云南罗平中三叠统关岭组二段碳酸盐岩微相分析
Carbonate microfacies in the second member of the Middle Triassic Guanling Formation in Luoping,Yunnan
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摘要: 通过详细的野外观察和室内镜下薄片分析,于中三叠统关岭组二段中初步识别出8种微相类型。结合宏观沉积构造及罗平生物群保存特征,认为云南罗平关岭组二段为碳酸盐岩缓坡沉积,可划分出深水盆地、深缓坡、深缓坡远端变陡、浅缓坡和后缓坡5个沉积相。沉积相在垂向上是向上变浅(海退)的沉积序列。罗平生物群的沉积环境为深水、低能、安静的海洋环境,突发的风暴事件导致了生物群大量死亡,并被迅速埋藏。Abstract: Eight carbonate microfacies are recognized for the second member of the Middle Triassic Guanling Formation in Luoping,Yunnan on the basis of the detailed field observation and thin section analysis.Macroscopic sedimentary structures and preservation of the Luoping biotas have revealed that the second member of the Middle Triassic Guanling Formation developed in the carbonate ramp environment,which consists of the deep-water basin,deep ramp,distally steepened deep ramp,shallow ramp and back ramp microfacies.Vertically,the sedimentary microfacies mentioned above display the shallowing-upward(regressive) depositional sequences.On the whole,the Luoping biotas occur in the deep-water,low-energy and quiet marine environments.The unexpected storm events led to the rapid death and burial of the biotas.
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