The mainland of China is composed of the North China Craton,the South China Craton,the Tarim Craton and other young orogehie belts.Amongst the three cratons,the North China Craton has been studied most and noted for i...The mainland of China is composed of the North China Craton,the South China Craton,the Tarim Craton and other young orogehie belts.Amongst the three cratons,the North China Craton has been studied most and noted for its widely-distributed Archean basement rocks.In this paper,we assess and compare the geology,rock types,formation age and geochemical composition features of the Archean basements of the three cratons.They have some common characteristics,including the fact that the crustal rocks prior to the Paleoarchean and the supracrustal rocks of the Neoarehean were preserved,and Tonalite-Trondhjemtite- Granodiorite (TTG)magmatism and tectono-magmatism occurred at about 2.7 Ga and about 2.5 Ga respectively.The Tarim Craton and the North China Craton show more similarities in their early Precambrian crustal evolution.Significant findings on the Archean basement of the North China Craton are coneluded to be:(1)the tectonic regime in the early stage (>3.1 Ga)is distinct from modem plate tectonics;(2)the continental crust accretion occurred mostly from the late Mesoarchean to the early Neoarehean period;(3)a huge linear tectonic belt already existed in the late Neoarchean period,suggesting the beginning of plate tectonics;and (4)the preliminary cratonization had already been completed by about 2.5 Ga. Hadean detrital zircons were found at a total of nine locations within China.Most of them show clear oscillatory zoning,sharing similar textures with magmatic zircons from interrnediate-felsic magmatic rocks. This indicates that a fair quantity of continental material had already developed on Earth at that time.展开更多
The formation, composition and evolution of the oldest continental crust is the logical starting point for discussing the differentiation and development of the crust-mantle system and the tectonic evolution of the Ea...The formation, composition and evolution of the oldest continental crust is the logical starting point for discussing the differentiation and development of the crust-mantle system and the tectonic evolution of the Earth. Searching for and identifying the oldest continental crust and investigating the processes and periodicity of crust formation and its subsequent development into cratons is a primary scientific topic of worldwide research [1]. The other important issues related to early Precambrian evolution include identifying tectonic divisions and determining the onset of plate tectonics. However, the rarity of preserved ancient continental crust due to its long-term reworking makes this research extremely challenging. Thus, finding and identifying the oldest rocks and zircons is the beginning of very exciting and important research. The occurrence of >3.8 Ga rocks in northern and eastern Canada, West Greenland and eastern Antarctica are difficult to access and so it is important to identify other occurrences of such rocks.展开更多
基金the Key Program of the Ministry of Land and Resources of China (121201102000150012,DD20160121-03, 121201102000150010-04,DD20160343-01)the National Natural Science Foundation of China (41172127,41472169).
文摘The mainland of China is composed of the North China Craton,the South China Craton,the Tarim Craton and other young orogehie belts.Amongst the three cratons,the North China Craton has been studied most and noted for its widely-distributed Archean basement rocks.In this paper,we assess and compare the geology,rock types,formation age and geochemical composition features of the Archean basements of the three cratons.They have some common characteristics,including the fact that the crustal rocks prior to the Paleoarchean and the supracrustal rocks of the Neoarehean were preserved,and Tonalite-Trondhjemtite- Granodiorite (TTG)magmatism and tectono-magmatism occurred at about 2.7 Ga and about 2.5 Ga respectively.The Tarim Craton and the North China Craton show more similarities in their early Precambrian crustal evolution.Significant findings on the Archean basement of the North China Craton are coneluded to be:(1)the tectonic regime in the early stage (>3.1 Ga)is distinct from modem plate tectonics;(2)the continental crust accretion occurred mostly from the late Mesoarchean to the early Neoarehean period;(3)a huge linear tectonic belt already existed in the late Neoarchean period,suggesting the beginning of plate tectonics;and (4)the preliminary cratonization had already been completed by about 2.5 Ga. Hadean detrital zircons were found at a total of nine locations within China.Most of them show clear oscillatory zoning,sharing similar textures with magmatic zircons from interrnediate-felsic magmatic rocks. This indicates that a fair quantity of continental material had already developed on Earth at that time.
基金supported by the National Natural Science Foundation of China(41472169)the Key Program of the Ministry of Nature and Resources of China(121201102000150012)
文摘The formation, composition and evolution of the oldest continental crust is the logical starting point for discussing the differentiation and development of the crust-mantle system and the tectonic evolution of the Earth. Searching for and identifying the oldest continental crust and investigating the processes and periodicity of crust formation and its subsequent development into cratons is a primary scientific topic of worldwide research [1]. The other important issues related to early Precambrian evolution include identifying tectonic divisions and determining the onset of plate tectonics. However, the rarity of preserved ancient continental crust due to its long-term reworking makes this research extremely challenging. Thus, finding and identifying the oldest rocks and zircons is the beginning of very exciting and important research. The occurrence of >3.8 Ga rocks in northern and eastern Canada, West Greenland and eastern Antarctica are difficult to access and so it is important to identify other occurrences of such rocks.
