Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton (NCC). The complex is composed of v...Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton (NCC). The complex is composed of various high-grade and multiply deformed rocks, including gray gneiss, basic granulite, amphibolite, fine-grained gneiss and marble, metamorphosed to upper amphibolite or granulite facies. It can be divided into four rock units: the Fuping TTG gneisses, Longquanguan augen gneisses, Wanzi supracrustals, and Nanying granitic gneisses. U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed. The data on metamorphic zircon rims give ages of 1.82-1.84 Ga, corresponding to the final amalgamation event of the NCC, whereas the data for igneous zircon cores yield two age populations at -2.10 and -2.51 Ga, with some inherited ages scattering between 2.5 and 2.9 Ga. These results suggest that the Wanzi supracrustals were derived from the Fuping TTG gneisses (-2.5 Ga) and the Nanying granitic gneisses (2.0-2.1 Ga) and deposited between 2.10 and 1.84 Ga. All zircons with -2.51 Ga age have positive initial εHf values from +1.4 to +10.9, suggesting an important crustal growth event at -2.5 Ga through the addition of juvenile materials from the mantle. The Hf isotope data for the detrital zircons further imply that the 2.8 Ga rocks are important components in the lower crust, which is consistent with a suggestion from Nd isotope data for the Eastern Block. The zircons of 2.10 Ga population have initial εHf values of-4.9 to +6.1, interpreted as mixing of crustal re-melt with minor juvenile material contribution at 2.1 Ga. These results are distinct from that for the Western Block, supporting that the Fuping Complex was emplaced in a tectonic active environment at the western margin of the Eastern Block.展开更多
Objective Though the Central Asian Orogenic Belt (CAOB) is characterized by widespread Phanerozoic crustal growth,there is little juvenile crust documented in its southeastern segment,northern margin of the North Chin...Objective Though the Central Asian Orogenic Belt (CAOB) is characterized by widespread Phanerozoic crustal growth,there is little juvenile crust documented in its southeastern segment,northern margin of the North China Craton(NCC)(Zhang et al,2007,2009).Late Carboniferous Dongwanzi ultramafic-mafic cumulate complex occurs in northern margin of the NCC and is intruded by a syenite with depleted Sr-Nd isotopes (Ma et al.,2014).However,the age and petrogenesis of this syenite is poorly constrained.In this study,we present new petrological,zircon U-Pb and Hf isotopic data of the Dongwanzi syenite,in order to put insights on its formation age and petrogenetic relationship with cumulates.展开更多
Paleo-to Mesoproterozoic sedimentary rocks in the southern margin of the North China Craton(NCC)are represented by the Ruyang and Luoyu groups.We studied the sedimentary rocks from the Yunmengshan and Beidajian format...Paleo-to Mesoproterozoic sedimentary rocks in the southern margin of the North China Craton(NCC)are represented by the Ruyang and Luoyu groups.We studied the sedimentary rocks from the Yunmengshan and Beidajian formations of the Ruyang Group and the Cuizhuang and Sanjiaotang formations of the Luoyu Group.Detrital zircon grains from these formations have U–Pb age populations of 3.64–3.31 Ga,2.96–2.86 Ga,2.72–2.59 Ga,2.56–2.47 Ga,2.45–2.0 Ga,1.99–1.85 Ga and 1.84–1.65 Ga.The geochemical features of the sedimentary rocks suggest that some of the sediments were sourced from intermediate to felsic magmatic rocks.The age groups of the detrital zircon are roughly consistent with the tectono-thermal events in the southern margin of the NCC.The Hf isotopic compositions of detrital zircon from the sedimentary rocks in Ruyang and Luoyu groups suggest that significant crustal growth and reworking of the NCC took place during the Neoarchean and early-to mid-Paleoproterozoic,while crustal reworking at the Paleoarchean and late-Paleoproterozoic,and crustal growth at the Mesoarchean.We suggest the depositional times of the Ruyang Group and Luoyu Group are constrained to no older than 1.75–1.7 Ga and 1.7–1.65 Ga,respectively.Formation of late-Paleoproterozoic basins related to the strike slip and extrusion tectonics that cross-cut the NCC during the late Paleoproterozoic(<1.75 Ga),and the late Paleoproterozoic sedimentation once isochronous developed in the southern margin of the NCC through the Taihang region of the interior NCC and linked the Yanshan–Liaoxi regions of the northern NCC.展开更多
