First records of Early Permian conodonts from eastern Myanmar and implications of paleobiogeographic links to the Lhasa Block and northwestern Australia

Abstract

An Early Permian (Cisuralian) conodont fauna is reported for the first time from the Sibumasu Terrane in eastern Myanmar. The conodont fauna includes Vjalovognathus nicolli and typical Mesogondolella idahoensis; some M. idahoensis possess transitional characters with M. lamberti and M. siciliensis. This fauna indicates a late Kungurian age. The longest range of the Taungnyo Group was from late Tournaisian to late Kungurian, and the range of the overlying Moulmein Limestone might be from late Kungurian through Guadalupian (Middle Permian). The nearly synchronous occurrence of identical conodont faunas from eastern Myanmar, the Lhasa Block and northwestern Australia provides important evidence that these tectonic units had a close paleogeographic, paleobiogeographic and paleoclimatic evolution during the late Cisuralian. The occurrence of this conodont fauna across the continuous boundary interval between the Taungnyo Group and Moulmein Limestone might indicate a paleoclimatic transition from Early Permian cool-water conditions to a Middle to Late Permian warm-water setting due to tectonic drifting of the relevant blocks and/or paleoclimatic amelioration after the Late Paleozoic Ice Age (LPIA) from Carboniferous to Cisuralian. This discovery also suggests that the terranes in eastern Myanmar are complicated by subsequent tectonic mergence and possibly of multiple origins based on the conodont and fusuline faunal affinities in different areas of eastern Myanmar.