CONTINENTAL TECTONIC FRAMEWORK OF WEST CHINA
GE Xiao hong,et al.(College of Earth Sciences,Jilin University,Changcun 130061,China)
In the process of carrying out "West Development"policy,the tectonic outline of West China continent is very important for the exploration of oil and gas and other mineral resources.According to the recent researches,we have got three new understandings of West China tectonic:(1)The studies of laser probe 40 Ar/ 39 Ar dating in deformed rocks in Altyn fault suggest that the strike slip event occurred or began at 97~89 Ma. These ages are consistent with the formation ages (102~85Ma) of the so called"Western Tectonic Joint" in Himalayan.Sinistral strike slip shearing has caused displacement to 350~400km along the Altyn fault zone,and tectonic zones and original basins are displaced from Late Cretaceous to Cenozoic.Therefore,the large scale displacement must be taken into consideration when discussing the formation of the tectonic framework of Northwest China,including the reconstructions of the Precambrian blocks (including Rodinia super continent),tectonic zones and orignal basins from Mesozoic to Early Tertiary.(2)The Tarim,Qaidam and Alxa block formed a Yangtze type non staleb craton in Paleozoic,called Western Craton,which is characterized by multiphase breaking at different locations,and together with the Yangtze South China,Indosinian,Australian plates compose the Gondwana continent during Late Sinian Early Paleozoic.The super continent broken up and drifted later.The blocks are tectonically displaced and located during Late Paleozoic Indosinian stage.They are further broken up and displaced during Himalayan stage and form separated basins (blocks).(3)The North Qilian Mountains is an Aulacogen formed due to the intra continent breakup of the West China craton,instead of an oceanic basin,during Early Paleozoic.The west extension of the aulacogen goes to the Manjia'er Awati depression at north central Tarim.The present framework and distribution are due to the sinistral displacement by the Altyn fault in Cenozoic.The Paleo Qilian Mountain was formed during the closing of the aulacogen in Paleozoic.Planation was preceded during Paleozoic through Triassic and the mountain belt was transformed into cratonic basin.Due to extension during Jurassic to Early Tertiary,the North Qilian Mountains formed part of the original Hexi Corridor land basins.The formation of the present Qilian Mountains occurs from Pliocene to Early Pleistocene during the uprising of the Qinghai Tibet Plateau.
【Fund】： 国家自然科学基金项目(科学部编号 49772 15 7)资助
【CateGory Index】： P542
【CateGory Index】： P542