Detailed studies on U-Pb ages and Hf isotope have been carried out in zircons from a carbonatite dyke associated with the Bayan Obo giant REE-Nb-Fe deposit,northern margin of the North China Craton(NCC),which provide ...Detailed studies on U-Pb ages and Hf isotope have been carried out in zircons from a carbonatite dyke associated with the Bayan Obo giant REE-Nb-Fe deposit,northern margin of the North China Craton(NCC),which provide insights into the plate tectonic in Paleoproterozoic.Analyses of small amounts of zircons extracted from a large sample of the Wu carbonatite dyke have yielded two ages of late Archaean and late Paleoproterozoic(with mean 207 Pb/206 Pb ages of 2521±25 Ma and 1921±14 Ma,respectively).Mineral inclusions in the zircon identified by Raman spectroscopy are all silicate minerals,and none of the zircon grains has the extremely high Th/U characteristic of carbonatite,which are consistent with crystallization of the zircon from silicate,and the zircon is suggested to be derived from trapped basement complex.Hf isotopes in the zircon from the studied carbonatite are different from grain to grain,suggesting the zircons were not all formed in one single process.Majority ofεHf(t)values are compatible with ancient crustal sources with limited juvenile component.The Hf data and their TDM2 values also suggest a juvenile continental growth in Paleoproterozoic during the period of 1940–1957 Ma.Our data demonstrate the major crustal growth during the Paleoproterozoic in the northern margin of the NCC,coeval with the assembly of the supercontinent Columbia,and provide insights into the plate tectonic of the NCC in Paleoproterozoic.展开更多
The Alxa Block is the westernmost part of the North China Craton(NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC.H...The Alxa Block is the westernmost part of the North China Craton(NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC.However, the Precambrian basement of the Alxa Block is still poorly studied. In this study, we present new in situ LA-ICPMS zircon U-Pb and Lu-Hf isotope data from the Diebusige Metamorphic Complex(DMC) which located in the eastern Alxa Block. Field and petrological studies show that the DMC consists mainly of metamorphic supracrustal rocks and minor metamorphic plutonic rocks and has experienced amphibolite-granulite facies metamorphism. Zircon U-Pb dating results suggested that the amphibolite sample yields a crystallization age of 2636 ± 14 Ma and metamorphic ages of 2517–2454 Ma and 1988–1952 Ma, proving the existence of exposed Archean rocks in the Langshan area and indicating that late Neoarchean to Paleoproterozoic metamorphic events existed in the Alxa Block. Two paragneiss samples show that the magmatic detrital zircons from the DMC yield 207Pb/206Pb ages ranging from 2.48 Ga to 2.10 Ga with two youngest peaks at 2.13 Ga and 2.16 Ga, respectively, and they were also overprinted by metamorphic events at 1.97–1.90 Ga and 1.89–1.79Ga. Compilation of U-Pb ages of magmatic detrital and metamorphic zircons suggested that the main part of the DMC may have been formed at 2.1–2.0 Ga. Zircon Lu-Hf isotope data show that the source materials of the main part of the DMC were originated from the reworking of ancient Archean crust(3.45–2.78 Ga). The Hf isotope characteristics and the tectonothermal event records exhibit different evolution history with the Khondalite Belt and the Yinshan Block and the other basements of the Alxa Block, indicating that the Langshan was likely an independent terrain before the middle Paleoproterozoic and was subjected to the middle to late Paleoproterozoic tectonothermal events with the Khondalite Belt as a whole.展开更多
