Pyrite and Pyrrhotite Textures and Composition in Sediments, Laminated Quartz Veins, and Reefs at Bendigo Gold Mine, Australia: Insights for Ore Genesis

The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

“…Similar to pyrite from Carlin-type deposits, growth zoning is a major factor controlling element distribution in pyrite in orogenic deposits. (Goldfarb et al, 2005;Large et al, 2007;Morey et al, 2008;Large et al, 2009;Sung et al, 2009;Thomas et al, 2011). The complexity of pyrite growth reflects the multistage evolution of orogenic Au deposits, where Au deposition is usually related to episodic pumping of fluids produced during greenschist to amphibolite facies devolatilization and that are structurally channelled into the retrograding parts of an orogen (Sibson et al, 1988;Goldfarb et al, 2005).…”

“…Gold tends to concentrate in As-rich zones and/or zones of intense brittle deformation in coarse-grained pyrite, in the relicts of framboidal pyrite (if preserved), and in areas of extensive pyrite recrystallization due to interaction with Au-bearing hydrothermal fluids. Gold content in pyrite decreases to < 1 ppm in pristine, unzoned pyrite (Ho et al, 1995;Large et al, 2007;Morey et al, 2008;Cook et al, 2009;Large et al, 2009;Sung et al, 2009;Thomas et al, 2011;Velásquez et al, 2014). Some generations of pyrite at Bendigo, Victoria, Australia, also reveal syndeformational growth marked by coupled changes in the concentrations of Au and As (Thomas et al, 2011).…”

“…Gold content in pyrite decreases to < 1 ppm in pristine, unzoned pyrite (Ho et al, 1995;Large et al, 2007;Morey et al, 2008;Cook et al, 2009;Large et al, 2009;Sung et al, 2009;Thomas et al, 2011;Velásquez et al, 2014). Some generations of pyrite at Bendigo, Victoria, Australia, also reveal syndeformational growth marked by coupled changes in the concentrations of Au and As (Thomas et al, 2011). SIMS and LA-ICP-MS elemental maps revealed that Au is incorporated into pyrite as inclusions of free Au and Au in solid solution (Mumin et al, 1994;Large et al, 2009 (Goldfarb et al, 2005; and references therein).…”

“…6a). In orogenic deposits, the analysed pyrite is related to a large variety of protholith including: black shales, intermediate volcanic rocks, granitic rocks and felsic porphyries, banded iron formations; and host-rocks include: dolerite, basalts, metabasalts, syenite, and ryodacite (Ho et al, 1995;Large et al, 2007;Wood and Large 2007;Morey et al, 2008;Cook et al, 2009;Sung et al, 2009;Thomas et al, 2011;Valásquez et al, 2014). Most pyrite analyses in these systems cluster within the same area in Au-As plots.…”

Molybdenite-tungstenite association in the tungsten-bearing topaz greisen at Vítkov (Krkonoše-Jizera Crystalline Complex, Bohemian Massif): indication of changes in physico-chemical conditions in mineralizing system

“…Cook et al 2009Cook et al , 2013Large et al 2009Large et al , 2014Sung et al 2009;Lin et al 2011;Thomas et al 2011;Pašava et al 2013Pašava et al , 2015Pašava et al , 2016 that Electron Microprobe Analysis (EMPA) and Laser Ablation Inductively Coupled Mass Spectroscopy (LA-ICP-MS) spot analyses and mapping are very useful for documentation and interpretation of trends of trace-element distribution in sulfides such as pyrite, arsenopyrite and sphalerite. Blevin and Jackson (1998) used LA-ICP-MS to measure a number of elements in molybdenite containing both Bi-mineral inclusions and Au.…”