| 湖北武当山南缘房县地区早古生代镁铁质岩石成因及大地构造意义 |
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| 关键词:mafic rocks petrogenesis Early Paleozoic Wudang Mountain South Qinling |
| 基金项目:中国地质科学院基本科研业务费项目(编号: YK1701; K1615);国家青年自然基金项目(编号: 41402180; 41602061) |
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| 摘要点击次数: 1986 |
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| Petrogenesis of the Early Paleozoic Mafic Rock in Fangxian Area on the Southern Margin of Wudang Mountain, Hubei Province,and Its Tectonic Significance |
| The Qingfeng–Xiangguang fault on the southern margin of Wudang Mountain is a dominant boundary for the South Qinling and Yangtze plates and is also an important link between the Mianlue zone and its eastward extension. Detailed field route investigation and systematic research reveal that the formerly assigned Neoproterozoic Yaolinghe Group volcanic rocks outcropped in Mengu area should be meta-basalt block of Late Ordovician ((444.9 ± 2.5) Ma), and it consists of a distinct mélange feature with the formerly assigned Sinian to Cambrian limestone and siliceous blocks and sandy schist matrix; zircon U-Pb dating of diabase which intruded into Meiziya Formation of Wutai area indicates an Early Silurian magmatic age ((432.4±3.3) Ma). Whole rock geochemistry of these samples indicates that both Mengu meta-basalts and Wutai diabase are typically characterized by high concentrations of TiO2, Nb, Ta, and Zr. The ratio of incompatible elements, rare earth element distribution patterns and trace element spider diagrams all display the feature of affinity of Ocean-island basalt (OIB). In addition, samples from the two areas appear to have all originated from the asthenospheric mantle and the magma was mainly formed by the high-pressure and low degree of partial melting of garnet lherzolite and underwent varying degrees of fractional crystallization and slight crustal contamination. Regional geological and discrimination diagrams both indicate that these samples do not represent a plume or continental rift, but exhibit a setting of oceanic intraplate. These results provide the pivotal evidence for accurate investigation of the Phanerozoic tectonic evolution of South Qinling Orogeny. |
| XU Guang,WANG Gang,WANG Zong-qi,WU Yu-dong,WANG Dong-sheng,WANG Jia-wei.2018.Petrogenesis of the Early Paleozoic Mafic Rock in Fangxian Area on the Southern Margin of Wudang Mountain, Hubei Province,and Its Tectonic Significance[J].Acta Geoscientica Sinica,39(3):306-318. |
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