The discovery and significance of the Pleistocene debris flow deposits on the western slope of the Longquan Mountains in western Sichuan
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摘要: 在川西地区龙泉山西坡首次发现了第四纪泥石流沉积。泥石流沉积相组合为AA1B、AA1C、AA1,反映泥石流为洪积扇扇中沉积组合,具有粘性泥石流的沉积特征。ESR测年及孢粉化石组合特征表明泥石流沉积于早-中更新世温暖湿润的气候环境下。龙泉山泥石流的形成反映了龙泉山早-中更新世之交的构造隆升,以及四川盆地盆地期夷平面的解体,是对早-中更新世之交青藏高原的隆起、季风的加强、暴雨式降水出现的沉积响应,对于研究四川盆地西部及青藏高原东缘第四纪构造运动及古气候特征具有重要的意义。Abstract: The Quaternary debris flow deposits were discovered for the first time on the western slope of the Longquan Mountains in western Sichuan. The sedimentary facies associations AA1B, AA1C and AA1 suggest that the debris flow deposits were accumulated in the central part of the alluvial fan, and represented by the viscous debris flow deposits. The ESR age dating and sporopollen assemblages show that the debris flow deposits were deposited under the warm and humid climatic conditions during the early-middle Pleistocene. The formation of the debris flow deposits has reflected the tectonic uplift of the Longquan Mountains at the early-middle Pleistocene boundary and breakup of the level surface in the Sichuan Basin, and may be the response to the Qinghai-Xizang Plateau uplift, strong monsoon and storm precipitation. The findings in this study may have important implications for better understanding of the Quaternary tectonism and palaeoclimates in the Sichuan Basin and eastern margin of the Qinghai-Xizang Plateau.
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Keywords:
- debris flow /
- Quaternary /
- western Sichuan /
- Longquan Mountains
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