A map of major Precambrian mafic dyke swarms and related units in the North China Craton is compiled, and the features and geological implications of these swarms are demonstrated. The Archean dyke swarms are availabl...A map of major Precambrian mafic dyke swarms and related units in the North China Craton is compiled, and the features and geological implications of these swarms are demonstrated. The Archean dyke swarms are available to portray the early crustal growth and cratonization. The middle Paleoproterozoic(2200–1850 Ma) swarms and related magmatic series could constrain the tectonic evolution: They approve that the craton was amalgamated by two sub-cratons. The late Paleoproterozoic(1800–1600 Ma), Mesoproterozoic(1400–1200 Ma) and Neoproterozoic(1000–800 Ma) series swarms are important in paleogeographic reconstruction: they indicate that North China might have connected with some of the North European and North American cratons during Proterozoic. Dyke swarms are not only geological timescales and tectonic markers but also evolution indicators of lithospheric mantle: they imply a rejuvenation of the sub-continental lithospheric mantle of North China at 1780–1730 Ma. These swarms occurred with several rifts, including the Hengling(2200–1970 Ma), Xuwujia(1970–1880 Ma), Xiong'er(1800–1600 Ma), Yan-Liao(1730–1200 Ma), and Xu-Huai(1000–800 Ma). Among them, the Xuwujia rift was possibly continental arc associated; whereas the others were intra-continental. In addition, the Xiong'er and Xu-Huai rifts were possibly triple junctions along the present southern and southeastern margins of the Craton, respectively. Different tectonic settings of these rifts and dyke swarms would result in diversified series of ore deposits.展开更多
The Western Kunlun Range in northern Qinghai-Tibet Plateau is composed of the North Kunlun Terrane,the South Kunlun Terrane and the Karakorum-Tianshuihai Terrane. Here we report zircon SHRIMP and LA-ICP-MS U-Pb ages o...The Western Kunlun Range in northern Qinghai-Tibet Plateau is composed of the North Kunlun Terrane,the South Kunlun Terrane and the Karakorum-Tianshuihai Terrane. Here we report zircon SHRIMP and LA-ICP-MS U-Pb ages of some metamorphic and igneous rocks and field observations in order to pro-vide a better understanding of their Precambrian and Palaeozoic-early Mesozoic tectonic evolution. Based on these data we draw the following conclusions: (1) The paragneisses in the North Kunlun Terrane are likely of late Mesoproterozoic age rather than Palaeoproterozoic age as previously thought,representing tectonothermal episodes at 1.0―0.9 Ga and ～0.8 Ga. (2) The North Kunlun Terrane was an orogenic belt accreted to the southern margin of Tarim during late Mesoproterozoic to early Neopro-terozoic,the two episodes of metamorphisms correspond to the assemblage and breakup of Rodinia respectively. (3) The Bulunkuole Group in western South Kunlun Terrane,which was considered to be the Palaeoproterozoic basement of the South Kunlun Terrane by previous studies,is now subdivided into the late Neoproterzoic to early Palaeozoic paragneisses (khondalite) and the early Mesozoic metamorphic volcano-sedimentary series; the paragneisses were thrust onto the metamorphic vol-cano-sedimentary series from south to north,with two main teconothermal episodes (i.e.,Caledonian,460―400 Ma,and Hercynian-Indosinian,340―200 Ma),and have been documented by zircon U-Pb ages. (4) In the eastern part of the South Kunlun Terrane,a gneissic granodiorite pluton,which intruded the khondalite,was crystallized at ca. 505 Ma and metamorphosed at ca. 240 Ma. In combination with geochronology data of the paragneiss,we suggest that the South Kunlun Terrane was a Caledonian accretionary orogenic belt and overprinted by late Paleozoic to early Mesozoic arc magmatism.展开更多
Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilia...Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilian terrane consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8–1.0 Ga (the Jinningian period); (2) most of the meta-argillo-arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu*= 0.47–0.71 and Ba/Ba*=0.16–0.64), with fDM and ENd (1.0 Ga) ranging from 1.87 to 2.26 Ga and from ?8.54 to ?4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks are a typical product of continent-continent collision, being probably related to the formation of the supercontinent Rodinia. These studies, combined with the study of high-grade basement rocks near the Qilian terrane, suggest that before the Jinningian period, the Qilian-Qaidam northern-margin terrane and Dunhuang-Alxa terrane were separated from each other, belonging to different plate systems of the North China craton and Yangtze platform respectively. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period.展开更多
