查看更多>>摘要:This study presents the first record of Early Permian alatoconchid bivalves from Thailand,the Erawan section,in the north of Loei fold belt with prolific fusulines in association with gastropods,and bra-chiopods.Fusuline taxa are dominated by Pseudofusulina sp.with Darvasites sp.,Staffella cf.labanalensis,Staffella sp.,Nankinella sp.,Neofusulinella sp.,Schubertella sp.,Pamirina darvasica,Pseudoendothyra sp.and others,indicating an Artinskian age.Fusuline wackestone with common,well-preserved smaller fora-minifers,Pseudovermiporella sp.and ostracods indicates a restricted lagoon environment with low to mod-erate water circulation.These fossils,along with well-preserved,articulated alatoconchids in life-position,suggest the autochthonous nature of the deposits in an intertidal environment.In the central part of the fold belt,the Pak Chong section exhibits intervals of alatoconchid biostromes and coquinites.Carbonate build-ups of the alatoconchid biostromes with gregarious bivalves,in life-position embedded in a micritic wackestone matrix,suggest their preferred life habit and environment.The bivalve coquinites containing packed bivalve shells and fragments,however,indicate a high-energy event.This rock fabric along with common fusuline storm sheets suggests occasional storm events in a restricted,with mod-erate water circulation to open lagoon environment.Fusulines are predominated by staffellids and others including Staffella sphaerica,Staffella sp.,Sphaerulina croatica,Pisolina subsphaerica,Nankinella sp.,Neoschwagerina simplex,Presumatrina sp.,Afghanella sp.and others,indicating a Wordian(Middle Permian)age.In the southern portion of the fold belt along the Thai-Cambodian border,the Khao Taa Ngog section contains limestone with alatoconchid shells with massive rugose corals which formed local carbonate build-ups in high-energy open platform environments.Poorly-sorted bioclasts with common fusuline tests,shell frag-ments and coated grains suggest an open marine,lagoon,back reef environment.The occurrence of a fusuline assemblage including Neoschwagerina sp.,Yabeina sp.,Lepidolina sp.,Codonofusiella sp.,Verbeekina ver-beeki and Chusenella sp.indicates the Capitanian(late Middle Permian)age.