Abstract

• The Pre-Paleozoic to Early Mesozoic rocks are well exposed in northwestern part of the southern Shan State. It is located about 13 km, NE of Ye-U, Ye-ngan Township, southern Shan State which lies in northwestern part of the Pindaya Range, located in the Eastern High Land (Shan-Tanintharyi Block). Ye ngan Township is a geologically very well-known to a great number of geologists. The present paper focused on the newly defined Pre Paleozoic to Early Mesozoic stratigraphy with two types of approach; data collection in the field and literary work in the library. The Ye-ngan Township comprises seven type sections and four reference sections of the Pre-Paleozoic to Lower Mesozoic strata such as, Chaung Magyi Group (Late Neoproterozoic), Molohein Group (late Jiangshanian to Furongian), Lokepyin Formation (Trmadocian to Floian), Wunbye Formation (Darriwilian), Nan-on Formation (Katian/ Caradocian), Tanshauk Member (Hirnantian), Linwe Formation (Silurian-Lochkovian), Zebingyi Formation (Pragian-Emsian), Maymyo Formation (Eifelian-Frasnian), Thitsipin Formation (Early to Upper Permian), and Nwabangyi Dolomite Formation (late Upper Permian-Induan to Olenikian). Most of the Paleozoic rock units are fossiliferous in Ye-ngan Township the Upper Cambrian is represented by the Molohein Group, bearing saukiid trilobites. The Lokepyin Formation which contains small brachiopods. The Wunbye Formation includes the nautiloids, brachiopods, sponge and receptaculitid algae. The Nan-on Formation is rich in fossils, among with cystoids, orthid brachiopods, bryozoans, sponges and trilobite have been recorded. The Tanshauk Member yields brachiopods and trilobites. The Linwe Formation (in the limestone) includes nautiloids, crinoids, cystoids, ostracods, conodonts; trilobites and graptolites occurred in the siliciclastic horizon. Some Devonian outcrops of the Zebingyi Formation and? Maymyo Formation are narrowly exposed in the Myogyi area where there are 2minor amounts of tentaculitids and ammonoids. There are so far no Carboniferous strata are discovered in this area. The Thisipin Formation contains rugose and tabulate corals, foraminifers mainly fusulinids, brachiopods, bryozoans, crinoids, gastropods and leaf fossils. The Nwabangyi Dolomite Formation has some fossils, ammonoids, conodonts, bivalves, and shark teeth. In completion of this works, detailed stratigraphic investigations are still needed in a matter of urgency.