The boundary between Jurassic and Cretaceous is the most problematical of all Phanerozoic system boundaries,have long been debated and not yet been resolved on a global scale.The Late Jurassic to the Early Cretaceous marine strata are extensively distributed in southern Tibet.In Gyangze,the strata are divided into the Weimei and Jiabula formations.In Nagarze and Gongga,they are divided into the Weimei and Sangxiu formations.