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The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus >
No.22 (1975/12) >

Title :ジャーガルとその母材に関する研究 : (第 1 報)沖縄本島, 具志頭村白土原の土壌粘土鉱物について(農芸化学科)
Title alternative :Studies on theJaagarusoils and their parent materials : I. Clay minerals of the soils at Shirachichibaru, Gushikami village, Okinawa Island (Department of Agricultural Chemistry)
Authors :渡嘉敷, 義浩
大屋, 一弘
鎮西, 忠茂
Authors alternative :Tokashiki, Yoshihiro
Oya, Kazuhiro
Chinzei, Tadashige
Issue Date :1-Dec-1975
Abstract :沖縄本島南部, 具志頭村白土原に堆積する赤褐色土壌, 白色土壌および青灰色土壌の粘土鉱物組成を選択溶解-示差赤外吸収スペクトル分析, X線回折分析, 示差熱-熱重量分析および電子顕微鏡観察によって調べた。また, これらの3種の土壌母材についても考察した。上層の赤褐色土壌では, 結晶性粘土鉱物はAℓ-バーミキュライト, イライトが主体で他にメタハロイサイト, モンモリロナイトが少量含まれ, 石英も付随した。非晶質成分は遊離の酸化鉄の他に未同定成分が含まれた。赤褐色土壌の母材は国頭礫層の粘土や礫, あるいは古生層の粘板岩であることを推察した。上層と次の青灰色土壌との間の白色土壌では, 結晶性粘土鉱物はメタハロイサイト, ハロイサイトが主体で他に少量のイライトが含まれるだけで, 石英をほとんど付随しなかった。非晶質成分は, ごく少量の遊離の酸化鉄の他に未同定成分が含まれた。白色土壌の母材は, 上層および下層のいずれの土壌母材とも異なる琉球石灰岩に由来することが示唆されたが, この土壌母材の確定は今後の研究を待たねばならない。下層の青灰色土壌では, 結晶性粘土鉱物はかなりの量のモンモリロナイト, イライトが主体で他にAℓ-バーミキュライト, メタハロイサイトが少量含まれ, 比較的に多くの石英が付随した。非晶質成分は先の2つの土壌と同様, 遊離の酸化鉄の他に未同定成分が含まれた。青灰色土壌の母材は泥灰岩であることを認めた。
Soils derived from the marl of Shimajiri beds, which are calledJaagaruby an Okinawa dialect, distribute in the central and southern parts of Okinawa Island occupying a predominant part of agricultural land. Objectives of the present paper was, as a series of research on the Jaagaru soils, to investigate clay mineralogy of the samples collected from three different horizons of Shirachichibaru soil, of which genesis was not yet identified in the Jaagaru area. The first horizon (0-40cm) consisted of reddish brown acid clayey material, the second horizon (150-200cm) was also acid but white and silty, and the third (500-550cm) was found to be bluish-gray, acid, and silty, but slightly effervescent with dilute hydrochloric acid. The clay fractions were investigated by means of selective dissolution, difference infrared spectroscopy, X-ray analysis, electron microcopy, and thermogravimetry. Obtained results were as follows : In the clay of the first horizon, the major cristalline minerals were Al-interlayering vermiculite and illite, accompanied by a small quantity of meta-halloysite and montmorillonite. Quartz was also contained. Amorphous minerals included free iron oxides and unidentified materials. It was assumed that the parent material of the horizon originated from Kunigami gravel or slate of Palaeozoic formation of which soils had similar clay mineralogy as reported by other investigators. The main crystalline minerals in the clay of the second horizon were meta-halloysite and halloysite, accompanied by a small quantity of illite. Quartz was not identified. Amorphous minerals were same with the above horizon. It was concluded that this horizon did not originate from the material of the underlying layer, but further studies were necessary to define a source of the horizon. A large quantity of montmorillonite and illite were found in the clay of the third horizon accompanying a small quantity of Al-interlayering vermiculite and meta-halloysite. The clay contained more quartz than that of the first horizon. Free iron oxides and unidentified materials were included in amorphous minerals as in the above horizon. This horizon was defined as derived from the marl of Shimajiri bed.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4330
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.22 p.177 -190
Appears in Collections:No.22 (1975/12)

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