Sedimentology and Stratigraphy of Phu Sung Fossil Site of the Lower Cretaceous Sao Khua Formation, Sakon Nakhon Province, Northeastern Thailand

Abstract

“Phu Sung”, a new fossil site in Sakon Nakhon Province was recently reported. Phu Sung fossils are very complete and in very well-preserved condition. They were found in reddish micaceous silty mudstone. The stratigraphy and sedimentology show that Phu Sung succession is a continental deposit in the fluvial system and it is in the Early Cretaceous Sao Khua Formation of the Khorat Group. According to lithology, fossils were deposited in a quiet environment, such as overbank deposit, small pond or oxbow lake margin. Sedimentary structures such as desiccation crack and calcrete indicate semi-arid to arid paleoclimate condition which probably corresponds to the taphonomy or preservation of the fossils.