Late Mesozoic Tectonic Evolution And Mineralization In The Siling Co Area,Tibet

The Siling Co area is located in the middle section of the Bangonghu-Nujiang metallogenic belt,and there are some prospecting breakthrough in the past several years,but no significant progress has been made in prospecting.There are many scientific problems to be solved,such as unknown the tectonic background of the newly discovered deposits background,tectonic evolution,the closed time of ocean basin,which severely restricted the prospecting work.Based on previous work including field geological investigation,sampling,zircon U-Pb geochronology and magmatic petrochemistry,the Late Mesozoic tectonic evolution in Siling Co area is studied from geochronology,oceanic plate stratigraphy,sedimentary paleogeography,petrochemistry of magmatic rocks,etc.Then the prospecting of metal minerals in the related tectonic evolution stage is further analyzed through integrating the distribution of tectonic evolution products,mineralization occurrence.The followings are the main achievement:Defining the tectonic framework of the multi-island / block ocean during the Pre-Toarcian.Since the pre-Toarcian of the early Jurassic Pliensbachian,the Siling Co area constrained by Dongqiao North fault to the north and the Shiquanhe-Jiali South fault to the south is the multi-island / block ocean pattern of the ocean rift stage.Concluding four stages of different systematic transformation and evolution from Early Jurassic Pliensbachian to Late Cretaceous Campanian period.The area underwent the multi-island / block oceanic rift stage in Pliensbachian and previous rift,valley-subduction stage from Toarcian to valanginian,subduction-collision stage from Hauterivian to Albian,and collision-intracontinental interaction stage from Turonian period to Campanian period.Siling Co area underwent the transformation from multi-island / block ocean rift system to fully convergent intracontinental systemA new understanding: the evolution is characterized by general convergence,dynamics and statics,stage development and gradual system change.The Siling Co area underwent the transformation from the ocean rift to the inner continent through several sub-events of subduction,collision and other tectonic events in the Late Mesozoic.The rifting in the Siling Co area since the Early Jurassic Pliensbachian period,accompanied by subduction(sub-event),lasted to valanjin.Subduction(sub-events)began in the early Jurassic Toarcian,and ended in the early Cretaceous Albian.The collision(sub-event)started from the Early Cretaceous Hauterivian,and continued to develop to the Late Cretaceous Campanian.In general,the trend of development was stronger at the north and strongest in the early Cretaceous Albian period.The intracontinental action(sub-event)was found in the pre-collisional area at the end of the collision(late Cretaceous Campanian).Summarizing regional metallogenic rules and the associated metallic ore of rift valley,subduction,collision(sub-event)was considered to be prospecting prospects.All have a certain prospecting prospect.A total of 11 prospecting areas have been delineated,including 3 grade A,6grade B and 2 grade C through integratingthe distribution of evolution products,mineralization occurrence and information characteristics of all prospecting methods of tectonic events based on the theory of tectonic metallogeny and comprehensive evaluation of effective information.