基金supported by the National Basic Research Program of China(Grant No.2012CB416601)the National Natural Science Foundation of China(Grant Nos.41322018,41072146)The LIPs-Supercontinent Reconstruction Project(www.supercontinent.org)
文摘A map of major Precambrian mafic dyke swarms and related units in the North China Craton is compiled, and the features and geological implications of these swarms are demonstrated. The Archean dyke swarms are available to portray the early crustal growth and cratonization. The middle Paleoproterozoic(2200–1850 Ma) swarms and related magmatic series could constrain the tectonic evolution: They approve that the craton was amalgamated by two sub-cratons. The late Paleoproterozoic(1800–1600 Ma), Mesoproterozoic(1400–1200 Ma) and Neoproterozoic(1000–800 Ma) series swarms are important in paleogeographic reconstruction: they indicate that North China might have connected with some of the North European and North American cratons during Proterozoic. Dyke swarms are not only geological timescales and tectonic markers but also evolution indicators of lithospheric mantle: they imply a rejuvenation of the sub-continental lithospheric mantle of North China at 1780–1730 Ma. These swarms occurred with several rifts, including the Hengling(2200–1970 Ma), Xuwujia(1970–1880 Ma), Xiong'er(1800–1600 Ma), Yan-Liao(1730–1200 Ma), and Xu-Huai(1000–800 Ma). Among them, the Xuwujia rift was possibly continental arc associated; whereas the others were intra-continental. In addition, the Xiong'er and Xu-Huai rifts were possibly triple junctions along the present southern and southeastern margins of the Craton, respectively. Different tectonic settings of these rifts and dyke swarms would result in diversified series of ore deposits.
基金the National Natural Science Foundation of China (Grant Nos40303007 and 40421303)Chinese Geology Survey (Grant No. 200113900070)
文摘The Western Kunlun Range in northern Qinghai-Tibet Plateau is composed of the North Kunlun Terrane,the South Kunlun Terrane and the Karakorum-Tianshuihai Terrane. Here we report zircon SHRIMP and LA-ICP-MS U-Pb ages of some metamorphic and igneous rocks and field observations in order to pro-vide a better understanding of their Precambrian and Palaeozoic-early Mesozoic tectonic evolution. Based on these data we draw the following conclusions: (1) The paragneisses in the North Kunlun Terrane are likely of late Mesoproterozoic age rather than Palaeoproterozoic age as previously thought,representing tectonothermal episodes at 1.0―0.9 Ga and ～0.8 Ga. (2) The North Kunlun Terrane was an orogenic belt accreted to the southern margin of Tarim during late Mesoproterozoic to early Neopro-terozoic,the two episodes of metamorphisms correspond to the assemblage and breakup of Rodinia respectively. (3) The Bulunkuole Group in western South Kunlun Terrane,which was considered to be the Palaeoproterozoic basement of the South Kunlun Terrane by previous studies,is now subdivided into the late Neoproterzoic to early Palaeozoic paragneisses (khondalite) and the early Mesozoic metamorphic volcano-sedimentary series; the paragneisses were thrust onto the metamorphic vol-cano-sedimentary series from south to north,with two main teconothermal episodes (i.e.,Caledonian,460―400 Ma,and Hercynian-Indosinian,340―200 Ma),and have been documented by zircon U-Pb ages. (4) In the eastern part of the South Kunlun Terrane,a gneissic granodiorite pluton,which intruded the khondalite,was crystallized at ca. 505 Ma and metamorphosed at ca. 240 Ma. In combination with geochronology data of the paragneiss,we suggest that the South Kunlun Terrane was a Caledonian accretionary orogenic belt and overprinted by late Paleozoic to early Mesozoic arc magmatism.
基金supported by China National Natural Science Foundation Grant 49732070.
文摘Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilian terrane consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8–1.0 Ga (the Jinningian period); (2) most of the meta-argillo-arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu*= 0.47–0.71 and Ba/Ba*=0.16–0.64), with fDM and ENd (1.0 Ga) ranging from 1.87 to 2.26 Ga and from ?8.54 to ?4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks are a typical product of continent-continent collision, being probably related to the formation of the supercontinent Rodinia. These studies, combined with the study of high-grade basement rocks near the Qilian terrane, suggest that before the Jinningian period, the Qilian-Qaidam northern-margin terrane and Dunhuang-Alxa terrane were separated from each other, belonging to different plate systems of the North China craton and Yangtze platform respectively. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period.
