| 黄河河套盆地段阶地砾石层的形成时代和物源分析 |
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| 引用本文：李维东,赵希涛,杨艳,吴珍汉.2020.黄河河套盆地段阶地砾石层的形成时代和物源分析[J].地球学报,41(4):515-524. |
| DOI：10.3975/cagsb.2020.031801 |
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| 基金项目:中国地质调查局地质调查项目(编号: DD20190367) |
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| 中文摘要:研究团队前期在河套地区发现了多级黄河阶地, 并厘定了其沉积时代, 但并未探讨其物源特征。在此工作的基础上, 我们首次从物源的角度对河套盆地段黄河的形成演化进行探讨。对黄河临河段T3阶地、黄河库布齐段T9阶地砾石层进行砾石统计, 发现两处古流向均为由西向东, 证明物源来自黄河上游方向。在临河段黄河T3阶地、库布齐段黄河T9阶地基座和下伏白垩纪基岩三处采集锆石样品, 发现河套盆地段黄河阶地下伏白垩纪基岩有三个主要峰值: 250~310 Ma、1550~2160 Ma、2340~2700 Ma, 而黄河T3阶地和T9阶地基座的锆石年龄谱除了以上三个峰值外, 在380~490 Ma和600~1420 Ma两个区间也有明显峰值。将其年龄谱与已发表的黄河各地质年代沉积物的锆石年龄谱进行对比, 我们发现白垩纪基岩的物源主要来自鄂尔多斯基底和周缘造山带, 而河套盆地段黄河河床至少从(5.16±0.50) Ma开始接受来自青藏高原东北部的碎屑物的堆积, 也即贯穿青藏高原东北部和河套盆地的黄河至少在此时就已经形成。 |
| 中文关键词:物源 阶地 河套盆地 黄河 |
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| Formation Age and Provenance Analysis of the Gravel Layer in the Yellow River Terraces of the Hetao Basin |
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| Abstract:The authors’ research group found a number of Yellow River terraces, defined the sedimentary age, but didn’t probe into the provenance. First, the formation and evolution of the Yellow River in the Hetao Basin were discussed with the tracing method based on the previous work. Gravel counting was conducted in the third terrace of Linhe and the ninth terrace of Kubuqi, which indicates that this place received sources from the upper Yellow River. Zircon samples were also collected in the third terrace of Linhe area, the ninth terrace foundation and the Cretaceous bedrock of Kubuqi area. The result shows that there are three main peak ranges, i.e., 250~310 Ma, 1550~2160 Ma and 2340~2700 Ma for the Cretaceous bedrock; in addition, there are two other ones, i.e., 380~490 Ma and 600~1420 Ma. Compared with age spectra of sediments of the Yellow River from different places and different periods, the authors found that sources of Cretaceous bedrock were mainly from Ordos Basin basement and peripheral orogenic belts, while the Yellow River in the Hetao Basin has received sources from the northeast Tibetan Plateau since at least (5.16±0.50) Ma ago. It is therefore concluded that the Yellow River running through ortheast Tibetan Plateau and Hetao Basin has taken shape since then. |
| keywords:source terrace Hetao Basin Yellow River |
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