Ostracod Boistratigraphy Near The J/K Boundary And The Boundary Discussions In Southern Junggar Basin

Southern Junggar is one important depocenter as a Jurrassic continental sedimentation, sepecially,_it is the baseline profile of the middle and upper Jurassic in northern Xinjiang. Fossils found involves fossil plants, pollen,_spores, round algae, bivalves, gastropods, conchostracans, ostracods, insects and_vertebrates, fish, amphibians, reptiles and early lactation and so on. In addition,_the layer of this profile at123and126exposed white tuff and pink tuffaceous sandstone, which is an excilant condition to study in biostratigraphy and the division of Jurassic/Cretaceous. In this conditions, we studied in this area and achieved some results following:1. SHRIMP zircon U-Pb achieved that Qigu profile should be attributed to middle Jurassic instead of Late Jurassic, and the Late Jurassic showing a great uncoformity.2. This article shows that, Mantelliana species of ostracod, which used to be considered to fist appeared in Late Jurrassic, and considered to be one of the standard fossils to the division of J/K boundary, should attribute to Middle Jurassic, this species appeared in an earlier time than we knew.3. The Qingshuihe group containing the combination of ostracod of Cypridea-Rhinocypris-Latonia-Djungarica, with which we combined the age of t early Cretaceous Berriasian to the Barremian period.