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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引用本文:陈树旺,金成洙,张允平,张立东,郭胜哲.2005.论辽西四合屯地区早白垩世构造-火山活动及生物事件[J].地球学报,26(3):241-248.
DOI:10.3975/cagsb.2005.03.08
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作者单位E-mail
陈树旺 东北大学辽宁沈阳110032
中国地质调查局沈阳地质矿产研究所辽宁沈阳110004 
sysshueang@163.com;sysshueang@cgs.gov.cn 
金成洙 中国地质调查局沈阳地质矿产研究所辽宁沈阳110004  
张允平 东北大学辽宁沈阳110032  
张立东 东北大学辽宁沈阳110032
中国地质调查局沈阳地质矿产研究所辽宁沈阳110004 
 
郭胜哲 东北大学辽宁沈阳110032  
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)
中文摘要:四合屯地区位于一个中生代火山一沉积盆地之中。该区早白垩世的主要构造行迹为NE向和NW向的断裂构造;这些断裂构造控制着火山一沉积盆地的边界和一些火山机构的分布。野外填图表明,该盆地内的早白垩世地层仅出露有义县组。义县组可进一步划分为3个段:第1段为含有沉凝灰岩夹层的基性、中基性火山岩;第2段是含有凝灰岩夹层和枕状熔岩的陆相沉积岩;第3段主要为玄武岩类。热河生物群(其中包括腹足类、双壳类、叶肢介、介形类、昆虫、鱼类、两栖类、爬行类、鸟类、哺乳类以及植物)化石主要产于义县组一段沉凝灰岩和二段的湖相泥质页岩中。化石发掘和微量元素分析表明,热河生物群经历了集群死亡和快速掩埋,火山活动的有毒气体是生物灾难事件的主要因素。根据同位素测年,义县组的时代为早白垩世。在此基础上,本文讨论了四合屯地区早白垩世构造一火山活动与生物事件的演化阶段:A阶段为盆地雏形的产生和早期的热河生物群;B阶段为第一次火山活动和生物灾难事件;C阶段为火山活动间歇期和热河生物群的繁衍;D阶段为火山喷汽与热河生物群的灾难事件;E阶段为火山灰沉降;F阶段为结束期。
中文关键词:早白垩世  构造火山活动  生物事件  四合屯  辽宁
 
Discussion on the Structural-Volcanic Activities and Biological Events During the Early Cretaceous in the Sihetun Area, Liaoning Province, China
Abstract: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.
keywords:structural-volcanic activity  biological event  Early Cretaceous  Sihetun  Liaoning
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