STRATA AND SPORES ASSOCIATION OF DOGAI CORING REDBEDS OF NORTH TIBETAN PLATEAU
Widespread fluvial redbeds are exposed widely in Qiangtang block of North Tibetan Plateau. Dating these redbeds can provide very important data for understanding the geological and deformational history of North Tibetan Plateau.The geological group of INDEPTH III studied the stratigraphy and deformation of Dogai Coring redbeds in North Tibetan Plateau, and discovered varieties of spores for time determination. The spores association corresponds to the vegetation dominated by arid grassland and in Late Miocence Pliocene period. The latest 40 Ar- 39 Ar dating of the basalt overlying Dogai Coring redbeds gives ages ranging from 2 5Ma to 3 2Ma, which provides upper limit age for strata and deformation of Dogai Coring redbeds. It is inferred that the Dogai Coring redbeds formed in Late Miocene, and the crustal shortening of Dogai Coring redbed basin, circa 50%, occurred at the end of Miocene Early Pliocene.The time of strata and deformation of Dogai Coring redbeds sets a new constrain for understanding the geodynamic process of the Tibetan Plateau.