| 洞庭盆地S3-7孔第四纪年代地层 |
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| 引用本文： | 赵举兴,李长安,张玉芬,强小科,熊德强.洞庭盆地S3-7孔第四纪年代地层[J].地球科学,2016,41(4):633-643. |
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| 作者姓名： | 赵举兴 李长安 张玉芬 强小科 熊德强 |
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| 作者单位： | 1.中国地质大学地球科学学院，湖北武汉 430074 |
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| 基金项目： | 国家自然科学基金项目41440002中国地质调查局项目1212011121142 |
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| 摘 要： | 洞庭盆地的形成与演化对长江中游乃至中国中部的地质环境变迁具有重要意义，但区内的第四纪年代地层研究一直不足.以洞庭盆地沉积中心——沅江凹陷的典型钻孔S3-7孔(孔深255.1 m)为研究对象，在详细的沉积物岩性描述和岩石地层划分的基础上，系统地进行了古地磁、ESR、AMS14C等测试，并建立了S3-7孔的年代地层序列.通过与其他两口典型钻孔的对比分析，初步建立了研究区的区域年代地层格架，结果显示洞庭盆地沉积中心下更新统底界位于各钻孔底部240~300 m，中更新统底界位于90~95 m，上更新统底界位于28~50 m，全新统底界位于1.5~3.1 m.平均沉积速率和分段线性方程的结果表明洞庭盆地覆盖第四纪区岩石地层单位的时代为:华田组的地质年龄为2 590~1 600 ka BP，湘阴组的地质年龄为1 600~920 ka BP，洞庭湖组的地质年龄为920~120 ka BP，安乡组的地质年龄为120~11 ka BP，全新统的地质年龄为11 ka BP至今.
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| 关 键 词： | 洞庭盆地 第四纪 年代地层 古地磁 地质年代学 地层学 |
| 收稿时间： | 2015-09-29 |
Quaternary Chronostratigraphy of Borehole S3-7 in Dongting Basin |
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| Abstract: | The formation and evolution of the Dongting basin are important for understanding the geological environmental evolution of the middle Yangtze drainage and even central China. However, Quaternary chronostratigraphy is still controversial in the area. In this study, one continuous borehole S3-7 with a depth of 255.1 m was taken from the Yuanjiang depression, the deposition center of the Dongting basin. Based on detailed stratigraphic and lithological interpretations, the borehole was dated by paleomagnetism, ESR and AMS14C, to establish its chronostratigraphic sequence. Compared with other two typical boreholes, the Quaternary chronostratigraphic sequence of the Dongting basin was established. The results suggest that the Plio-Pleistocene and Early-Middle Pleistocene boundaries of the central Dongting basin are located at the depths of 240-300 m and 90-95 m, respectively, and the boundaries of Middle-Late Pleistocene and Pleistocene/Holocene are located at the depths of 28-50 m and 1.5-3.1 m, respectively. Average deposition rate and piecewise linear equation show that the timing of lithological units in coverage area are as follows: 2 590-1 600 ka BP for the Huatian Formation, 1 600-920 ka BP for the Xiangyin Formation, 920-120 ka BP for the Dongtinghu Formation, 120-11 ka BP for the Anxiang Formation and younger than 11 ka BP for the Holocene. |
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