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第四紀地層對比之研究: 生物地層:化石帶不明顯 岩性地層:局部而受控於沈積環境 時間地層:值得一試 定年法之限制: 一、不同材料 14C :漂木,貝類 FT :火成岩 TL , ESR :沈積物,貝類 二、不同年限. 河階之定年: 新地體構造特性 河流下切速率 定年方法: ( 1 ) 14 C :採樣不容易 適用年限短 ( 2 ) TL , ESR :採樣不容易 ( 3 )?.
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第四紀地層對比之研究: 生物地層:化石帶不明顯 岩性地層:局部而受控於沈積環境 時間地層:值得一試 定年法之限制: 一、不同材料 14C:漂木,貝類 FT :火成岩 TL,ESR:沈積物,貝類 二、不同年限
河階之定年: 新地體構造特性 河流下切速率 定年方法: (1)14C:採樣不容易 適用年限短 (2)TL,ESR:採樣不容易 (3)?
Application of the Diffusion Model in Slope Evolution Journal of the Geological Society of China 35(4), 407-419.
Morphological Dating • Down wearing and decrease of slope angles through time • Maintenance of steep angles and parallel retreat of slope segments.
Diffusion Model (linear) • Assumptions • Material conservation • Material homogeneous Mass transport rate = m
The rate of change in elevation (dy/dt)at a point on a hillslope is proportional to the curvature (d2y/dx2).
Simulation of Poly-cyclic Terraces Once the terrace scarps are formed, the slope evolves due to the lateral erosion of river at the bottom and direct erosion on the slope surface.
Mid-section Maximum-Slope-Angle (MSA) MSA decreases non-linearly with the diffusivity and t, kt. MSA decreases more rapidly with a larger diffusivity.
Diffusivity is a function of lithology and climate, indicating its various in different places and time duration. • Diffusivity can be derived by terrace with known age. Ex: Tahan river. • LT, 90 m2/ka; FT, 10 m2/ka • Diffusivity has a linear relationship with the height