地質調査研究報告
Online ISSN : 2186-490X
Print ISSN : 1346-4272
ISSN-L : 1346-4272
52 巻 , 8 号
地質調査研究報告
選択された号の論文の3件中1~3を表示しています
論文
  • 王 平安
    2001 年 52 巻 8 号 p. 327-345
    発行日: 2001/11/30
    公開日: 2015/04/25
    ジャーナル フリー
    Sanjiang orogen is a NS-trending collisional orogenic belt between Indian plate and Yangtze block of the South China plate, and also an important metallogenetic belt in southwestern China. The collision process between Eurasia plate and Indian plate started from Mesozoic times, which resulted in strong and frequent magmatic activities then after. After Cenozoic, the stronger and more frequent tectono-magmatism and volcanic eruptions provided fracture spaces and plenty of heat sources for epithermal activity in this area. As an active geothermal field, the Rehai geothermal field situates in the southern part of the Sanjiang orogen, and is composed of two sub-scale geothermal fields-the Huanggua-qing-Liuhuang-tang in northeast and Reshui-tang in southwest. Rocks that outcrop in this geothermal field are mainly late Cretaceous granitoids with minor late Tertiary and Quaternary volcanics, sandstone and conglomerate. Strong volcanisms in Pliocene to Pleistocene were recognized and early Pleistocene dacite and andicitic terrestrial volcanics distribute in the Huanggua-qing-Liuhuangtang geothermal field (i.e. Rehai geothermal field in narrow sense). 62 hot spring groups occur along a NS-striking main fault in the Rehai geothermal field. Hydrochemical types of the spring water are mainly Na-Cl-HCO3 and Na-HCO3-Cl types, secondly Na-SO4 type, Na-Cl type, Ca-Na-HCO3-SO4 type and Mg-Ca-HCO3 type.Temperature of spring water on the surface is 24~102°C, and pH value is 2~9.8. Geothermometers of SiO2, Na/K, Na-K-Ca, and Na-K-Ca-Mg, of the hot spring waters in the Rehai geothermal field, were used to evaluate the reservoir temperature, which yielded results of >270~100℃ from below 600 m to the surface. The hydrothermal alteration and gold mineralization process are still going on in that area, and the Lianghe gold deposit was formed between the Zao-tang River and the Xiao-shui River in Liuhuang-tang-Huanggua-qing geothermal area in the northeast sector of the geothermal field. This deposit is about 6 km2 in area, with several kinds of spring sinter, hydrothermal alteration and breccia, and is one of the most recently formed hot spring-type gold deposits in China.Au content in hot spring water, surface sinter, bottom sinter, acid leaching zone, and stockwork quartz veins, is 0.01~0.16 ppb, 0.001~0.63 ppm, 0.004~0.17 ppm, 0.001~0.73 ppm, and 0.003~4.65 ppm, respectively. Ag content in silica cap reaches 0.001~54.5 ppm. Based on the average of Au and Ag content, Au/Ag ratio is always less that 0.1 (1 : 10~1 : 19). δ18OH2O,δDH2O, and δ13CCO2, values of hot spring waters in the Tengchong Lianghe area are -12.3‰~-5.1‰, -68.9‰~-55.7‰,and -5.2‰~-1.6‰,respectively. δ34S values of hot spring water, native sulfur, and sulfides such as pyrite, are mainly -2‰~+2‰. Liquid composition of fluid inclusions in quartz from breccia of Liuhuang tang area is H2O 72%, H2S 28%; vapor composition is CO2 67.1%, H2S 12.6%, and H2 20.3%. The δ18O values for quartz from quartz veins in the Lianghe gold deposit are between 5.0‰ and 8.8‰ (averaged 7.3‰ for 10 samples), and 2.3‰~12.4‰ (averaged 7.6‰ for 6 samples) for silicified Pliocene sandstone (whole rock). Soil and rock geochemical investigation results suggest a tendency of high concentration or anomalies of Bi, Li, Rb, As, Sb, Hg, and Sn in or near hot spring areas, and Mn, Ni, Co, Pb, and Zn around or out of hot spring areas.
  • 寺島 滋, 太田 充恒, 今井 登, 岡井 貴司, 御子柴 真澄, 谷口 政碩
    2001 年 52 巻 8 号 p. 347-369
    発行日: 2001/11/30
    公開日: 2015/04/25
    ジャーナル フリー
    土壌地球化学図の作成に関する予察的研究の一環として,関東各地の沖積層から柱状試料を採取して主・微量元素を分析し土壌の母材や元素の広域分布特性,地球化学的挙動等を研究した.沖積層土壌の母材は,主として火山噴出物と河川由来砕屑物であり,両者の割合は地形・地質的な要因で変化する.沖積層土壌における元素濃度の鉛直変化は,火山灰質土のそれに比べて小さかった.これは堆積速度が速く, 表層~下層の風化度や腐植含有量の差が小さいためと考えられた.沖積層土壌中の砂質粒子は主として河川由来である.砂質粒子は風化・変質に伴って微細化するが,この際アルカリ・アルカリ土類金属が溶出・流失し,細粒部分ではアルミニウム,チタン,各種重金属等が相対的に高濃度になる.山間部の規模が小さい沖積面では,集水域の基盤地質と土壌の化学組成の特徴は類似する.広大な平野部を流下する河川の下流域では,基盤岩砕屑物は均質化されており,粒度組成の相違が化学組成を変動させる主因である.沖積層土壌の化学組成は,同一地域の火山灰質土に比べてアルミニウム,チタン,重金属類に之しく,アルカリ・アルカリ土類金属に富む特徴があり,概括的には河川や湖沼の堆積物に類似する.
概報
  • Kuttickat Paul SHAJAN
    2001 年 52 巻 8 号 p. 371-382
    発行日: 2001/11/30
    公開日: 2015/04/25
    ジャーナル フリー
    インド南西岸,Kerala州沿岸域のPeriyar,Muvattupuzha川及びCochin汽水域周辺の底質堆積物の地化学的 検討を行い,元素の分布とj農集パターン,起源,そして元素分布の規制要因と環境からの混入について検討した.河川堆積物試料は砂質シル卜ないし砂で,汽水性および沿岸堆積物はシルト質砂から泥である.検討の結果,堆積 物粒度組成が元素分布の主要な規制要因であることが明らかになった.汽水性ならびに沿岸堆積物ではMn,Ca, Al, Ti, Fe, Na, P, K, Mg, Li, Sc, V, Cr, Co, Ni, Cu, Zn, As, Rb, Ta, Zr, Nb, Pbそして灼熱減量組成に富み,Siに乏しい.有機物に富む試料でも同様なFe,Al, Mg, P, Cu, Ni, Co, CrそしてVの挙動を示す.その他の可能性のある 元素濃集要因として,Fe/Mn水酸化物による金属元素の吸着と重鉱物の濃集があげられる.Fe, Mg, P, Zn, Ba, Pb, Cd, BiそしてCrは多くの試料で濃集しているが,これは全ての試料に人為的汚染が生じており,特にPeriyar川 とその河口域にもっとも大きな重金属類の濃集が認められる.
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