The Origin of the Sediment-Hosted Kanmantoo Cu-Au Deposit, South Australia: Mineralogical Considerations

Geological and Atmospheric Sciences Publications Geological and Atmospheric Sciences

4-2018

The origin of the sediment-hosted Kanmantoo Cu-Au deposit, South Australia: Mineralogical considerations

Meaghan V. Pollock Iowa State University

Paul G. Spry Iowa State University, [email protected]

Katherine A. Tott Iowa State University

Alan Koenig U.S. Geological Survey

Ross A. Both

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Abstract Multiply deformed sediments of the Cambrian Kanmantoo Group, which were metamorphosed to the amphibolite facies, host numerous Cu-Au, Fe-S, and Pb-Zn-Ag-(Cu-Au) deposits, of which the largest Cu- Au deposit is Kanmantoo (34.5 Mt @ 0.6% Cu and 0.1 g/t Au). Mineralization at Kanmantoo is characterized by discordant and pipe-like orebodies (Kavanagh and Emily Star) along with mineralization locally concordant to bedding (Nugent) that is spatially related to meta-exhalative rocks. Previous studies have suggested a syn-sedimentary origin for the Pb-Zn-Ag-(Cu-Au) and Fe-S deposits, whereas the Kanmantoo deposit remains controversial, with syn-sedimentary, metamorphogenic, and post-peak metamorphic models having being applied. The stratiform nature of some parts of the Nugent orebody, and disseminated sulfides locally concordant to bedding along with the recognition of a zone of chalcopyrite-magnetiterich rocks at the syn-sedimentary Wheal Ellen Pb-Zn-Ag-(Cu-Au) deposit, which shows a metallic mineral assemblage almost identical to the most common assemblage at Kanmantoo, supports a genetic link between the Pb-Zn-Ag-(Cu-Au) deposits and Cu-Au mineralization, and is consistent with a metamorphosed syn-sedimentary model for Cu-Au mineralization. The discordant nature of most orebodies at Kanmantoo is the result of the mineralization having formed as stockwork zones in sub-seafloor pipes. arV ying degrees of remobilization were subsequently associated with syn- to post-peak metamorphism. Major and trace element compositions, coupled with principal component analyses, show that the compositions of garnet, biotite, staurolite, chlorite, muscovite, and magnetite in metamorphosed altered rocks spatially associated with sulfide mineralization at Kanmantoo can be distinguished from those, where present, in metamorphosed country rocks (i.e., metapsammites and metapelites). Garnet, chlorite, biotite, and muscovite in quartz garnetite within quartz mica schist associated with the Nugent orebody are elevated in Mn (up to 19.5wt% MnO – garnet, 2,825 ppm – chlorite, 3,206 ppm – biotite, and 108 ppm – muscovite) and Zn (up to 170 ppm – garnet, 1,602 ppm – chlorite, 1,592 ppm – biotite, and 108 ppm – muscovite) relative to samples in other orebodies and in unmineralized rocks elsewhere in the Kanmantoo Group. Such enrichments in these elements mimic similar enrichments in the same minerals in metamorphosed altered rocks associated with Pb-Zn-Ag-(Cu- Au) deposits in the Kanmantoo Group. Biotite in metamorphosed altered rocks at Kanmantoo contains elevated concentrations of Pb (up to 110 ppm), and, in general, Zn (up to 841 ppm), whereas muscovite is also elevated in Pb, Zn, and Cu (up to 272 ppm Pb, 78 ppm Zn, and 173 ppm Cu). Staurolite in these same rocks contains up to 1.6wt% ZnO (with one outlier that contains 3.2wt%ZnO) and is considerably more enriched in Zn than in unaltered country rocks (∼0.1wt% Zn). The trace element enrichments in silicates studied here constitute a potential pathfinder ot metamorphosed Cu-Au mineralization in the Kanmantoo Group and emphasize the geochemical and genetic links between the Pb-Zn-Ag-(Cu-Au) and Cu-Au deposits.

Disciplines Geochemistry | Geology | Sedimentology

Comments This article is published as Pollock, Meaghan V., Paul G. Spry, Katherine A. Tott, Alan Koenig, Ross A. Both, and Joseph Ogierman. "The origin of the sediment-hosted Kanmantoo Cu-Au deposit, South Australia: Mineralogical considerations." Ore Geology Reviews 95 (2018): 94-117. doi:10.1016/ j.oregeorev.2018.02.017.

Authors Meaghan V. Pollock, Paul G. Spry, Katherine A. Tott, Alan Koenig, Ross A. Both, and Joseph Ogierman This article is available at Iowa State University Digital Repository: https://lib.dr.iastate.edu/ge_at_pubs/340 Ore Geology Reviews 95 (2018) 94–117

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Ore Geology Reviews

journal homepage: www.elsevier.com/locate/oregeorev

The origin of the sediment-hosted Kanmantoo Cu-Au deposit, South T Australia: Mineralogical considerations ⁎ Meaghan V. Pollocka, Paul G. Sprya, , Katherine A. Totta, Alan Koenigb, Ross A. Bothc, Joseph Ogiermand a Department of Geological and Atmospheric Sciences, 253 Science Hall, Iowa State University, Ames, IA 50011-1027, USA b U.S. Geological Survey, Denver Federal Center, Denver, CO 80225, USA c 23 Windsor Street, Fullarton 5063, South Australia, Australia d Robust Resources, Level 34, Gateway Building, 1 Macquarie Place, Sydney 2000, New South Wales, Australia

ABSTRACT

Multiply deformed sediments of the Cambrian Kanmantoo Group, which were metamorphosed to the amphibolite facies, host numerous Cu-Au, Fe-S, and Pb-Zn-Ag-(Cu-Au) deposits, of which the largest Cu-Au deposit is Kanmantoo (34.5 Mt @ 0.6% Cu and 0.1 g/t Au). Mineralization at Kanmantoo is characterized by discordant and pipe-like orebodies (Kavanagh and Emily Star) along with mineralization locally concordant to bedding (Nugent) that is spatially related to meta-exhalative rocks. Previous studies have suggested a syn-sedimentary origin for the Pb-Zn-Ag-(Cu-Au) and Fe-S deposits, whereas the Kanmantoo deposit remains controversial, with syn-sedimentary, metamorphogenic, and post-peak metamorphic models having being applied. ThestratiformnatureofsomepartsoftheNugentorebody, anddisseminatedsulfides locally concordant to bedding along with the recognition of a zone of chalcopyrite-magnetiterich rocks at the syn-sedimentary Wheal Ellen Pb-Zn-Ag-(Cu-Au) deposit, which shows a metallic mineral assemblage almost identical to the most common assemblage at Kanmantoo, supports a genetic link between the Pb-Zn-Ag-(Cu-Au) deposits and Cu-Au mineralization, and is consistent with a metamorphosed syn-sedimentary model for Cu-Au mineralization. The discordant nature of most orebodies at Kanmantoo is the result of the mineralization having formed as stockwork zones in sub-seafloor pipes. Varying degrees of remobilization were subsequently associated with syn- to post-peak metamorphism. Major and trace element compositions, coupled with principal component analyses, show that the compositions of garnet, biotite, staurolite, chlorite, muscovite, and magnetite in metamorphosed altered rocks spatially associated with sulfide mineralization at Kanmantoo can be distinguished from those, where present, in metamorphosed country rocks (i.e., metapsammites and metapelites). Garnet, chlorite, biotite, and muscovite in quartz garnetite within quartz mica schist associated with the Nugent orebody are elevated in Mn (up to 19.5 wt% MnO – garnet, 2,825 ppm – chlorite, 3,206 ppm – biotite, and 108 ppm – muscovite) and Zn (up to 170 ppm – garnet, 1,602 ppm – chlorite, 1,592 ppm – biotite, and 108 ppm – muscovite) relative to samples in other orebodies and in unmineralized rocks elsewhere in the Kanmantoo Group. Such enrichments in these elements mimic similar enrichments in the same minerals in metamorphosed altered rocks associated with Pb-Zn-Ag-(Cu-Au) deposits in the Kanmantoo Group. Biotite in metamorphosed altered rocks at Kanmantoo contains elevated concentrations of Pb (up to 110 ppm), and, in general, Zn (up to 841 ppm), whereas muscovite is also elevated in Pb, Zn, and Cu (up to 272 ppm Pb, 78 ppm Zn, and 173 ppm Cu). Staurolite in these same rocks contains up to 1.6 wt% ZnO (with one outlier that contains3.2wt%ZnO)andisconsiderablymoreenrichedinZnthaninunalteredcountryrocks(∼0.1 wt% Zn). The trace element enrichments in silicates studiedhereconstituteapotentialpathfinder to metamorphosed Cu-Au mineralization in the Kanmantoo Group and emphasize the geochemical and genetic links between the Pb-Zn-Ag-(Cu-Au) and Cu-Au deposits.

1. Introduction existing ore deposits, particularly stratabound massive sulfide deposits (e.g., Solomon and Groves, 1994; Cartwright and Oliver, 2000; There is considerable debate in the literature concerning the role of Marshall and Spry, 2000). Disputed issues include the origin of massive metamorphic processes in the formation and/or modification of pre- sulfide deposits in metamorphic rocks, the source of the metals, and the

⁎ Corresponding author. E-mail address: [email protected] (P.G. Spry). https://doi.org/10.1016/j.oregeorev.2018.02.017 Received 27 September 2017; Received in revised form 1 February 2018; Accepted 11 February 2018 Available online 13 February 2018 0169-1368/ © 2018 Elsevier B.V. All rights reserved. M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117 ways to explore for such deposits. Ore deposit models center on whe- high-density sediment gravity flows within an extensional back-arc ther the base metal mineralization is syn-sedimentary and subsequently basin (i.e., Kanmantoo Trough) along the Paleo-Pacific margin of metamorphosed, or whether it is syn-deformational and formed during Gondwana (Flöttmann et al., 1998; Gum, 1998; Jago et al., 2003). metamorphism (i.e., metamorphogenic). There are many examples in Development of the Kanmantoo Trough commenced in the early Cam- the literature where both models have been applied to the same deposit brian due to extensional tectonism along the southeast margin of the including the Broken Hill Pb-Zn deposit, Australia (Laing et al., 1978; Mount Lofty Ranges. The fault-controlled basin was filled with clastic Parr and Plimer, 1993; White et al., 1996; Large et al., 1996), Can- and minor carbonate sediments derived from the Ross Orogen and de- nington Pb-Zn-Ag deposit (Walters and Bailey, 1998; Chapman and posited in a shallow- to deep-marine environment (Parker, 1986; Williams, 1998; Roache, 2004), and Dongshengmiao Zn-Pb-Cu deposit, Flöttmann et al., 1998; Toteff, 1999; Haines et al., 2001). China (Peng et al., 2007; Zhang et al., 2010; Zhong et al., 2015b). In an The stratigraphic sequence of the Kanmantoo Group has been var- attempt to decipher the origin of some of these contentious deposits, iously defined by Forbes (1957), Thomson and Horowitz (1962), Marshall and Spry (2000) invoked a probabilistic approach in which 15 Mirams (1962), Daily and Milnes (1971, 1972, 1973), Dyson et al. guidelines were evaluated. These can be lumped under four major ca- (1996), and Jago et al. (2003). Utilizing the most recent nomenclature tegories: 1. General guidelines (primacy of solid-state remobilization of Jago et al. (2003), the Kanmantoo Group unconformably overlies the and proportionality of data); 2. Structural and textural guidelines; 3. Early Cambrian Normanville Group, which consists of platform carbo- Petrography and fluid inclusions; and 4. Isotopes and other geochem- nates, sandstone, siltstone, shale, and minor volcanic rocks (Flöttmann ical tracers. et al., 1998; Gum, 1998). The Kanmantoo Group is divided into the The Cambrian Kanmantoo Group, South Australia, consists of mul- Keynes and Bollaparudda subgroups with the latter hosting the base tiply deformed pelitic and psammitic rocks that were regionally meta- metal deposits and largely consisting of a package of deep sea sediments morphosed to the amphibolite facies. The Tapanappa Formation of the (Flöttmann et al., 1998). Within the Bollaparudda subgroup, the Ta- Kanmantoo Group hosts Cu-Au, Pb-Zn-Ag-(Cu-Au), Fe-S, and minor As, lisker Formation is a metamorphosed sandstone, with subordinate Bi, and W deposits. Although there is consensus that the Fe-S deposits siltstone and calc-silicate rocks (e.g., Cooalinga Member), which hosts are syn-sedimentary, the origin of the Kanmantoo Cu-Au deposit, is the Mt. Torrens Pb-Zn-Ag and Talisker Pb-Ag-As deposits, and the controversial (Seccombe et al., 1985; Oliver et al., 1988; Marshall and overlying Nairne Pyrite Member with sulfide-enriched, pyritic meta- Spry, 2000). A syn-sedimentary model for the Pb-Zn-Ag-(Cu-Au) mi- siltstone lenses that hosts Fe-S deposits (e.g., Brukunga deposit). The neralization was favored by Toteff (1999) but a structural model was overlying Tapanappa Formation is the primary host to Cu-Au (e.g., more recently proposed by Singer (2008) for the Angas Pb-Zn-Ag de- Kanmantoo, Bremer, South Hill) and Pb-Zn-Ag-(Cu-Au) deposits (e.g., posit. The three most widely cited genetic models for the Kanmantoo Angas, Wheal Ellen, Aclare, Strathalbyn, Scotts Creek) and consists deposit are: 1. A syn-sedimentary origin in which sulfide mineralization predominantly of metamorphosed sandstone and greywacke with in- formed by hydrothermal processes at or below the seafloor. In this tercalated siltstone and pyritic mudstone (Seccombe et al., 1985; Spry model, the deposit was subsequently metamorphosed and variably re- et al., 1988; Both, 1990; Toteff, 1990; Gum, 1998). A discontinuous unit mobilized (Verwoerd and Cleghorn, 1975; Seccombe et al., 1985; of quartz-biotite-garnet-andalusite ± staurolite rock, which extends Parker, 1986; Spry et al., 1988; Both, 1990; Belperio et al., 1998; Toteff, intermittently for over ∼30 km from about 10 km north of Kanmantoo 1999; Burtt, 2008); 2. A syn-metamorphic model in which sulfide mi- toward Strathalbyn, hosts many of the Cu-Au and Pb-Zn-Ag-(Cu-Au) neralization was introduced during peak metamorphism (Thomson, deposits and is considered to be a regional stratabound alteration zone 1975; Parker, 1986; Solomon and Groves, 1994; Gum, 1998; Oliver that was subsequently metamorphosed (Seccombe et al., 1985). et al., 1998; Schiller, 2000; Burtt, 2008); and 3. A post-peak meta- A U-Pb age of zircon in the Sellick Hill tuff near the top of the morphic model where ore-bearing fluids were derived from an orogenic Normanville Group yields a maximum age for the Kanmantoo Group of granite late in the Delamerian Orogeny (Foden et al., 1999; Focke et al., 522 ± 2 Ma (Jenkins et al., 2002). The minimum age (514 ± 3 Ma) of 2009; Schmidt Mumm et al., 2009; Tedesco, 2009; Wilson, 2009; the Kanmantoo Group was obtained by Foden et al. (2006) using zircon Arbon, 2011; Lyons, 2012). U-Pb ages in the earliest syn-deformational magmatic intrusion (i.e., The current contribution involves a petrographic, textural, and Rathjen Gneiss). Based on these dates, it is apparent that the Kan- major, minor, and trace element mineral study of common rock- mantoo Group was rapidly deposited over 8 ± 5 Myr. Igneous activity forming silicates and oxides (i.e., garnet, biotite, staurolite, chlorite, related to the Kanmantoo Group includes syn-tectonic I- and S-type muscovite, magnetite) spatially associated with Cu-Au mineralization granites (e.g., Rathjen Gneiss, Palmer Granite, Encounter Bay Granite; in three (Nugent, Emily Star, Kavanagh) of ten orebodies currently re- Milnes et al., 1977; Foden et al., 2002b), and MORB-like intrusions cognized in the Kanmantoo deposit. An aim of this study is to com- (Chen and Liu, 1996) followed by late-Delamerian E-MORB tholeiite plement the probabilistic approach of Marshall and Spry (2000) by dikes (Foden et al., 2002a) and post-Delamerian (490–480 Ma) tholeiite focusing on the mineralogy of the deposit to help understand the origin dikes, plutons, and A-type granites (Turner et al., 1992; Turner, 1996; of the sulfide mineralization. A second aim of the study is to develop a Foden et al., 1999). geochemical fingerprint for non-sulfide minerals spatially associated The onset of the Delamerian Orogeny in the Late Cambrian with Cu-Au mineralization at Kanmantoo. Although trace element stu- (514 ± 3 Ma; Foden et al., 2006) terminated sedimentation in the dies of minerals are increasingly being used as a pathfinder to ore de- Kanmantoo Trough and included three primary deformation events posits and to discriminate between ore deposit types (e.g., apatite, (Offler and Fleming, 1968; Fleming and White, 1984; Parker, 1986; Belousova et al., 2002; gahnite, O’Brien et al. 2015a,b; magnetite, Both, 1990; Mancktelow, 1990; Preiss, 1995; Oliver et al., 1998). Based Dupuis and Beaudoin, 2011; garnet, Spry et al., 2007), this study is on the structural and magmatic history, Fleming and White (1984) among the first to use the compositions of multiple minerals in meta- suggested compression spanned approximately 35 Myr, whereas later morphic rocks as potential vectors to base metal mineralization. U-Pb and Rb-Sr ages by Foden et al. (2006) proposed a shorter period (∼24 Myr) of orogenesis from 514 to 490 Ma during which time uplift, 2. Regional geology cooling, and extension related to post-tectonic magmatism commenced. The orogeny is characterized by a metamorphic gradient that reflects The Kanmantoo Cu-Au deposit occurs in the Tapanappa Formation higher temperatures in the north and east, ranging from greenschist of the Kanmantoo Group within the Adelaide Fold Belt (Fig. 1; Sprigg facies (∼350–400 °C; biotite zone) to upper amphibolite facies and Campana, 1953; Seccombe et al., 1985). The Kanmantoo Group is a (∼650–700 °C; fibrolite/sillimanite zone) with local zones of migmatite structurally thickened package (∼7–8 km thick; Haines et al., 2001)of near the Palmer Granite (Fleming and White, 1984; Mancktelow, 1990; metamorphosed pelitic and psammitic rocks that were deposited as Sandiford et al., 1990; Dymoke and Sandiford, 1992; Oliver et al., 1998;

