马榕, 张婉莹, 何梦颖. 基于碎屑锆石U-Pb年龄对黄土高原黄土的空间物源差异分析[J]. 海洋地质前沿, 2019, 35(1): 35-42. DOI: 10.16028/j.1009-2722.2019.01004
    引用本文: 马榕, 张婉莹, 何梦颖. 基于碎屑锆石U-Pb年龄对黄土高原黄土的空间物源差异分析[J]. 海洋地质前沿, 2019, 35(1): 35-42. DOI: 10.16028/j.1009-2722.2019.01004
    MA Rong, ZHANG Wanying, HE Mengying. SPATIAL PROVENANCE DIFFERENCE OF THE LOESS ON LOESS PLATEAU BASED ON DETRITAL ZIRCON U-PB AGE[J]. Marine Geology Frontiers, 2019, 35(1): 35-42. DOI: 10.16028/j.1009-2722.2019.01004
    Citation: MA Rong, ZHANG Wanying, HE Mengying. SPATIAL PROVENANCE DIFFERENCE OF THE LOESS ON LOESS PLATEAU BASED ON DETRITAL ZIRCON U-PB AGE[J]. Marine Geology Frontiers, 2019, 35(1): 35-42. DOI: 10.16028/j.1009-2722.2019.01004

    基于碎屑锆石U-Pb年龄对黄土高原黄土的空间物源差异分析

    SPATIAL PROVENANCE DIFFERENCE OF THE LOESS ON LOESS PLATEAU BASED ON DETRITAL ZIRCON U-PB AGE

    • 摘要: 黄土高原地处我国中部,面积广阔。虽然前人使用多种研究方法对黄土高原的黄土物源进行了研究,但目前仍然缺乏对黄土高原黄土空间物源差异的系统研究和分析,分析黄土高原黄土的空间物源差异也对阐释粉尘的运输机制有重要意义。通过对黄土高原及周边不同区域的17个黄土样品进行了碎屑锆石U-Pb年龄测试,其年龄组成主要有7个年龄区间:0~100 Ma,100~350 Ma,350~600 Ma,600~1 100 Ma,1 100~1 500 Ma,1 500~2 300 Ma和2 300~2 800 Ma。通过对17个样品点锆石U-Pb年龄谱的对比发现,黄土高原黄土因多种因素呈现了一定的相似性,促使黄土高原不同空间位置的黄土中碎屑锆石的U-Pb年龄谱总体上呈现相似性的原因主要为多次沉积和充分混合。但仍然在局部存在差异,主要表现为:黄土高原北部黄土与南部黄土相比,北部黄土缺少年龄小于100 Ma的锆石,这组年龄的锆石可能来自鄂尔多斯盆地南缘。而最西部的西宁黄土和最东部的邙山黄土相比缺少年龄为1 500~2 300 Ma、峰值为2 000 Ma左右的锆石,而邙山黄土被证明主要来自黄河河漫滩,这可以证明黄河在黄土高原形成中起了重要的作用。黄土高原是多源区、多成因的,而不同区域的黄土物源组成与其最近源区的相关性最大,因此,在进行黄土高原物源分析时应充分考虑区域沉积环境。

       

      Abstract: The Loess Plateau covers a vast area in the central part of China. Our predecessors have used a variety of research methods to study the provenance of the loess from different points of view. However, systematic researches are still lacking on the spatial difference in provenance of the loess, which is critical important to the explanation of transport mechanism of the dust. A total of 17 samples are collected by the authors from both the Loess Plateau and its surrounding areas for detrital zircon U-Pb dating. Results show that there are seven zircon age groups, i.e. 0-100 Ma, 100-350 Ma, 350-600 Ma, 600-1 100 Ma, 1 100-1 500 Ma, 1 500-2 300 Ma and 2 300-2 800 Ma. After comparison of the zircon U-Pb age spectra of the 17 samples, it is found that the loess from the plateau has certain similarities, and the main reasons for the similarity are multiple redeposition and thorough mixing. However, there are still differences in some areas. For examples, the loess in the northern part of the plateau lacks zircons younger than 100 Ma, which may come from the southern margin of the Ordos Basin, while the western Xining loess is short of zircon with a peak value of about 2 000 Ma comparing to the eastern Mangshan loess. The Mangshan loess is mainly from the floodplain of the Yellow River, which may suggest that the Yellow River has played an important role in the formation of Loess Plateau. The loess Plateau has multiple provenances and different genesis, and the composition of the loess is dominated by its nearest source area. Therefore, the regional sedimentary environment should be fully considered when the provenance analysis of Loess Plateau is carrying out.

       

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