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

IF 1.4 4区 地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY
Geological Journal Pub Date : 2025-01-16 DOI:10.1002/gj.5132
Hao Hu, Yuan Li, Zhiguang Zhou, Guosheng Wang, Shen Gao, Jianfeng Chen, Chenfei Feng
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引用次数: 0

摘要

华北克拉通在罗迪尼亚超大陆内的构造位置由于区内新元古代早期岩浆岩的缺乏,导致古地磁资料有限。在华北克拉通北缘白云鄂博裂谷带西北部,在白云鄂博群内发现了一个新元古代变质辉长岩侵入体。这一发现为解决这一关键科学问题提供了重要的地质见解。利用岩石学、全岩地球化学、锆石U-Pb年代学、Sr-Nd同位素分析等方法对辉长岩成因、物源及其构造背景进行了研究。变质辉长岩锆石206Pb/238U加权平均年龄925.9±7.2 Ma,低SiO2(46.46% ~ 48.28%)、高Na2O(2.95% ~ 3.56%)、低K2O(0.661% ~ 1.41%),具有亚碱性拉斑玄武岩特征。富大离子亲石元素Rb、Ba、Th、U、K、Pb,贫高场强元素Nb、Ta。岩石还富集轻稀土元素,呈现负Eu异常,εNd(t)值为正(+0.1 ~ +0.8)。变质辉长岩具有同时期基性侵入岩的地球化学特征和Nd同位素组成,包括华北克拉通东南部945 ~ 890 Ma基性岩、华北克拉通中部~925 Ma大石沟基性岩群、华北克拉通北部固阳~925 Ma辉长岩和华北克拉通西部朗山~ 827 ~ 819 Ma辉长岩。这一年龄表明,辉长岩可能代表了新元古代早期华北克拉通中东部大规模基性岩浆事件的反应,可能与罗迪尼亚超大陆的初始分裂有关。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Discovery and Significance of the Neoproterozoic Gabbro Intrusion in the Bayan Obo Group Along the Northern Margin of the North China Craton

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.

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来源期刊
Geological Journal
Geological Journal 地学-地球科学综合
CiteScore
4.20
自引率
11.10%
发文量
269
审稿时长
3 months
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.
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