辽西上白垩统大兴庄组地层层序及时代
Stratigraphic sequence and age of the Upper Cretaceous Daxingzhuang Formation in western Liaoning province
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摘要: 辽宁西部白垩系上统大兴庄组主要分布于锦州、义县地区，在朝阳波罗赤、阜新碱锅等地也有零星出露。除阜新等地区为中基性火山熔岩及火山碎屑岩外，均为中酸性、酸性火山熔岩、熔岩碎屑岩、火山碎屑岩、火山碎屑沉积岩及次火山岩。角度不整合覆于白垩系下统义县组、九佛堂组、沙海组之上，平行不整合覆于白垩系孙家湾组之上，K—Ar同位素年龄值为80．83Ma，属晚白垩世。该期火山活动以爆发—喷溢交替进行为特点，间有次火山岩侵入，活动强度微弱，分布局限。
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关键词:
- 辽宁西部 上白垩统 大兴庄组
Abstract: The Upper Cretaceous Daxingzhuang Formation in western Liaoning is mainly distributed in Jinzahou and Yixian and also outcrops sporadically in the Boluochi ,Chaoyang,and Jianguo,Fuxin.Ex-cept in the Fuxin area where it is composed of intermediate-basic lavas and pyroclastic rocks,in other ar-eas it consists of intermediate-acid and acid lavas,lava-clastic rocks,pyroclastic rocks,pyroclastic-sedi-mentary rocks and subvolcanic rocks.It lies unconformably on the Lower Cretaceous Yixian,Jiufutang and Sahai Formations and disconformably on the Cretaceous Sunjiawan Formation.Its K-Ar age is80.83Ma ,indicating a Late Cretaceous age.This phase of volcanism is characterized by alternating explosion and out-pouring.In the late phase subvolcanic rocks were in truded.The activity was weak and the distribution of the subvolcanic rocks is limited. -
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