REVIEW Geochemistry of hydrothermal gold deposits: A review Yongfeng Zhu*, Fang An, Juanjuan Tan Key Laboratory of Orogenic Belts and Crustal Evolution of Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing 100871, China Received 13 October 2010; accepted 9 April 2011 Available online 25 May 2011 KEYWORDS Geochemistry; Hydrothermal fluid; Alteration; Gold deposits Abstract Mineral assemblages formed during hydrothermal alteration reflect the geochemical compo- sition of ore-forming fluids. Gold is mainly transported in solution as AueCl and AueS complexes. The change of physicochemical conditions such as temperature, pressure, oxygen fugacity, and sulfur fugacity are effective mechanisms for gold precipitation. Gold tends to be concentrated in the vapor phase of fluids at high temperatures and pressures. AueAs and AueSb associations are common in gold deposit. Native antimony and/or arsenic e native gold assemblages may precipitate from hydrothermal fluids with low sulfur fugacity. Hydrothermal fluids forming epithermal gold deposits are Au-saturated in most cases, whereas fluids of Carlin-type are Au-undersaturated. Quasi-steady As-bearing pyrite extracts solid solu- tion Au from hydrothermal fluids through absorption. The capability of As-bearing pyrite to absorb Au from under-saturated fluid is the key to the formation of large-scale Carlin-type deposits. With increasing new data, studies on the geochemistry of gold deposits can be used to trace the origin of ore-forming fluids, the source of gold, and the transporting form of Au and other ore-forming elements, such as Si, S, F, Cl, As and Ag. ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved. 1. Introduction Ore deposits are the product of crustal evolution in specific areas and at particular stages. Hence, a full understanding of the local geological setting is a prerequisite in studying the genesis of ore deposits (Hedenquist and Lowenstern, 1994; Simmons and Brown, 2006; Zhu et al., 2007b; Hou et al., 2008; Baker et al., 2010). Studies of the geochemistry of ore deposits are based on the structure and formation of ores. Models for ore genesis and exploration rely on the analysis of the various elements, their ore- forming conditions (p, T , f(O 2 ), f(S 2 ), etc.), and their processes of concentration. During the reaction between ore-bearing hydro- thermal fluids and wall-rocks, some elements are concentrated in specific locations to form hydrothermal ore deposits. Hydro- thermal ore systems can be found in various geological settings * Corresponding author. E-mail address: yfzhu@pku.edu.cn (Y. Zhu). 1674-9871 ª 2011, China University of Geosciences (Beijing) and Peking University. Production and hosting by Elsevier B.V. All rights reserved. Peer-review under responsibility of China University of Geosciences (Beijing). doi:10.1016/j.gsf.2011.05.006 Production and hosting by Elsevier available at www.sciencedirect.com China University of Geosciences (Beijing) GEOSCIENCE FRONTIERS journal homepage: www.elsevier.com/locate/gsf GEOSCIENCE FRONTIERS 2(3) (2011) 367e374