文摘Located in the middle segment of the Trans-North China Orogen, the Fuping Complex is considered as a critical area in understanding the evolution history of the North China Craton (NCC). The complex is composed of various high-grade and multiply deformed rocks, including gray gneiss, basic granulite, amphibolite, fine-grained gneiss and marble, metamorphosed to upper amphibolite or granulite facies. It can be divided into four rock units: the Fuping TTG gneisses, Longquanguan augen gneisses, Wanzi supracrustals, and Nanying granitic gneisses. U-Pb age and Hf isotope compositions of about 200 detrital zircons from the Wanzi supracrustals of the Fuping Complex have been analyzed. The data on metamorphic zircon rims give ages of 1.82-1.84 Ga, corresponding to the final amalgamation event of the NCC, whereas the data for igneous zircon cores yield two age populations at -2.10 and -2.51 Ga, with some inherited ages scattering between 2.5 and 2.9 Ga. These results suggest that the Wanzi supracrustals were derived from the Fuping TTG gneisses (-2.5 Ga) and the Nanying granitic gneisses (2.0-2.1 Ga) and deposited between 2.10 and 1.84 Ga. All zircons with -2.51 Ga age have positive initial εHf values from +1.4 to +10.9, suggesting an important crustal growth event at -2.5 Ga through the addition of juvenile materials from the mantle. The Hf isotope data for the detrital zircons further imply that the 2.8 Ga rocks are important components in the lower crust, which is consistent with a suggestion from Nd isotope data for the Eastern Block. The zircons of 2.10 Ga population have initial εHf values of-4.9 to +6.1, interpreted as mixing of crustal re-melt with minor juvenile material contribution at 2.1 Ga. These results are distinct from that for the Western Block, supporting that the Fuping Complex was emplaced in a tectonic active environment at the western margin of the Eastern Block.
基金supported by the National Science Foundation of China(grants 41302042 and 41672217)the Fundamental Research Funds for the Central Universities(grants N170104022).
文摘Objective Though the Central Asian Orogenic Belt (CAOB) is characterized by widespread Phanerozoic crustal growth,there is little juvenile crust documented in its southeastern segment,northern margin of the North China Craton(NCC)(Zhang et al,2007,2009).Late Carboniferous Dongwanzi ultramafic-mafic cumulate complex occurs in northern margin of the NCC and is intruded by a syenite with depleted Sr-Nd isotopes (Ma et al.,2014).However,the age and petrogenesis of this syenite is poorly constrained.In this study,we present new petrological,zircon U-Pb and Hf isotopic data of the Dongwanzi syenite,in order to put insights on its formation age and petrogenetic relationship with cumulates.
基金financially funded by the National Key Research and Development Program of China (No. 2016YFC0601002)Opening Foundation of State Key Laboratory of Continental Dynamics, Northwest University (No. 17LCD05)+3 种基金National Science and Technology Major Project (No. 2016ZX05004001)National Natural Science Foundation of China (No. 41602042)Fundamental Research Funds for the Central Universities (No. 201912026)supported by Taishan Scholar Program to Prof. Sanzhong Li
文摘Paleo-to Mesoproterozoic sedimentary rocks in the southern margin of the North China Craton(NCC)are represented by the Ruyang and Luoyu groups.We studied the sedimentary rocks from the Yunmengshan and Beidajian formations of the Ruyang Group and the Cuizhuang and Sanjiaotang formations of the Luoyu Group.Detrital zircon grains from these formations have U–Pb age populations of 3.64–3.31 Ga,2.96–2.86 Ga,2.72–2.59 Ga,2.56–2.47 Ga,2.45–2.0 Ga,1.99–1.85 Ga and 1.84–1.65 Ga.The geochemical features of the sedimentary rocks suggest that some of the sediments were sourced from intermediate to felsic magmatic rocks.The age groups of the detrital zircon are roughly consistent with the tectono-thermal events in the southern margin of the NCC.The Hf isotopic compositions of detrital zircon from the sedimentary rocks in Ruyang and Luoyu groups suggest that significant crustal growth and reworking of the NCC took place during the Neoarchean and early-to mid-Paleoproterozoic,while crustal reworking at the Paleoarchean and late-Paleoproterozoic,and crustal growth at the Mesoarchean.We suggest the depositional times of the Ruyang Group and Luoyu Group are constrained to no older than 1.75–1.7 Ga and 1.7–1.65 Ga,respectively.Formation of late-Paleoproterozoic basins related to the strike slip and extrusion tectonics that cross-cut the NCC during the late Paleoproterozoic(<1.75 Ga),and the late Paleoproterozoic sedimentation once isochronous developed in the southern margin of the NCC through the Taihang region of the interior NCC and linked the Yanshan–Liaoxi regions of the northern NCC.
