{"title":"华北克拉通北缘白云鄂博群新元古代辉长岩侵入的发现及其意义","authors":"Hao Hu, Yuan Li, Zhiguang Zhou, Guosheng Wang, Shen Gao, Jianfeng Chen, Chenfei Feng","doi":"10.1002/gj.5132","DOIUrl":null,"url":null,"abstract":"<div>\n \n <p>The tectonic position of the North China Craton within the Rodinia supercontinent remain unclear due to the scarcity of early Neoproterozoic magmatic rocks in the region, resulting in limited paleomagnetic data. In this study, we report the discovery of a Neoproterozoic metamorphic gabbro intrusion within the Bayan Obo Group, located in the northwestern Bayan Obo rift zone at the northern margin of the North China Craton. This finding offers crucial geological insights into addressing this key scientific question. We utilised petrography, whole-rock geochemistry, zircon U–Pb geochronology, and Sr-Nd isotopic analysis to investigate the genesis and source of the gabbroic rock and its tectonic setting. The metamorphosed gabbro has a zircon <sup>206</sup>Pb/<sup>238</sup>U weighted mean age of 925.9 ± 7.2 Ma, with low SiO<sub>2</sub> (46.46%–48.28%), high Na<sub>2</sub>O (2.95%–3.56%), and low K<sub>2</sub>O (0.761%–1.41%), and has the signature of sub-alkaline tholeiitic basalt. It is enriched in large-ion lithophile elements (Rb, Ba, Th, U, K, Pb) and depleted in high-field-strength elements (Nb, Ta). The rock is also enriched in light rare earth elements, shows a negative Eu anomaly, and has a positive <i>ε</i>Nd(<i>t</i>) value (+0.1 ~ +0.8). The metamorphosed gabbro shares geochemical characteristics and Nd isotopic compositions with contemporaneous mafic intrusions, including the 945–890 Ma mafic sills in southeastern North China Craton, the ~925 Ma Dashigou mafic dike swarm in central North China Craton, the ~925 Ma gabbro in Guyang, northern North China Craton, and the 827–819 Ma gabbro in Langshan, western North China Craton. This age suggests that the gabbro may represent a response to a large-scale mafic magmatic event in central-eastern North China Craton during the early Neoproterozoic, potentially linked to the initial breakup of the Rodinia supercontinent.</p>\n </div>","PeriodicalId":12784,"journal":{"name":"Geological Journal","volume":"60 6","pages":"1409-1430"},"PeriodicalIF":1.4000,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Discovery and Significance of the Neoproterozoic Gabbro Intrusion in the Bayan Obo Group Along the Northern Margin of the North China Craton\",\"authors\":\"Hao Hu, Yuan Li, Zhiguang Zhou, Guosheng Wang, Shen Gao, Jianfeng Chen, Chenfei Feng\",\"doi\":\"10.1002/gj.5132\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div>\\n \\n <p>The tectonic position of the North China Craton within the Rodinia supercontinent remain unclear due to the scarcity of early Neoproterozoic magmatic rocks in the region, resulting in limited paleomagnetic data. In this study, we report the discovery of a Neoproterozoic metamorphic gabbro intrusion within the Bayan Obo Group, located in the northwestern Bayan Obo rift zone at the northern margin of the North China Craton. This finding offers crucial geological insights into addressing this key scientific question. We utilised petrography, whole-rock geochemistry, zircon U–Pb geochronology, and Sr-Nd isotopic analysis to investigate the genesis and source of the gabbroic rock and its tectonic setting. The metamorphosed gabbro has a zircon <sup>206</sup>Pb/<sup>238</sup>U weighted mean age of 925.9 ± 7.2 Ma, with low SiO<sub>2</sub> (46.46%–48.28%), high Na<sub>2</sub>O (2.95%–3.56%), and low K<sub>2</sub>O (0.761%–1.41%), and has the signature of sub-alkaline tholeiitic basalt. It is enriched in large-ion lithophile elements (Rb, Ba, Th, U, K, Pb) and depleted in high-field-strength elements (Nb, Ta). The rock is also enriched in light rare earth elements, shows a negative Eu anomaly, and has a positive <i>ε</i>Nd(<i>t</i>) value (+0.1 ~ +0.8). The metamorphosed gabbro shares geochemical characteristics and Nd isotopic compositions with contemporaneous mafic intrusions, including the 945–890 Ma mafic sills in southeastern North China Craton, the ~925 Ma Dashigou mafic dike swarm in central North China Craton, the ~925 Ma gabbro in Guyang, northern North China Craton, and the 827–819 Ma gabbro in Langshan, western North China Craton. This age suggests that the gabbro may represent a response to a large-scale mafic magmatic event in central-eastern North China Craton during the early Neoproterozoic, potentially linked to the initial breakup of the Rodinia supercontinent.