Sedimentary Facies of Miocene Clastic Strata in the Kalewa- Mawlaik Area, Sagaing Region, Myanmar

Abstract

The present study would offer the Sedimentary Facies of Miocene clastic sedimentary rock units of Letkat Formation (Early Miocene), Natma Formation (Middle Miocene) and Shwethamin Formation (Late Miocene) exposed in the southwestern Chindwin Basin, situated in Kalewa-Mawleik Area, Sagaing Region. The study is mainly focus on outcrop-based sedimentary facies analysis. During Early Miocene, Letkat Formation was deposited in a fluvial-river system of the lowstand systems tract deposits (LST) deeply incised into the underlying Yaw Formation during relative sea-level fall, also be regarded as an incised fluvial channel-fill (IVF). The lower part of The Letkat Formation is characterized by high bed-load gravelly and sandy, multi-storey sand bodies of braided channel-complexes with general lack of the overbank fines. The middle part is constructed with the shallow and broad amalgamated sandy channels with thick laminated sheets probably deposited as a result of unconfined sheet flooding, and minor overbank fines. The upper part is becoming dominated with thick overbank-floodplains fines interbedded with the isolated major channels, minor channels or crevasse channels, and thin crevasse splays or laminated sand sheets. The lower part Natma Formation is dominated with thick overbank-floodplains fines interbedded with the isolated major channels, minor channels or crevasse channels, and thin crevasse splays or laminated sand sheets in the fluvial system. The upward change in sand-body architectures within the sequence and lateral interconnected and amalgamated channel and meander belt systems with poorly preserved floodplain deposits. The lower part of Shwethamin Formation is characterized by high bed-load gravelly and sandy, multi-storey sand bodies of braided channel-complexes. The middle part is constructed with the shallow and broad amalgamated sandy channels where as the upper part is dominated with thick overbank-floodplains fines.

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