恆春半島晚更新世珊瑚礁海階上覆紅色土壤母質來源之探討
Other Title
Possible Scenarios of Parental Material Origins for the Red-Color Soils Overlaying Late Pleistocene Reef Marine Terraces in the Hengchun Peninsula
Journal
中國地理學會會刊
Journal Volume
48
Journal Issue
48期
Pages
1-18
Start Page
1
End Page
18
Date Issued
2012-06
Author(s)
Abstract
自晚更新世以來，受構造活動影響，在恆春半島形成數段珊瑚礁海階，其上均覆有均質的紅顏色土壤，然過去對於這些土壤母質來源與成因，尚無明確之定論；在地質調查中，這些紅色土壤被劃分為太平層（或相當於鵝鸞鼻層），被認為是陸相的沉積物，惟部份學者認為該土壤成因類似於地中海地區的脫鈣紅土，由土壤下方的珊瑚礁石灰岩受淋溶後的殘餘矽酸鹽類物質所化育而成。本研究考察了恆春半島各海階土壤地層剖面特徵，結果顯示多數土壤下方並無與石灰岩有直接接觸之關係，並且進一步分析各土壤的質地和砂粒礦物組成，其結果指出土壤的質地中砂粒含量偏高，且細砂（0.1-0.25mm）等級含量較高，此與河流沉積物和風成沙丘砂的質地結果相仿，另砂粒礦物的組成上亦不似珊瑚礁石灰岩以碳酸鹽類礦物為主，反而以石英、長石等礦物為大宗，故海階下覆之石灰岩應無法提供足夠的矽酸鹽類礦物，作為上覆土壤母質的來源。據此結果，應可合理推斷恆春半島諸海階土壤母質的來源，主要是階地離水過程中，來自河流沖積，或是風力堆積之砂質沉積物，而珊瑚礁石灰岩等僅部分提供土壤所含之碳酸鹽物質。
The parent materials of the soils over the reef-marine terraces in the Hengchun Peninsula have been debated for the past several decades. Some geologists believed that the soils on the reef terraces derived from the inland-fluvial deposits. However, the hypothesis that the soils originated in the residual-siliceous materials from the dissolution of the reef-limestone were proposed by others to explain the soil formation in the Hengchun Peninsula. We investigated the pedo-stratigraphic relationship of the soils on the reef-marine terrace in the Hengchun Peninsula. It was suggested that most soils overlaid the fluvial pebbles or mudstones instead of reef limestone. It indicated that there was not genetic relationship between the soils and the beneath reef-limestone. Besides, the sand factions of all soils were more than 40 % and fine-sand fraction contents of the soils were high, as similar as the fluvial or eolian sand-dune deposits. Dominant sand minerals of the soils, measured by XRD, were quartz and feldspar, whereas contents of those two minerals in reef-limestone were less. Therefore, we hypothesized that the soils on the reef-terraces in the Hengchun Peninsula originated in the fluvial as well as eolian sand-dune deposit that covered on the terrace after being abandoned by the sea-level. Only partial carbonates of the soils were derived from the reef-limestone inputs.
Subjects
脫鈣紅土
土壤母質
珊瑚礁石灰岩
海階
陸源沉積物
恆春半島
terra-rossa soils
parent materials
reef limestone
marine terrace
inland deposit
the Hengchun Peninsula
Publisher
中華民國地理學會
Type
journal article