Geochemistry of Erosion Processes on Badland Slopes

DOI Web Site 4 Citations 60 References

Bibliographic Information

Other Title
  • バッドランド斜面における侵食プロセスに関する地化学的検討
  • バッドランド シャメン ニ オケル シンショク プロセス ニ カンスル チ カガクテキ ケントウ タイワン ナンブ デイカザン ガ ブンプ スル コテイコウソウ デ ノ チョウサ
  • A Case Study of the Gutingkeng Formation Where Mud Volcanoes are Distributed in Southern Taiwan
  • ―台湾南部，泥火山が分布する古亭坑層での調査―

Search this article

Description

 Understanding erosion processes is important to prevent natural disasters such as slope failure and bedrock erosion in immature sedimentary rocks. Pliocene–Pleistocene illite-rich, non-smectite mudstone of the Gutingkeng Formation is distributed over 250 km2 in southern Taiwan, forming badlands (locally called moon-world) with mud volcanoes nearby. These volcanoes erupt saline water and natural gas, and producing a Na+, Ca2+, Cl-, and SO42- rich unsaturated Popcorn crust, which covers the mudstone slope surfaces in the moon-world area. In the crust porewater, ion strength reaches about 10 mol/L; zeta potential on particle surfaces shows a highly positive voltage. Repulsion occurs between particles under this high voltage in the crust, which is rapidly slaked to form mud by heavy precipitation. The zone that is rapidly slaked by precipitation reaches 10-20 cm beneath the crust surface. Ion strength of porewater of fresh mudstone is 0.5 mol/L approaches 0 mV (range 0.2-0.5 mol/L, pH 4-6). The surface charge of particles decreases with the infiltration of precipitation into the crust and fresh rock, with a minus surface charge occurring with increased rain infiltration. This leads to many cracks forming on the surface of mudstone, which is different from the mechanism of rapid slaking.<br> Evaporation from the 10-20 cm-thick zone between the crust and the underlying fresh mudstone would stop if water was not supplied from depth, which is supported by in-situ measurements of water evaporation in the field. These mudstones erode readily under high precipitation because of the repulsion caused by the high ion strength of porewater. High-salinity porewater including mudstone is distributed near the active mud volcanoes where saline water rises and there is a rapid uplift rate. Rapid slaking occurred with some elements in the concentrated crust and near the surface drying zone.

Journal

Citations (4)*help

See more

References(60)*help

See more

Related Projects

See more

Keywords

Details 詳細情報について

Report a problem

Back to top