Izu Peninsula in central Japan, the northern tip of the Izu‐Bonin arc, hosts numerous epithermal Au–Ag vein deposits of low‐sulfidation style. All have similar vein textures, mineralogy, and alteration. Geochemical data from fluid inclusions in vein quartz, the mineralogy and mineral chemistry of alteration, and stable isotope data indicate that auriferous hydrothermal activity occurred under subaerial conditions. The K–Ar ages of auriferous vein minerals are <1.5 Ma, indicating that the mineralization took place after extensive submarine volcanism for the host rocks. These observations suggest that Au–Ag mineralization was synchronous with the development of an extensional regime of the Izu block after its collision with the Honshu arc after 1.5 Ma. This collision resulted in the shifting of the Izu block far from the trench to the rear position, and the subduction of the Izu block along the Suruga trough to the west and along the Sagami trough to the east. The reararc position of the Izu block and double subduction resulted in crustal extension, upwelling of asthenospheric mantle, and tholeiitic magmatism reflected by mafic dyke swarms and subsequent monogenetic volcanic activity in the Izu peninsula. The timing of the Au mineralization in the Izu Peninsula during the beginning of lithospheric extension is similar to that of the Sado Au–Ag deposit on Sado island in the Japan Sea. Two mineralization events coincide with extensive tholeiitic mafic volcanism and injections of dyke swarms related to the back‐arc opening of the Japan Sea. The geological setting of the Au–Ag mineralization in Izu and Sado is also similar to that of the epithermal Au–Ag deposits in northern Nevada, where mineralization was contemporaneous with crustal extension and tholeiitic mafic magmatism derived from the asthenospheric mantle. This study suggests that epithermal Au mineralization at shallow crustal depths is a product of large‐scale lithospheric evolution.

中文翻译：

---

日本中部伊豆半岛地壳扩展过程中的金矿化对双重俯冲的响应

日本中部的伊豆半岛（伊豆-波宁弧的北端）拥有许多低硫化型的超热金-银脉矿床。全部具有相似的静脉纹理，矿物学和蚀变。脉石英中流体包裹体的地球化学数据，蚀变的矿物学和矿物化学以及稳定的同位素数据表明，在地下条件下发生了含铁热液活动。含金脉矿物的K-Ar年龄<1.5 Ma，表明成矿作用是在广泛的海底火山作用之后发生的。这些观察结果表明，在1.5 Ma之后，金与银的矿化与伊豆地块与本州弧的碰撞后的伸展带发展同步。这次碰撞导致伊豆地块从海沟向后方移动，伊豆地块沿西面的Suruga槽和东部的相模上槽俯冲。伊豆地块的弧后位置和两次俯冲作用导致地壳伸展，软流圈地幔上涌，铁质基岩群反映出的胶质岩浆作用以及随后伊豆半岛的单相火山活动。岩石圈伸展开始时伊豆半岛金矿化的时间与日本海佐渡岛上的佐渡金银沉积相类似。两次成矿事件与大量的高铁质铁镁质火山活动以及与日本海后弧开放有关的堤防群的注入相吻合。伊豆（Izu）和佐渡（Sado）的金银（Au-Ag）矿化的地质环境也与内华达州北部的超热金银（Au-Ag）矿床的地质环境相似，那里的矿化与地壳扩张和软流圈地幔产生的胶质岩浆岩浆作用同时发生。这项研究表明，浅地壳深度的超热金矿化是岩石圈大规模演化的产物。