Carbonate microfacies in the second member of the Middle Triassic Guanling Formation in Luoping,Yunnan

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.