95 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Norites and Gabbros NT Mafic dikes, plugs, QLD and sills (very abundant, abundant, few) WA Synorogenic Granite SA NSW

Rathjen Gneiss See VIC Enlargement Early Cambrian TAS KANMANTOO GROUP Balquihidder Formation

Tunkalilla Formation Kitticoola Mount Torrens Tapanappa Formation Talisker Formation Nairne Pyrite Member Backstairs Passage Formation

BREMER FAULT Carrickalinga Head Formation 35.0o Normanville Group Brukunga Neoproterozoic FAULT NAIRNE Undifferentiated Adelaidean Mount sediments Kanmantoo Barker Scotts Creek Kanmantoo Garnetiferous units in Tapanappa Bremer Formation SI Callington South Thrust fault Hill Aclare Fault (undifferentiated) Kanmantoo Syncline

Strathalbyn Anticline Anticline Wheal Syncline Ellen Sulfide deposits

Strathalbyn Angas Strathalbyn

0 20 Kilometers

Macclesfield Syncline o 139 00’

Fig. 1. Geologic map of the Kanmantoo region showing the location of the Kanmantoo Cu-Au deposit and regional Pb-Zn-Ag-(Cu-Au) and Cu-Au deposits, most of which are hosted in the Tapanappa Formation (SI = St. Ives prospect). Structural features, lithologies (including garnetiferous alteration zones), and known intrusive rocks are shown. Inset shows the location of the Kanmantoo region in Australia (modiﬁed after Chen and Liu, 1996; Toteﬀ, 1999).

Foden et al., 1999; Hammerli et al., 2016). Based on a Sm-Nd age of The first deformation event (D1) was also the most penetrative, monazite, xenotime, and apatite in migmatite near the Palmer Granite, producing a regional slaty cleavage (S1) and major upright folds (F1). Hammerli et al. (2014) concluded that peak metamorphism occurred at The second deformation event (D2) was accompanied by peak meta- 512 ± 22 Ma. Proposed heat sources during metamorphism include morphic conditions and overprinted D1 structures with a weak crenu- crustal extension due to mantle upwelling and syn-tectonic magmatism lation (S2)ofD1 slaty cleavage, and weak folds (F2, e.g., Kanmantoo (Sandiford et al., 1990; Chen and Liu, 1996). Orogenesis was proceeded syncline; Talbot, 1964; Preiss, 1987; Mancktelow, 1990; Belperio et al., by post-tectonic (490–480 Ma) bimodal magmatism comprising A-type 1998). The final deformation event (D3) appears as open folds (F3), granite intrusions southeast of the Adelaide Fold Belt and mafic intru- faults, and a weak crenulation (S3) localized in the eastern Mount Lofty sions at Black Hill (Milnes et al., 1977; Turner et al., 1992; Turner, Range (Offler and Fleming, 1968; Mancktelow, 1990). One of the major 1996; Foden et al., 1999). structural features of the Kanmantoo Group in the eastern Mount Lofty

96 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Metagraywackes, minor quartz mica schist. 0 500 GB

METERS Quartz mica schist, garnet-andalusite-biotite schist, metagraywacke. Gradational into underlying GB unit west and south of Kanmantoo mine Mainly coarse grained garnet-andalusite-biotite schist (host to most copper mineralization). Increasing quartz mica schist to west and ? south of Kanmantoo mine Mine Road soil covered Cu ? Carbonaceous metasiltstones, minor calc-silicate, quartzite META-EXHALITES Weakly layered quartz garnetite rock KANMANTOO Cu e.g. main exhalite unit, Kanmantoo, MINE associated minor quartz-garnet-magnetite BIF (GB) Tailings and quartz-garnet-cummingtonite schist (GC) Fine-grained, pale pink garnet-feldspar rock

Dump Drillhole locations for this study 35o 09’ Geological boundary Cu KAVANAGH 1 2 Adelaide-Melbourne Railway Bedding trend lines EMILY STAR Fold axis, plunge direction GC 3 5 NUGENT 4 Fault/thrust (observed, inferred) ? Cu Old mine workings

? Cu Cu Cu Kanmantoo orebodies

Cu Cu BackBack Callington Callington Road Road SCOTTS ?

CREEK ? ? Pb, Zn, Ag ? Cu 139o 00’ soil covered

Fig. 2. Geologic map of the Kanmantoo deposit area, showing the location of meta-exhalites, orebodies, and drill core locations from this study. 1. KTDD54, Kavanagh. 2. KTDD149, Kavanagh. 3. KTDD141, Nugent. 4. KTDD125, Nugent. 5. KTDD34, Emily Star (modiﬁed after Toteﬀ, 1999).

Range is the southerly plunging Kanmantoo syncline, which formed as a including hornblende (Si, Al, Mg, Ca), ilmenite (Ti, Fe), albite (Al, Na), result of west-vergent compression during D2 (Thomson and Horowitz, spessartine (Al, Mn), pyrope (Si, Mg), K-feldspar (K), gahnite (Zn, Al), 1962; Mancktelow, 1990; Preiss, 1995; Belperio et al., 1998; Toteff, tugtupite (Cl), and apatite (F). Chlorite and biotite are reported as XFe, 1999; Schiller, 2000). The hinge of the syncline trends north–south which is the molar proportion of total iron relative to iron and mag- subparallel to the major Kanmantoo and Bremer Faults to the east nesium (i.e., XFe = Fe/(Fe + Mg)). (Fig. 1). Trace element concentrations (1123 analyses) were measured at the U.S. Geological Survey in Denver, Colorado using laser ablation-in- 3. Sampling, analytical methods, and data classification ductively coupled plasma-mass spectrometry (LA-ICP-MS), comprising a Photon Machines Analyte LA system (excimer 193 nm) coupled to a 3.1. Sample collection and analytical methods PerkinElmer DRC-e ICP-MS. Depending on the grain size and presence of inclusions, minerals were ablated using spot sizes of 30, 40, 65, 85, μ Approximately 150 polished thin sections were prepared from 110, and 135 m. Analyses were externally calibrated using the basalt samples collected from diamond drill cores KTDD149, KTDD54, glass microbeam reference standard GSD-1G (USGS), and internally KTDD34, KTDD141, and KTDD125 from the Kavanagh, Emily Star, and standardized using values of Al (garnet, biotite, staurolite, chlorite, Nugent orebodies (Fig. 2). muscovite) and Fe (magnetite) from electron microprobe analyses. Major element compositions (2490 analyses) of garnet, biotite, GSD-1G was analyzed three times during a 10-h day to correct for in- staurolite, chlorite, muscovite, and magnetite were obtained using a strument sensitivity drift. Concentrations of elements were determined ff JEOL JXA-8900 Electron Probe Microanalyzer at the University of using o -line calculations, following the procedures of Longerich et al. Minnesota. Analyses were conducted using a 15 kV accelerating voltage (1996). Signals were screened for microinclusions before further data with a 20nA beam current, a 1–2 μm spot size, and mineral standards processing (Nadoll and Koenig, 2011). Trace element concentrations

97 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117 that are typically above detection limits for all minerals include 24Mg, AB 27Al, 28Si, 47Ti, 51V, 52Cr, 55Mn, 57Fe, 59Co, 60Ni, 66Zn, and 71Ga, And whereas other elements above detection limits are mineral speciﬁc.

3.2. Data classiﬁcation

Trace element data were pre-treated following the method of Croghan and Egeghy (2003) such that LA-ICP-MS results that include CD up to 40% censored data were substituted with the detection limit di- Grt Po And And vided by the square root of 2. To unconstrain the data used for multivariate statistics and more easily recognize patterns in the dataset, a Qtz centered log-ratio transformation was applied using CoDaPack version Bt 2.01.15 (Muriithi, 2015). Using a multivariate statistical approach, Grt Cpy 1 mm 0.5 mm trace element data for garnet and biotite were discriminated through principal component analysis (PCA) on JMP Pro version 11.0.0. Prin- E And F cipal component analysis is a statistical method that extracts the Grt-Qtz Grt dominant sources of variation (i.e., principal components are the ei- Bt-Chl-Grt genvectors of a variance–covariance matrix) in a multivariate dataset, St thereby distinguishing trends in large datasets (Davis, 2002). In the Qtz present study, the following elements were analyzed: Li, Mg, Ca, Sc, Ti, Bt 1 mm V, Cr, Mn, Fe, Co, Ni, Zn, Ga, Ge, Sr, Y, Sn, Cs, Tl, and Pb, although the elements Ni, Sr, Sn, Cs, Tl, and Pb were generally below detection limits G H and not discussed further. Bt

4. Local geology Grt Po+Cpy Chl Qtz 4.1. Lithology Po+Cpy Po 1 cm 1 mm The Kanmantoo Cu-Au deposit is spatially associated with three I J major rock types: quartz-mica schist (QMS), a quartz-biotite-garnet- Po andalusite ± chlorite ± staurolite ± magnetite rock, and biotite- Cpy garnet-chlorite rock, the last of which is the immediate host to much of Ilm the sulfide mineralization. Minor rock types include exhalites (e.g., Mag quartz garnetite, garnet-quartz-cummingtonite schist, plagioclase rock, 1 cm banded iron formation), gahnite-bearing mica schist, pyritic schist, and 0.5 mm calc-silicate rocks (Verwoerd and Cleghorn, 1975; Seccombe et al., 1985; Oliver et al., 1998; Toteff, 1999; Schiller 2000). KL Quartz-mica schist consists principally of fine-grained quartz, bio- Cpy tite, muscovite, and feldspar with lesser garnet, chlorite, magnetite, Chl ilmenite, and sulfides (Fig. 3A; Spry et al., 1988). Whole rock compo- Po Mag sitions obtained by Spry (1976) and Drexel (1978) show that QMS contains 30–125 ppm Cu, 13–26 ppm Pb, and 68–175 ppm Zn. Relict bedding is defined by alternating bands of quartzofeldspathic and mi- Cpy 0.5 mm caceous schists, which are thought to represent original psammitic and pelitic rocks (Schiller, 2000). Fig. 3. Hand sample photos, photomicrographs, and a back-scattered electron image of The quartz-biotite-garnet-andalusite ± chlorite ± staurolite ± magnetite altered and unaltered rocks, and ore associated with the Kanmantoo deposit. A. Quartz- mica schist showing psammitic banding (S ) from KTDD141, Nugent; B. Garnet-andalu- and garnet-biotite-chlorite rocks are interpreted to be metamorphosed hydro- 0 site-biotite schist with porphyroblastic andalusite (And) from KTDD149, Kavanagh; C. thermally altered rocks. Whole rock analysis by Oliver et al. (1998) and Poikiloblastic andalusite with garnet (Grt), biotite (Bt), pyrrhotite (Po), and quartz (Qtz) Schiller (2000) show that these rocks involved a loss of K, Ca,Naandagainof in garnet-andalusite-biotite schist, plane-polarized light, KTDD149-586.2 m, Kavanagh; Fe, Mg, Si, and S during the alteration process. One common variant, garnet- D. Chalcopyrite (Cpy) in garnet within andalusite porphyroblasts in garnet-andalusite- andalusite-biotite schist (GABS), occurs as a series of lenses that run north–- biotite schist, upper plane-polarized light, lower reflected light, KTDD149-497.4 m, south through the Kanmantoo deposit for approximately 10 km in a N–Sdi- Kavanagh; E. Poikiloblastic andalusite, garnet, and staurolite (St) with biotite and quartz rection (Schiller, 2000; Wilson, 2009). Common minerals include garnet, an- in garnet-andalusite-biotite-staurolite schist, plane-polarized light, KTDD54-52 at 179.9 m, Kavanagh; F. Biotite-garnet-chlorite schist with garnet-quartz and biotite- dalusite, biotite, and quartz with minor staurolite, muscovite, chlorite, chlorite-garnet zones from a stockpile in the Kanmantoo mine; G. Biotite, chlorite, and fi – magnetite, ilmenite, rutile, and sul des (Fig. 3B D). Bulk rock compositions quartz with porphyroblastic garnet intergrown with pyrrhotite and chalcopyrite in bio- of GABS show that they contain 28–165 ppm Cu, 32–38 ppm Pb, and tite-garnet-chlorite-schist, plane-polarized light, KTDD149-497.4 m, Kavanagh; H. Meta- 71–113 ppm Zn (Spry, 1976; Drexel, 1978). Banding, which Wilson (2009) banded iron formation hand specimen, magnetite-quartz-cummingtonite-garnet from interpreted as relict bedding, is marked by coarse-grained layers of andalusite exhalite horizon ∼ 1 km north of the Kanmantoo deposit; I. Quartz garnetite hand spe- fi that grade into a finer-grained assemblage of andalusite-biotite-quartz. Anda- cimen, alternating ne grained laminations of quartz and spessartine garnet from exhalite horizon ∼ 1 km north of the Kanmantoo deposit; J. Ilmenite (Ilm)-magnetite (Mag)- lusite porphyroblasts are typically 5 mm in length but can range up to 3 cm, chalcopyrite-pyrrhotite ore, KTDD54-17 at 109.0 m, Kavanagh; K. Chalcopyrite-pyr- and occur within a well-developed schistose biotite-quartz matrix. rhotite-magnetite ore with chlorite (Chl), KTDD54-46 at 164.0 m, Kavanagh; L. Back- Garnet-andalusite-biotite-staurolite schist (GABSS) is a common variety scattered electron image of native bismuth, laitakarite, pyrite, and Se-bearing galena, of GABS that is enriched in staurolite and chlorite, and depleted in quartz KTDD54-45 at 163.7 m, Kavanagh.