基金supported by the National Natural Science Foundation of China (Grant Nos. 41603053)the National Key R & D Program of China (No. 2018YFC0604206)
文摘Detailed studies on U-Pb ages and Hf isotope have been carried out in zircons from a carbonatite dyke associated with the Bayan Obo giant REE-Nb-Fe deposit,northern margin of the North China Craton(NCC),which provide insights into the plate tectonic in Paleoproterozoic.Analyses of small amounts of zircons extracted from a large sample of the Wu carbonatite dyke have yielded two ages of late Archaean and late Paleoproterozoic(with mean 207 Pb/206 Pb ages of 2521±25 Ma and 1921±14 Ma,respectively).Mineral inclusions in the zircon identified by Raman spectroscopy are all silicate minerals,and none of the zircon grains has the extremely high Th/U characteristic of carbonatite,which are consistent with crystallization of the zircon from silicate,and the zircon is suggested to be derived from trapped basement complex.Hf isotopes in the zircon from the studied carbonatite are different from grain to grain,suggesting the zircons were not all formed in one single process.Majority ofεHf(t)values are compatible with ancient crustal sources with limited juvenile component.The Hf data and their TDM2 values also suggest a juvenile continental growth in Paleoproterozoic during the period of 1940–1957 Ma.Our data demonstrate the major crustal growth during the Paleoproterozoic in the northern margin of the NCC,coeval with the assembly of the supercontinent Columbia,and provide insights into the plate tectonic of the NCC in Paleoproterozoic.
基金funded by the Basic Scientific Research Fund of the Institute of Geology, Chinese Academy of Geological Sciences (Grant No. J2103)National Key Research and Development Project of the Ministry of Science and Technology of China (Grant No. 2017YFC0601301)+1 种基金the National Natural Science Foundation of China (Grant No. 41972224)the China Geological Survey (Grant No. DD2019004)。
文摘The Alxa Block is the westernmost part of the North China Craton(NCC), and is regarded as one of the basement components of the NCC. Its geological evolution is of great significance for the understanding of the NCC.However, the Precambrian basement of the Alxa Block is still poorly studied. In this study, we present new in situ LA-ICPMS zircon U-Pb and Lu-Hf isotope data from the Diebusige Metamorphic Complex(DMC) which located in the eastern Alxa Block. Field and petrological studies show that the DMC consists mainly of metamorphic supracrustal rocks and minor metamorphic plutonic rocks and has experienced amphibolite-granulite facies metamorphism. Zircon U-Pb dating results suggested that the amphibolite sample yields a crystallization age of 2636 ± 14 Ma and metamorphic ages of 2517–2454 Ma and 1988–1952 Ma, proving the existence of exposed Archean rocks in the Langshan area and indicating that late Neoarchean to Paleoproterozoic metamorphic events existed in the Alxa Block. Two paragneiss samples show that the magmatic detrital zircons from the DMC yield 207Pb/206Pb ages ranging from 2.48 Ga to 2.10 Ga with two youngest peaks at 2.13 Ga and 2.16 Ga, respectively, and they were also overprinted by metamorphic events at 1.97–1.90 Ga and 1.89–1.79Ga. Compilation of U-Pb ages of magmatic detrital and metamorphic zircons suggested that the main part of the DMC may have been formed at 2.1–2.0 Ga. Zircon Lu-Hf isotope data show that the source materials of the main part of the DMC were originated from the reworking of ancient Archean crust(3.45–2.78 Ga). The Hf isotope characteristics and the tectonothermal event records exhibit different evolution history with the Khondalite Belt and the Yinshan Block and the other basements of the Alxa Block, indicating that the Langshan was likely an independent terrain before the middle Paleoproterozoic and was subjected to the middle to late Paleoproterozoic tectonothermal events with the Khondalite Belt as a whole.