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Abstract Study of the spatial and mineralogical distribution of gold and silver in the Rosebery north end orebody indicates that both silver and gold are concentrated in massive sphalerite-galena-pyrite ore and barite mineralization. Six styles of gold mineralization have been ...

The Permian-Triassic boundary in marine sediments from Redback2 drill hole in Perth basin in Western Australia is makred by a change from massive bioturbated mudstone enriched in heavy and oxianionic trace elements to microbial laminated mudstone enriched in trace elements indicative of low oxygen ocean bottom environments. C and S isotopes variations across the boundary display an ‘S’ pattern. d13C change from -24‰ to -31‰ , whereeas d34S change from -47‰ to heavier than -25‰ in wholerocks and up to 0‰ in pyrite nodules. The lighter signature of wholerocks is likely due to an admixture of sulfur from sulphides dissolved in seawater and adsorbed on sedimentary/organic particles. C and S isotopic signatures and the general enrichment of siderophile trace elements suggest anoxic ocean bottom in latest Permian. Permian sedimentary horizons enriched in toxic elements, such as Ni, Co, Se, As, Te, Sb, correlated with wholerock sulphur isotopes may indicate mafic volcanic H2S and trace ele...

Pyrite from surface outcrops and diamond drill core near sediment-hosted gold occurrences in the Selwyn basin have been analyzed using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). Samples from the orogenic gold 3Ace occurrence, in southeast Yukon, are interbedded fine-grained sandstones and silty black phyllites from the Neoproterozoic Hyland Group. Samples from the Carlin-type Conrad occurrence, in central-east Yukon, are dark grey to black shales from the Neoproterozoic Windermere Supergroup. Surface outcrop samples are representative of regional lithologies and are distal (>5 km) from known mineral occurrences. Diamond drill holes are distal, in a deposit sense, and show minor alteration and mineralization; samples are from barren intervals of shale and phyllite. LA-ICPMS spot analyses were all conducted on fresh pyrites, including unoxidized pyrites from weathered surface samples. All data are from microcrystalline pyrite nodules and framboids inter...

A review of previous studies of the world’s large hydrothermal gold deposits indicates that the largest deposits tend to show complicated parageneses where multiple gold enrichment events and processes have been involved in the deposit generation. These observations suggest that multistage processes may even be a requirement for the formation of large deposits. In some deposits (e.g. Witwatersrand, Boddington Cadia, Sukhoi Log or Carlin) the different enrichment processes occur millions of years apart. In others, such as many large porphyry deposits, the different stages are much closer in time. In many deposits, particularly sedimentary-hosted deposits, early diffuse enrichment occurs within a particular province that is then upgraded by more focused processes (e.g., Sukhoi Log; Kalgoorlie). The presence of this early diffuse enrichment could explain the tendency for gold deposits to cluster into camps.
This model has important implications, as the presence or absence of multiple gold events could be used to discriminate, at the exploration and feasibility stages, between small deposits with single stage ore genesis and more complicated deposits with multistage enrichment and the potential for larger gold endowment.

During sedimentation and diagenesis of carbonaceous shales in marine continental margin settings, Au
is adsorbed from seawater and organic matter and becomes incorporated into sedimentary pyrite. LAICPMS
analysis of over 4000 sedimentary pyrite grains in 308 samples from 33 locations around the
world, grouped over 123 determined ages, has enabled us to track, in a first order sense, the Au content
of the ocean over the last 3.5 billion years. Gold was enriched in the Meso- and Neoarchean oceans,
several times above present values, then dropped by an order of magnitude from the first Great Oxidation
Event (GOE1) through the Paleoproterozoic to reach a minimum value around 1600 Ma. Gold content
of the oceans then rose, with perturbations, through the Meso- and Neoproterozoic, showing a steady
rise at the end of the Proterozoic (800 to 520 Ma), which most likely represents the effects of the
second Great Oxidation Event (GOE2). Gold in the oceans was at a maximum at 520 Ma, when oxygen
in the oceans rose to match current maximum values. In the Archean and Proterozoic, the Au content
of seawater correlates with the time distribution of high-Mg greenstone belts, black shales and banded
iron formations, suggesting that increases in atmospheric oxygen and marine bio-productivity, combined
with the higher background of Au in komatiitic and Mg-rich basalts were the first order causes of the
pattern of Au enrichment in seawater. We suggest the lack of major Au deposits from 1800 to 800 Ma, is
explained by the low levels of Au in the oceans during this period.