98 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

(Fig. 3E). It contains garnet, andalusite, biotite, staurolite, and chlorite with Schiller (2000) estimated a peak metamorphic pressure of 3–4 kbar lesser quartz, sulfides, and magnetite. A weak foliation is defined by coarse- with peak temperatures of 530–565 °C and 480–510 °C at the Kan- grained biotite and muscovite. Where staurolite is the dominant mineral, it mantoo deposit based on phase equilibria and mineral geothermo- occurs with biotite as elongate grains up to 1.5 cm across. Staurolite-poor metry, respectively. Note that although Oliver et al. (1998) placed zones are characterized by finer-grained staurolite that occurs within a garnet growth syn- or post-peak metamorphism, Schiller (2000) sug- biotite-garnet-chlorite matrix (Toteff, 1999; Schiller, 2000). gested that garnet grew syn- to post-D1 but pre-peak metamorphism, Biotite-garnet-chlorite schist (BGCS) occurs within GABS and GABSS which is associated with D2. and immediately envelopes Cu-Au mineralization in the Kavanagh and Emily Star orebodies (Fig. 3F and G). The typical mineral assemblage con- 4.3. Mineralization sists of biotite, garnet, chlorite, quartz, and minor pyrrhotite, chalcopyrite, and magnetite. However, Spry et al. (1988) also noted other assemblages in Copper mineralization occurs as stockwork vein selvages and pipe- the altered rock package that include quartz-chlorite-garnet-biotite ± like podiform lenses dominated by chalcopyrite with lesser amounts of chalcopyrite, staurolite-biotite-garnet ± pyrrhotite ± chalcopyrite, staur- pyrrhotite, magnetite, pyrite, ilmenite, marcasite, sphalerite, cubanite, olite-biotite-garnet-chlorite ± chalcopyrite, and staurolite-chlorite-magne- chalcocite, covellite, pentlandite, mackinawite, cobaltite, molybdenite, tite ± pyrrhotite ± chalcopyrite. wolframite, bismuthinite, native bismuth, laitakarite, Se-bearing ga- Exhalative rocks, using the terminology of Ridler (1971) and Parr lena, native gold, and native silver (Fig. 3J–L; Seccombe et al., 1985; and Plimer (1993), were recognized by Toteff (1999) in QMS and GABS Faulkner, 1996; Gum, 1998; Oliver et al., 1998; Schiller, 2000; Abbott within 3 km of the Kanmantoo mine (Fig. 3H and I). The most promi- et al., 2005; Arbon, 2011). Sulfide lodes are commonly discordant to nent exhalative horizon occurs within and along strike from the Nugent relict bedding in the Kavanagh orebody and are enveloped in lenses of orebody in a north–south trending direction. In the Nugent orebody, GABS and BGCS that steeply plunge 80° northeast (Seccombe et al., exhalative rocks are manifested as a 10-m thick spessartine garnet- 1985; Flöttmann et al., 1998; Gum, 1998; Toteff, 1999). Sulfides also quartz rock (i.e., quartz garnetite) that consists of garnet, muscovite, occur within S2-parallel veins, shears, and fault zones, and as massive quartz, biotite, and lesser pyrite, pyrrhotite, and chalcopyrite. North- pockets, bands, and disseminations parallel to relict bedding (Preiss, east and east of the Kavanagh orebody an exhalative unit consisting of 1995; Gum, 1998; Oliver et al., 1998; Abbott et al., 2005). Although banded iron formation, up to 19 m wide, contains quartz, magnetite, sulfides occur in lenses of GABS, Schiller (2000) found that lodes as- cummingtonite, and minor garnet, which extends intermittently for sociated with BGCS contain the highest copper grades. The stratiform ∼1.8 km, is the most prominent exhalative unit in the Kanmantoo nature of the Nugent orebody can be observed in drill core where sul- Group (Smith, 1998; Toteff, 1999). Between the Nugent orebody and fides parallel alternating layers of garnet and quartz, and because of the the banded iron formation is an outcrop of gahnite-bearing muscovite concordancy of sulfides to bedding in adjacent drill holes (David schist. Other exhalative rocks identified by Toteff (1999) include Rawlins, personal communication, September 2017). Unfortunately, we magnetite-rich andalusite schist and albitite. At the Scotts Creek Pb-Zn- were unable to observe sulfide mineralization in the Nugent pit because Ag-(Cu-Au) prospect, 2.5 km SW of the Kanmantoo mine, sulfide mi- of a wall collapse that covered mineralization prior to the current study. neralization is enclosed in a fine-grained spessartine garnet-plagioclase Chalcopyrite in the Kanmantoo deposit occurs as disseminated grains, rock. generally up to 4 mm in length, intergrown with pyrrhotite and secondary Pyritic schist and calc-silicate horizons occur within quartzofelds- pyrite, and also as massive bands and veins. Sulfide ± quartz veins are pathic schists above and below base-metal mineralization (Schiller, typically cm- to m-scale in length and range from 1 to 15 mm across 2000). Pyritic schists are enriched in pyrite with lesser pyrrhotite, ga- (Schiller, 2000). Chalcopyrite grains may also contain inclusions of pyr- lena, and sphalerite, whereas calc-silicates are enriched in amphibole rhotite, magnetite, sphalerite, secondary pyrite, native bismuth, bismuthi- (i.e., hornblende and actinolite), plagioclase, and quartz. Pyritic schist nite, galena, and native gold. Pyrrhotiteoccursasabundantanhedralgrains. and calc-silicate rocks are thought to be derived from sulfide-rich black Magnetite is commonly associated with chlorite, and occurs as euhedral to shale and marl, respectively (Jensen and Whittle, 1969; Gum, 1998; subhedral grains up to 0.5 mm in diameter. Three generations of pyrite are Schiller, 2000). noted: pre-metamorphic colloform pyrite with inclusions of magnetite, ilmenite, sphalerite, and chalcopyrite, late syn-metamorphic euhedral pyrite 4.2. Structure and metamorphism in veins with chalcopyrite, and supergene botryoidal melnikovite pyrite locally intergrown with marcasite that is likely after pyrrhotite along with The Kanmantoo deposit is located on the western limb of the late cavity-filling supergene pyrite (Seccombe et al., 1985). Schiller (2000) Kanmantoo syncline and is spatially associated with a smaller-scale and Arbon (2011) observed two generations of chlorite, an early Fe-poor parasitic synform that runs directly through the main pit, termed the (Mg-rich) chlorite and a later Fe-rich chlorite hosting magnetite and bis- “Mine Synform” (Schiller, 2000). This feature is a shallow southerly muth minerals. plunging F2 fold with a slightly east-dipping axial plane (Seccombe et al., 1985; Toteff, 1999). The western limb of the synform is char- 5. Results acterized by indistinct bedding, shear planes sub-parallel to the S2 schistosity that strikes north and plunges steeply to the east, and bou- 5.1. Mineral compositions dinaged veins, whereas on the eastern limb clearly defined bedding and rare shear planes are observed (Schiller, 2000). Bedding ranges from Analyses of silicates (garnet, biotite, staurolite, chlorite, and muscovite) fine laminations to > 1 m wide massive beds, which are commonly and oxides (magnetite) were obtained from 104 samples from five drill folded and vary from tight folds in QMS to open folds in GABS. One of holes intersecting the Kavanagh, Emily Star, and Nugent orebodies. the best-preserved microstructures is a well-developed S2 schistosity Representative major, minor, and trace element compositions of garnet, that has a general north-south trend and wraps around porphyroblasts, biotite, staurolite, chlorite, muscovite, and magnetite in garnet-andalusite- which locally contain D1 planar inclusion trails (Spry et al., 1988; biotite schist (GABS), garnet-andalusite-biotite-staurolite schist (GABSS), Oliver et al., 1998). Shears are common features at all scales in the and biotite-garnet-chlorite schist (BGCS) at Kanmantoo are given in Table 1. Kanmantoo deposit. Faults consist of cm- to m-scale normal and reverse Supplementary files of major element and trace element data collected for faults that commonly cross-cut one another (Wilson, 2009). Three types this study are in an electronic supplement that accompanies the paper. of veins occur at the mine and consist of the assemblages quartz ± Major element compositions of garnet, biotite, staurolite, and muscovite in sulfide, sulfide ± quartz, and quartz-silicate ± sulfide (Schiller, unmineralized altered and unaltered schist from the Kanmantoo Group 2000; Wilson, 2009). were derived from the studies of Bollenhagen (1993), Smith (1998),and

99 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Table 1 Representative compositions of garnet, biotite, staurolite, chlorite, and muscovite.

Garnet Biotite Staurolite Chlorite Muscovite Magnetite

Wt.% 1 2 3 4 5 6 7 8 9 10 11 12

SiO2 36.64 36.97 37.20 35.28 35.96 34.59 27.62 27.50 23.69 24.00 46.58 –

TiO2 0.01 0.00 0.04 1.56 1.98 1.48 0.46 0.45 0.06 0.03 0.21 0.98

Al2O3 20.26 21.06 21.29 20.74 21.12 20.9 53.26 53.79 24.25 25.49 34.85 0.44

Fe2O3 –– ––––– –0.13 0.92 – 67.05 FeO 38.90 37.66 22.07 20.08 20.85 21.23 14.91 14.12 27.20 25.29 1.95 32.18 MnO 1.39 2.69 14.67 0.13 . 0.04 0.07 0.10 0.03 0.08 0.01 0.00 MgO 2.57 1.53 2.43 8.99 7.96 7.26 1.39 1.07 13.00 12.90 0.73 0.03 CaO 0.47 0.34 2.33 0.01 0.06 0.06 ––. 0.01 0.01 –

Na2O3 –– – 0.26 0.32 0.14 ––0.02 – 0.53 –

K2O –– – 9.09 8.72 9.69 ––0.03 0.01 9.59 – ZnO –– ––––0.39 1.06 ––– 0.00 F –– – 0.01 – . ––. 0.01 . – Cl –– – 0.03 0.02 0.18 ––0.01 . 0.04 –

H20 –– – 3.97 4.01 . ––11.36 11.49 4.47 – Total 100.24 100.27 100.02 100.14 100.14 99.45 98.10 98.09 99.78 100.23 98.98 100.68

Number of atoms in formulae (garnet oxygen basis 12, staurolite 23, biotite 12, chlorite 38, muscovite 11, magnetite 4) Si 2.974 3.011 2.996 5.319 5.365 5.308 3.850 3.832 4.997 4.989 6.231 – Ti 0.000 0.000 0.002 0.177 0.177 0.171 0.048 0.047 0.010 0.005 0.021 0.029 Al 1.938 2.022 2.021 3.685 3.713 3.780 8.752 8.834 6.035 6.265 5.490 0.017 Fe3+ –– ––––– –0.020 0.144 – 1.925 Fe2+ 2.528 2.565 1.487 2.531 2.601 2.725 1.739 1.646 4.798 4.397 0.218 1.029 Mn 0.095 0.186 1.001 0.017 0.000 0.005 0.008 0.012 0.004 0.014 0.001 0.000 Mg 0.311 0.186 0.292 2.020 1.770 1.662 0.289 0.222 4.087 3.999 0.146 0.001 Ca 0.041 0.029 0.201 0.001 0.010 0.011 ––0.001 0.003 0.001 – Na –– – 0.075 0.093 0.043 ––0.019 0.000 0.138 – K –– – 1.748 1.660 1.897 ––0.015 0.004 1.637 – Zn –– ––––0.040 0.109 ––– 0.000 OH –– – 3.990 3.995 3.953 ––15.996 15.981 3.991 – F –– – 0.003 – 0.001 –––0.019 –– Cl –– – 0.007 0.005 0.046 ––0.004 0.000 0.009 – Total 7.887 7.999 8.000 23.259 23.147 23.381 14.726 14.704 35.987 35.820 17.889 3.000 Li 34.40 9.45 17.08 46.55 55.82 47.50 178.15 352.91 38.43 17.94 7.53 0.63 Na 129.06 38.05 107.93 – 2,917 946.18 – 95.05 12.86 15.97 – 13.80 Mg 13,619 9,871 14,621 50,343 50,914 42,234 6,514 6,534 83,412 210,476 3,629 83.49 Al 111,000 113,000 113,000 109,000 113,000 110,000 282,000 285,000 127,000 130,000 122,000 360.24 Si 150,266 151,425 174,317 24,053 217,842 156,874 15,473 127,471 119,195 124,753 18,425 2,741 P 556.36 181.11 38.19 270.79 30 103.91 296.78 46.52 258.22 55.29 30.38 3,525 K –– – 68,148 87,026 72,884 45.38 – 227.23 – 52,922 43.22 Ca 1208 3813 15,487 112.95 99.16 31.45 – 61.02 593.55 31.45 – 251.37 Sc 34.64 32.30 26.49 35.11 9.54 15.78 0.65 0.85 5.08 6.17 14.56 – Ti 80.82 16.56 130.84 9,318.74 10,963 8,063.00 2,917.91 2,380.76 500.56 388.84 607.01 0.47 V 26.40 15.29 39.76 229.16 312.57 291.75 119.72 83.11 66.35 250.08 67.61 787.27 Cr 92.91 33.13 57.49 160.43 123.99 363.11 357.00 161.82 18.43 183.08 104.34 1746 Mn 6646 86,265 77,797 775.31 131.93 375.09 572.48 462.46 364.10 270.94 64.12 79.33 Fe 257,323 1,881,583 421,388 151,374 169,184 143,980 108,816 100,989 199,296 195,496 14,003 344.22 Co 15.56 21.51 5.99 43.73 47.18 81.04 101.41 36.40 88.12 84.17 5.90 730,000 Ni 1.26 0.32 – 137.26 67.75 172.40 3.30 22.38 101.52 66.41 1.68 27.69 Cu 26.91 – 1.59 0.04 652.60 625.71 0.26 54.57 2.01 0.89 3.86 39.53 Zn 9.50 22.99 20.16 462.97 212.48 72.93 4,098.73 7,989.46 129.42 183.73 3.50 19.21 Ga 3.52 5.28 4.89 52.71 79.14 26.78 290.76 185.05 46.80 80.27 38.25 23.17 Ge 5.48 6.90 17.14 1.35 0.30 1.15 4.03 6.70 1.98 0.40 1.41 142.10 As 1.07 0.50 1.29 – 1.29 1.05 0.93 1.16 8.25 –– 0.50 Rb 0.05 0.02 0.03 470.49 588.88 462.13 0.01 0.29 0.21 0.04 195.94 1.41 Sr 0.03 0.04 0.05 3.99 3.63 0.64 0.04 0.20 0.07 0.53 15.73 1.27 Yb 18.34 1,723.99 3,121.36 0.01 0.60 0.43 0.01 0.05 0.33 0.28 0.01 0.32 Zr 9.66 5.42 4.33 4.10 0.96 4.81 0.07 1.88 0.65 1.70 0.02 0.81 Nb 0.02 0.02 0.07 36.04 45.15 36.37 4.61 3.59 0.39 0.82 5.09 6.59 Mo –– ––––0.06 – 1.22 1.02 – 0.23 Cd –– 0.89 1.33 5.23 – 0.21 5.13 0.72 3.17 –– In 0.06 0.10 0.04 0.75 0.03 – 0.03 0.48 0.49 – 0.19 – Sn 1.77 0.71 0.88 11.84 6.26 9.66 0.56 0.26 1.59 1.68 6.33 – Sb –– – 0.76 – 0.33 0.08 1.10 0.55 –– 7.47 Cs –– – 15.04 19.67 11.79 – 0.13 0.03 – 0.63 – Ba 0.26 0.06 – 846.98 682.31 513.54 0.27 0.29 1.01 0.24 857.60 0.12 La –– – – 0.04 0.02 –––0.05 – 5.45 Ce 0.00 ––0.07 0.07 0.03 – 0.03 0.09 0.22 – 0.16 Pr 0.15 –––0.06 0.01 – 0.05 0.02 –– 0.14 Nd 0.10 – 0.23 – 0.70 0.10 – 0.88 – 0.30 0.06 – Sm 0.76 0.53 3.57 – 0.17 –– 0.17 0.44 0.15 – 0.12 Eu 0.02 0.39 1.41 0.10 0.04 0.03 0.01 0.16 0.31 0.01 0.06 – Gd 0.50 7.48 38.31 – 0.27 0.12 0.06 0.17 0.18 0.05 – 0.07 Tb 0.84 4.45 16.27 – 0.03 0.01 0.00 0.03 0.02 0.02 0.00 0.27 Dy 4.23 55.80 139.16 – 0.46 0.05 0.09 0.14 0.14 0.05 – 0.15 (continued on next page)

100 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Table 1 (continued)

