open access

https://hdl.handle.net/2115/38463

Cathodoluminescence and Trace Elements in Quartz : Clues to Metal Precipitation Mechanisms at the Asachinskoe Gold Deposit in Kamchatka

英語

Asachinskoe

2008

21st Century COE for Neo-Science of Natural History, Hokkaido University

Origin and Evolution of Natural Diversity : Proceedings of the International Symposium, The Origin and Evolution of Natural Diversity, held from 1-5 October 2007 in Sapporo, Japan

175-184

International Symposium, "The Origin and Evolution of Natural Diversity". 1–5 October 2007. Sapporo, Japan.

The Asachinskoe epithermal gold deposit in South Kamchatka, Russia, is a low-sulfidation type deposit which consists of Au-Ag bearing quartz-adularia-illite veins. Cathodoluminescence (CL) analysis using optical microscope and scanning electron microscope and trace element analysis of quartz using electron probe micro-analyzer (EPMA) were performed to elucidate the relationships between CL structures, trace element concentrations of different quartz generations, and metal precipitation mechanism of the Asachinskoe deposit. Five sequences of quartz crystallization can be distinguished within the mineralized vein of the bonanza zone. Most distinctive trace elements in quartz are Al (av. 1463 ppm) and K (av. 350 ppm). Colloform and microcrystalline quartz with moderate to dull red-brown CL coexists with electrum (Au-Ag alloy), naumannite-aguilarite (ss) and polybasite-pearceite (ss). The Au-Ag-Se precipitation is related to fluid boiling, and the Se enrichment is attributed to relative oxidizing mineralization conditions. Almost non-luminescent, dark brown luminescent quartz forming the matrix of the hydrothermal breccia coexists with electrum, tetrahedrite-tennantite (ss) and covellite. The Au-Ag-Cu precipitation is associated with rapidly precipitated quartz and adularia, and is due to sudden decompression and fluid boiling related to the hydrothermal brecciation.

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BA85842508