Morphology of gravels from the Yangluo Formation in the Southern Piedment of Dabie Mountains

As one of the most important Quaternary strata in the middle reach of Yangtze River, the gravel layers within the Yangluo Formation are distributed in the north bank of the Yangtze River at the southern foot of Dabie Mountains. There are two views on the origin of the gravel layers. One view holds that the gravel layers of Yangluo Formation are alluvial sediments of the Ancient Yangtze River, which formed terraces on the north bank of the Yangtze River after later tectonic uplifting. Another view is that they are the alluvial fans at the southern foot of Dabie Mountains. As gravel's morphology records its evolution, the study of its morphology can be used to reconstruct palaeoenvironment. In our project, 25 gravel layer profiles were chosen to select total 2693 gravels for measurement of morphological parameter, including 1377 gravels from 14 profiles in Hengdian Town and 1316 gravels from 11 profiles in Yangluo Town. Zingg classification shows that most gravel is mainly oblong shape, and it is mainly distributed in the transitional and fluvial facies in the Sneed Folk triangle. There is a large amount of schist in the gravel layer. The morphological characteristics of the gravel layer of Yangluo Formation indicate that it is of alluvial-diluvial fan deposits formed by rivers at the southern foot of Dabie Mountains.