U-Pb zircon age for the Daohugou Biota at Ningcheng of Inner Mongolia and comments on related issues
U-Pb zircon age for the Daohugou Biota at Ningcheng of Inner Mongolia and comments on related issues
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DOI：
10.1007/s11434-006-2165-2
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发表时间：
2006-11-01
影响因子：
--
通讯作者：
Yang Zhiqing
中科院分区：
文献类型：
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作者：
Liu Yongqing;Liu Yanxue;Yang Zhiqing
对内蒙古宁城道虎沟生物群和辽西凌源热水塘火山岩进行了SHRIMP锆石U-Pb年龄测定。结果表明，道虎沟生物群的形成时代为168 ~ 164 ~ 152 Ma。道虎沟生物群与含蝾螈化石组合为同一生物群，发育时间为168 ~ 152 Ma，即中侏罗世晚期至晚侏罗世早期。道虎沟生物群含岩系以不整合面产于九龙山组之上，上覆有晚侏罗世土城子组和早白垩世含热河生物群的岩石，主要由火山-沉积岩组成，属正常层序。建议将道虎沟生物群及相关地层与跳鸡山组（辽西蓝旗组）或其同期岩进行对比。因此，道虎沟生物群与热河生物群既不能视为一个生物群，也不能视为热河生物群的最早组成部分。道虎沟生物群及相关岩石和义县组分别形成于不同的火山-沉积构造时期。
SHRIMP U-Pb zircon dating was carried out for the Daohugou Biota near Ningcheng of Inner Mongolia and for lavas overlying or underlying salamander-bearing strata at Reshuitang in Lingyuan of West Liaoning. The results suggest that the Daohugou Biota occurred at an interval from 168 Ma to 164-152 Ma. Both the Daohugou Biota and the salamander-bearing fossil assemblage are the same biota and thus developed from 168 to 152 Ma, i.e. from late Middle Jurassic to the early Late Jurassic. The Daohugou Biota-bearing rocks, resting on the Jiulongshan Formation in disconformity and being overlain in unconformity by Late Jurassic Tuchengzi Formation and Early Cretaceous rocks containing the Jehol Biota, are mainly composed of volcanic-sedimentary rocks in a normal sequence. It is recommended that the Daohugou Biota and the related stratigraphy should be correlated with the Tiaojishan Formation (Lanqi Formation in West Liaoning) or its synchronous rocks. It is suggested that the Daohugou Biota and the Jehol Biota would be neither taken into one biota nor considered as the earliest elements of the Jehol Biota. The Daohugou Biota and the related rocks and the Yixian Formation were respectively formed in different periods of volcanic-sedimentary tectonics.