摘要
大别山北麓陆相中生代地层发育 ,由于缺乏可靠生物化石证据 ,地层的划分和对比直到现在仍然存在巨大分歧 ,这制约了造山带研究的深入。根据对发现的火山岩碎屑和 K- Ar同位素年代学数据 (10 3.6— 138.3Ma)研究 ,表明凤凰山组、周公山组和毛坦厂组同属于早白垩世 ,并且可能是同期异相产物 ;覆盖在毛坦厂组之上的黑石渡组亦为早白垩世。根据地层接触关系、同位素年龄数据和岩相对比 ,三尖辅组以中侏罗世为主 ,可能跨早、晚侏罗世 ,与防虎山组和圆筒山组为同期异相。已有的石榴石重矿物分析和孢粉研究支持上述结论。地层接触关系表明白大畈组为早白垩世火山岩。
The continental Mesozoic strata on the northern margin of Dabei Orogenic Belt are well deve loped, but owing to the lack for convincing fossil evidence, the division and correlation of these strata have been a controversial subject for a long time. Thus, an intensive study of the orogenic belt has been limited. Studies of the debris of the discovered volcanic rocks and their characteristics as well as the K Ar isotopic geochronology show that the Fenghuangtai, Zhougongshan, and Maotanchang Formations all belong to the Early Cretaceous and are probably the heteropic contemporaneous products. The Heishidu Formation overlying the Maotanchang Formation is also Early Cretaceous in age. Based on the stratigraphic contact, isotopic dating, and lithofacies correlation, the Sanjianpu Formation is mostly of Middle Jurassic age and probadly straddles the Early Middle Jurassic and Middle Late Jurassic boundaries. The Sanjianpu Formation and the Yuantongshan Formation are contemporaneous and heteropic. The analyses of the garnets and the sporopollen support the conclusion mentioned above. The stratigraphic contact shows that the Baidafan Formation is volcanic rocks of Early Cretaceous age.
出处
《地层学杂志》
CSCD
北大核心
2002年第3期178-186,220,共10页
Journal of Stratigraphy
基金
国家重点基础研究发展规划项目 (编号 :G19990 75 5 0 7)资助
