ABSTRACT Epithermal Au-Ag veins of the Hauraki goldfield are mostly hosted by volcanic rocks and are enclosed by extensive zones of hydrothermal alteration that are generally 6–50 km2 in areal extent. The rocks are altered to a variety of hydrothermal minerals; the most common include quartz, adularia, illite, mixed-layered illite-smectite, chlorite, pyrite, calcite, albite and smectite. Some alteration minerals have zoned distributions. Widespread illite grades successively into overlying and bordering illite-smectite and outlying smectite. Significant quartz veins mainly occur in illite-altered rocks, but some can occur in illite-smectite altered rocks. Adularia commonly surrounds veins and can occur in rocks up to >500 m laterally from veins. Ammonium (NH4) minerals, when present, have a restricted distribution occurring laterally <100–300 m from veins. The significance of alteration minerals can be understood from a geothermal context where the system scale zonation of illite, illite-smectite and smectite outline the broad thermal structure of the former hydrothermal system, with illite formed in the hotter portion. Widespread adularia indicates zones of inferred high permeability and the upflow of boiling hydrothermal fluids. Most significant quartz veins occur in rocks altered to adularia and / or illite, restricting the target area, although both minerals can occur >500 m from veins. Where present, NH4-minerals further restrict the target area.

中文翻译：

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新西兰浅成热液 Au-Ag 矿床的热液蚀变矿物学足迹

摘要 Hauraki 金矿的低温热液 Au-Ag 矿脉主要由火山岩组成，并被广泛的热液蚀变带包围，通常面积为 6-50 平方公里。岩石被改变成各种热液矿物；最常见的包括石英、冰晶石、伊利石、混合层状伊利石-蒙脱石、绿泥石、黄铁矿、方解石、钠长石和蒙脱石。一些蚀变矿物具有分区分布。广泛的伊利石先后分级为上覆和接壤的伊利石-蒙脱石和外围蒙脱石。显着的石英脉主要出现在伊利石蚀变岩中，也有部分出现在伊利石-蒙脱石蚀变岩中。Adularia 通常围绕着静脉，并且可以出现在离静脉横向超过 500 m 的岩石中。铵 (NH4) 矿物，当存在时，横向分布< 距静脉 100-300 m。蚀变矿物的重要性可以从地热环境中理解，其中伊利石、伊利石-蒙脱石和蒙脱石的系统规模分带勾勒出前热液系统的广泛热结构，伊利石形成在较热的部分。广泛分布的灰岩表明推断的高渗透率区域和沸腾热液流体的上升流。最重要的石英脉出现在变质为灰岩和/或伊利石的岩石中，限制了目标区域，尽管这两种矿物都可以出现在距脉 500 m 以上的地方。如果存在，NH4 矿物会进一步限制目标区域。伊利石-蒙脱石和蒙脱石勾勒出前热液系统的广泛热结构，伊利石形成于较热的部分。广泛分布的灰岩表明推断的高渗透率区域和沸腾热液流体的上升流。最重要的石英脉出现在变质为灰岩和/或伊利石的岩石中，限制了目标区域，尽管这两种矿物都可以出现在距脉 500 m 以上的地方。如果存在，NH4 矿物会进一步限制目标区域。伊利石-蒙脱石和蒙脱石勾勒出前热液系统的广泛热结构，伊利石形成于较热的部分。广泛分布的灰岩表明推断的高渗透率区域和沸腾热液流体的上升流。最重要的石英脉出现在变质为灰岩和/或伊利石的岩石中，限制了目标区域，尽管这两种矿物都可以出现在距脉 500 m 以上的地方。如果存在，NH4 矿物会进一步限制目标区域。