Garnet Biotite Staurolite Chlorite Muscovite Magnetite

Ho 0.66 13.33 29.81 0.00 0.03 0.02 0.02 0.03 0.02 0.03 0.01 0.01 Er 1.74 35.83 94.40 0.01 0.13 0.03 – 0.13 0.07 0.03 –– Tm 0.07 4.21 12.96 – 0.08 0.01 – 0.03 – 0.01 –– Yb 1.90 26.83 94.01 – 0.20 0.11 – 0.79 0.13 0.07 – 0.14 Lu 0.18 2.82 13.37 – 0.03 0.01 – 0.09 0.04 0.04 – 0.43 Hf 0.29 ––0.01 – 0.20 0.01 ––0.35 0.01 – Ta 0.01 0.02 0.05 2.89 3.70 2.90 1.31 1.31 0.02 0.07 0.20 0.10 W 0.05 0.04 – 1.18 1.30 0.92 0.16 0.71 0.46 0.26 3.19 – Tl 0.09 ––3.07 4.30 2.86 0.00 – 0.03 0.03 0.38 11.83 Pb 0.35 0.48 – 55.83 36.33 24.72 0.02 10.92 0.16 9.62 0.02 0.07 Bi – 0.01 – 0.04 0.08 0.09 0.01 3.70 – 0.02 0.01 6.42 Th 0.04 – 0.13 – 0.22 0.05 –––0.16 –– U 0.02 0.02 0.11 0.06 0.08 0.06 0.00 0.07 0.03 0.47 0.04 0.73

Major elements are by electron microprobe analyses and given in weight%, whereas trace elements are given in ppm and derived from LA-ICP-MS analyses. 1 Garnet in garnet-andalusite- biotite-staurolite schist, Kavanagh (KTDD54-40); 2 Garnet in garnet-andalusite-biotite schist, Emily Star (KTDD34-17); 3 Garnet in quartz-garnetite (exhalite), Nugent (KTDD141-66.0); 4 Biotite in garnet-andalusite-biotite schist, Kavanagh (KTDD149-90.7); 5 Biotite in garnet-andalusite-biotite schist, Emily Star (KTDD34-3); 6 Biotite in garnet-biotite-chlorite schist, Nugent (KTDD125-5); 7 Staurolite in garnet-andalusite-biotite schist, Kavanagh (KTDD149-294.8); 8 Staurolite in garnet-andalusite-biotite schist, Emily Star (KTDD34-10); 9 Chlorite in garnet-andalusite-biotite-staurolite schist, Kavanagh (KTDD54-45); 10 Chlorite in garnet-biotite-chlorite schist, Nugent (KTDD125-16); 11 Muscovite in garnet-andalusite-biotite schist, Kavanagh (KTDD149-200.7); 12 Magnetite in garnet-biotite-chlorite schist, Kavanagh (KTDD54-43); - below detection limits.

Hammerli et al. (2016), and compared with the compositions of silicates Major and trace element bivariate plots of garnet (in ppm) are presented and oxides in mineralized altered rocks that were obtained here. A limited in terms of Zn vs. Mn (Fig. 8A), Zn vs. Gd (Fig. 8B), Ge vs. Gd (Fig. 8C), and number of trace element data for biotite, muscovite, and garnet in un- Co vs. V (Fig. 8D).TheplotsofZnvs.Mn,andZnvs.Gdreflect the patterns mineralized country rock schist are given in Hammerli et al. (2016) and are showninthePCAinthatthecompositionofgarnetindrillholeKTDD141 also compared with data obtained for these minerals in the present study. (Nugent) are distinguished, primarily due to the enrichment in Zn for garnet Note that end-member garnet compositions shown in the supplementary in altered rocks from Kavanagh and KTDD125 (Nugent), with the composi- file take into account Fe in both the tetrahedral (Fe2+)andoctahedral tions of garnet from Emily Star forming a transition between these two (Fe3+) sites, although the Fe content in the latter site is minor to non- clusters of data. Set apart from the clustered samples in Fig. 8A, garnet in existent in nearly all analyses. Nugent (KTDD141) occurs as an isolated group of data characterized by elevated Zn (up to 170 ppm) and Mn (up to 19.5 wt% MnO). For comparison, garnet analyzed from pelitic and psammitic rocks in the Tapanappa 5.1.1. Garnet Formation, metamorphosed to amphibolite facies ∼ 25 km northeast End-member compositions of garnet from GABS, GABSS, BGCS, of Kanmantoo, contains 13.6–16.8 ppm Zn and 1.6–7.4 wt% MnO quartz-mica schist (QMS), and quartz garnetite are plotted relative to (Bollenhagen, 1993; Smith, 1998; Hammerli et al., 2016). Enrichment in Ge stratigraphy and assay values of Cu and Au in the five drill holes studied (0.23–27.8 ppm) and Gd (∼10.1–66.0 ppm) in garnet from both drill holes here (Fig. 4), along with a ternary diagram (Fig. 5), and bimodal plots intersecting the Nugent orebody can be distinguished from those associated of Ca vs. Mn (Fig. 6A) and Fe vs. Mn (Fig. 6B). Figs. 5 and 6A and B also with the Kavanagh and Emily Star orebodies, which generally have Ge va- show the compositions of garnet from unmineralized altered and un- lues < 10 ppm and Gd values < 24 ppm (6.13–16.9 ppm Gd in Hammerli altered schist from Bollenhagen (1993), Smith (1998), and Hammerli et al., 2016; Fig. 8C). Additionally, garnet in Nugent (KTDD141) is depleted et al. (2016). Garnet in these schists shows the following range of in Co (< 18 ppm) relative to garnet in altered rocks from the Kavanagh and compositions: 0.25–2.3 wt% CaO, 1.6–7.4 wt% MnO, and 29.4–39.0 wt Emily Star orebodies (4.77–93.5 ppm Co; Fig. 8D). In a plot of Co vs. V % FeO. Garnet in GABS, GABSS, and BGCS from the Kavanagh and (Fig. 8D), the trace element compositions of garnet from the two Kavanagh Emily Star orebodies and drill hole KTDD125 through the Nugent drill holes overlap. Garnet in altered rocks associated with drill hole orebody are generally more Fe-rich (31.1–42.0 wt% FeO), and are KTDD149 are generally more enriched in Co (up to 78.5 ppm), whereas those markedly different in composition from garnet in GABS and quartz- from KTDD54 commonly have V concentrations < 20 ppm. Those of garnetite in drill hole KTDD14 that intersects the northern end of the Hammerli et al. (2016) range from 32.1 to 43.9 ppm V. Nugent orebody (17.8–33.0 wt% FeO, 5.07–19.5 wt% MnO, Rare earth element (REE) patterns for garnet normalized to chondrite 1.38–5.01 wt% CaO; Table 2). values of McDonough and Sun (1995) show enrichment in heavy REEs A principal component analysis (PCA, n = 384) of major, minor, (HREE) relative to light REEs (LREE; Fig. 9A–C). Garnet in altered rocks from and trace elements that are typically above detection limits (i.e., Li, Mg, drill hole KTDD141 (Nugent) show more elevated normalized HREE values Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, Ga, Ge, and Y) was undertaken to than those in drill hole KTDD125 (Nugent). Of 62 REE patterns obtained further identify compositional variations for garnet in altered rocks here, 46 are characterized by a weak negative Eu anomaly with Eu/Eu∗ <1 0.5 associated with the Kavanagh, Emily Star and Nugent orebodies (Eu/Eu∗ =(Euchondrite/([Smchondrite/Gdchondrite] ); Taylor and McLennan, (Fig. 7A–C). The scores of the first two principal components are re- 1985), whereas 16 patterns exhibit weak positive anomalies of close to 2. presented along the x- and y-axes on the bivariate score plot (Fig. 7A). Some variability occurs in the Nd concentration in garnet, which is likely the Scores for garnet from the Kavanagh orebody and drill hole KTDD125 result of it incorporating varying amounts of unidentified inclusions of a from the Nugent orebody generally overlap, and can be distinguished LREE mineral. from garnet in altered rocks in drill hole KTDD141 (Nugent) that are offset to the left in Fig. 7A. Garnet in Emily Star possesses compositions that transition between these two clusters of data. Principal component 5.1.2. Biotite 1 (PCA1) accounts for 39.9% of variance and reveals a negative cor- Biotite from QMS, GABS, GABSS, and BGCS in the Kavanagh, Emily relation between Ca, Ti, Mn, Zn, Ge, and Y, and Li, Mg, Sc, V, Cr, Fe, Co, Star, and Nugent orebodies show a compositional range with values of and Ga, whereas PCA2 accounts for 11.9% of variance and shows a 13.8–25.9 wt% FeO, 6.39–13.2 wt% MgO (Fig. 10A), intermediate XFe negative correlation between Li, Sc, V, Mn, Fe, Ga, Ge, and Y, and Mg, ratios of 0.38 to 0.67, and AlIV of 2.59 to 2.81 (Fig. 10B). Biotite with

Ca, Ti, Cr, Co, and Zn (Fig. 7C). the lowest XFe ratios are those in the Nugent orebody (0.38 to 0.52) that

101 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

A. KTDD149 (Kavanagh) B. KTDD54 (Kavanagh) C. KTDD34 (Emily Star) 100 100 Cu % Cu % 2.5 2.5 25 50 25 50 75 Cu % 75

0 0 0

05 52 001 5 0 4 8 0 5 0 0 0 0

100

50 20 200

300 100

400

150

500 60

588.6 1.2 71.3 0.8 0 0.4

198.2 0 0.8 0.4 0 0.6 0.3 Alm + Pyr Alm + Pyr

Alm + Pyr

srG

srG srG

spS

spS Au ppm Au ppm Au ppm spS

D. KTDD141 (Nugent) E. KTDD125 (Nugent) 100 100 25 50 75

25 50 Cu % Cu % 75 0 0 1 2 0 2 4 0 0 0 Quartz veining Overburden 10.8 Quartz-mica schist 15.1 Quartz garnetite 20 20.1 (exhalite) 50 27.2 Garnet-andalusite- biotite schist 37.2 Biotite-garnet 40 chlorite schist 81.7 87.0 Garnet-andalusite- biotite-staurolite 100 107.0 112.7 schist 118.9 60 123.4 62.4 127.1 66.0

77.1 150 80 153.5 162.7 167.1 87.3

89.8 0 3 2 1 15

0 174.3 5 25 Alm + Pyr

Alm + Pyr

srG srG

spS Au ppm Au ppm spS

Fig. 4. Schematic stratigraphic sections with corresponding Cu and Au assay values, and garnet compositions in terms of grossular (Grs), spessartine (Sps), and almandine (Alm) + pyrope (Pyr). A. KTDD149, Kavanagh; B. KTDD54, Kavanagh; C. KTDD34, Emily Star; D. KTDD141, Nugent; E. KTDD125, Nugent. were sampled from drill hole KTDD141. Although limited in number, orebodies, but have a wider range of AlIV values (2.37 to 2.99). In biotite analyzed by Bollenhagen (1993) and Hammerli et al. (2016) general, biotite in unmineralized schist is enriched in Mn and depleted from country rock mica schists in the Kanmantoo Group have similar in Al relative to those associated with Cu-Au mineralization.

XFe ratios to those in rocks spatially associated with the Kanmantoo Representative trace element compositions of biotite are shown in

102 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Alm + Pyr Emily Star (KTDD34) observed for the PCA for garnet, samples of biotite in QMS from 10 Nugent (KTDD141) 90 KTDD141 (Nugent) plot separately and can be distinguished from the Nugent (KTDD125) 20 other samples analyzed here primarily due to the high score value of Kavanagh (KTDD149) 80 country rocks Zn. 30 Kavanagh (KTDD54) 70 Bollenhagen (1993) 40 Smith (1998) 60 5.1.3. Staurolite Pb-Zn-Ag deposits 50 Staurolite in QMS, GABS, GABSS, and BGCS are Fe-rich (12.1–17.2 wt% Hammerli et al. (2016) 50 FeO, X =0.82–0.89). Of the 62 samples of staurolite analyzed here, 61 60 Fe 40 contain up to 1.60 wt% ZnO, with one outlier sample (KTDD125-2) that 70 30 contains up to 3.20 wt% ZnO (Fig. 11A). The major element compositions are 80 similar to those reported previously from the Kanmantoo deposit by Schiller 20 (2000) that contain up to 1.32 wt% ZnO. Trace element analyses show that 90 10 staurolite also contains elevated concentrations of Mn (46–2,070 ppm), Co (23.4–344 ppm), and V (14.9–285 ppm; Table 1). Bivariate plots (in terms of Spess Gros 90 80 70 60 50 40 30 20 10 ppm) are shown for Zn vs. Mn (Fig. 11B) and Co vs. V (Fig. 11C). Although drill holes KTDD149 and KTDD54 intersect the Kavanagh orebody, Zn and Co Fig. 5. Ternary plot of average garnet composition for individual samples from the values are markedly diﬀerent in that most samples from KTDD149 contain up Kanmantoo deposit and country rock schist (Bollenhagen, 1993; Smith, 1998; Hammerli et al., 2016) shown by an ellipse. The compositional ﬁeld of garnet associated with Pb-Zn- to 16,230 ppm Zn and 344 ppm Co, whereas samples from drill hole KTDD54 Ag-(Cu-Au) deposits is shown as a separate ellipse. contain < 9,622 ppm Zn and < 121 ppm Co (Fig. 11C).

Table 1. Bivariate plots (in ppm) for Zn vs. Mn, and Zn vs. Pb are shown 5.1.4. Chlorite in Fig. 10C and D, respectively. In these plots, biotite in KTDD141 is As was recognized previously by Schiller (2000) and Arbon (2011) and fi – distinguished from biotite in other drill holes due to an enrichment in veri ed here, chlorite consists of an early Mg-rich variety (XFe =0.38 0.69) – both Mn and Zn (> 1,070 ppm Mn and > 410 ppm Zn). Relative to and a late Fe-rich variety (XFe =0.71 0.95; Fig. 12A). Although both fi biotite compositions in unaltered country rock schist obtained by generations are associated with sul de mineralization, the Fe-rich chlorite is Hammerli et al. (2016), which contain 23.6–167 ppm Zn and spatially associated with magnetite and Bi mineralization. Chlorite from 0.41–11.4 ppm Pb, biotite in most samples from the Kanmantoo deposit GABS, GABSS, and BGCS in the Kavanagh, Emily Star, and Nugent are elevated in Pb (9.27–110 ppm); those from drill hole KTDD141 (KTDD141) orebodies cluster toward the ripidolite end-member, whereas (Nugent) are elevated in Zn (413–1,592 ppm). thosefromKTDD125(Nugent)occuroverabroadercompositionalrange. A principal component analysis (n = 217) of the 10 trace elements Magnesium-rich chlorite in drill hole KTDD141 (Nugent) has a narrow – – for biotite typically above detection limits (i.e. Co, Cs, Ni, Pb, Sc, Sn, Sr, compositional range of 15.8 18.3 wt% MgO and 19.1 22.3 wt% FeO, Tl, V, and Zn) was used to further identify sources of compositional whereas Mg-rich chlorite in Kavanagh and Nugent (KTDD125) ranges from – variation in biotite associated with QMS, GABS, GABSS, and BGCS from 11.5 to 14 wt% MgO and 24.4 29.8 wt% FeO. Those from Emily Star are – – the Kavanagh, Emily Star, and Nugent orebodies (Fig. 12E and F). characterized by less Mg (6.28 10.8 wt% MgO) and more Fe (29.3 35.4 wt Scores for the first two principal components show a score plot of % FeO) relative to chlorite from NugentandKavanagh.Conversely,Fe-rich PCA1 = 24.2% and PCA2 = 18.7% (Fig. 10E). Biotite in GABS, GABSS, chlorite from Kavanagh (KTDD54) and Nugent (KTDD125) are more Fe-rich – – and BGCS from Kavanagh, Emily Star, and approximately half the (24.6 40.7 wt% FeO) and Mg-poor (3.40 13.9 wt% MgO; Fig. 12B). samples from Nugent (KTDD125) are compositionally similar and Other than the major elements (Mg, Fe, Al, and Si), chlorite is en- cluster around the center of the score plot. Scores for the other half of riched in Mn, Co, Zn, Ba, and Pb (Table 1). Mg-rich chlorite from samples from KTDD125 sit to the right of the main cluster, due to en- KTDD141 (Nugent), contains > 1780 ppm Mn and 725 to 1600 ppm richments in Cs, Tl, and to a lesser extent Pb and Sr (Fig. 10F). As Zn (Fig. 12C), whereas Fe-rich chlorite from Kavanagh and Nugent (KTDD125) contains 153–628 ppm Mn and 106–202 ppm Zn. It is noted

0.45 A 2.8 B

0.40 2.4 0.35 Country rock schist 2.0 0.30 0.25 1.6 Emily Star (KTDD34) Ca (apfu) 0.20 Fe (apfu) 1.2 Nugent (KTDD141) Nugent (KTDD125) 0.15 Kavanagh (KTDD149) 0.8 Kavanagh (KTDD54) 0.10 Bollenhagen (1993) 0.4 0.05 Country rock schist Smith (1998) Hammerli et al. (2016) 0 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Mn (apfu) Mn (apfu)

Fig. 6. Compositions of garnet from the Kanmantoo deposit and country rock schist (noted by an ellipse; Bollenhagen, 1993; Smith, 1998; Hammerli et al., 2016). A. Ca (apfu) vs. Mn (apfu). B. Fe (apfu) vs. Mn (apfu).

