Abstract: In comparison with the modern and ancient alluvial fan analogues, the matrix-supported carbonatite boulders and pebbles discretely cropping out to the northeast of Liujing town in Guangxi province, where they unconformably overlie the Lower Devonian Moding and Najiao formations, were described and studied. These discrete red coarse deposits represent the remains of different parts of one Paleogene alluvial fan respectively rather than isolated Devonian collapse in carbonatite cave or other depositions presumed by some related scholars. Based on the causer analysis, the Paleogene alluvial fan is proposed as piedmont alluvial fan sourced by the carbonate hinterland under a dry climate.

Key words: Guangxi province, Liujing, Paleogene, carbonate conglomerate, alluvial fan, dry climate

摘要： 利用现代山麓冲积扇鉴别特征，辅以古冲积扇特征，对广西横县六景火车站南侧角度不整合覆盖下泥盆统莫丁组和那叫组下段，被新近系大面积覆盖而呈两部分远距离割裂状态的一套红色泥砂基底碳酸盐岩粗-巨砾岩进行描述和研究，发现其分别为古近纪始新世早中期同一冲击扇的扇根及扇中和扇缘残存部分，并非长期以来学者们所推测的孤立的泥盆纪碳酸盐岩洞穴垮塌等其他沉积体。在成因分析的基础上，认为该冲积扇为一典型的古近纪早期干旱气候条件下，母岩区为陡峻碳酸盐岩山体的古山麓冲积扇。

关键词: 广西, 六景, 古近纪, 碳酸盐砾石, 冲积扇, 干旱气候