[O-08] Poster presentations by senior high school students

[O08-P45] Gravel composition and hinterland evolution of the Miocene Tanabe Group in the Kii Peninsula, Japan

*Amane Yamashita¹, *Yumeru Takeda¹, *Yuma Fujita¹, *Kazuma Hamanaka¹ (1.Wakayama Prefectural Tanabe Senior High School)

In the Kii Peninsula, the Miocene Tanabe Group is deposited over the accretionary complex. The purpose of this study is to clarify the geological evolution of the hinterland from changes in the composition of conglomerates contained in the Tanabe Group.
We investigated the composition of gravel types at 3 sites in the Asso Formation, 9 sites in the Shirahama Formation, 11 sites in the Toshima Conglomerate Formation, and 6 sites in the Mezu Conglomerate Formation of the Tanabe Group. Based on the characteristics of the gravel composition, it is thought that at the time of the deposition of the Tanabe Group, the Ryujin Formation of the Shimanto Belt and metamorphic rocks of the Sambagawa Belt formed a nappe structure. And the metamorphic rocks of the Sambagawa Belt were exposed near to the deposition site of the Tanabe Group. In addition, the Toshima Conglomerate and Mezu Conglomerates are thought to be strata in which gravel from the Asso Formation and Shirahama Formation was eroded and redeposited.