103 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Table 2 Compositions of metamorphosed unmineralized country rock in the Kanmantoo group compared to samples from the Kanmantoo deposit.

Garnet Biotite Muscovite

Country rockA,B,E 1 2 Country rockA,E 1 2 Country rockA,E FeO wt% 29.4–39.0 17.8–33.0 31.1–42.0 16.3–22.8 13.8–18.9 18.1–25.9 0.34–3.38 MnO wt% 1.6–7.4 5.07–19.5 0.29–7.29 0–0.34 0–0.05 0–0.16 0.00–0.10 MgO wt% 1.7–2.6 1.41–2.88 1.15–3.03 7.7–10.9 9.47–13.2 6.39–10.4 0.17–0.80 CaO wt% 0.25–2.3 1.38–5.01 0.15–2.01 0.08–0.35 0–0.19 0–0.18 0.03–0.26 V ppm 32.1–43.9 39.7–61.2 1.57–87.7 221–679 126–212 66.5–545 187–298 Co ppm – 2.78–17.9 4.77–93.5 – 23.0–61.0 22.7–263 – Cu ppm – 0.09–7.54 0.03–7.65 1.5–374 1.77–139 0.04–24,330 < 2.85 Zn ppm 13.6–16.8 18.7–170 0.51–52.0 23.6–214 413–1592 21.6–841 1.78–6.89 Ge ppm – 8.27–27.8 0.23–22.1 – 0.30–2.87 0.00–4.57 – Gd ppm 6.13–16.9 10.1–66.0 0.00–60.0 0.13–0.57 0.17–1.97 0.02–5.62 – Pb ppm 0.02–0.17 0.19–3.64 0.02–3.75 0.41–11.4 21.1–168 9.27–110 0.79–23.9

Muscovite Staurolite Chlorite 1 2 Country rockA,C,D 2 1 2 Fe-rich chlorite FeO wt% 0.65–0.78 0.74–2.68 12.9–15.4 12.1–17.2 19.1–22.3 24.4–35.4 24.6–40.7 MnO wt% 0–0.01 0–0.05 0.18–0.55 0–0.19 0–0.07 0–0.13 0.01–0.17 MgO wt% 0.58–0.88 0.18–0.98 1.0–1.59 0.94–1.76 15.8–18.3 6.28–14.1 3.40–13.9 CaO wt% 0–0.03 0–0.04 ––0–0.04 0–0.09 0–0.05 ZnO wt% ––0.11 0.09–3.20 –– – V ppm 15.8–116 40.9–370 – 14.9–285 78.9–209 15.4–293 98.9–272 Co ppm 0.97–2.28 0.37–7.74 – 23.4–344 20.5–98.7 15.6–400 65.3–190 Cu ppm 3.86–14.42 0.25–173 – 0.4–112 0.25–61.7 0.04–593 0.09–27.5 Zn ppm 77.6–108 0.51–77.6 – 1,856–17,134 725–1602 13.4–763 106–202 Ge ppm 0.13–1.53 0.09–5.00 – 0.23–10.7 0.07–4.00 0.07–9.85 0.10–3.64 Gd ppm ∼0.07 0.06–1.17 – 0.02–0.88 0.09–1.31 0.02–2.1 0.04–1.34 Pb ppm 102–118 0.02–272 – 0.00–13.9 0.04–18.0 0.00–29.8 0.03–1.45

Compositions of garnet, biotite, and muscovite are shown for unmineralized metapelites and metapsammites in the Kanmantoo Group compared with compositions characteristic of those in (1) QMS and quartz garnetite from KTDD141 (Nugent) and those from (2) GABS, GABSS, and BGCS from KTDD54, KTDD149, KTDD34, and KTDD125 (Kavanagh, Emily Star, Nugent); Major element composition of staurolite in unmineralized metapelites and metapsammites from the Kanmantoo Group compared to those in (2); Chlorite compositions at the Kanmantoo deposit only for (1) those in QMS and quartz garnetite from KTDD141 (Nugent) compared to those in (2), and late Fe-rich chlorite from Nugent and Kavanagh. A Bollenhagen (1993). B Smith (1998). C Toteff (1999). D Schiller (2000). E Hammerli et al. (2016). here that chlorite in Emily Star is characterized by an enrichment in Cu in GABS, GABSS, and BGCS. Concentrations above detection limits (up to 593 ppm) relative to all other samples that typically contain < were observed for Al (1,375–7,070 ppm), Ca (50–12,000 ppm), Ti 10 ppm Cu. The reason for this is unclear, although it is possible that (265–4,520 ppm), V (291–5,085 ppm), Cr (1.0–1,285 ppm), Cu the laser ablation analysis contained an inclusion of chalcopyrite. (0.01–23,200 ppm), Zn (0.10–12,715 ppm), and Ga (3.3–252 ppm; Table 1). A bivariate plot (in ppm) of Ni vs. Cr shows that relative to 5.1.5. Muscovite magnetite compositions obtained by Tedesco (2009), magnetite ana- Trace element compositions of muscovite from QMS, GABS, lyzed here from Emily Star is elevated in Ni (up to 407 ppm), whereas and BGCS that are generally above detection limits include Na some samples from Kavanagh are elevated in Cr (up to 1,285 ppm; (2,306–31,032 ppm), Mg (2,283–11,071 ppm), Ca (115–1,183 ppm), Ti Fig. 14A). A plot of Sn/Ga (ppm) vs. Al/Co (ppm) was developed by (385–4977 ppm), V (31–724 ppm), Cr (7–751 ppm), Sr (31–973 ppm), Singoyi et al. (2006) to assess provenance of hydrothermal magnetite – and Ba (2,014–31,023 ppm; Table 1). Muscovite in unaltered country from skarns, iron oxide-copper gold, Broken Hill-type Pb-Zn-Ag, and fi rocks in the Kanmantoo Group contain 155–465 ppm Mn, 187 volcanic-hosted massive sul de (VHMS) deposits. Although there is no fi –298 ppm V, and 8.98–125 ppm Sr (Hammerli et al., 2016). In Fig. 13A, designated eld for SEDEX deposits, it should be noted here that most fi compositions of muscovite from Kavanagh (KTDD149) and Emily Star magnetite from the Kanmantoo deposit plots within the VHMS eld occur in a cluster (0–111 ppm Zn and 0–193 ppm Mn), whereas Nugent (Fig. 14B). (KTDD141) samples from GABS are comparatively elevated in Zn – – fi (60 152 ppm) and Mn (23 63 ppm), speci cally those within QMS 6. Discussion (152–212 ppm Zn, 148–211 ppm Mn). A positive linear relationship 2 ∼ (R = 0.60) between Ga and V + Cr occurs for muscovite in samples 6.1. The origin of the Kanmantoo deposit from the Kanmantoo deposit (Fig. 13B). Muscovite from Emily – Star spans nearly the entire range of values (79 183 ppm Ga, In order to assess the origin of the Kanmantoo deposit, the following – 158 1116 ppm V + Cr), whereas those from KTDD141 (Nugent), espe- characteristics need to be considered in light of the pre-metamorphic – cially those from QMS, have lower concentrations (64 108 ppm Ga, syn-sedimentary (e.g., Seccombe et al., 1985; Toteff, 1999), metamor- – 37 858 ppm V + Cr). Relative to compositions in unaltered country phogenic (e.g., Oliver et al., 1998; Schiller, 2000), and post-peak me- – rock schist (8.98 125 ppm Sr), muscovite from GABS and BGCS in the tamorphic models (e.g., Foden et al., 1999; Tedesco, 2009; Wilson, – Emily Star orebody is enriched in Sr (292 978 ppm). 2009; Arbon, 2011; Lyons, 2012) that have been proposed: 1) structural and textural relationships, 2) petrological, 3) mineral chemistry and 5.1.6. Magnetite sulfide assemblages, 4) stable isotopes, 5) composition and conditions Magnetite is intergrown with chlorite, chalcopyrite, and pyrrhotite of the ore-forming fluids, and 6) source of metals.

104 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

8 A 1.0 B 6 Ti Kavanagh, Nugent (KTDD125) Zn 4 Nugent 0.5 Li (KTDD141) Ca 2 Mg

0 Cr Co 0 Sc Ge Ga -2 Y V Mn Component 2 (11.9%) -4 Component 2 (11.9%) -0.5 Emily Star Fe -6

n=384 -8 -1.0 -8 -6 -4 -2 0 2 4 6 8 -1.0 -0.5 0 0.5 1.0 Component 1 (39.9%) Component 1 (39.9%) Eigenvalues Number % 20 40 60 80 Cum % 1.0 C 1 39.861 39.861 2 11.888 51.749 3 10.339 62.088 0.5 4 7.315 69.403 5 6.468 75.871 6 4.965 80.836 7 4.575 85.411 0 8 4.063 89.473 9 3.045 92.518 10 2.371 94.889 -0.5 11 2.013 96.902 12 1.897 98.800 Component 1 13 1.200 100.000 -1.0 Li Mg Ca Sc Ti V Cr Mn Fe Co Zn Ga Ge Y 1.0 Emily Star (KTDD34) Nugent (KTDD141) Nugent (KTDD125) 0.5 Kavanagh (KTDD149) Kavanagh (KTDD54) 0

-0.5

Component 2 -1.0 Li Mg Ca Sc Ti V Cr Mn Fe Co Zn Ga Ge Y

Fig. 7. Principal component analysis (n = 384) of garnet for 14 elements, Li, Mg, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Zn, Ga, Ge, and Y. A. Score plot of the ﬁrst two principal components with percent variance for component 1 and 2 on the X and Y axis, respectively. B. Loading plot showing the vector representation of data projected onto the score plot for each element. C. Eigenvalues of the 13 principal components. D. Loadings of the elements in the ﬁrst two principal components.

6.1.1. Structural and textural relationships fractures, and faults in a series of randomly oriented sulﬁde-bearing Most orebodies within the Kanmantoo Cu-Au deposit are variably veins and lenses (Verwoerd and Cleghorn, 1975; Seccombe et al., 1985; dipping and typically subparallel to the S2 schistosity (Seccombe et al., Wilson, 2009). Mineralization in Emily Star locally parallels bedding 1985; Oliver et al., 1998; Schiller, 2000), although Wilson (2009) noted and wraps around a south-plunging S2 fold, whereas ore lenses in the the relationship between mineralization and late-stage, east-dipping Nugent orebody trend southwest-northeast and parallel relict bedding extensional faults. Mineralization in the Kavanagh orebody dips to the (S0). The stockwork nature of the Kavanagh and Emily Star orebodies east and roughly parallels north-northeast trending shear zones, reinforces the concept proposed by Seccombe et al. (1985) that sulﬁde

105 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

175 175 A B 150 150

125 125

100 100 Zn (ppm) Zn (ppm) 75 Country rock schist 75

50 50

25 25 Country rock schist 0 0 0 50 100 150 200 250 300 350 0 10 20 30 40 50 60 70 Mn (ppm [103]) Gd (ppm) 30 100 C D Emily Star (KTDD34) 90 Nugent (KTDD141) 25 Nugent (KTDD125) 80 Kavanagh (KTDD149) 70 Kavanagh (KTDD54) 20 Hammerli et al. (2016) 60 15 50

Ge (ppm) 40 Co (ppm) 10 30 20 5 10

0 0 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 80 90 Gd (ppm) V (ppm)

Fig. 8. Compositions of garnet from the Kanmantoo deposit and country rock schist (outlined in A, B; Hammerli et al., 2016) A. Zn (ppm) vs. Mn (ppm·103). B. Zn (ppm) vs. Gd (ppm). C. Ge (ppm) vs. Gd (ppm). D. Co (ppm) vs. V (ppm). mineralization formed in the feeder zone of a SEDEX deposit, which is manifestation of a basement fault that reactivated during formation of observed elsewhere at, for example, the Rammelsberg Cu-Zn-Pb de- the Kanmantoo Trough and was a potentially important control on posit, Germany (Leach et al., 2005). Locally, sulfide mineralization mineralization. parallels bedding (Lindqvist, 1969; Wilson, 2009, Fig. 4, p. 55). The parallelism of the Nugent orebody to S0 and its discordancy to S2, 6.1.2. Petrological however, is difficult to reconcile with syn-deformational (i.e., meta- The immediate host to much of the Cu ore at Kanmantoo is biotite- morphogenic or post-peak metamorphic) models. Post-orogenic sulfide garnet-chlorite schist enveloped in garnet-andalusite-biotite schist (an quartz veins described by Tedesco (2009) likely resulted from the re- Fe-Mg-rich, Na-Ca-poor unit; Toteff, 1999). The garnet-andalusite-bio- mobilization of syn-sedimentary sulfides. tite and sulfide-enveloping biotite-garnet-chlorite rocks were con- An annealed metamorphic fabric and deformation twinning in sidered by Seccombe et al. (1985), Faulkner (1996), and Toteff (1999) chalcopyrite and pyrrhotite, the presence of an assumed pre-meta- to be the manifestation of a metamorphosed alteration halo, whereas morphic alteration halo enriched in Fe and Mg, and depleted in Ca and Gum (1998) and Oliver et al. (1998) suggested that they are a product Na (Seccombe et al., 1985; Spry et al., 1988; Belperio et al., 1998; of syn-metamorphic metasomatism. The spatial association of a garnet-

Toteﬀ, 1999), the presence of chalcopyrite and pyrrhotite in S1 inclu- andalusite-biotite rock is not unique to the Kanmantoo deposit area. sion trails in andalusite porphyroblasts (a D1-3 mineral), and colloform This rock extends intermittently for > 30 km in a unit that passes pyrite with magnetite-ilmenite-sphalerite-chalcopyrite inclusions sug- through the Scotts Creek Pb-Zn prospect, the South Hill Cu-Au prospect, gests the presence of Cu ore prior to peak metamorphism (D2; Seccombe adjacent to the Wheal Ellen Pb-Zn-Ag-(Cu-Au) deposit and St. Ives et al., 1985; Marshall and Gilligan, 1987; Spry et al., 1988; Schiller, prospects, and envelopes the Angas Pb-Zn-Ag deposit. The precursor 2000). Parker (1986) proposed the spatial association of Cu-Au mi- to GABS was considered by Schiller (2000) to be a mixture of quartz, neralization to a northwest-trending shear zone, which may be a illite, chlorite, iron oxides and hydroxides, and minor plagioclase. The

106 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

10000 10000 A B n=20 n=2 1000 1000

100 100

10 10 Sample/Chondrite Sample/Chondrite 1 1

0.1 0.1 KTDD054 KTDD149 KTDD034 0.01 0.01 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 10000 C n=16 1000

