| Permian High Ba-Sr Granitoids: Geochemistry, Age and Tectonic Implications of Erlangshan Pluton, Urad Zhongqi, Inner Mongolia |
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| 作者姓名： | LUO Hongling WU Tairan ZHAO Lei HE Yuankai JIN Xu |
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| 作者单位： | The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China |
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| 基金项目： | This research was financially supported by the National Natural Science Foundation of China (No. 40672146). We thank Song Biao and Dong Chunyan for considerable help during the SHRIMP analyses. Discussions with He Guoqi and Han Baofu are greatly appreciated. |
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| 摘 要： | Abstract: Erlangshan Pluton from Urad Zhongqi, central Inner Mongolia, is located in the middle segment of the northern margin of the North China Plate. The rocks consist mainly of diorites with gneissic structure. Petrochemical characteristics reveal that the diorites belong to metaluminous, high-potassium calc-alkaline series, with chemical signatures of I-type granites. They are characterized by low SiO2 contents (56.63%–58.53%) and A/CNK (0.90–0.96), high Al2O3 contents (17.30%–17.96%) and Na2O/K2O ratios (1.20–1.70), enrichment in large ion lithophile elements (LILE, e.g., Ba=556–915 ppm, Sr=463–595 ppm), and relative depletion in high field strength elements (HFSE, e.g., Nb, Ta, Ti) in primitive mantle-normalized spidergram, and right-declined rare earth element patterns with slightly negative Eu anomalies (d?Eu=0.72–0.90). They have Sr/Y ratios (20–25) evidently less than Kebu Pluton (49–75) to its east. Sensitive high resolution ion micro-probe U-Pb zircon dating of the diorites has yielded an intrusive age of 270±8?Ma. This leads us to conclude that Erlangshan diorites were formed by mixing between the middle or lower crustal-derived magma and minor mantle-derived mafic magma, followed by fractional crystallization, which was trigged by crustal extension and fault activity in post-collisional setting.
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| 关 键 词： | high Ba-Sr granitoids sensitive high resolution ion micro-probe U-Pb fractional crystallization post-collision northern margin of the North China Plate |
| 收稿时间： | 2/4/2009 12:00:00 AM |
| 修稿时间： | 3/2/2009 12:00:00 AM |
Permian High Ba-Sr Granitoids: Geochemistry, Age and Tectonic Implications of Erlangshan Pluton, Urad Zhongqi, Inner Mongolia |
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| Authors: | LUO Hongling WU Tairan ZHAO Lei HE Yuankai and JIN Xu |
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| Institution: | The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China;The Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, Beijing 100871, China; School of Earth and Space Sciences, Peking University, Beijing 100871, China |
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| Abstract: | Erlangshan Pluton from Urad Zhongqi.central Inner Mongolia,is located in the middle segment of the northern margin of the North China Plate.The rocks consist mainly of diorites with gneissic structure.Petrochemicai characteristics reveal that the diorites belong to metaluminous,high-potassium calc-alkaline series,with chemical signatures of 1-type granites.They are characterized by low SiO2 contents(56.63%-58.53%)and A/CNK(0.90-0.96),high Al2O3 contents(17.30%-17.96%)and Na2O/K2O ratios(1.20-1.70),enrichment in large ion lithophile elements(LILE,e.g.,Ba=556-915ppm,Sr=463-595 ppm),and relative depletion in high field strength elements(HFSE,e.g.,Nb,Ta,Ti)in primitive mantle-normalized spidergram.and right-declined rare earth element patterns with slightly negative Eu anomalies(δEu=0.72-0.90).They have Sr/Y ratios(20-25)evidently less than Kebu Pluton (49-75)to its east.Sensitive high resolution ion micro-probe U-Pb zircon dating of thediOrites has yieldIed an intrnsive a2e of 270±8 Ma.This leads US to conclude that Erlangshan diorites were formed by mixing between the middle or lower crustal.derived magma and minor mantle-derived mafic magnm,followed by fractional crystallization,which was trigged by crustal extension and fault activity in post-coilisional setting. |
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| Keywords: | high Ba-Sr granitoids sensitive high resolution ion micro-probe U-Pb fractional crystallization post-collision northern margin of the North China Plate |
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