Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan
Oxygen isotope study of the Kamioka Zn-Pb skarn deposits, Central Japan
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DOI：
10.1007/bf00190385
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发表时间：
1990-07
影响因子：
4.8
通讯作者：
H. Shimazaki;M. Kusakabe
中科院分区：
文献类型：
--
作者：
H. Shimazaki;M. Kusakabe
神冈锌铅矿床由富含单斜辉石的矽卡岩组成，取代了飞弹片麻岩中的石灰岩透镜体。矿区已知的火成岩有古生代变碱岩、早侏罗世船津花岗岩和晚白垩世斑状岩脉岩岩。对矿床中单斜辉石和石英的八种氧同位素组成进行了分析（表 1），并对矿床周围主要岩石单元的一些矿物和岩石（表 2）进行了分析。估计形成沉积物的流体的氧同位素比率范围低至-4‰至+3‰ (SMOW)。这些值远低于岩浆水的预期值，表明该地区的火成岩都不是夕卡岩和成矿流体的直接来源。相反，数据显示，这些沉积物是由大气水源溶液的巨大对流循环形成的，而白垩纪晚期隐藏的岩岩侵入促进了这种循环。
The Kamioka Zn-Pb deposits consist of clinopyroxene-rich skarns replacing limestone lenses in Hida gneissose rocks. Paleozoic metabasite, early Jurassic Funatsu granitic rocks and late Cretaceous porphyritic dikes and stocks, are the known igneous rocks in the mining area. Oxygen isotopic compositions of eight separates each of clinopyroxene and quartz from the deposits (Table 1), and some minerals and rocks from the major rock units around the deposits (Table 2), have been analyzed. The estimated oxygen isotopic ratios of the fluids responsible for the formation of the deposits, range as low as -4‰ to +3‰ (SMOW). These values are considerably lower than expected from magmatic waters, and demonstrate that none of the igneous rocks in the area could be a direct source of the skarn- and ore-forming fluids. The data instead show that the deposits are formed by a huge convective circulation of solutions of meteoric water origin, promoted by a hidden batholithic intrusion at the time of the late Cretaceous.