P—T—t—deformation—fluid characteristics of lode gold deposits: evidence from alteration systematics

Origin and Characteristics of the Shwetagun Deposit, Modi Taung-Nankwe Gold District and the Kunzeik and Zibyaung Deposits, Kyaikhto Gold District in Mergui Belt, Myanmar: Implications for Fluid Source and Orogenic Gold Mineralization

“…In comparison, Wyman et al (2016) explored the presence of magmatic fluids in various orogenic gold deposits worldwide, as well as providing a comprehensive review of mineralizing fluids in orogenic gold systems. The formation of the widespread alteration of albite-silica-chlorite-sericite-carbonate-pyrite associated with the gold-bearing quartz veins in the MB was a major enhancing mineralizing mechanism for many other orogenic gold deposits worldwide (e.g., Phillips, 1993;McCuaig and Kerrich 1998;Goldfarb et al, 2005). The worldwide examples of these structural setting of the orogenic gold deposits are recorded at Golden Mile in Kalgoorlie, Western Australia, Western Lachlan Orogen in Victoria, SE Australia, Buller Terrane in western South Island, New Zealand, Meguma Terrane in Nova Scotia, Canada and Main Divide and Pingfengshan gold mine in Taiwan (Table 3; Shackleton et al, 2003;Bierlein et al, 2004;Groves et al, 1998Groves et al, , 2003Goldfarb et al, 2001Goldfarb et al, , 2005Craw et al, 2010).…”

“…The microthermometric characteristics of fluid inclusions, alteration types, host rocks and tectonic setting related to various stages of vein formation of the mineralized quartz vein systems of Shwetagun (Modi Taung-Nankwe) and the Kyaikhto gold districts are remarkably similar. A majority of orogenic gold deposit studies have reported ore-mineralizing fluids to be of low salinity and aqueous-carbonic in composition (e.g., McCuaig and Kerrich 1998;Ridley and Diamond, 2000;Groves et al, 2003; Notes: T m-CO2 -melting temperature of CO 2 ; T m-cla -melting temperature of CO 2 clathrate; T h-CO2 -partial homogenization temperature of CO 2 inclusions; T h -total homogenization temperature of inclusions; T m-ice -final ice melting temperature; wt% NaCl eq., weight percent NaCl equivalent. 2019).…”

Archaean Gold Mineralization in an Extensional Setting: The Structural History of the Kukuluma and Matandani Deposits, Geita Greenstone Belt, Tanzania

“…The close spatial relationship of gold with meta-ironstone and the intrusive margins of the KIC indicate a litho-chemical control on mineralization, with sulphidation of the magnetite-rich units being particularly important. It is therefore assumed that much of the gold entered the system as sulphur complexes, which destabilized upon contact with Fe-rich lithologies, i.e., magnetite-rich units [25,[67][68][69][70][71]. Compared to other major deposits in the GGB, mineralization in Kukuluma and Matandani is more pyrrhotite-arsenopyrite-rich, which may reflect a combination of higher metamorphic grade, reduced conditions due to the presence of graphitic shale, and host-rock control.…”

“…Compared to other major deposits in the GGB, mineralization in Kukuluma and Matandani is more pyrrhotite-arsenopyrite-rich, which may reflect a combination of higher metamorphic grade, reduced conditions due to the presence of graphitic shale, and host-rock control. The presence of porphyry dykes in association with mineralization, not just in the Matandani pit but also at Geita Hill [24] and Nyankanga [25], would suggest that igneous fluids may have caused mineralization; even though for Archaean Greenstone terrains in general devolatization reactions during regional metamorphism are generally credited as being the primary source for mineralizing fluids [3,8,70]. It is beyond the scope of this paper to fully discuss the origin of gold-bearing fluids, which will require additional isotopic and fluid inclusion studies.…”

“…The structural controls on gold mineralization at Kukuluma and Matandani conform with models for Archaean gold mineralization more broadly, as summarized by [8,9], in the sense that mineralization is late-tectonic, appears to occur as a single event during a shift in the far field stress, precedes cratonic stabilization, and is associated with a range of structural traps created earlier in the deformation and intrusive history of the belt. However, the Kukuluma, Matandani, and Area 3 deposits do not fit the orogenic model, as defined by [9,70] or [2]. In review papers on gold mineralization, the Geita mine is commonly classified as a Neoarchaean, BIF-hosted, orogenic gold deposit [1][2][3]6,7] related to subduction-accretion systems, with all mafic sequences deposited in a subduction-back arc environment [27,36].…”