| 东阿拉善地块诺尔公群石英岩的碎屑锆石年龄特征——物源区制约及其地质意义 |
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| 引用本文： | 宫江华,张建新,王宗起,王东升,杜显峰.东阿拉善地块诺尔公群石英岩的碎屑锆石年龄特征——物源区制约及其地质意义[J].岩石矿物学杂志,2017,36(1):1-19. |
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| 作者姓名： | 宫江华 张建新 王宗起 王东升 杜显峰 |
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| 作者单位： | 中国地质科学院 矿产资源研究所 国土资源部成矿作用与资源评价重点实验室, 北京 100037;中国地质科学院 地质研究所, 北京 100037;中国地质科学院 矿产资源研究所 国土资源部成矿作用与资源评价重点实验室, 北京 100037;中国地质科学院 矿产资源研究所 国土资源部成矿作用与资源评价重点实验室, 北京 100037;中国地质科学院 矿产资源研究所 国土资源部成矿作用与资源评价重点实验室, 北京 100037 |
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| 基金项目： | 基本科研业务费专项基金（K1403） |
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| 摘 要： | 传统上将阿拉善地块东部变质基底"阿拉善岩群"之上的一套以石英岩、浅粒岩、碳酸盐岩及碎屑岩为主的浅变质地层称为诺尔公群,并根据区域地层对比及叠层石化石将其归为"长城纪"。为进一步限定地层时代,对诺尔公群底部3件石英岩进行LA-MC-ICP-MS锆石U-Pb测年,获得的年龄主要集中在2 530~2 500 Ma和1 950~1 850 Ma两个年龄段内,另外还获得少量年龄为~1.69 Ga、~2.0 Ga、~2.15 Ga、~2.35 Ga、~2.7 Ga和~3.4 Ga的锆石。其中,最年轻的碎屑锆石年龄限定了诺尔公群底部石英岩的沉积时代晚于1.69 Ga,结合上覆地层的年龄数据将诺尔公群的沉积时代大致限定为1.69~1.29 Ga,肯定了阿拉善地块存在中元古代地层。石英岩中~2.5 Ga和~1.95 Ga两个显著的碎屑锆石年龄峰符合典型的华北克拉通物源区特征,因此认为,阿拉善地块在太古代-中元古代具有与华北克拉通相似的构造环境,是华北克拉通的一部分。
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| 关 键 词： | 阿拉善地块 中元古代 诺尔公群 石英岩 碎屑锆石 LA-MC-ICP-MS |
| 收稿时间： | 2016/10/8 0:00:00 |
| 修稿时间： | 2016/12/12 0:00:00 |
Detrital zircon age characteristics of quartzites from Nuoergong Group in eastern Alxa Block: Provenance and geological significance |
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| GONG Jiang-hu,ZHANG Jian-xin,WANG Zong-qi,WANG Dong-sheng and DU Xian-feng.Detrital zircon age characteristics of quartzites from Nuoergong Group in eastern Alxa Block: Provenance and geological significance[J].Acta Petrologica Et Mineralogica,2017,36(1):1-19. |
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| Authors: | GONG Jiang-hu ZHANG Jian-xin WANG Zong-qi WANG Dong-sheng and DU Xian-feng |
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| Institution: | MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China;MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China;MLR Key Laboratory of Metallogeny and Mineral Assessment, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China |
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| Abstract: | The Nuoergong Group, a suite of low-grade metamorphic strata composed mainly of quartzite, leucoleptite, carbonate and clastic rocks, was traditionally considered overlying directly the metamorphic basement named "Alxa Group" in eastern Alxa Block. Its formation age was identified as Changchengian based on regional stratigraphic correlation and stromatolites fossils. In order to precisely constrain the stratigraphic time, the authors present LA-MC-ICP-MS zircon U-Pb dating results for samples of three quartzite bodies from the lower Nuoergong Group. These zircon ages are mainly concentrated in the 2 530~2 500 Ma and 1 950~1 850 Ma, while a few zircons have ~1.69 Ga, ~2.0 Ga, ~2.15 Ga, ~2.35 Ga, ~2.7 Ga and ~3.4 Ga ages. The youngest zircon grain of 1.69 Ga indicates that the lower Nuoergong Group was accumulated after ~1.69 Ga. In combination with previously obtained ages of overlying strata, the authors have reached the conclusion that the deposition age of Nuoergong Group is between 1.69 Ga and 1.29 Ga and there exist the Meso-proterozoic strata in Alxa Block. The most prominent ~2.5 Ga and ~1.95 Ga age peaks suggest its affinity with the North China Craton. Therefore, it is held that they have similar tectonic environments and the Alxa Block was a part of North China Craton from Archean to Mesoproterozoic. |
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| Keywords: | Alxa Block Mesoproterozoic Nuoergong Group quartzite detrital zircon LA-MC-ICP-MS |
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