Fulai Liu

The Precambrian Geology of the Tibetan Plateau

The Tibetan Plateau, which includes all the Tibet and Qinghai Provinces, the southern Xinjiang and Gansu Provinces and the western Sichuan and Yunnan Provinces, is a tectonically active region among the Indian, Yangtze, Tarim, and North China blocks. On the basis of the geological background, it can be divided into the Altyn-Qaidam-West Qinling orogenic system, the Kara Kunlun-Bayan Har-Chamdo-Simao orogenic system, and the Southern Qiang-Gangdise-Himalaya-Baoshan orogenic system from north to south, separated by the Kangxiwa-Southern Kunlun-Madoi-Maqen suture zone and the Longmuco-Two Lake-Lancang River suture zone, respectively. Every orogenic system can be further divided into several terranes by suture zones (melanges) consisting of deep-sea sediment residues, ophiolites (melanges), and high-pressure metamorphic rocks. This chapter describes the distribution, composition, protolith and metamorphic ages, and metamorphic characteristics of the Precambrian geologic units of the terranes and suture zones. Also included are research progress, existing problems, and an overview of different opinions from different researchers on the Precambrian history of the terranes. Additionally, a preliminary summary is given for major geological events and tectonic evolution of every Precambrian orogenic system. The Tibetan Plateau is vast in territory, but the Precambrian geological units distribute scatteredly in tectonic melanges of or between the terranes. Although abundant studies have been made about the Precambrian geology of the Tibetan Plateau, the overall level of geological research is much lower than those of other Precambrian terranes in China. Geochronologic data for each geologic unit is also of confusion, which led to divergence on their protolith and metamorphic ages, tectonic attributes, and other aspects, so the crustal evolution studies of the Precambrian Tibetan Plateau need to be further deepened.