Sulfide nodules composed of pyrite occur within black shales in the Lucky Bay area of the Bulong Domain,
Eastern Goldfields Superterrane, Yilgarn Craton, Western Australia that correlate with the Neoarchean
Black Flag Group. Detailed petrography reveals a variety of shapes and textures, from spherical to ovoid
and zoned to uniform. Some nodules have recrystallized, resulting in a later generation of pyrite. All
have been affected by post-depositional metamorphism, as evidenced by pressure shadows containing
quartz
±
mica
±
carbonate assemblages. LA-ICP-MS analyses show that these nodules are enriched in a
range of trace elements, including Co, Ni, Cu, Ag, Sb, Te, Au, Tl, Pb, and Bi. Gold and Te concentrations range
from 0.3 to 1 ppm and 10 to 50 ppm, respectively. The Black Flag Group equivalents stratigraphically and
structurally underlie a younger basin east of Lucky Bay that contains turbidites, sandy debris flows and
BIF, the latter of which hosts several gold deposits at Randalls, 60 km SE of Kalgoorlie. It is likely that
the lateral equivalents of the nodular sulfide-bearing black shale originally occurred stratigraphically
beneath what is now the ore horizon at Randalls. Given its anomalous Au and Te content, this lithology is
a potential contributor of gold to the BIF-hosted gold deposits of the Randalls Goldfield, as well as other
similar gold resources elsewhere in the Eastern Goldfields Superterrane.

Gold-copper-bismuth mineralization in the Tennant Creek goldfield of the Northern Territory occurs in pipe-like, ellipsoidal, or lensoidal lodes of magnetite ± hematite ironstones which are hosted in turbiditic sedimentary rocks of Proterozoic age. Fluid inclusion studies have revealed four major inclusion types in quartz associated with mineralized and barren ironstones at Ten nant Creek; (1) liquid-vapour inclusions with low liquid/vapour