100

1 Sample/Chondrite

0.1 KTDD141 KTDD125 0.01 La Ce Pr Nd Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

Fig. 9. Chondrite-normalized rare earth element patterns for garnet. A. KTDD54 and KTDD149, Kavanagh. B. KTDD34, Emily Star. C. KTDD141 and KTDD125, Nugent. metamorphic minerals are similar to those in aluminous stratabound the world spatially associated with metamorphosed exhalative/in- hydrothermal alteration zones associated with metamorphosed base halative massive sulfide deposits (i.e., Broken Hill-type, VHMS, and metal sulfide deposits elsewhere in the world (e.g., LaRonde Penna, SEDEX; Spry, 2000; Spry et al., 2000; Slack, 2012; Steadman and Spry, Dubé et al., 2007; Snow Lake, Bailes et al., 2016). 2015). Given that such exhalites are generally associated with meta- There is a spatial association of meta-exhalative rocks with Pb-Zn- morphosed syn-sedimentary deposits, it would be remarkable that the Ag-(Cu-Au) and Cu-Au mineralization at the Strathalbyn, Wheal Ellen, same types of exhalative units spatially associated with metamorphosed Scotts Creek, Aclare, and Angas Pb-Zn-Ag-(Cu-Au) deposits, and the Pb-Zn-Ag-(Cu-Au) SEDEX deposits are also spatially associated with the Kanmantoo Cu-Au deposit (Fig. 1; Toteff, 1999). At Kanmantoo, banded Kanmantoo deposit if it has a syn-deformational origin (Marshall and iron formation (quartz ± magnetite ± cummingtonite ± rock) occurs Spry, 2000). Not only are the exhalative units associated with the over a distance of > 1 km north of the deposit and along strike from Kanmantoo deposit the most extensive in the Kanmantoo Group, they gahnite-bearing rocks (Toteff, 1999). A stratigraphically equivalent unit also occur in and along strike from the Nugent orebody that is con- of quartz garnetite rock occurs further south within and along strike formable to bedding. from the Nugent orebody. Toteff (1999) also identified numerous out- crops of iron formation, quartz-garnet-cummingtonite rocks, and pla- 6.1.3. Mineral chemistry and sulfide assemblages gioclase rocks in the vicinity of the Kanmantoo deposit. Similar rocks Major element compositions of garnet, staurolite, and minor chlorite also occur in and along strike from the Scotts Creek (quartz garnetite), obtained here from samples of GABS, GABSS, and BGCS from the Kavanagh Angas (quartz-garnet rock, quartz-gahnite rock), St. Ives (gahnite- (KTDD54, KTDD149), Emily Star (KTDD34), and Nugent (KTDD125 only) bearing GABS), and Wheal Ellen deposits (iron formation, gahnite-rich orebodies, show that they are generally Fe-rich as was previously re- rocks). All of these exhalative rocks occur at the same stratigraphic cognized by Schiller (2000), Wilson (2009),andArbon (2011),whereas level within the Tapanappa Formation (the so-called Angas Garnet biotite has an intermediate composition (XFe =0.38–0.67). Garnet asso- Member of Gum, 1998). Similar rocks have been described elsewhere in ciated with the Kavanagh, Emily Star, and Nugent (KTDD125) orebodies

107 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

3.2 3.0 A B Eastonite Siderophyllite 2.9 2.8 country rock schist 2.8 2.4 2.7 2.0 2.6

Emily Star (KTDD34) IV

1.6 Al 2.5 Phlogopite Biotite Nugent (KTDD141) Fe (apfu) 2.4 1.2 Nugent (KTDD125) Kavanagh (KTDD149) 2.3 country rock schist 0.8 Kavanagh (KTDD54) 2.2 Bollenhagen (1993) 0.4 Smith (1998) 2.1 Hammerli et al. (2016) 0 2.0 Phlogopite Annite 0 0.5 1.0 1.5 2.0 2.5 3.0 0 0.2 0.4 0.6 0.8 1.0 Mg (apfu) Fe/(Fe+Mg)

1600 C 1600 D

1400 1400

1200 1200

1000 1000

800 800 Zn (ppm) Zn (ppm) country rock 600 600 schist

400 400

200 200 country rock schist 0 0 0 500 1000 1500 2000 2500 3000 3500 0 20 40 60 80 100 120 140 160 180 Mn (ppm) Pb (ppm)

E 1.0 F 4 V Co

0.5 2 Sc Sn Nugent Cs (125) 0 0 Tl Sr Pb

-2 Ni Component 2 (18.7%) Component 2 (18.7%) -0.5

-4 Nugent Zn n=217 (141) -1.0 -4 -2 0 2 4 -1.0 -0.5 0 0.5 1.0 Component 1 (24.2%) Component 1 (24.2%)

Fig. 10. Compositions of biotite from the Kanmantoo deposit and country rock schist (outlined; Bollenhagen, 1993; Hammerli et al., 2016) and principal component analysis (n = 217) using 10 elements, Sc, V, Co, Ni, Zn, Sr, Sn, Cs, Tl, Pb. A. Fe (apfu) vs. Mg (apfu). B. AlIV (apfu) vs. Fe/(Fe + Mg). C. Zn (ppm) vs. Mn (ppm). D. Zn (ppm) vs. Pb (ppm). E. Score plot of the ﬁrst two principal components with percent variance for component 1 and 2 on the X and Y axis, respectively. F. Loading plot showing the vector representation of data projected onto the score plot for each element.

108 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

A 1.0 100 Emily Star (KTDD34) A Schiller (2000) Nugent (KTDD125)

Kavanagh (KTDD149) 0.8 Daphnite 80 Kavanagh (KTDD54)

60 0.6 Brunsvigite Frequency

40 Fe/(Fe+Mg) 0.4

20 Ripidolite 0.2 Pycnochlorite

0 Clinochlore Penninite 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 0 Corundophyllite Pseudothuringite ZnO (wt. %) 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 20000 Si (apfu) B Emily Star (KTDD34) Nugent (KTDD125) 2 Kavanagh (KTDD149) B R = 0.930 Kavanagh (KTDD54) 40 Slope = -1.33 15000 Fe-rich chlorite

30 10000 Zn (ppm) 20 FeO (wt. %) 5000 Emily Star (KTDD34) Nugent (KTDD141) 10 Nugent (KTDD125) 0 Kavanagh (KTDD149) 0 500 1000 1500 2000 2500 Kavanagh (KTDD54) Mn (ppm) 0 0 4 8 12 16 20 350 C MgO (wt. %)

300 1600 C

250 1400

200 1200

Co (ppm) 150 1000

100 800 Zn (ppm) 600 50 400 0 0 50 100 150 200 250 300 200 Fe-rich chlorite V (ppm)

Fig. 11. Compositions of staurolite. A. Histogram in terms of wt.% ZnO. B. Zn (ppm) vs. 0 Mn (ppm). C. Co (ppm) vs. V (ppm). Not shown in 11A is a single outlier for sample 0 500 1000 1500 2000 2500 3000 KTDD125-2 that contains 3.2 wt% ZnO, which is an average of two analyses. Mn (ppm) Fig. 12. Compositions of chlorite. A. Chlorite end-member compositions, including Fe- contains higher concentrations of FeO, lower amounts of MnO and about rich chlorite at Kanmantoo from Schiller (2000). B. FeO (wt.%) vs. MgO (wt.%) showing a negative linear relationship. C. Zn (ppm) vs. Mn (ppm). the same CaO contents as garnet in QMS and quartz garnetite in Nugent drill hole KTDD141. Not only are there diﬀerences in major element compositions between garnet from QMS and quartz garnetite, and those asso- shown in the respective PCAs and associated loading plots (Fig. 7A, B and ciated with GABS, GABSS, and BGCS in the other orebodies, but there are 10E, F). In terms of trace element compositions, garnet and biotite in QMS also diﬀerences in trace element compositions for both garnet and biotite as and quartz garnetite from KTDD141 (Nugent) contain elevated Zn (up to

109 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

120 100 A Emily Star (KTDD34) B 100 Nugent (KTDD141) 80 QMS Kavanagh (KTDD149)

80 Kavanagh (KTDD54) Hammerli et al. (2016) 60 60 Ga (ppm) Zn (ppm) 40 40 QMS

20 20 R2 = 0.598 Country rock schist Slope = 0.0658 0 0 0 100 200 300 400 500 0 100 200 300 400 500 600 700 Mn (ppm) V+Cr (ppm)

Fig. 13. Compositions of muscovite from the Kanmantoo deposit and country rock schist (outlined in 13A; Hammerli et al., 2016). A. Zn (ppm) vs. Mn (ppm) showing an ellipse of muscovite in QMS from KTDD141, Nugent. B. Ga (ppm) vs. V + Cr (ppm) showing a positive linear relationship with a slope of 0.0658 and R2 value of 0.598.

170 ppm in garnet and 1,592 ppm in biotite) relative to these minerals in by Hillgrove Resources at Wheal Ellen identified new zones of Cu-rich KTDD125 (Nugent), KTDD54 (Kavanagh), KTDD149 (Kavanagh), and mineralization (1 m @ 2.55% Cu and 1 m Cu @ 1.74% Cu; http://www. KTDD34 (Emily Star). However, what is notable is that major and trace hillgroveresources.com.au/article/SA_Exploration/Wheal_Ellen_ element compositions of garnet and biotite are similar to the compositions Project?section_id=41). Petrographic studies of one of these zones of these minerals spatially associated with the Wheal Ellen, Angas, and show that typical massive sphalerite-galena-pyrite ± pyrrhotite ± Scotts Creek Pb-Zn-Ag-(Cu-Au) occurrences in the Kanmantoo Group chalcopyrite mineralization grades into the assemblage sphalerite- (100–252 ppm Zn in garnet and up to 1,200 ppm Zn in biotite; Tott et al. chalcopyrite-pyrite-magnetite ± pyrrhotite (Fig. 17A and B). The 2016). Garnet associated with these Pb-Zn-Ag-(Cu-Au) deposits contains presence of magnetite along with chalcopyrite, which has not been 1.02–6.31 wt% CaO and 8.96–24.05 wt% MnO (Toteff, 1999), and is similar described previously in ore from Wheal Ellen, resembles the chalco- in composition to garnet in QMS and quartz garnetite from KTDD141 pyrite-magnetite assemblages seen at Kanmantoo, further suggesting a (Nugent). genetic link between the Cu-Au and Pb-Zn-Ag-(Cu-Au) deposits. Uti- The primary metallic mineral assemblage in the Kanmantoo deposit lizing the ore fluid composition proposed by Seccombe et al. (1985) for consists of chalcopyrite, pyrrhotite, and magnetite with lesser amounts formation of the Kanmantoo deposit, which was based on the stability of primary and secondary pyrite (Seccombe et al., 1985), whereas that of the primary assemblage pyrrhotite, chalcopyrite, magnetite, and associated with Pb-Zn-Ag-(Cu-Au) occurrences mostly contains spha- minor pyrite, the bulk sulfur isotopic composition of the aqueous spe- lerite, galena, and primary pyrite, with lesser amounts of chalcopyrite, cies in a slightly acid, low salinity, hydrothermal fluid associated with pyrrhotite, and magnetite. However, there are two exceptions among sediment-hosted and VHMS deposits, and the solubility of Cu as a the Pb-Zn-Ag-(Cu-Au) deposits where zones of Cu form part of the de- copper chloride complex, a plot of logfO2 versus temperature super- posit (Strathalbyn and Wheal Ellen). For example, Duncan et al. (1971) imposed onto the system Fe-S-O, which also shows the solubilities of reported Pb-Zn and Cu zones along strike from each other at the Wheal chalcopyrite and sphalerite (Large, 1977), reveals that a change in Ellen deposit with Cu mineralization occurring in veins. Recent drilling temperature of ∼25 °C could account for the metallic mineral

500 A Emily Star (KTDD34) B 400 Kavanagh (KTDD54) Skarns Y Tedesco (2009) 50

300 5

BHT 0.5

Ni (ppm) 200 Sn / Ga IOCG 0.05 VHMS 100 Tedesco (2009) 0.005 YYY Y YY YY Y Y Y Y Y Y 0 0.0005 0 200 400 600 800 1000 1200 1400 0.55 50 500 5000 50000 Cr (ppm) Al / Co

Fig. 14. Compositions of magnetite. A. Ni (ppm) vs. Cr (ppm) with an outline of magnetite compositions from elsewhere in the Kanmantoo Group (Tedesco, 2009). B. Sn/Ga vs. Al/Co used for provenance of hydrothermal ore deposits (after Singoyi et al., 2006).

110 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

assemblages at Kanmantoo and Wheal Ellen (Fig. 16). For the conditions shown in Fig. 16, the Cu-rich assemblage would form at ∼265 °C (Kanmantoo), while the Cu-Zn-rich assemblage could conceivably form

around 240 °C (Wheal Ellen), at approximately the same fO2 conditions.

6.1.4. Stable isotopes Sulfur isotope studies of Cu-Au, Pb-Zn-Ag-(Cu-Au), and Fe-S deposits in the Kanmantoo Group were undertaken by Jensen and Whittle (1969), Seccombe et al. (1985), Gum (1998),andLyons (2012). Seccombe et al. (1985) proposed a dual sulfur source of Cambrian seawater (δ34S=∼ +30‰, relative to Cañon Diablo troilite) and biogenic sulfur from the Nairne Pyrite Member (δ34S=−17‰). Isotopic values at the Kanmantoo Cu-Au deposit (δ34S=+8± 2.3‰) are generally heavier than those associated with the other Cu-Au (Bremer, South Hill) and Pb-Zn-Ag-(Cu-Au) occurrences (δ34S=−4.7 to + 6.5‰). Seccombe et al. (1985) attributed the variability in the isotopic compositions for the various deposits as being the result of different degrees of mixing of sulfur from these two sources, and to variations 34 in temperature, pH, δ S, total S, ionic content, or fO2 during ore deposition. Both Oliver et al. (1998) and Marshall and Spry (2000) advocated that the sulfur isotope compositions of sulfides do not constrain a model of formation for the Kanmantoo deposit and could allow for both syn-sedimentary and syn- deformational origins. Oliver et al. (1998) preferred a felsic igneous rock sourceforsulfurattheKanmantoodeposit,buttheclosestoutcroppingfelsic body (Monarto granite) occurs 13 km to the east of the Kanmantoo deposit (Schiller, 2000). An intrusive body below the Kanmantoo deposit, is yet to be reported in the literature. As with sulfur isotopes, ore models based on oxygen isotopes are not well constrained. Oliver et al. (1998) advocated a 500 m zone of locally depleted whole-rock oxygen isotope values (δ18O = +6.4 to +9.3‰, relative to V-SMOW) within and adjacent to the Kanmantoo deposit Fig. 15. Photomicrographs of Cu-rich ore zone from the Wheal Ellen Pb-Zn-Ag-(Cu-Au) that formed as a result of localized fluid flow derived from a crystal- deposit. A. Sphalerite (Sp)-galena (Gn)-pyrite (Py)-chalcopyrite (Cpy)-pyrrhotite (Po) ore, lizing magma. However, Marshall and Spry (2000) suggested the iso- WH006-151.6 m; B. Sphalerite-pyrite-chalcopyrite-magnetite ore, WH006-151.9 m. topic anomaly could just as easily result from hydrothermal fluid flow related to the formation of massive sulfide deposits via syn-sedimentary hydrothermal exhalations (e.g., Nesbitt, 1996; Brauhart et al., 2000; -25 pH = 5 Lerouge et al., 2001). S = 10-3 M 6.1.5. Composition and conditions of the ore-forming fluids -30 1M NaCl fl Wheal Ellen The syn-sedimentary model does not rely upon uid inclusion data, Fe O as any primary fluid inclusions would have been erased during meta- Kanmantoo 3 4 -35 morphism. The lack of syn-depositional volcanics requires an internally derived heat source, such as an unusually high geothermal gradient Fe2O3 (common in sedimentary exhalative deposits; Leach et al., 2005) in the -40 sediments below the Tapanappa Formation, or a thinning lithosphere (Seccombe et al., 1985; Both, 1990). Due to the rapid rate of sedi-

mentation in the Kanmantoo Trough (8 ± 5 Ma; Foden et al., 2006), 2 -45 and based on the location of the Nairne Pyrite Member, hydrothermal f o convective cells sourced from formation water and seawater circulated FeS2 log FeS to at least 3–4 km depth and were subsequently concentrated along -50 faults (Seccombe et al., 1985). Oliver et al. (1998) suggested a two-phase fluid flow syn-metamorphic model for which the fluid was a mixture of metamorphic and -55 magmatic components. Based on oxygen and sulfur isotopes and a hy-

pothesized increase in metamorphic grade approaching the Kanmantoo

etirelahps )qa( nZ mpp 6 mpp nZ )qa( )qa( nZ mpp 1 mpp nZ )qa( fi -60 deposit, Oliver et al. (1998) proposed the rst phase involved the emplacement of regional synorogenic granitic bodies that drove lateral and up-temperature flow of metamorphic fluids. The second phase localized ore fluids at the site of deposition, with the magmatic fluid component -65 1 ppm Cu (aq)chalcopyrite6 ppm Cu (aq) 50 100 150 200 250 300 350 being derived from an unidentified granite body directly beneath the T (oC) deposit. Regardless of the presence or absence of such an intrusive synorogenic body, or even a syn-sedimentary intrusive rock, which may fi – Fig. 16. Stability elds of Fe-S-O minerals in log fo2 temperature (°C) space for a 1 M have been responsible for the formation of the Fe-rich alteration as- fl ∑ −3 NaCl uid at pH = 5 and S=10 M showing the relationship of the assemblage semblage spatially associated with the Kanmantoo deposit, such a chalcopyrite-pyrrhotite-magnetite at Kanmantoo and the assemblage sphalerite-chalcopyrite-pyrite-magnetite at Wheal Ellen (modified after Large, 1977). single intrusion would not account for the regional stratabound alteration zone in the Tapanappa Formation.

