| Mesozoic Bimodal Volcanic Suite in Zhalantun of the Da Hinggan Range and Its Geological Significance： Zircon U-Pb Age and Hf Isotopic Constraints |
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| 作者姓名： | ZHANG Jiheng GE Wenchun WU Fuyuan and LIU Xiaoming College of Earth Sciences Jilin University Changchun Jilin Institute of Geology and Geophysics Chinese Academy of Sciences Beijing Key Laboratory of Continental Dynamics |
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| 摘 要： | 1 Introduction Mesozoic volcano-intrusive rocks are widely distributed in the Da Hinggan Range of northeastern China, and are considered as one of the most spectacular geological sights in eastern Asia. Recently, studies on granites with high εNd(t) values and Phanerozoic crustal growth in the Centra Asian Orogenic Belt have greatly promoted fundamental research into the geology of this area (Jahn et al., 2000, 2001, 2004; Wu et al., 2000, 2002, 2003). However, work on the eruption time,…
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| 关 键 词： | 中生代 火山岩 锆石 同位素 |
| 收稿时间： | 2005-06-13 |
| 修稿时间： | 2005-09-21 |
Mesozoic Bimodal Volcanic Suite in Zhalantun of the Da Hinggan Range and Its Geological Significance: Zircon U-Pb Age and Hf Isotopic Constraints |
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| Authors: | ZHANG Jiheng GE Wenchun WU Fuyuan and LIU Xiaoming College of Earth Sciences Jilin University Changchun Jilin Institute of Geology and Geophysics Chinese Academy of Sciences Beijing Key Laboratory of Continental Dynamics |
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| Institution: | Northwest University |
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| Abstract: | Abstract Mesozoic bimodal volcanic rocks of basaltic andesite and rhyolite are widely distributed in the Da Hinggan Range, but their petrogenetic relationships and geodynamic implications are rarely constrained. Detailed studies on doleritic and porphyry dikes in the Zhalantun area indicate that they display features of magma mixing, suggesting their coeval formation. In situ zircon U‐Pb dating shows that the porphyry was emplaced in the Early Cretaceous with a 206Pb/238U age of 130±1 Ma. Zircons from the dolerite also yield an Early Cretaceous emplacement age of 12412 Ma although some inherited zircons have been identified. These age results indicate that the Early Cretaceous was an important period of magmatism in the Da Hinggan Range. Zircons from porphyry are characterized by positive value of εHf(t) as high as 10.3±0.5 with Hf depleted mantle model age of 349–568 Ma, whereas magmatic zircons from the dolerite have εHf(t) value of 11.0±1.4 with Hf depleted mantel model age of 342–657 Ma, consistent with those from the porphyry. Considering other data on the geological evolution of this area, it is concluded that the mafic magma originated from the partial melting of Paleozoic enriched lithospheric mantle, whereas the felsic magma came from recycling of juvenile crust formed during the Paleozoic. Both of the protoliths are closely related to the subduction of the Paleo‐Asian Ocean during the Paleozoic, indicating that the Paleozoic is an important period of large‐scale crustal growth in the area |
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| Keywords: | volcanic rocks zircon U-Pb dating Hf isotope crustal growth Da Hinggan Range NE China |
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