Study of Andesite Weathering in Northern Taiwan Using Micromorphological Approaches

以微形態學方式研究台灣北部安山岩之風化

Victor B. Asio ； 陳尊賢(Zueng-Sang Chen)

《台灣林業科學》 13卷4期 (1998/12) Pp. 259-269

https://doi.org/10.7075/TJFS.199812.0259

摘要

迄今對安山岩之風化過程研究資料之報導仍有限。本研究擬透過微形態之研究，以便在台灣北部過濕潤亞熱帶氣候自然條件下得到安山岩風化過程之資訊，並嘗試由此資料去說明其在基礎土壤學及生態學上之應用。結果顯示，研究區安山岩之風化很快速。岩石之微構造及礦物成份之穩定性會大大影響風化之過程。與已發表之文獻吻合之處為角閃石與輝石會比長石先被溶解。本研究觀察到安山岩之風化過程大約可分成四個階段，小顆粒角閃石與輝石的溶解作用會導致鐵錳氧化物之生成與累積，在風化岩石之周圍可生成鐵錳氧化物之被覆物質，在岩石溶解處則有大量之鐵氧化物可與土壤基體混成一體。腐石之多孔性特性則直接與此研究區灰燼土之高孔隙率有關。

關鍵字

微形態學 ； 安山岩 ； 風化 ； 生態 ； 灰燼土

並列摘要

Very limited information has been reported concerning andesite weathering. This study was conducted to gain, through a micromorphological approach, information on the nature of andesite weathering under the prevailing perhumid subtropical climate of northern Taiwan. An attempt was also made to interpret the pedological and ecological implications of the information gained. Results show that andesite weathering in the study area is relatively rapid. The microstructure of the rock as well as the stahility of the mineral components appear to greatly influence the progress of weathering. In agreement with published literature, amphibole and pyroxene appeared to dissolve ahead of feldspar. Four approximate stages of the weathering process were approached based on the micromorphological study. Dissolution of small amphibole and pyroxene grains result in the accumulation of Fe and Mn oxides. Fe and Mn coatings tend to form along the boundaries of the weathered grains. Substantial amounts of Fe oxides are assimilated into the matrix near the site of dissolution. The porous nature of the saprolite is directly related to the high porosity of Andisols in this study area.

並列關鍵字

micromorphology ； andesite ； weathering ； ecology ； Andisols