</p>\\n </div>\",\"PeriodicalId\":12784,\"journal\":{\"name\":\"Geological Journal\",\"volume\":\"60 6\",\"pages\":\"1409-1430\"},\"PeriodicalIF\":1.4000,\"publicationDate\":\"2025-01-16\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Geological Journal\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1002/gj.5132\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geological Journal","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1002/gj.5132","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
Discovery and Significance of the Neoproterozoic Gabbro Intrusion in the Bayan Obo Group Along the Northern Margin of the North China Craton
The tectonic position of the North China Craton within the Rodinia supercontinent remain unclear due to the scarcity of early Neoproterozoic magmatic rocks in the region, resulting in limited paleomagnetic data. In this study, we report the discovery of a Neoproterozoic metamorphic gabbro intrusion within the Bayan Obo Group, located in the northwestern Bayan Obo rift zone at the northern margin of the North China Craton. This finding offers crucial geological insights into addressing this key scientific question. We utilised petrography, whole-rock geochemistry, zircon U–Pb geochronology, and Sr-Nd isotopic analysis to investigate the genesis and source of the gabbroic rock and its tectonic setting. The metamorphosed gabbro has a zircon 206Pb/238U weighted mean age of 925.9 ± 7.2 Ma, with low SiO2 (46.46%–48.28%), high Na2O (2.95%–3.56%), and low K2O (0.761%–1.41%), and has the signature of sub-alkaline tholeiitic basalt. It is enriched in large-ion lithophile elements (Rb, Ba, Th, U, K, Pb) and depleted in high-field-strength elements (Nb, Ta). The rock is also enriched in light rare earth elements, shows a negative Eu anomaly, and has a positive εNd(t) value (+0.1 ~ +0.8). The metamorphosed gabbro shares geochemical characteristics and Nd isotopic compositions with contemporaneous mafic intrusions, including the 945–890 Ma mafic sills in southeastern North China Craton, the ~925 Ma Dashigou mafic dike swarm in central North China Craton, the ~925 Ma gabbro in Guyang, northern North China Craton, and the 827–819 Ma gabbro in Langshan, western North China Craton. This age suggests that the gabbro may represent a response to a large-scale mafic magmatic event in central-eastern North China Craton during the early Neoproterozoic, potentially linked to the initial breakup of the Rodinia supercontinent.
期刊介绍:
In recent years there has been a growth of specialist journals within geological sciences. Nevertheless, there is an important role for a journal of an interdisciplinary kind. Traditionally, GEOLOGICAL JOURNAL has been such a journal and continues in its aim of promoting interest in all branches of the Geological Sciences, through publication of original research papers and review articles. The journal publishes Special Issues with a common theme or regional coverage e.g. Chinese Dinosaurs; Tectonics of the Eastern Mediterranean, Triassic basins of the Central and North Atlantic Borderlands). These are extensively cited.
The Journal has a particular interest in publishing papers on regional case studies from any global locality which have conclusions of general interest. Such papers may emphasize aspects across the full spectrum of geological sciences.