Terristrial humidity increase during mid-Cretaceous : Cretaceous research in Mongolia for understanding of greenhouse Earth system

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The lacustrine deposits of the mid-Cretaceous Shinekhudag Formation and middle Jurassic Eedemt Formation in southeast Mongolia are investigated through the following two strategy : (1) Establishment of chronostratigraphy by carbon-isotopic stratigraphy, conchostracans biostratigraphy, and fission-track age dating of intercalated tuffaceous rocks, and (2) Reconstruction of terrestrial paleoclimatic changes by cyclicity of the rhythmically alternating shale-dolomite, paleoweathering changes based on mineral and major elemental ratios, and paleotemperature changes based on organic geochemical proxy (TEX_<86>). The results reveal that these lacustrine strata record orbital-controlled paleoclimatic (precipitation and temperature) changes in inland Asia during the OAE intervals.