111 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

The post-peak metamorphic model relies on fluid inclusion data in pri- Pb and Zn and considering a depletion of 17 ppm Cu in the Backstairs mary fluid inclusions formed during metamorphism in Cu-bearing quartz Passage Formation, his data would yield ∼35 Mt of Cu. Such a pre- veins and titanium-in-quartz geothermometry (Focke et al., 2009; Schmidt liminary calculation demonstrates that there should be more than en- Mumm et al., 2009; Tedesco, 2009). Tedesco (2009) showed they were high ough base metals to generate all the known base metal deposits in the salinity fluid inclusions (26–32 NaCl eq. wt.%) that formed at 372° ± 2.7 °C. Kanmantoo Group from exhalative processes, including the Kanmantoo He attributed the high salinities to a magmatic input, despite the fact that Cu deposit. fluids in sedimentary exhalative systems range from 10 to 30 wt% NaCl Based largely upon the results of their sulfur isotope study, Seccombe (Leach et al., 2004; Polito et al., 2006). We consider that the lower tem- et al. (1985) suggested that the Kanmantoo deposit was formed from a peratures reflect the remobilization of pre-metamorphic Cu during post-peak hydrothermal fluidthatcirculatedtothebaseoftheKanmantooGroupand metamorphism, as based on U-Th-Pb dates of Wilson (2009) on monazite in interacted with the isotopically light pyritic units, including the Nairne garnet in unmineralized rocks (492 ± 15 Ma) and sulfide-bearing rocks Pyrite Member. They also suggested that these pyritic units could have been (492 ± 9 Ma). a source of metals. Although the Cu, Pb, and Zn values of pyritic schists vary markedly in the Kanmantoo Group, they are anomalous in these metals 6.1.6. Source of metals relative to other rock types. Schiller (2000) analyzed 27 pyritic schists Recent studies by Pitcairn et al. (2006), Yardley and Cleverley originally collected by George (1967) and found median values of 111 ppm (2015), Zhong et al. (2015a), Hammerli et al. (2016), and Finch and Cu, 3,970 ppm Zn, and 3,520 ppm Pb. These metals are present in chalco- Tomkins (2017) have evaluated the role in which metals are released to pyrite, sphalerite, and galena along with a variety of other less abundant metamorphic fluids as a result of dehydration and desulfidation during sulfides and sulfosalts (Nenke, 1972), but they also occur as trace elements prograde metamorphism. Studies of the Otago and Alpine schist, New in the lattice of pyrite and pyrrhotite. Although evaporites are not known in Zealand by Pitcairn et al. (2006), and of metasediments in a meta- the Kanmantoo Group, a source of Cl to carry Cu, Pb, and Zn as chloride morphic aureole surrounding the Ballachulish igneous complex, Scot- complexes could have been derived from the precursors to scapolite, which land by Finch and Tomkins (2017), show that even though prograde is common in the Talisker and Backstairs Passage Formation, or the pre- metamorphism may release metals including Au, As, Bi, Sb, and W to a cursor to Cl-bearing apatite, which was reported by Hammerli et al. (2016) metamorphic fluid to conceivably form orogenic gold deposits, Cu, Zn, as a detrital mineral in the Kanmantoo Group. Although it may be possible and Pb are not released to metamorphic fluids to the same extent. Al- to generate sufficient Cu to form a Cu-Au deposit the size of Kanmantoo by though not specifically discussing the formation of Pb-Zn-Ag-(Cu-Au) or dehydration and desulfidation during prograde metamorphism associated Cu-Au deposits in the Kanmantoo Group, Hammerli et al. (2015, 2016) with the conversion of pyrite to pyrrhotite as proposed by Finch and noted that the Pb and Zn concentrations in staurolite-absent metase- Tomkins (2017), there is no textural evidence to show that pyrrhotite dimentary rocks and in biotite in the eastern part of the Kanmantoo formed by the breakdown of pyrite in the Kanmantoo Group. Moreover, Group decreased at higher metamorphic grades, the implication being Hammerli et al. (2015, 2016) showed no evidence to suggest that Cu was that Pb and Zn could be released during dehydration to form Pb-Zn released from pelitic and psammitic rocks during prograde metamorphism deposits. However, it should be noted that Cu is not released during from greenschist to upper amphibolite facies. prograde metamorphism, implying that such a mechanism was unlikely to have been responsible for the formation of the Kanmantoo deposit. 6.2. Preferred model of formation for the Kanmantoo Cu-Au deposit Alternatively, Oliver et al. (1998) proposed a late syn-tectonic model whereby Cu was released from a hidden syn-orogenic granite as it The mineralogical and geochemical data obtained in the present crystallized below the Kanmantoo deposit. In proposing a post-orogenic study support the premetamorphic syn-sedimentary model of Seccombe granitic source of metals for the Kanmantoo deposit, Arbon (2011) et al. (1985), Toteff (1999), and Marshall and Spry (2000). Sediments in considered that Bi was a diagnostic indicator of such a source, in part the Kanmantoo Group were deposited rapidly in the Kanmantoo Trough because of the general association of Bi with magmatic ore deposits. over a short 8 ± 5 Ma period (522 ± 2 to 514 ± 3 Ma, Jenkins et al., However, it should be noted that Bi can occur in accessory phases in 2002; Foden et al., 2006). Extension in the trough, accompanied by a sedimentary exhalative deposits where it has been found, for example, thinning lithosphere, generated an abnormally steep geothermal grain association with the metamorphosed sediment-hosted Roca de Po- dient, forming convective hydrothermal fluids (300–350 °C, reducing nent Cu deposit, Spain (Canet et al., 2003; Haldar, 2013). brine) to depths of at least 4 km (Seccombe et al., 1985). These circu- Schiller (2000) suggested that MORB-like meta-dolerite dikes, plugs, lating fluids leached Cu, Pb, Zn, Ag, Au, Bi, Cl, and S from the basal and sills may have been a source of heat and possibly metals. However, sediments in the Kanmantoo Group (i.e., Normanville Group, Carrick- the mafic rocks are younger than the metasedimentary rocks of the alinga Head Formation, Backstairs Passage Formation, and particularly Kanmantoo Group, as indicated by a U-Pb zircon age of 510 ± 2 Ma, the Talisker Formation), and then rose along syn-sedimentary growth which suggests that some of the mafic rocks formed post-peak meta- faults, which include the reactivated prominent Nairne and Bremer morphism (Chen and Liu, 1996). This late age negates the possibility faults, during basin development. The fluid likely migrated via a pro- that mafic rocks were a heat source for syn-sedimentary Cu-Au miner- cess of seismic pumping as advocated by Seccombe et al. (1985) and alization. Toteff (1999). Active syn-sedimentary faulting in the Kanmantoo In considering the potential for the presence of SEDEX Pb-Zn de- Trough, as evidenced by abrupt variations in the thickness of sediments posits in the Kanmantoo Group other than those already identified, in the Kanmantoo Group, likely provided the conduits necessary for ore Gum (1998) did a simple mass balance calculation by considering the emplacement (Thomson, 1975; Parker, 1986; Toteff, 1990, 1999). ∼1 km thick Backstairs Passage Formation at the base of the Kan- Fluids focused along these growth faults and then permeated the Ta- mantoo Group as a source of metals with 14 ppm Pb and 2 ppm Zn panappa Formation to produce a regional stratabound hydrothermal being leached from the sediments. The amount of metals leached was zone consisting of quartz, illite, chlorite, iron oxides and hydroxides, based upon the difference between the average metal content of sand- and minor plagioclase (Schiller, 2000). At the Kanmantoo deposit, re- stone and the median values of base metals in the Backstairs Passage latively sulfur-poor fluids, which produced the dominant metallic mi- Formation. A total of ∼28 Mt Pb and 4 Mt Zn was determined from this neralogy of chalcopyrite-pyrrhotite-magnetite, formed several or- calculation. Because he did not consider metals being leached from the ebodies including Kavanagh and Emily Star in a subsurface, stockwork Carrickalinga Head Formation, members of the Normanville Group, or feeder zone. Locally, more S-rich fluids produced minor pyrite in the pyritic units of the Talisker Formation, the amount of Pb-Zn derived deposit (Fig. 17). Overall, the hydrothermal fluids were enriched in Fe, from sediments based on his calculation is consequently a minimum. Mg, and Cu ( ± S), and depleted in Na and Ca (e.g., Schiller, 2000). Using the same assumptions made by Gum (1998) for his calculation of Higher up in the stockwork zone, the hydrothermal system continued to

112 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Schematic Model

Fe-Mn Hydrothermal Strathalbyn, Sediments Wheal Ellen (BIF, quartz garnetite) Pb-Zn-Ag±Cu Nugent Cu-Au Feeder Zone (Kavanagh & Emily Star)

Hydrothermal Alteration + Fe, Mg - Ca, Na Footwall metapelites and metapsammites

Fig. 17. Schematic diagram of the proposed genetic model of the Kanmantoo deposit showing the spatial relationship of Kavanagh and Emily Star to Nugent in the subsurface feeder zone, and the spatial relationship of the Kanmantoo Cu-Au deposit to the Strathalbyn and Wheal Ellen Pb-Zn-Ag-(Cu-Au) deposits. The pre-metamorphic hydrothermal alteration zone (now manifested as GABS(S)) and hydrothermal sediments (i.e., precursor to quartz garnetite and meta-BIF) are also shown. vent Cu-bearing fluids that produced the stratiform Nugent deposit. It is proposed here that the Cu orebodies at Kanmantoo are syn- Exhalations of Fe-Mn ± Zn-rich hydrothermal fluid at the seawater- sedimentary and formed in an exhalative system in a sub-seafloor en- rock interface, produced an extensive (> 1 km long) horizon of che- vironment. Deposits that formed within the hydrothermal vent asso- mical sediments along strike from the Nugent orebody. These fluids ciated with hydrothermally altered rocks (i.e., GABS, GABSS, BGCS) carried the chemical components to form the precursors to banded iron include the Kavanagh and Emily Star orebodies. Part of the Nugent formation, quartz garnetite, and gahnite-bearing schist. The strata- orebody where it is intersected by drill hole KTDD125 is also associated bound alteration and attendant Cu-Au mineralization was subsequently with these altered rocks. However, where the Nugent orebody is in- metamorphosed to the middle amphibolite facies to produce GABS, tersected by drill hole KTDD141, the spatially associated rocks consist GABSS, and BGCS, with the Cu orebodies being deformed during peak mostly of QMS intercalated with minor quartz garnetite. metamorphism and locally remobilized to form quartz-chalcopyrite ± The only trace element study conducted on silicates in the andalusite ± staurolite veins (Tedesco, 2009) late in the Delamerian Tapanappa Formation was that of Hammerli et al. (2016) on garnet, Orogeny. The Nugent orebody is distinguished from other orebodies by biotite, feldspar, muscovite, and titanite in unmineralized metapelitic being locally conformable to bedding and possessing mineralogical and and metapsammitic rocks unrelated to sulfide mineralization who de- geochemical characteristics (i.e., spatial association with exhalative termined their concentration in rocks at different metamorphic grades rocks, and major, minor, and trace element compositions of garnet and (greenschist to upper amphibolite facies). Hammerli et al. (2016) de- biotite) of syn-sedimentary Pb-Zn-Ag-(Cu-Au) deposits located else- termined the composition of 30 trace elements (Li, V, As, Cu, Pb, Zn, where in the Kanmantoo Group. Rb, Sr, Y, Zr, Nb, Mo, Sb, Cs, Ba, Hf, Ta, Th, and U, as well as 11 REEs). For the base metals (Cu, Pb, Zn), Pb in biotite in the altered rocks at 6.3. Mineral compositions as exploration guides Kanmantoo (9.3–110 ppm) is elevated relative to biotite (up to 11.4 ppm Pb) analyzed by Hammerli et al. (2016) in schists that were The major, minor, and trace element composition of minerals has subjected to peak metamorphic temperatures of approximately 475° to long been used as a tool for mineral exploration and to discriminate 600 °C (i.e. conditions similar to those at the Kanmantoo deposit), as it between ore deposit types (e.g., apatite, Belousova et al., 2002; tour- was Zn in 49% of biotite analyses (Table 3). Values of Mn in biotite maline, Griffin et al., 1996; maghemite and hematite, Schmidt Mumm associated with these rocks is approximately the same as those reported et al. 2012; magnetite, Dupuis and Beaudoin, 2011; garnet, Gaspar by Hammerli et al. (2016), whereas biotite in quartz garnetite rocks et al., 2008). The use of the major element composition of minerals as associated with the Nugent deposit contains up to 3,206 ppm Mn. The exploration guides in metamorphic terranes has largely focused on concentration of Cu in biotite in unmineralized schists and altered rocks variations in the Fe/(Fe + Mg) ratio of ferromagnesian silicates (e.g., associated with the Kanmantoo deposit are indistinguishable from those garnet, biotite, chlorite, staurolite) as a potential vector to ore (e.g., in unmineralized schists analyzed by Hammerli et al. (2016). In con- Nesbitt, 1996; Bryndzia and Scott, 1987). However, detailed studies trast, approximately two thirds of Cu (64%), Pb (69%), and Zn (72%) using the major, minor, and trace element compositions of silicates values for muscovite analyzed here are greater than the values analyzed (e.g., garnet, biotite, muscovite, staurolite, chlorite), and oxides in by Hammerli et al. (2016) in unmineralized rocks. The Cu concentra- metamorphosed altered rocks and ore deposits are limited in number tion of garnet in the unmineralized rocks of Hammerli et al. (2016) was and have largely been restricted to garnet (e.g., Spry et al., 2007; below detection limits, but there seems to be no distinction between the Heimann et al., 2009), tourmaline (Griffin et al., 1996), gahnite (e.g., Pb and Zn values of garnet in altered rocks at Kanmantoo versus the O’Brien et al. 2015a,b), biotite (Spry et al., 2015), and magnetite (Spry unmineralized rocks analyzed by Hammerli et al. (2016). In contrast, et al., 2015; Makvandi et al., 2016). the Mn and Zn values of garnet in quartz garnetite in the Nugent

113 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

Table 3 Concentrations of Cu, Pb, and Zn in garnet, biotite, and muscovite from QMS, GABS, GABSS, BGCS, and quartz garnetite from the Kanmantoo deposit compared to those from unmineralized altered and unaltered rocks from Hammerli et al. (2016).

