| 甘肃北山红石山蛇绿岩锆石U-Pb年代学研究及构造意义 |
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| 引用本文： | 王国强,李向民,徐学义,余吉远,武鹏.甘肃北山红石山蛇绿岩锆石U-Pb年代学研究及构造意义[J].岩石学报,2014,30(6):1685-1694. |
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| 作者姓名： | 王国强 李向民 徐学义 余吉远 武鹏 |
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| 作者单位： | 国土资源部岩浆作用成矿与找矿重点实验室, 西安地质调查中心, 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 西安地质调查中心, 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 西安地质调查中心, 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 西安地质调查中心, 西安 710054;国土资源部岩浆作用成矿与找矿重点实验室, 西安地质调查中心, 西安 710054 |
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| 基金项目： | 本文受中国地质调查局工作项目（1212011085077、12120113046300）和科技外事部工作项目（1212011120133、12120113014000）联合资助. |
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| 摘 要： | 红石山蛇绿岩位于中蒙边境附近,出露于红石山-百合山-蓬勃山蛇绿混杂岩带最西段。岩石地球化学分析表明,红石山蛇绿岩中的玄武岩主量、微量及稀土元素皆显示类似MORB型玄武岩的地球化学特征,表现为低Na2O+K2O（2.99%）和P2O5（0.08%）,中等含量TiO2（1.46%）;LREE球粒陨石标准化分配型式具平坦型和轻稀土略微富集的特征。微量元素原始地幔标准化分配型式显示出富集大离子亲石元素（Rb、K）的特征,HFSE变化相对较为稳定。红石山蛇绿岩中的辉长岩的LA-ICP-MS锆石U-Pb同位素定年结果显示,其形成时代为346.6±2.8Ma,代表该蛇绿岩形成时代,即为早石炭世。结合前人研究成果,笔者认为红石山蛇绿岩可能为石炭纪大陆裂谷向大洋转化的构造环境下形成的初始小洋盆,其向西可与新疆境内的巴音沟蛇绿岩对比,二者同属“红海型”洋盆初始洋壳的地质记录。
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| 关 键 词： | 红石山蛇绿岩 辉长岩 锆石U-Pb年龄 红海型洋盆 北山 |
| 收稿时间： | 4/8/2013 12:00:00 AM |
| 修稿时间： | 2013/8/12 0:00:00 |
Ziron U-Pb chronological study of the Hongshishan ophiolite in the Beishan area and their tectonic significance |
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| WANG GuoQiang,LI XiangMin,XU XueYi,YU JiYuan and WU Peng.Ziron U-Pb chronological study of the Hongshishan ophiolite in the Beishan area and their tectonic significance[J].Acta Petrologica Sinica,2014,30(6):1685-1694. |
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| Authors: | WANG GuoQiang LI XiangMin XU XueYi YU JiYuan and WU Peng |
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| Institution: | MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, Xi'an 710054, China;MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, Xi'an 710054, China;MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, Xi'an 710054, China;MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, Xi'an 710054, China;MLR Key Laboratory for the Study of Focused Magmatism and Giant Ore Deposits, Xi'an Center of Geological Survey, Xi'an 710054, China |
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| Abstract: | The Hongshishan ophiolite is located adjacent to the border area between China and Mongolia, and in the west of Hongshishan-Baiheshan-Pengboshan ophiolite belt. Analyses of rock geochemistry shows that the basalt are characterized by low contents of Na2O+K2O(2.99%)and P2O5(0.08%), and a nearly flat chondrite-normalized REE pattern with only slightly enriched LREE. An primitive mantle-normalized spider diagram shows enrichment in LILE(e.g., Rb, K)and stabilization in HFSE. The authors for the first time do the research about the chronological study of zircons from the gabbros by the method of LA-ICP-MS U-Pb. The weighted mean ages of the zircons are 346.6±2.8Ma, suggesting an Early Carboniferous. Combining previous studies, we propose the explanation about the tectonic setting: the Hongshishan ophiolite formed in a transition tectonic setting from continental rift to ocean, which is a small ocean basin, the product of the rift extention. In addition, the Hongshishan ophiolite can be compared with the westard Bayingou ophiolite, which is all the geological record of the embryonic ocean crust in Early Carboniferous. |
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| Keywords: | Hongshishan ophiolite Gabbro Zircon U-Pb dating "Red-sea"-type ocean basin Beishan |
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