| 鄂尔多斯盆地北部杭锦旗地区下石盒子组多物源体系: 来自矿物学及碎屑锆石U-Pb年代学的证据 |
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| 引用本文： | 刘凯,王任,石万忠,张威,覃硕,齐荣,徐立涛.鄂尔多斯盆地北部杭锦旗地区下石盒子组多物源体系: 来自矿物学及碎屑锆石U-Pb年代学的证据[J].地球科学,2021,46(2):540-554. |
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| 作者姓名： | 刘凯 王任 石万忠 张威 覃硕 齐荣 徐立涛 |
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| 作者单位： | 1.中国地质大学资源学院, 湖北武汉 430074 |
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| 摘 要： | 鄂尔多斯盆地北部上古生界砂岩碎屑组分、岩屑类型和重矿物组合具有明显的东西分带性，但是其物源来源及差异性尚不明确.利用锆石LA-ICP-MS U-Pb定年方法，对鄂尔多斯盆地北部杭锦旗地区下石盒子组碎屑锆石年龄分布及变化特征进行了研究，明确了不同年龄组分碎屑锆石的来源，并分析了不同物源体系及差异性.结果表明:不同地区下石盒子组碎屑矿物含量存在明显差异，由西向东岩屑含量逐渐增加，石英含量逐渐减小；下石盒子组锆石年龄主要呈现280~340 Ma、400~450 Ma、1 700~2 000 Ma和2 200~2 500 Ma 4个峰值区间段，从东部地区到西部地区，锆石显生宙年龄组分所占比例逐渐增加，且中部、西部地区新出现400~450 Ma的年龄段；对比周源岩体同位素年龄，西部地区物源主要来自于阿拉善地块，东部和中部地区物源主要来自于大青山-乌拉山、阴山和集宁地区，同时中部地区还受到阿拉善地块物源输入的影响；结合下石盒子组砂岩锆石定年结果和碎屑矿物含量、岩屑类型分布特征，认为杭锦旗地区发育多物源体系，并据此将研究区分为西部物源区、中部混合物源区及东北部物源区.
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| 关 键 词： | 鄂尔多斯盆地北部 下石盒子组 碎屑矿物含量 锆石U-Pb定年 物源分析 地质年代学 |
| 收稿时间： | 2020-02-13 |
Multiple Provenance System of Lower Shihezi Formation in Hangjinqi Area,Northern Ordos Basin: Evidence from Mineralogy and Detrital Zircon U-Pb Chronology |
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| Liu Kai,Wang Ren,Shi Wanzhong,Zhang Wei,Qin Shuo,Qi Rong,Xu Litao.Multiple Provenance System of Lower Shihezi Formation in Hangjinqi Area,Northern Ordos Basin: Evidence from Mineralogy and Detrital Zircon U-Pb Chronology[J].Earth Science-Journal of China University of Geosciences,2021,46(2):540-554. |
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| Authors: | Liu Kai Wang Ren Shi Wanzhong Zhang Wei Qin Shuo Qi Rong Xu Litao |
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| Affiliation: | (Faculty of Earth Resources,China University of Geosciences,Wuhan 430074,China;Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education,China University of Geosciences,Wuhan 430074,China;Exploration and Development Research Institute,SINOPEC North China Company,Zhengzhou 450006,China) |
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| Abstract: | The detrital mineral contents,debris types and heavy mineral assemblages of Upper Paleozoic sandstone are obviously different from the east to west in the northern Ordos Basin.However,the provenance of sandstone still remains unclear.The distribution and variation characteristics of detrital zircon ages were studied using LA-ICP-MS dating of the detrital zircons from sandstones of Lower Shihezi Formation in the Hangjinqi area,Ordos Basin.The source of detrital zircons of different age components is identified,and difference of provenance system is analyzed.The main conclusions can be drawn as follows.Detrital mineral content of Lower Shihezi Formation is different in different regions,with quartz content decreasing and lithic fragment content increasing from west to east.Detrital zircons of Lower Shihezi Formation yield four peak ages of 280-340 Ma,400-450 Ma,1700-2000 Ma,and 2200-2500 Ma,and the proportion of Phanerozoic age of zircons gradually increases from east to west,with zircons having age range from 400 Ma to 450 Ma only appearing in the western and middle regions.By comparing the isotopic ages for the plutons in and around research areas,the sandstone of Lower Shihezi Formation in the western region mainly sourced from Alxa Block while in the middle and eastern regions mainly sourced from Daqingshan-Wulashan,Yinshan and Jining areas,and the provenance of middle region was also affected by Alax Block.Based on the difference of zircon ages,detrital mineral content and rock fragment component of Lower Shihezi Formation,it is believed that multiple provenance systems exist,which can be divided into western provenance,middle mixture provenance and northeast provenance in the Hangjinqi area. |
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| Keywords: | northern Ordos Basin Lower Shihezi Formation detrital mineral content zircon U-Pb dating provenance analysis geochronology |
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