九江中更新世红土物质来源研究 |
投稿时间:2022-04-22 修订日期:2022-05-25 |
关键词:Red earth Middle Pleistocene Jiujiang Zircon U-Pb age |
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摘要: |
Provenance tracing study of Middle Pleistocene red earth in the Jiujiang area, South China |
The Middle Pleistocene red earth widely distributed in South China. However, it’s source areas are still controversial. The sedimentary age of the Jiujiang red earth profile has been well defined by previous studying. At the same tieme, it is an ideal section for studying the source of the red earth material in the Middle Pleistocene due to its continuous deposition and well exposed. Through the analysis of two detrital zircon samples from the Middle Pleistocene red earth in Jiujiang, we have obtained 177 concordant zircon U-Pb ages. The peak ages are mainly concentrated in Neoproterozoic (816 Ma, 801 Ma, and 991 Ma), Paleoproterozoic (2019 Ma, 2022 Ma, and 2481 Ma), and Neoarchean (2502 Ma), with insignificant Mesozoic peak age (135 Ma). The results show that the gobi, deserts, Loess Plateau, Tarim Basin and North China Plain in Northern China are not the main source regions of the Middle Pleistocene red earth in Jiujiang. The Early Pleistocene diluvial fan at the northern piedmont of Lushan mountain provided sufficient materials for the development of the Middle Pleistocene red earth in Jiujiang. The detrital zircon U-Pb age compositions of the Middle Pleistocene red earth are different from those of the Late Pleistocene loess in Jiujiang. Different climatic conditions dominated the development of red earth in Middle Pleistocene and loess in Late Pleistocene in Jiujiang area, but both were sedimentary responses to environmental changes caused by the tectonic uplift of Tibetan Plateau. |
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