泰国北部三叠系Lampang群Doi Long组的有孔虫组合与沉积环境(英文)

A rich foraminiferal assemblage,consisting of abundant Aulotortus sinuosus and A.tumidus in association with Lamelliconus multispirus,Endoteba ex gr.controversa,E.ex gr.badouxi,Endotebanella kocaeliensis,Endotriada tyrrhenica,Endotriadella wirzi,Malayspirina fontainei,Ammobaculites rhaeticus,Diplotremina astrofimbriata,Agathammina austroalpina,and others,was found in the Doi Long Formation of the Triassic Lampang Group,Northern Thailand.These foraminifers suggest that the formation is referable to the Carnian(early Late Triassic),which is consistent with the age estimated by ammonoids.In microfacies,peloidal grainstone,bioclastic grainstone,sponge-microbial boundstone,and oolitic grainstone were recognized in the Doi Long Formation.Based on microfacies,three depositional facies,the lagoon facies,reef facies,and shoal facies,are recognized in this formation.These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting.