鄂尔多斯盆地南部中侏罗统直罗组沉积物源:来自古流向与碎屑锆石U-Pb年代学的证据
发布时间：2019-04-02 03:07
【摘要】：采用LA-ICP-MS碎屑锆石原位微区测年方法,对鄂尔多斯盆地南部黄陵地区及彬县地区中侏罗统直罗组砂岩进行了碎屑锆石U-Pb年龄分布特征研究,统计和对比盆地周缘岩体的同位素年代学结果,结合盆地南部直罗组地层典型露头实测古水流数据,综合研究了盆地南部直罗组沉积物源。结果表明:(1)黄陵地区直罗组样品总体呈169~438 Ma、1 435~2 083 Ma、2 300~2 767 Ma三个年龄组,对应峰值分别为274 Ma、1 851 Ma和2 366 Ma。彬县地区直罗组样品总体呈213~485 Ma、802~974 Ma、1 633~1 894 Ma和2 143~2 739 Ma 4个年龄组,对应峰值分别为430Ma、450Ma、1 720Ma和2 254Ma。(2)黄陵地区直罗组地层物源主体来自西北部阿拉善地块的中酸性侵入岩及变质岩。彬县地区直罗组地层物源主体来自西部的北、中祁连造山带,源岩为中酸性侵入岩、基性侵入岩及变质岩,同时存在火山岩、碎屑岩及变质碎屑岩的部分贡献。(3)盆地南部直罗组下段地层各典型露头古水流优势方向集中于110°~140°,表明古流向以向东和东南为主,即该时期物源主要来自盆地西、西北方向,这与碎屑锆石年代学对比所指示的物源区相一致,这些物源分析结果对于进一步认识侏罗纪时期盆地原型及古地理格局具有较重要的参考价值。
[Abstract]:LA-ICP-MS in situ microdating of clastic zircons was used to study the age distribution of clastic zircons from the middle Jurassic Zhiluo formation sandstone in the Huangling area and Binxian area of the southern Ordos basin, and the age distribution characteristics of the clastic zircon were studied. Based on the isotopic chronological results of the peripheral rock masses of the basin and the paleocurrent data measured at the typical outcrops of the Zhiluo formation in the southern part of the basin, the sediment sources of the Zhiluo formation in the southern part of the basin are comprehensively studied. The results showed that: (1) in Huangling area, the corresponding peak values were 274 Ma,1 851 Ma and 2 366 Ma., respectively, in three age groups: 169 / 438 Ma,1 435 / 2083 Ma,2 300 / 2 767 Ma, respectively, and the corresponding peak values of the samples were 274 Ma,1 851 Ma and 2 366 Ma., respectively. The corresponding peak values were 430 Ma and 450 Ma, respectively, in four age groups of 213,485 Ma,802~974 Ma,1 633, 1,894 Ma and 2 143, 2,739 Ma in Binxian district, respectively, and the corresponding peak values were 430Ma and 450Ma, respectively, and the corresponding peaks were 430Ma and 450Ma, respectively. 1 720Ma and 2254 Ma. (2) the provenance of the Zhiluo formation in Huangling area is mainly from the intermediate-acid intrusive rocks and metamorphic rocks of the Alashan block in northwest China. The stratigraphic provenance of Zhiluo formation in Binxian area is mainly from the northern and middle Qilian orogenic belts in the west. The source rocks are intermediate acid intrusive rocks, basic intrusive rocks and metamorphic rocks, and volcanic rocks exist at the same time. Some contributions of clastic rocks and metamorphic clastic rocks. (3) the dominant directions of typical outcrop paleocurrent in the lower strata of the Zhiluo formation in the southern part of the basin are concentrated in the range of 110 掳~ 140 掳, indicating that the paleo-direction is mainly eastward and southeastward, that is, the provenance of this period is mainly from the west of the basin. In the northwest direction, this is consistent with the provenance area indicated by the chronological comparison of clastic zircon. These provenance analysis results have important reference value for further understanding the prototype and palaeogeographic pattern of Jurassic basin.
【作者单位】： 大陆动力学国家重点实验室;西北大学地质学系;陕西延长石油(集团)油气勘探公司延长气田采气一厂;
【基金】：国家自然科学重点基金项目(41330315) 中国地质调查局工作项目(12120114009201) 西北大学大陆动力学国家重点实验室科学技术部专项经费资助项目
【分类号】：P534.52;P597.3
，
本文编号：2452177
[Abstract]:LA-ICP-MS in situ microdating of clastic zircons was used to study the age distribution of clastic zircons from the middle Jurassic Zhiluo formation sandstone in the Huangling area and Binxian area of the southern Ordos basin, and the age distribution characteristics of the clastic zircon were studied. Based on the isotopic chronological results of the peripheral rock masses of the basin and the paleocurrent data measured at the typical outcrops of the Zhiluo formation in the southern part of the basin, the sediment sources of the Zhiluo formation in the southern part of the basin are comprehensively studied. The results showed that: (1) in Huangling area, the corresponding peak values were 274 Ma,1 851 Ma and 2 366 Ma., respectively, in three age groups: 169 / 438 Ma,1 435 / 2083 Ma,2 300 / 2 767 Ma, respectively, and the corresponding peak values of the samples were 274 Ma,1 851 Ma and 2 366 Ma., respectively. The corresponding peak values were 430 Ma and 450 Ma, respectively, in four age groups of 213,485 Ma,802~974 Ma,1 633, 1,894 Ma and 2 143, 2,739 Ma in Binxian district, respectively, and the corresponding peak values were 430Ma and 450Ma, respectively, and the corresponding peaks were 430Ma and 450Ma, respectively. 1 720Ma and 2254 Ma. (2) the provenance of the Zhiluo formation in Huangling area is mainly from the intermediate-acid intrusive rocks and metamorphic rocks of the Alashan block in northwest China. The stratigraphic provenance of Zhiluo formation in Binxian area is mainly from the northern and middle Qilian orogenic belts in the west. The source rocks are intermediate acid intrusive rocks, basic intrusive rocks and metamorphic rocks, and volcanic rocks exist at the same time. Some contributions of clastic rocks and metamorphic clastic rocks. (3) the dominant directions of typical outcrop paleocurrent in the lower strata of the Zhiluo formation in the southern part of the basin are concentrated in the range of 110 掳~ 140 掳, indicating that the paleo-direction is mainly eastward and southeastward, that is, the provenance of this period is mainly from the west of the basin. In the northwest direction, this is consistent with the provenance area indicated by the chronological comparison of clastic zircon. These provenance analysis results have important reference value for further understanding the prototype and palaeogeographic pattern of Jurassic basin.
【作者单位】： 大陆动力学国家重点实验室;西北大学地质学系;陕西延长石油(集团)油气勘探公司延长气田采气一厂;
【基金】：国家自然科学重点基金项目(41330315) 中国地质调查局工作项目(12120114009201) 西北大学大陆动力学国家重点实验室科学技术部专项经费资助项目
【分类号】：P534.52;P597.3
，
本文编号：2452177
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