THE SEQUENCE OF THE TECTONIC MOVEMENTS AND THE MEGASTAGES OFTECTONIC DEVELOPMENT IN CHINA

In the geological history of China there have occurred at least 13 strong tectonic movements, of which 4 are of major importance for the division of the stages of geological-structural development; they are the Fuping, Luliang, Jinning and Indosinian movements. Taking these four tectonic movements as the turning points, the tectonic development of China may be divided into five megastages: Archean, Eo-Algonkian, Neo-Algonkian, Early Neo aic and Late Neogaic. The Archean megastage（＞3500—2500m.y.）.The Archean megastage witnessed two tectonic movements or tectono-thermal metamorphism events, namely, the Qianxi Movement and the Fuping Movement. The Qianxi Movement resulted in the formation of a metamorphic series of granulite facies, accompanied by intense migmatization and granitization.The terminal age of the metamorphism is about 3100m.y.The Fuping Movement took place in the late Archean and gave rise to a metamorphic series of amphibolite facies, accompanied by intense migmatization and granitization.The unconformities resulting from this movement are widespread in the Sino-Korean massif.2500 m.y.may be considered to be the terminal age of the metamorphism related to the Fuping Movement. The Eo-Algonkian megastage（2500—1700 m.y.）.This megastage involved two strong tectonic movements, the wutai and Luliang movements. The Wutai Movement started in the late part of the early proterozoic. The type area is the Wutai Mountains, northern Shansi, Where the Wutai Group overlies the Hutuo Group With pronounced unconformities. The unconformities produced by the syntectonic movement may also be seen in the Luliang, Zhongtiao,Yinshan and Yanshan Mountains as well as in eastern Liaoning and Jiaodong. Simultaneously With or later than the metamorphism of the Wutai Group,extensive intrusions of granite and pegmatite took place in the Sino-Korean massif. The termi nal metamorphic age of the Wutai Group is about 2050m.y. The Luliang Movement refers to a violent tectonic movement taking place in the late part of the middle proterozoic. It marked the close of the geological history of this megastage and gave rise to the Sino-Korean massif. The isotopic ages of granite, pegmatite and metamorphic rocks related to this movement mainly range from 1800 to 1700 m.y. The Neo-Algonkian megastage（1700—800 m.y.）. This megastage experienced the Dongchuan, Sibao and Jinning movements. The Dongchuan Movement,represented mainly by the unconformities between the Lower and the Upper Kunyang Group, took place about 1400 m.y.ago. The Sibao Movement took place about 1000m.y. ago. The locality after which this movement is named is in northern Guangxi. The Sibao Group is in pronounced angular unconformity With the overlying Banxi Group. The Jinning movement,represented by the unconformi ties between the Sinian and the pre-Sinian, refers to the tectonic movement that took place between 900—700m.y.B.P. This movement led to the formation of the basement of the yangtze and Tarim massifs. The Early Neogaic megastage（Sinian-Triassic）. The fundamental feature of the geological-structural development of China during this period is that With intensifying crustal activity the structural disintegration became marked steadily, thus forming the tectonic framework characterized by alternating platforms and geosynclines. Through the Xingkai, Qilian and Tianshan movements, the entire Chinese continent other than a few regions such as Xizang and Taiwan rose and became land after the late Triassic Indosinian Movement. The Xingkai Movement, which occurred at the end of the Early Cambrian, affected the whole Central Asian-Mongolian geosyncline belt. The relics left by the Qilian Movement are chiefly observed in the Qilian Mountains and South China, while its influence has been felt almost all over China. The Qilian Movement may be divided into three tectonic phases which took place at the ends of the Middle Ordovician, Late Ordovician and Late Silurian, respectively. All the three phases were accompanied by intense magmatic activity. The geological relics of the Tianshan Movement are chiefly found over vast areas north of the Tianshan-Yinshan Mountains,in the Kunlun fold system and the Qinling fold system and in South China. This movement may be divided into three phases: the Late Devonian, the end of the Early Carboniferous and the end of the Early Permian. The Indosinian Movement mainly took place in the eastern part of China and the Qinghai-Xizang plateau and may be divided into three principal phases: the end of the Latinian of the Middle Triassic, the end of the Middle Triassic and the end of the Late Triassic. The Late Neogaic megastage（Jurassic-Tertiary）, After the Indosinian Move24 ment, significant changes took place in the tectonic framework of China. In the eastern part of China occurred a series of large-scale,NNE-SSW-trending uplifts.ubsidence and deep fracture zones and related volcanic-intrusive rock belts, thus causing the E-W-trending structural subzones in the eastern part of China to turn into near-N-S-trending ones. In the southwestern part of China, great changes were displayed by the gradual closing up of the Tethys-Himalayan sea and the big-magnitude uplift of ht the Qinghai-Xizang plateau. The most important tectonic phases of the Yanshan Movement took place at the ends of the Middle Jurassic,Late Jurassic and Early Cretaceous. The Himalayan Movement refers to the tectonic movement which took place from the Tertiary to the beginning of the Quaternary, The important tectonic phases took place at the end of the Eocene, in the late Miocene and at the end of the pliocene.