| 鄂尔多斯盆地西南部上三叠统延长组碎屑锆石U-Pb定年及其物源意义 |
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| 引用本文： | 孙迪,冯乔,刘震,卢朝进,夏鲁.鄂尔多斯盆地西南部上三叠统延长组碎屑锆石U-Pb定年及其物源意义[J].地质学报,2017,91(11):2521-2544. |
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| 作者姓名： | 孙迪 冯乔 刘震 卢朝进 夏鲁 |
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| 作者单位： | 1) 中国石油大学油气资源与探测国家重点实验室，北京，102249； 2) 中国石油大学地球科学学院，北京，102249,3) 山东科技大学地球科学与工程学院，山东青岛，266590,1) 中国石油大学油气资源与探测国家重点实验室，北京，102249； 2) 中国石油大学地球科学学院，北京，102249,1) 中国石油大学油气资源与探测国家重点实验室，北京，102249； 2) 中国石油大学地球科学学院，北京，102249,1) 中国石油大学油气资源与探测国家重点实验室，北京，102249； 2) 中国石油大学地球科学学院，北京，102249 |
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| 基金项目： | 海外青年学者合作研究基金 |
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| 摘 要： | 由于构造位置的特殊性和勘探开发工作的局限性,鄂尔多斯盆地西南部上三叠统延长组6段的物源分析一直存在较大的分歧。本文选取鄂尔多斯盆地西南部里78井、庄33井、演40井以及汭水河地区上三叠统长6段砂岩为研究对象,运用LA-ICP-MS U-Pb方法对样品中的碎屑锆石进行了年代学研究。结果表明,4个样品都存在250~350 Ma、400~660 Ma、920~1200 Ma、1750~1950 Ma和2200~2600 Ma 5个基本相近的年龄区间,与之对应的峰值年龄主要集中在284~330 Ma、430~460 Ma、950~1000 Ma、1850~1915 Ma以及2250~2450Ma。通过与邻区碎屑锆石年龄分布特征对比并结合重矿物资料,对研究区长6段物源的方向、母岩时代及岩性进行了系统全面的分析,认为研究区物源具有多方向、多时期、多岩石类型的特点,主要来自于盆地西南缘、南缘分布的北秦岭西段、北祁连东段及西秦岭的加里东期岩浆岩、晋宁期岩体和位于盆地东北部的古元古代孔兹岩系,盆地西北缘阿拉善地块的华力西期岩浆岩、鄂尔多斯地块东南部的变质基底也提供了部分物源。这一研究结果将有助于进行原盆沉积环境的恢复和指导下一步油气勘探的部署。
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| 关 键 词： | 碎屑锆石U Pb定年 重矿物 物源分析 长6段 鄂尔多斯盆地西南部 |
| 收稿时间： | 2016/8/5 0:00:00 |
| 修稿时间： | 2016/12/27 0:00:00 |
Detrital Zircon U-Pb Dating of the Upper Triassic Yanchang Formation in Southwestern Ordos Basin and Its Provenance Significance |
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| SUN Di,FENG Qiao,LIU Zheng,LU Chaojin and XIA Lu.Detrital Zircon U-Pb Dating of the Upper Triassic Yanchang Formation in Southwestern Ordos Basin and Its Provenance Significance[J].Acta Geologica Sinica,2017,91(11):2521-2544. |
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| Authors: | SUN Di FENG Qiao LIU Zheng LU Chaojin and XIA Lu |
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| Institution: | 1) State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, 102249;2) College of Geosciences, China University of Petroleum, Beijing, 102249,3) College of Geological Science and Engineering, Shandong University of Science and Technology, Qingdao, Shandong, 266590,1) State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, 102249;2) College of Geosciences, China University of Petroleum, Beijing, 102249,1) State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, 102249;2) College of Geosciences, China University of Petroleum, Beijing, 102249 and 1) State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing, 102249;2) College of Geosciences, China University of Petroleum, Beijing, 102249 |
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| Abstract: | Due to the special tectonic location and the limit of exploration work, it has been controversial about the provenance of the Chang 6 of Upper Triassic Yanchang Formation in the southwestern Ordos Basin. Four samples of clastic rocks were collected from wells Li78, Zhuang33, Yan40 and the strata of Chang 6 in the Ruishuihe area in southwestern Ordos Basin to conduct the LA ICP MS zircon U Pb isotope geochronologic dating. The results show that all samples have five similar age groups: 250~350 Ma, 400~660 Ma, 920~1200 Ma, 1750~1950 Ma and 2200~2600 Ma. Corresponding to it, the peak age of every group concentrates on 284~330Ma, 430~460 Ma, 950~1000 Ma, 1850~1915 Ma and 2250~2450 Ma respectively. This study carried out a comprehensive analysis of provenance position, parent rock time, and lithology of Chang 6 section through comparison with age distribution of detrital zircons from adjacent areas and heavy minerals data. The results indicate that the provenance of the study area has characteristics of multi orientation, multi period and multi type. The main sources of Chang 6 Formation are the igneous rocks and metamorphic rocks of Caledonian and Jinningian periods from the western part of North Qinling Mountain, the eastern part of North Qilian Mountain and West Qinling in the southwestern Ordos Basin as well as Paleoproterozoic khondalite series from the northeastern Ordos Basin. Besides, Variscan magmatic rocks from Alxa Block in the northwestern basin and metamorphic basement rocks from the southeastern part of Ordos Block also made partial contribution. This result is helpful for restoring sedimentary environment of prototype basin and guiding next step work of oil exploration. |
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| Keywords: | U Pb dating of detrital zircon heavy mineral provenance analyse the Chang 6 of Upper Triassic Yanchang Formation southwestern Ordos Basin |
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