Characteristics of Lacustrine Highresolution Sequence Stratigraphy underArid Climate : a case study of Yuyang Formation (Late Cretaceous) in Southwest of Jianghan Basin

Key words: 
• Jianghan Basin /
• Yuyang Formation /
• highresolution sequence stratigraphy /
• flood period & /
• interflood period /
• baselevel cycle

Abstract: The sequence in Yuyang Formation of lateCretaceous in southwest of Jianghan Basin is controlled by arid climate. Due to the evolution of climate, the flood period and interflood period alternately occur. In shortterm cycle, the sandstone of channel microfacies and sandflat microfacies deposits in flood period and the mudstone of mudflat microfacies deposits in interflood period. In midterm cycle, there appear several assemblages of shortterm sequence cycle. The main flood period usually lasts quite a long time with a large scale, so there deposits a set of thick grey sandstone of channel microfacies and mudstone of distal microfacies with interlayers of laminar red mudstone of mudflat microfacies .Moreover, there is a set of sandflat, mixedflat and mudflat microfacies in the main interflood period. Different from the two cycles above, in longterm cycle, it has a trend that the scales of the channel decrease in main flood period while the thicknesses of red mudflat increase in interflood period. All these characters in mid& longterm sequence cycle suggest the climate has a tendency to become more and more arid. In terms of the characters of sequences and microfacies in arid climate evolution, the authors build up a set of highresolution stratigraphic sequence and make the stratigraphic correlation.