The Kalgoorlie goldfield (~50 Moz Au produced), famous for its long mining history and diversity of precious-metal telluride minerals, is a world-class Neoarchean Au-Ag-Te district which includes the Golden Mile Super Pit, the largest single gold deposit in the Eastern Goldfields of Western Australia, and the smaller but nonetheless significant Mt. Charlotte deposit, 3 km to the north.  The gold ore at Kalgoorlie is of two types – a Au- and Te-rich first stage (Golden Mile, or Fimiston, ore), which constitutes the bulk of the Au endowment, followed by a relatively Te-poor second stage (Mt. Charlotte ore).  Fimiston-stage ore is characterized by deformed quartz-carbonate structures termed ‘lodes’: thin (1-10 cm) zones of quartz/ankerite/gold/telluride-rich vein breccias with haloes of fine-grained pyrite, muscovite, ankerite, and tourmaline.  Charlotte-stage ore is primarily hosted by ankerite-pyrite-rich alteration selvages around flat-sided, undeformed bucky quartz veins and is the only ore style present in the Mt. Charlotte mine itself. The primary host unit for both mineralization styles is the Golden Mile Dolerite, one of several dolerite intrusions in the mafic-ultramafic volcanic succession of the Kalgoorlie Terrane.
Along with the large amount of mafic metavolcanics, consistent with typical greenstone belt stratigraphy, the Kalgoorlie goldfield contains at least three fine-grained carbonaceous (meta) black shale units (from oldest to youngest: the Kapai Slate; an unnamed interflow shale near the top of the Paringa Basalt; and black shale forming the base of the Black Flag Group).  Each of these units contains varying amounts of syn-sedimentary, diagenetic, and hydrothermal-metamorphic pyrite and pyrrhotite, including well-preserved pyrite nodules.  Nodules at the Golden Mile Super Pit vary in diameter from a few mm to several cm, can have several concentric zones of pyrite with internally variant textures, and are commonly deformed into ovoid shapes.  There are also horizons of pyrrhotite nodules within certain sections of these units; like their pyrite counterparts, these are commonly concentrically zoned and show evidence of later deformation.  Rare examples of thin massive sulfide beds are also present in the interflow shale near the top of the Paringa Basalt.
LA-ICP-MS imaging of pyrite nodules from each of the three black shale units reveals complex (and sometimes spectacular) concentric compositional zonation that parallels the growth zones.  Trace element concentrations vary within different nodule bands in a coherent pattern, with Au, Ag, Te, and As typically enriched together in certain zones.  Gold content is particularly high in the Paringa Basalt interflow shale nodules, which average 3-4 ppm Au as well as 30-40 ppm Ag, 30-40 ppm Te, and 1,000 ppm As.  Samples taken several kilometers to the south (along strike) and west of the Golden Mile of the Kapai Slate and Black Flag Group shale also contain disseminated and nodular pyrite enriched in Au, Ag, Te, and As at levels comparable to samples of those formations within the deposit.  However, in distal samples of the Paringa interflow shale, there is only laminated and nodular pyrrhotite, marked by enrichments in Au, Ag, Sb, Te, Tl, Pb, and Bi relative to a later (and presumably metamorphic) pyrrhotite which cross-cuts and partially replaces the earlier pyrrhotite.
Lead isotope studies of nodules from the three shale units, as well as pyritic ore samples from two separate Fimiston-stage lodes and one Mt. Charlotte-stage sample, have been undertaken to help resolve relative timing issues.  Nodular pyrite from each shale formation has a distinct isotopic composition, with the Kapai Slate samples being the least radiogenic, followed by those from the Paringa interflow shale and, lastly, the Black Flag shale.  These data result in progressively younger Pb-Pb model ages, in keeping with the established stratigraphic order.  In contrast, ore pyrites contain a wide spread of relatively unradiogenic to radiogenic isotopic compositions, partially overlapping with the nodular pyrites.
Sulfur isotope studies (32S, 33S, and 34S) have provided evidence on S source(s) for the nodules and ore-stage pyrites.  Whereas the cores of most nodules contain pyrite with negative Δ33S, a signal thought to be derived from seawater sulfate, the rims of the same have positive Δ33S, which may result from metabolization of atmospheric elemental S.  By contrast, ore-related pyrites (both Fimiston- and Mt. Charlotte-stage) have no or little Δ33S anomalies.
The shape, internal textures, and distinct trace element enrichment and zonation, evidently little affected by ore-forming processes, suggests the nodules are syn-sedimentary to early diagenetic.  There is virtually no evidence that gold or other elements have been added to the nodules during hydrothermal ore events; gold, along with many other elements, remains a coherent part of the primary nodule structure. Lead and S isotope studies on the pyrite nodules provide strong supportive evidence of an early marine sedimentary age for the nodules: the Pb isotopes give an age roughly equivalent to progressive sedimentation of the black shale host rocks, and the S isotopes are best explained by marine sulfate being the original S source for the nodules. 
The evidence is compelling that there was enrichment of Au-Ag-Te-Hg-As during inter-volcanic sedimentation and diagenesis in the Kapai Slate, the interflow shale near the top of the Paringa Basalt, and Black Flag shale, before the formation of the Fimiston-stage gold-telluride lodes.  While this work does not permit us to comment on the gold source issue in the Kalgoorlie deposits, the fact remains that syngenetic/diagenetic gold pre-concentration in fine-grained, sulfidic, moderate- to deep-water sediments likely occurred across the Eastern Goldfields between ~2700-2680 Ma.

... represent clastic input from turbidity currents sourced partly by the erosion of vein-style mineraliza ... sedimentary-exhalative models "must be rejected," based on the sedimentological, textural, andisotopic data. Detailed structural studies of the ores and host rocks led Hinman et al ...