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Characteristic mineralizations and alterations of the Kuroko- and Vein types deposits.

黑子型和矿脉型矿床的特征矿化和蚀变。

基本信息

批准号：
59470042
负责人：
ISHIHAWA Yohei
金额：
$ 4.22万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1984
资助国家：
日本
起止时间：
1984 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-59470042/
关键词：
Kuroko deposit Vein-type deposit Hydrothrmal alteration Superposed alteration Uwamuki Kuroko deposit Kosaka mine Fukazawa Kuroko deposit Ezuri Kuroko deposit 北鹿地域

项目摘要

The Ezuri Kuroko deposit, located nearly at the central part of the Hokuroku district, Akita Prefecture. In the area host volcanic rocks were hydrothermally altered during Kuroko mineralization and vein-type mineralization of the younger stage.The following two kind of hydrothermal alteration envelopes are reconginized in the volcanic rocks. (1) Hydrothermal alteration related to the kuroko mineralization at the earlier stage. The cenrtal part of the deposit is characterized by the sericite and K-feldspar assemblage. The alteration zones show gently crossed relationships to the formation boundaries with marshroom-like shape. (2) Hydrothermal alteration related to the vein-type mineralization at the later stage. The central part of the deposit is characterized by the pyrophyllite and Mg-chlorite is present around the quratz porphyry intrusion. The alteration zones show steeply cross cutting relationships to the formation boundaries with funnel-like shape.The latter is superposing upon the former, especially around the Iwagami vein-type deposit. These facts mentioned above suggest that the pyrophyllitization and mineralization of the Iwagami vein-type deposit took place at the near surface of land during the late Miocene hydrothrmal activity with quratz porphyry intrusion. Predominated distribution of the Mg-chlorite is around the quratz porphyry may indicate that the magnesium fixation have been promoted by the hydrothrmal solutions with high ionic activity of magunesium at the later stage.

江折黑子存款，位于秋田县北六区的中部附近。区内容矿火山岩在黑矿成矿和较年轻阶段的脉型成矿作用中发生了热液蚀变，火山岩中发现了以下两种热液蚀变包体。(1)与黑矿成矿作用有关的早期热液蚀变。存款中心部位以绢云母和钾长石组合为特征。蚀变带与地层边界呈平缓交叉关系，呈沼泽状。(2)热液蚀变与后期脉状矿化有关。存款的中心部分的特点是叶蜡石和镁橄榄石是存在于周围的库拉茨斑岩侵入体。蚀变带与地层边界呈漏斗状陡切关系，后者叠加在前者之上，尤其是在岩上脉型存款周围。上述事实表明，岩上脉型存款的叶蜡石化和矿化发生在近地表的晚中新世热水活动与quratz斑岩侵入。富镁斑岩周围镁离子的优势分布可能表明富镁斑岩后期高镁离子活性的热液促进了镁的固定。