段，主要以伸展构造样式为主。

Meso-cenozoic Tectonic Evolution and Tectonic Styles in the Bohai Bay Basin

Lithogeochemical analysis of volcanic rocks shows that the Meso cenozoic magmatic activities in the Bohai Bay Basin can be approximately grouped into 5 stages and the Meso cenozoic structural evolution in the Bohai Bay Basin are correspondingly divided into 5 phases. ①The Indosinian lithological association was composed of syenogranite and adamellite and was dominated by extensional tectonic setting; ②The Early Yanshanian lithological association was composed of Eilat stone and high strontium granit and was dominated by compressional tectonic setting; ③The Late Yanshanian lithological association was composed of acidic rocks and alkali prone rocks, such as granite of type A, graniton, syenite and tholeiitic calc alkali basalt, and was dominated by extensional and lithosphere thinning tectonic settings; ④The lithologic association of the third member of Shahejie Formation and Dongying Formation was dominated by alkali basalt. Lithosphere thinning got weak and the pull apart Bohai Bay Basin was formed during this period. ⑤After the the Guantao Formation was deposited, the igneous rocks became alkali basalt, the tectonic activity got relatively weak and the Bohai Bay area entered into mass depression. In combination with the seismic interpretation, it is believed that Indo Chinese epoch was dominated by extensional tectonic style, the Early Yanshanian epoch was dominated by contraction tectonic style, the Late Yanshanian Early Himalayan epoch was dominated by negative reverse tectonic style, the period during which the third member of Shahejie Formation and Dongying Formation were deposited was dominated by shear tectonic style, and the period after the deposition of the Guantao Minghuazhen Formations was dominated by extensional tectonic style because the basin was in mass depression.