Pyrometasomatic Copper-Iron Sulphide Ore Deposits of the Yoshiwara
Pyrometasomatic Copper-Iron Sulphide Ore Deposits of the Yoshiwara
复制标题
吉原火交代铜铁硫化物矿床
DOI：
10.11456/shigenchishitsu1951.9.37_276
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发表时间：
1959
期刊：
影响因子：
--
通讯作者：
Motomi Mori
中科院分区：
文献类型：
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作者：
M. Miyahisa;Motomi Mori
吉原矿位于平大-山之武地区著名的铜矿带，属于中生代晚期，西中国和北九州的成矿区。矿区周围的主要岩石是古生代沉积物，如粘土岩、砂岩和石灰岩，以及基性熔岩和凝灰岩。这些地层被白垩纪不整合的花岗闪长岩岩基和玢岩脉侵入。该矿的火成交代存款与花岗闪长岩有成因联系，公认的火成活动成矿序列如下：（1）玢岩侵入;（2）花岗闪长岩侵入;（3）石榴辉石矽卡岩形成并有铜金矿物沉积;（4）黄铁矿、赤铁矿、磁铁矿等铁矿物沉积;（5）铅锑矿物沉积。成矿后，矿床被N10° ~ 40 ° E高角度走滑断层切割，灰岩层的褶皱构造是主要矿体定位的重要因素，玢岩脉也是部分黄铁矿矿体定位的重要因素。(1)存款1号铜矿床由鞍礁状矽卡岩矿体组成。它们沿着粘土岩（上盘）和石灰岩（下盘）之间向东倾伏的复背斜的顶部。据此，作者认为，交代作用是沿着褶皱石灰岩层的复背斜顶点发生的，上盘的粘土岩形成了矿化溶液上升的盖层。(2)2号铜矿存款的上部沿走向沿着呈透镜状。它位于背斜的北翼，灰岩层不规则地夹有其他沉积物。(3)2号矿石存款的下部呈管状。它被封闭在褶皱的厚石灰岩床内，并进一步与玢岩脉有关。矿体与周围灰岩的分界不明显。(4)杉谷、小口、东、西等铁硫化物矿床矿体是块状黄铁矿的透镜状或管状矿体，取代矽卡岩铜矿石、玢岩、石灰岩等，有的受先存玢岩脉控制，矿区内未观察到花岗岩接触面。矿石可能来自隐伏的花岗闪长岩侵入体。
The Yoshiwara Mine is located in the well known copper zone of the Hiraodai-Sannotake District belonging to the late Mesozoic, metallogenetic province of West Chugoku ane North Kyushu. The prevailing rocks in the environs of the mine are Paleozoic sediments, such as clayslate, sandstone and limestone, and basic lava and tuff. These strata are intruded by discordant granodiorite batholiths and porphyrite dikes of Cretaceous age. The pyrometasomatic deposit of the mine is genetically related to the grano diorite.The recognized sequence of igneous activity and mineralization is as follows : (1) intrusion of porphyrite, (2) intrusion of granodiorite, (3) formation of garnet-pyroxene skarn with deposition of copper-gold minerals, (4) deposition of iron minerals such as pyrite, hematite and magnetite, and (5) deposition of lead-antimony minerals. After the mineralization, the deposits were cut by some high-angle strike-slip faults trending N10°-40°E.The most important factor in the localization of the main ore bodies is the fold structure of the limestone bed, and also, porphyrite dikes are a contributing factor in some pyrite ore bodies.(1) Copper Ore Deposit No. 1 consists of some skarn ore bodies in a saddle-reef form. They lie along the crest of an east-plunging anticlinorium between clayslate (hanging wall) and limestone (foot wall). From this the writers consider that replacement has taken place along the anticlinorium apex of the folded limestone bed and that the clayslate of the hanging wall forms a cap rock for ascending mineralizing solutions.(2) The upper part of the Copper Ore Deposit No. 2 shows a lenticular form in cross-section along the strike. It lies in the north limb of the anticline, where the limestone bed is irregularly intercalated with other sedimentaries.(3) The lower part of the Ore Deposit No. 2 occurs as a pipe-like mass. It is enclosed within the folded thick limestone bed, and further, is associated with porphyrite dikes. The boundary between the ore body and the surrounding limestone is not sharp.(4) Iron-sulphide deposits, such as the Sugitani, the Koguchi, the East, and the West Ore Bodies are lenticular or pipe-like bodies of massive pyrite which replace skarn-copper ore, porphyrite, limestone, etc. Some of them are controlled by the pre-existing porphyrite dikes.The granite contact is not observed in the mining area. Ore may have come from hidden intrusives of granodiorite.