Sedimentary facies, depositional processes and climatic controls in a Triassic Lake, Tanzhuang Formation, western Henan Province, China

摘要: The Middle to Upper Triassic Tanzhuang Formation represents part of the infill early Mesozoic Jiyuan-Yima Basin. upper this stratigraphic unit records deposition within prevailing shallow lake conditions. Well-developed sequences crop out near Jiyuan, western Henan Province, central China. Six sedimentary facies clustered into two assemblages were recognized in lacustrine section. Facies assemblage 1 consists stacked coarsening-upward composed, from base top, organic-rich shales (facies E, type I), laminated siltstones A) and current-rippled sandstones B). Units record progradation small mouth-bar deltas a perennial open system under temperate humid 2 lacks clear vertical pattern interbedded fine-grained carbonates C); deformed wave-reworked D); II) clayey mudstones F). also perennial, hydrologically-open, system, but characterized by strong seasonal climatic control. Water stratification probably occurred several periods history. Pangaean megamonsoonal influence is envisaged explain seasonality imprint evidenced toward column.