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

Presentation on theme: "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"— Presentation transcript:

1 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

2 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）？

3 Application of the Diffusion Model in Slope Evolution
Journal of the Geological Society of China 35(4),

4 Morphological Dating Down wearing and decrease of slope angles through time Maintenance of steep angles and parallel retreat of slope segments.

5 Diffusion Model (linear)
Assumptions Material conservation Material homogeneous Mass transport rate = m

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7 k = erosion constant or diffusivity

8 The rate of change in elevation (dy/dt)at a point on a hillslope is proportional to the curvature (d2y/dx2).

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10 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.

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14 Mid-section Maximum-Slope-Angle (MSA)
MSA decreases non-linearly with the diffusivity and t, kt. MSA decreases more rapidly with a larger diffusivity.

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16 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

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18 Simulation of the Active Fault Scarp

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