| Geochemistry of the Caledonian Basic Volcanic Rocks at the South Margin of the Qinling Orogenc Belt,and Its Tectonic Implications |
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| 摘 要： | The geochemistry of the basic volcanic rocks at the south margin of the Qinling orogenic belt(SMQOB) suggests that they were formed in an intraplate tectonic setting.The REE distribution patterns show these rocks are strongly enriched in LREE with high ∑REE, and their trace elements geochemistry is similar to that of contimental flood basalt.All the above evidence suggests that the Caledonian basic volcanic rocks in the SMQOB were tholeiitic basalts formed in an intraplate spreading-initial rift tectonic setting.The characteristics of regional geology and geochemistry indicate that there was an intraplate spreading-rift tectonic setting between the South Qingling block and the Yangtze block in the Caledonian epoch.The dynamic spreading in this district began in the Early Caledonian and then the intraplate spreadinginitial rifts were formed in the Late Caledonian.As a result of spreading of the Tethys and geodynamic processes in deep mantle ,the Mianlue-Huashan oceanic basin was formed between the Qinling block and the Yangtze block in Devonian,and the Qinling microplate was separated from the northern part of the Yangtze plate.
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| 关 键 词： | 地球化学 火山岩 秦岭造山带 稀土元素 地质构造 |
Geochemistry of the Caledonian basic volcanic rocks at the south margin of the Qinling orogenic belt, and its tectonic implications |
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| Authors: | Dong Yunpeng Zhou Dingwu Zhang Guowei Zhu Bingquan |
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| Institution: | (1) Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 510640 Guangzhou, China;(2) Department of Geology, Northwest University, 710069 Xi’ an, China |
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| Abstract: | The geochemistry of the basic volcanic rocks at the south margin of the Qinling orogenic belt (SMQOB) suggests that they were
formed in an intraplate tectonic setting. The REE distribution patterns show these rocks are strongly enriched in LREE with
high ∑REE, and their trace elements geochemistry is similar to that of continental flood basalt. All the above evidence suggests
that the Caledonian basic volcanic rocks in the SMQOB were tholeiitic basalts formed in an intraplate spreading-initial rift
tectonic setting. The characteristics of regional geology and geochemistry indicate that there was an intraplate spreading-rift
tectonic setting between the South Qinling block and the Yangtze block in the Caledonian epoch. The dynamic spreading in this
district began in the Early Caledonian and then the intraplate spreadinginitial rifts were formed in the Late Caledonian.
As a result of spreading of the Tethys and geodynamic processes in deep mantle, the Mianlue-Huashan oceanic basin was formed
between the Qinling block and the Yangtze block in Devonian, and the Qinling microplate was separated from the northern part
of the Yangtze plate.
This research project was financially supported by the National Natural Science Foundation of China (Nos. 49773187, 49572145). |
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| Keywords: | Qinling orogenic belt geochemistry Tethys limited oceanic basin basic volcanic rock |
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