Abstract

• The aim of this paper are to classify the sandstones of Kalaw Formation and to describe diagenesis of these sandstones of the Tigyit area. The research area lies in Tigyit area, Shan State (South) and its situated in the tectonic province of Shan-Tanintharyi Block of Myanmar. The study area is mainly composed of Mesozoic to Cenozoic clastic sediments and subordinate amount of Paleozoic to Mesozoic age of carbonate rocks. Petrographic studies of the selected sandstone samples collected from the Kalaw Formation were carried out in detail. The sandstones of Kalaw Formation have less than 75 percent of detrital framework and 25 percent matrix. The detrital grains are composed of quartz, feldspar, mica, various kinds of rock fragments and very little heavy minerals. Mediumgrained sandstones of Kalaw Formation fall in “Litharenites” and fine-grained sandstones of Kalaw Formation fall in the field of “Arkose”. Generally, three processes of diagenesis are observed in the sandstones. These are; compaction, cementation and authigenesis.