Microbialites in Middle Ordovician Wunbye Formation and Permian Thitsipin Limestone Formation, Theingon-Kyauktaw Area, Ywangan Township, Southern Shan State, Myanmar

Abstract

The study area is the Permian strata of the southern Shan State and this paper described mainly the Permian Thitsipin Limestone Formation of morphology of microbialite structures, to provide a simple field classification. Microbialites are abundant in marine sediments of Thitsipin Formation. It occurs as isolated masses, in many places faulted against older rocks. In this area, the distribution of microbialites are good but in small sizes and somes are well exposed isolated carbonate buildups serve as models for the form and the development of microreef. Based on the geometric forms of microbialites, mainly three types of stromatolite structures are characteristics. They are: cryptalgal laminite, laterally linked hemispheroids of LLH type and discrete spheroids of either randomely or concentrically arranged spheroids. LLH type stromatolites are referred to the protected intertidal mud flats, where wave action is slight. Low intertidal areas that are exposed to wave and agitated shallow water below low water mark are inferred by the SS type. Moreover microbialites bearing sequences are ordered by small cycles of sequences, it was due to fluctuations of water level and it controlled the facies patterns. All in all, the sequences of the Thitsipin Limestone Formation grew at shallow to moderately deep sites in stenohaline and oligotrophic conditions. Moreover, the uppermost part of this sequence of stromatolites bearing strata is as like the microreef.

AAPG Datapages/Search and Discovery Article #90336 ©2018 AAPG Asia Pacific Region, The 4th AAPG/EAGE/MGS Myanmar Oil and Gas Conference, Myanmar: A Global Oil and Gas Hotspot: Unleashing the Petroleum Systems Potential, Yangon, Myanmar, November 13-15, 2018