| 鄂尔多斯盆地上三叠统延长组凝灰岩夹层Th元素的富集特征 |
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| 引用本文： | 邱欣卫,刘池洋,毛光周,邓 煜,王飞飞.鄂尔多斯盆地上三叠统延长组凝灰岩夹层Th元素的富集特征[J].地质通报,2010,29(8):1185-1191. |
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| 作者姓名： | 邱欣卫 刘池洋 毛光周 邓 煜 王飞飞 |
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| 作者单位： | 1. 大陆动力学国家重点实验室/西北大学含油气盆地研究所,陕西,西安,710069
2. 山东科技大学地质科学与工程学院,山东,青岛,266510 |
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| 基金项目： | 国家自然科学基金(重大研究计划)重点项目，陕西省"13115"科技创新工程重大科技专项项目，国家重点基础研究发展计划("973")项目，和西北大学研究生自主创新资助项目 |
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| 摘 要： | 鄂尔多斯盆地上三叠统延长组凝灰岩夹层分布广泛,能谱测井资料解释凝灰岩夹层Th元素含量为25×10~(-6)～35×10~(-6),元素地球化学测试结果Th含量在15×10~(-6)～80×10~(-6)之间,平均36.6×10~(-6),明显高于与其互层的泥岩或炭质泥岩的平均值,也高于地球各圈层的平均值,属于Th富集状态。延长组凝灰岩夹层中Th的富集可能主要有2个方面的原因,其一是原始岩浆中Th含量较高,因其性质相对不活泼,未发生明显的迁移;其二是凝灰岩经历了较强烈的水解蚀变作用,蚀变产物以粘土矿物为主,从而可能吸附了上下地层中的Th,最终导致了凝灰岩夹层中Th的富集。Th的富集可以作为研究区识别凝灰岩夹层的标志,有利于进行更精细的地层对比。同时,Th/U比值反映出的延长期凝灰岩沉积作用所引起的元素迁移和古环境变化,可能对延长组优质烃源岩的发育有重要作用。
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| 关 键 词： | 鄂尔多斯盆地 上三叠统延长组 沉积环境 凝灰岩夹层 烃源岩 Th元素 |
Enrichment feature of thorium element in tuff interlayers of Upper Triassic Yanchang Formation in Ordos basin, China |
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| QIU Xin-wei,LIU Chi-yang,MAO Guang-zhou,DEND Yu,WANG Fei-fei.Enrichment feature of thorium element in tuff interlayers of Upper Triassic Yanchang Formation in Ordos basin, China[J].Geologcal Bulletin OF China,2010,29(8):1185-1191. |
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| Authors: | QIU Xin-wei LIU Chi-yang MAO Guang-zhou DEND Yu WANG Fei-fei |
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| Abstract: | Tuff interlayers distribute widely in Yanchang Formation of Ordos basin. The data of natural gamma spectrometry logging shows that the thorium content is 25×10-6~35×10-6 in tuff layer. The results of element geochemical test indicate that the content of thorium is from 15×10-6 to 80×10-6, and average is 36.6×10-6, which is obviously higher than the average of any other lithospheres and the upper and lower layers of tuff interlayers. There are two factors may cause the enrichment of thorium element in tuff interlayer of Yanchang Formation. Firstly, the thorium content of original magma is very high, and the geochemistry attribution of thorium is inactive, so the migration of thorium is relatively not obvious; the other factor is tuff had experienced intensive alteration at the process of diagenesis, and the primary products are clay minerals, which might have adsorbed thorium element from upper and lower layers. The enriching characteristic of thorium element can be a sign of recognizing the tuff interlayer in the study area, which is favorable for more delicate strata correlation. At the same time, the ratio of Th/U reflects the elements emigration and palaeo-environmental changing caused by volcanic tuff sedimentary process, and it might play an important role during the developing of excellent petroleum source rock of Yanchang Formation. |
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| Keywords: | Ordos basin Upper Triassic Yanchang Formation sedimentary environment tuff interlayer petroleum source rock thorium element |
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