| 论辽西四合屯地区早白垩世构造-火山活动及生物事件 |
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| 关键词:structural-volcanic activity biological event Early Cretaceous Sihetun Liaoning |
| 基金项目:中国地质调查局项目“北票、上园、义县、地藏寺等4幅1:5万区域地质调查”(编号:J4.1.12) |
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| Discussion on the Structural-Volcanic Activities and Biological Events During the Early Cretaceous in the Sihetun Area, Liaoning Province, China |
| Sihetun area is situated in a Mesozoic volcanic-sedimentary basin. The main structures of Early Cretaceous in the area are NE and NW faults, which control not only the major boundaries of the basins, but also some volcanic edifices. Based on the field mapping, the Yixian Formation, which is the only strata of Early Cretaceous in the area, may be subdivided into three members: The first member is of basic and intermediate-basic volcanic rocks with intercalations of tuffite beds. The second member is mainly of sedimentary beds of lacustrine facies with intercalations of crystal tuff, tuffite and some pillow lavas. And the third member is mainly of basalt. The Jehol Biota (including gastropods, bivalves, conchostracans, ostracods, insects, fishes, amphibians, reptiles, birds, mammals, as well as fossil plants) occurs mainly in tuffite beds of the first member and muddy shale beds the second member of Yixian Formation. Excavation and trace element analysis indicates: Jehol biota experienced mass mortality and rapid burial; toxic gases of the volcanic activities are the main factors of biological catastrophic event. According to isotopic dating, the Yixian Formation is Early Cretaceous in age. By comprehensive studying, six evolutionary stages (from A to F) of the structural-volcanic activities and biological events during Early Cretaceous in Sihetun area are also discussed. Stage A is "formation of the embryonic basin and the early members of Jehol Biota"; Stage B is "the first volcanic activity and biological hazard"; Stage C is "the dormant of volcanic activity and the development of Jehol biota"; Stage D is "the volcanic exhalation and the catastrophe of Jehol biota"; Stage E is "tuff sediment"; and Stage F is "the end" respectively. |
| CHEN Shu-wang,JIN Cheng-zhu,ZHANG Yun-ping,ZHANG Li-dong,GUO Sheng-zhe.2005.Discussion on the Structural-Volcanic Activities and Biological Events During the Early Cretaceous in the Sihetun Area, Liaoning Province, China[J].Acta Geoscientica Sinica,26(3):241-248. |
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