摘要
对贵州省关岭县新铺乡毛凹剖面上三叠统瓦窑组底部岩性薄片进行了观察 ,根据生物含量的多少 ,可以区分出 3种岩性 :泥晶灰岩、含生屑泥晶灰岩、泥晶生屑灰岩。结合生物群组合面貌分析 ,认为关岭动物群埋藏于水体较深且宁静、低能、盐度正常、气候温暖的环境下。同时牙形石Paragondolella属、双壳类Halobia属剖面分布暗示了水体还原事件的发生。结合古氧化还原度敏感元素的丰度变化和化石分异度分析 ,认为动物群得以完美埋藏 ,有 2点是至关重要的因素 :(1)沉积速率慢 ,岩性结构致密 ,颗粒细小 ,使生物能完整沉积 ;(2 )爬行动物化石层、化石分异度曲线和w(Ce) w(La)比值大于 2 ,且正向漂移呈现一一对应关系表明 ,缓慢沉积过程中 ,水体还原缺氧给生物埋藏提供了必须的氧隔离层 ,防止死亡生物氧化分解。
Petrological samples collected from the Upper Triassic Wayao Formation bearing the Guanling Fauna,located in Xinpu area of Guanling County,Guizhou Province,were observated under microscope.Three kinds of lithology can be distinguished on the basis of the bio|abundance.Considering the bio|assemblage of the Guanling Fauna,its taphonomic environment characteristics can be concluded as follows:the sea water was relatively deep,lower energy,peachful and anoxic condition with normal paleosalinity and warmer climate.In addition,the distributions of the conodont Paragondolella and the bivalve Halobia confirm the taphonomic environment and indicate the occurrence of the anoxic event as well.The study of paleoredox markers and fossil diversity finds two main significant factors.One is the fine grain and compact texture of marly limestone bearing the Guling Fauna,which makes the remains deposit nearly intact.The other is the layer of reptile and crinoid fossils coincide well with w(Ce)/ w(La) value over 2^0 and increasing positively,which reveals a high anoxic condition just like a protecting cover which keep the remains out of the oxygen.
出处
《北京大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2004年第6期864-871,共8页
Acta Scientiarum Naturalium Universitatis Pekinensis
基金
教育部重点基金 (0 10 0 6 )
北京大学九八五基金资助项目
关键词
关岭动物群
上三叠统
瓦窑组
爬行动物化石层
埋藏环境
Guanling Fauna
Upper Triassic
Wayao Formation
layer of reptile fossils
taphonomic environment