Garnet n Cu (ppm) Pb (ppm) Zn (ppm)

1 Unmineralized 6 n.d. 0.02–0.17 13.6–16.8 This study 375 0.03–7.65 0.02–3.75 0.51–170 2 – 48% 10% 3 – 29%: 17% Kavanagh, 9.5% Nugent, 2.5% Emily Star 49%: 20.5% Kavanagh, 23% Nugent; 5.5% Emily Star 4 – 23%: 13% Kavanagh, 10% Nugent (KTDD125 only) 41%: ∼13.6% Kavanagh, ∼13.6 Emily Star, ∼13.6% Nugent (KTDD125 only)

Biotite 1: Unmineralized 15 1.54–374 0.93–11.4 23.6–214 This study 224 0.04–24,330 9.27–168 21.46–1592 2 43% 0.40% 50% 3 7%: Emily star only 99.6%: All samples 49.1%: All samples 4 50%: All samples – 0.9%: Kavanagh (KTDD54) only

Muscovite 1: Unmineralized 8 < 2.85 3.88–23.9 3.82–76.6 This study 39 0.25–173 0.01–272 0.51–108 2 36% 16% 20% 3 64%: All samples 69%: 46% Emily star, 18% Nugent (KTDD141 only), 5% 72%: 44% Emily star, 18% Nugent (KTDD141 only), 10% Kavanagh Kavanagh 4 – 15%: Kavanagh only 8%: Kavanagh only

1. Concentrations in samples from unmineralized altered and unaltered country rock from Hammerli et al. (2016, peak metamorphic T of rocks from ∼475° to 600 °C); 2. Percentage of samples from this study that fall within the same range as those in 1; 3. Percentage of samples from this study that are enriched relative to those in 1; 4. Percentage of samples from this study that are depleted relative to those in 1. Proportion of samples from each orebody that make up the percentages in 3 and 4 are shown. No data: n.d. orebody are enriched (up to 19.5 wt% MnO, 170 ppm Zn) relative to massive sulfide orebodies (up to 130 m wide), garnet in garnetite ex- garnet analyzed by Hammerli et al. (2016). Moreover, the high Mn hibit positive Eu anomalies proximal to the vent system whereas ne- content of garnet in quartz garnetite resembles that of garnet spatially gative Eu anomalies are found in garnet in stratigraphically equivalent associated with Pb-Zn-Ag-(Cu-Au) deposits in the Kanmantoo Group rocks distal to the Broken Hill vent system, in some quartz garnetite (Tott et al., 2016), and massive sulfide deposits in other metamorphic within ore, or proximal to very small Broken Hill-type deposits where terranes where it has been shown to be an important tool in exploration the ratio of hydrothermal to detrital components is small (Heimann (e.g., Spry et al., 2000; Averill, 2001; Heimann et al., 2009). et al., 2009). Similarly, positive anomalies were reported by Spry et al. The Zn content of staurolite in metamorphosed massive sulfide (2015) for garnet in the small metamorphosed massive Dammberget deposits is commonly enriched (e.g., up to 9 wt% ZnO, Bleikvassli Zn- Zn-Pb-Ag deposit in the Stollberg ore field, Sweden. This positive Pb-(Cu) deposit, Norway, Rosenberg et al., 1998; up to 6.9 wt% ZnO, anomaly for garnet in altered rocks occurs over a distance of approxi- LaRonde Penna Zn-Au-Ag-Cu-Pb deposit, Dubé et al., 2007) and has mately 100 m on either side of the deposit. Further away from the been shown to be a good indication of proximity to sulfides (e.g., Spry, sulfide mineralization the Eu anomaly in garnet is negative. At Kan- 2000; Spry et al., 2000). Toteff (1999) noted that staurolite in “normal” mantoo, garnet in GABS, GABSS, and BGCS generally shows a negative country rock in the Kanmantoo Group was depleted in Zn (∼0.1 wt% Eu anomaly, although ∼ 25% show weakly positive anomalies. As- ZnO) relative to staurolite in GABSS (up to 1.32 wt% ZnO; Schiller, suming the ore fluid was hot (> 250 °C) and reducing (Seccombe et al., 2000), the latter of which is consistent with up to 1.60 wt% ZnO ob- 1985) at Kanmantoo, the most likely cause for the negative Eu tained in the same rock type herein (with a single outlier of 3.20 wt% anomalies in garnet is a high ratio of detrital to hydrothermal compo- ZnO). For comparison, up to 5.6 wt% ZnO occurs in staurolite from the nents in the precursors to GABS, GABSS, and BGCS. Angas Pb-Zn-Ag deposit (Tott et al., 2016). Approximately 95% of chlorite at Kanmantoo (Fig. 12A) has an inter-

Chondrite-normalized rare earth element plots for garnet show de- mediate composition (XFe = ∼0.5–0.7, so-called Fe-poor chlorite of pleted LREEs and elevated heavy REEs (See Fig. 9A-C). This pattern Schiller, 2000) and is associated with Cu-Au ore, whereas minor Bi mi- 3+ likely reflects the uptake of HREEs as a substitute for Al , which de- neralization is linked to the Fe-rich variety of chlorite (XFe = ∼ >0.7, pends on the metamorphic fluid temperature, ƒO2, detrital input, REE Arbon, 2011), where it replaced the rims of garnet and staurolite. Magne- content of the metamorphic fluid, metamorphic fluid-rock ratio, and sium-rich chlorite from Nugent in drill hole KTDD141 contains considerably fractionation between the premetamorphic hydrothermal fluid and higher Mn (> 1,780 ppm) and Zn (400–1,600 ppm Zn, Fig. 12C) than the precursor minerals (Bau, 1991; Otamendi et al., 2002; Heimann et al., more Fe-rich chlorite from diamond drill hole KTDD125 (Nugent) and the 2009; Moore et al., 2013; White, 2013). The presence of positive Eu Kavanagh orebody (153–628 ppm Mn and 106–202 ppm Zn). anomalies in garnet has been used in the past as an indicator of Magnetite has been extensively used as an exploration guide for proximity to sulfide mineralization in metamorphic terranes (Spry metamorphosed Zn-Pb-Ag deposits, iron oxide-copper–gold deposits, et al., 2000, 2015; Rozendaal and Stalder, 2001; Heimann et al., 2009). volcanogenic massive sulfide deposits, porphyry deposits, Fe-Cu skarn Positive Eu anomalies reflect reduced, higher temperatures (> 250 °C) deposits, Ni-Cu-PGE deposits, Kiruna-type deposits, and banded iron of the premetamorphic hydrothermal fluids in equilibrium with pre- formations (Dupuis and Beaudoin, 2011; Nadoll et al., 2012, 2014). The cursor materials that may have formed proximal to ore emplacement presence of magnetite alone is indicative of proximity to Cu miner- whereas negative Eu anomalies reflect an increased detrital component alization at Kanmantoo as it can occur in high-grade ore in the as- that is carried in an oxidized, lower temperature (< 250 °C) hydro- semblage chlorite-magnetite, or it occurs in BIF along strike from sul- thermal fluid. The negative anomalies in garnet may also be associated fide mineralization. The trace element compositions obtained by with sulfide mineralization more distal to a vent system or proximal to a Tedesco (2009) from the Kavanagh orebody (drill holes KTDD053 and vent where the hydrothermal system is small. At the giant Broken Hill KTDD117) are similar to those obtained here from ten samples from Pb-Zn-Ag deposit, where garnet-rich rocks are spatially associated with Kavanagh (drill hole KTDD54). However, the Ni contents of magnetite

114 M.V. Pollock et al. Ore Geology Reviews 95 (2018) 94–117

(five of six analyses) from four samples from Emily Star have markedly comments and numerous suggestions of Adriana Heimann and Nigel higher concentrations of Ni versus those from Kavanagh, even though Kelly significantly improved the quality of the paper. Franco Pirajno is the Cr contents are about the same (Fig. 14A). The reason for variability thanked for his editorial assistance. in Ni concentrations is unclear. Appendix A. Supplementary data 7. Conclusions Supplementary data associated with this article can be found, in the The Kanmantoo Cu-Au deposit is the likely product of a syn-sedi- online version, at http://dx.doi.org/10.1016/j.oregeorev.2018.02.017. mentary sub-seafloor hydrothermal exhalative system in which the Kavanagh and Emily Star orebodies formed in a stockwork feeder zone References associated with hydrothermally altered rocks (i.e., the precursor to GABS, GABSS, BGCS), which was subsequently metamorphosed. The Abbott, P., Burtt, A., Ferguson, D., Moriarty, K., 2005. Cambrian mineral resources come Nugent orebody formed proximal to a hydrothermal vent on the sea- of age- the Kanmantoo revival. MESA J. 36, 6–11. fl Arbon, H., 2011. Bismuth distribution in the Cu-Au mineralisation of the Kanmantoo oor in an environment to similar to that responsible for the formation deposit, South Australia. Unpublished B.Sc. Honours thesis, Adelaide, University of of syn-sedimentary Pb-Zn-Ag-(Cu-Au) deposits in the Tapanappa Adelaide, Australia, pp. 77. Formation of the Kanmantoo group as evidenced by stratiform miner- Averill, S.A., 2001. The application of heavy indicator mineralogy in mineral exploration with emphasis on base metal indicators in glaciated metamorphic and plutonic ter- alization, spatially associated meta-exhalites, and similar enrichments ranes. In: In: McClenaghan, M.B., Bobrowsky, P.T., Hall, G.E.M., Cook, S.J. (Eds.), of Mn and Zn in silicates from QMS and quartz garnetite in the Nugent Drift exploration in glaciated terrain, Geological Society of London 185. Special orebody and QMS in the Pb-Zn-Ag-(Cu-Au) deposits. There is a genetic Publication, London, pp. 69–81. link between the two deposit types that is supported by the strati- Bailes, A.H., Galley, A.G., Paradis, S., Taylor, B.E., 2016. Variations in large synvolcanic alteration zones at Snow Lake, Manitoba, Canada, with proximity to associated vol- graphic equivalence of the Kanmantoo deposit and stratiform Pb-Zn-Ag- canogenic massive sulfide deposits. Econ. Geol. 111, 933–962. (Cu-Au) deposits. The presence of a chalcopyrite-pyrite-magnetite zone Bau, M., 1991. Rare-earth element mobility during hydrothermal and metamorphic fluid- fi at the Wheal Ellen Pb-Zn-Ag-(Cu-Au) deposit further supports this ge- rock interaction and the signi cance of the oxidation state of europium. Chem. Geol. 93, 219–230. netic link as it shows that the two end-member types of deposits (Cu-Au Belousova, E.A., Griffin, W.L., O’Reilly, S.Y., Fisher, N.I., 2002. Apatite as an indicator and Pb-Zn-Ag-(Cu-Au)) may form from similar hydrothermal fluids. The mineral for mineral exploration: trace-element compositions and their relationship to sub-parallel nature of the Kavanagh ( ± Emily Star) orebody to syn- host rock type. J. Geochem. Expl. 76, 45–69. Belperio, A.P., Preiss, W.V., Fairclough, M.C., Gatehouse, C.G., Gum, J., Hough, J., Burtt, deformational features (i.e., S2, east-dipping extensional faults, north- A., 1998. Tectonic and metallogenic framework of the Cambrian Stansbury Basin – northeast trending shear zones, fractures, and faults) is attributed to its Kanmantoo Trough, South Australia. AGSO J. Aust. Geol. Geophys. 17, 183–200. discordancy to bedding in a premetamorpic hydrothermal vent with Bollenhagen, W.J., 1993. The influence of bulk rock MnO on garnet development in metamorphic rocks of andalusite-staurolite grade; Kanmantoo, South Australia. subsequent in situ remobilization of the Cu ore during the Delamerian Unpublished B.Sc. Honours thesis, Adelaide, University of Adelaide, Australia, pp. 33. Orogeny. Both, R.A., 1990. Kanmantoo Trough geology and mineral deposits. In: Hughes, F.E. Exploration efforts on the regional scale in the Kanmantoo Group (Ed.), Geology of the Mineral Deposits of Australia and Papua New Guinea. The Australasian Institute of Mining and Metallurgy, Melbourne, pp. 1195–1203. should focus on garnet-andalusite-biotite ± chlorite ± staurolite ± Brauhart, C.W., Huston, D.L., Andrew, A.S., 2000. Oxygen isotope mapping in the magnetite and biotite-garnet-chlorite rocks in the Tapanappa Panorma VMS district, Pilbara Craton, Western Australia: applications to estimating Formation of the Kanmantoo Group since they are known to be spatially temperatures of alteration and to exploration. Miner Deposita 35, 727–740. associated with base metal mineralization and represent metamor- Bryndzia, L.T., Scott, S.D., 1987. The composition of chlorite as a function of sulfur and oxygen fugacity: An experimental study. Am. J. Sci. 287, 50–76. phosed stratabound hydrothermal alteration zones. In the search for Burtt, A.C., 2008. Kanmantoo Trough, in: South Australian mineral explorers guide, Cu-Au deposits on the local scale, garnet, biotite, staurolite, and mus- (Chap. 8), pp. 1–20. covite should at least be analyzed for Pb, Zn, Cu, and Mn, since biotite is Canet, C., Alfonso, P., Melgarejo, J.-C., Jorge, S., 2003. PGE-bearing minerals in Silurian SedEx deposits in the Poblet area, southwestern Catalonia. Spain. Can. Mineral. 41, elevated in Pb and generally in Zn, whereas muscovite is likely to be 581–595. elevated in Pb, Zn, and Cu. Staurolite is Zn-rich and garnet is Mn-rich in Cartwright, I., Oliver, N.H.S., 2000. Metamorphic fluids and their relationship to the quartz garnetite compared to unmineralized country rocks and con- formation of metamorphosed and metamorphogenic ore deposits. Rev. Econ. Geol. 11, 81–96. stitute excellent exploration guides, as does the presence of magnetite Chapman, L.H., Williams, P.J., 1998. Evolution of pyroxene-pyroxenoid-garnet alteration (regardless of its trace element composition). Although positive Eu at the Cannington Ag-Pb-Zn deposit, Cloncurry district, Queensland, Australia. Econ. anomalies have been used in the past to indicate proximity to hydro- Geol. 93, 1369–1389. Chen, Y.D., Liu, S.F., 1996. Precise U-Pb zircon dating of a post-D2 meta-dolerite: con- thermal ore deposits in metamorphic terranes elsewhere (e.g., Broken straints for rapid tectonic development of the southern Adelaide Fold Belt during the Hill Pb-Zn-Ag, Heimann et al., 2009; Dammberget Pb-Zn-Ag, Spry et al., Cambrian. J. Geol. Soc. London 153, 83–90. 2015), the paucity of positive Eu anomalies in garnet from Kanmantoo Croghan, C.W., and Egeghy, P.P., 2003. Methods of dealing with values below the limit of detection using SAS. Southern SAS User Group (St. Petersburg, Florida, 22–24 suggests that this feature is not a good exploration guide to Cu-Au de- September 2003), pp. 5. posits in the Kanmantoo Group. From a practical standpoint, given the Daily, B., Milnes, A.R., 1971. Stratigraphic notes on Lower Cambrian fossiliferous me- resistate nature of staurolite, garnet, and magnetite, these minerals can tasediments between Campbell Creek and Tunkalilla Beach in the type section of the be sampled from stream sediments, soil, or outcrop, whereas biotite, Kanmantoo Group, Fleurieu Peninsula, South Australia. Trans. R. Soc. S. Aust. 95, 199–214. chlorite, and muscovite should be extracted from altered metamorphic Daily, B., Milnes, A.R., 1972. Revision of the stratigraphic nomenclature of the Cambrian rocks from outcrop or subcrop. Kanmantoo Group, South Australia. J. Geol. Soc. Aust. 19, 179–202. Daily, B., Milnes, A.R., 1973. Stratigraphy, structure and metamorphism of the Kanmantoo Group (Cambrian) in its type section east of Tunkalilla Beach, South Acknowledgements Australia. Trans. R. Soc. S. Aust. 97, 199–214. Davis, J.C., 2002. Statistics and Data Analysis in Geology, 3rd ed. John Wiley & Sons, New Funding for this project was provided by the Geological Survey of York, 656 pp. Drexel, J.F., 1978. Geology and geochemistry of the South-eastern Freeway – Mt Barker South Australia and a Society of Economic Geologists Fellowship Grant summit to Callington section. S. Aust. Dep. Mines Energy Rep. 150, 39–49. to MVP. We gratefully acknowledge Anette von der Handt (University Dubé, B., Mercier-Langevin, P., Hannington, M.D., Lafrance, B., Gosselin, P., Gosselin, G., of Minnesota) for assistance with the electron microprobe analyses and 2007. The LaRonde Penna world-class Au-rich volcanogenic massive sulfide deposit, Abitibi, Quebec: mineralogy and geochemistry of alteration and implications for Hillgrove Resources for access to the Kanmantoo mine and core sam- genesis and exploration. Econ. Geol. 102, 633–666. ples. We would specifically like to thank David Rawlins, Hayden Arbon, Duncan, N., Mills, B.G., Nixon, W.H., 1971. 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