碩士 / 國立彰化師範大學 / 地理學系 / 98 / Red soils developed on the coral reef limestone have been regarded as a product of long-term weathering from the limestone. However, many of the recent studies indicated, in stead of in-situ weathering from the parental limestone, these red soils may developed from the deposits with addition of aeolian material. According to the field observation, there are sharp boundary between the surface red soils and the underlain limestone strata. It suggests a different parent material for the red soils, or an alternative by complex pedogenesis in soil development. The goal of this study is to explore the source and the mechanism of the red soils developed on the Liuchiuyu Island based on the soil morphology and the chemical properties. In addition, the immobile element, Ti, was chosen to calculate mass balance analysis. The weathering rate was determined by the dating control to the terrace surface and negative mass flux.
The soil development indices are calculated for the soils sampled from each geomorphic surface of the island. The results show the soils of the highest surface in altitude from each part of the island are equivalent in degrees of soil development. It suggests the Liuchiuyu Island was uplifted simultaneous, followed the geologic events of breaking the island into four parts. The higher altitude of the soil, the higher degree of soil development is observed. The soils in the study form a soil chronosequence, supporting previous correlation on the marine terraces. The soil development indices prove themselves a good indicator for soil development and geomorphic correlation. The major and trace elements in the red soils suggests the material of the Liuchiuyu Mudstone formation as their parent material, instead of the coral reef limestone. However, the chemical signature indicate the drift sand transported by longshore currents may have added as one end member to the parental material of the Liuchiuyu red soils. This is related with the mudstone foundation erosion by sea during the uplifting of island forming.
The result of mass balance analysis indicated that loss and gain of element varied in soil profiles. Time is not the major factor influencing the amount of element's loss. K is the most significant leaching loss element than others, and Zr has a slight loss. It means Zr is immobile in opposition to other elements.
| Identifer | oai:union.ndltd.org:TW/098NCUE5136022 |
| Date | January 2010 |
| Creators | Pei-Jing Wu, 吳珮菁 |
| Contributors | Heng Tsai, 蔡衡 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 130 |
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