Analysis of the origin of gravels and sedimentary environment in the Quaternary Baeguiri Formation, Hantangang River Geopark

초록

The Quaternary Baeguiri Formation, distributed in the UNESCO Hantangang River Global Geopark, is a formation characterized by unconsolidated sediments. This formation overlies the Devonian Misan Formation marked by an angular unconformity, and is underlain by the Quaternary basalt. The Baeguiri Formation reflects the paleo-topography of the Hantan River before the emplacement of basalt, showing different sedimentary structures depending on the location. This study attempts to identify the sedimentary environment of the Baeguiri Formation by investigating the exposures overlain by basalt. Five sites, including Gomunri (G), Eundaeri (E), Jangjingyo (J), Baeguigyo (B), and Hantangang Dam (HD), were selected. Various types of sedimentary layers were observed, including a layer composed of clay and fine-coarse grain sand, in addition to layers composed of gravel in the Baeguiri Formation. These layers are proposed to have been formed by slumping, the formation of sedimentary dunes by the slumping, and the change in the shape of the channel. Most of the gravels were comparable with bedrock within 20 km, and the sedimentary environment of the Baeguiri Formation could be interpreted as a fluvial environment by synthesizing the survey results of each site.

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