Study of Sedimentary Facies and Environment of the Nieerku Formation, Suzihe Basin, Eastern Liaoning

Key words: 
• eastern Liaoning /
• Cretaceous /
• Nieerku Formation /
• sedimentary facies /
• sedimentary environment

Abstract: The Suzihe Basin is a Lower Cretaceous small fault basin in eastern Liaoning Province. The continental deposits in the basin offer unique conditions for the study of the evolution of the paleoenvironment and paleoclimate of terrestrial settings during the Cretaceous. The sediments of the late Lower Cretaceous Nieerku Formation in the Suzihe Basin contain various clastic and mud rocks, typical deposits and divers terrestrial fossils. An analysis of the sedimentary rock types, the sedimentary structure, fossils and sedimentation sequence, recognized fan delta facies and lake facies. The fan delta facies are divided into fan delta plain subfacies, fan delta front subfacies and pre-fan delta subfacies. The lake facies primarily contain shore to shallow-lake mudstones and sandstones. It was found that the Nieerku Formation formed on the steep slope of a faulted lacustrine basin in a fan delta/lake sedimentary system that underwent intermittent flooding. The Nieerku Formation evolved in a sedimentary environment from fan delta to lake, then to fan delta, indicating that the faulted lacustrine basin experienced two evolutionary stages: a deep depressional period and an early shrinkage period. The characteristics of the sedimentary rocks and facies, combined with paleontological data, specific sediments, clay minerals and geochemical data, confirm that the climate was generally hot and dry/humid in eastern Liaoning during the late Lower Cretaceous, which corresponds to a “greenhouse” climate, but the warm climate was not static. This supports the generally held view that the Cretaceous climate was turbulent.