Architectural controls on porphyry Au-Cu mineralization in the Cadia Valley, NSW PDF
Preview Architectural controls on porphyry Au-Cu mineralization in the Cadia Valley, NSW
AAArrrccchhhiiittteeeccctttuuurrraaalll cccooonnntttrrrooolllsss ooonnn PPPaaalllaaaeeeooozzzoooiiiccc pppooorrrppphhhyyyrrryyy AAAuuu---CCCuuu mmmiiinnneeerrraaallliiisssaaatttiiiooonnn iiinnn ttthhheee CCCaaadddiiiaaa VVVaaalllllleeeyyy,,, NNNSSSWWW CCaaddiiaa HHiillll,, DDeecceemmbbeerr 22000055 AAnntthhoonnyy CC HHaarrrriiss,, DDaavviidd RR CCooookkee,, NNaatthhaann FFooxx,, AAnnaa LLiissaa CCuuiissoonn,, RRiicchhaarrdd TToossddaall,, MMeelliissssaa GGrroooommee,, IIaann PPeerrcciivvaall,, PPaauull DDuunnhhaamm,, DDeeaann CCoolllleetttt,, JJoohhnn HHoolllliiddaayy,, CChhaarrlloottttee MM AAlllleenn CCaaddiiaa ddiissttrriicctt –– rreessoouurrcceess CCaaddiiaa HHiillll,, NNoovveemmbbeerr 22000088 DDeeppoossiitt RReessoouurrccee ((MMtt)) AAuu ((gg//tt)) CCuu ((%%)) AAllkkaalliicc ppoorrpphhyyrryy AAuu––CCuu CCaaddiiaa EEaasstt 22,,334477 00..4444 00..2288 CCaaddiiaa HHiillll 442277 00..4433 00..1122 RRiiddggeewwaayy 115522 00..7777 00..3399 CCaaddiiaa QQuuaarrrryy // EExxtteennddeedd 5533 00..3399 00..2222 MMaaggnneettiittee CCuu––AAuu sskkaarrnn BBiigg CCaaddiiaa 3377 00..3344 00..4477 DDDiiissstttrrriiicccttt tttoootttaaalll::: 444444 MMMooozzz AAAuuu,,, 777...999888 MMMttt CCCuuu Newcrest Mining Ltd 2009 Resources & Reserves Statement –August 2010 CCaaddiiaa ddiissttrriicctt –– ggeeoollooggyy Tertiary Basalt RRRiiidddgggeeewwwaaayyy Middle Silurian BBBiiiggg CCCaaadddiiiaaa Waugoola Group Ordovician - Silurian Cadia Intrusive CCCaaadddiiiaaa QQQuuuaaarrrrrryyy Complex LLLiiittttttllleee CCCaaadddiiiaaa Ordovician Forest Reefs Volcanics CCCaaadddiiiaaa HHHiiillllll Weemalla Formation CCCaaadddiiiaaa EEEaaasssttt NNeeww SSoouutthh WWaalleess NN MMiinnee NN CCaaddiiaa SSyyddnneeyy 00 11 kkmm VVVooolllcccaaannniiiccc aaarrrccchhhiiittteeeccctttuuurrreee CCCaaadddiiiaaa EEEaaasssttt RRRiiidddgggeeewwwaaayyy BBBiiiggg CCCaaadddiiiaaa NNNWWW SSSEEE CCCaaadddiiiaaa HHHiiillllll SSSeeeaaa LLLeeevvveeelll CCCaaarrrbbbooonnnaaattteee ppplllaaatttfffooorrrmmm Evolving low-relief, multiple vent volcanic complex developed across an area of active marine sedimentation • Vents comprised mafic to intermediate lava flows, cryptodomes, dykes and sills • Stacked lava sequences, including hyaloclastites, massive lavas and their reworked equivalents, are up to 1 km thick OOOrrrdddooovvviiiccciiiaaannn vvvooolllcccaaannniiisssmmm aaannnddd ssseeedddiiimmmeeennntttaaatttiiiooonnn s c i n a c l o V s f e e R • The volcaniclastic units contain rare mid- t s e Darriwilian (Da2-3) to late Gisbornian (Gi2) r o graptolites (reworked?) F • There are also conodonts, brachiopods, fragmentary coral and trilobites • Detrital zircons from the Weemalla Fm have U- Pb ages ~454 Ma m • Faunal ages that are diagnostically Eastonian F (Ea3 – ca. 452 Ma) have been recognized in the a l l a upper parts of the FRV m e •• TThhee FFoorreesstt RReeeeffss VVoollccaanniiccss wweerree ddeeppoossiitteedd e W dduurriinngg tthhee EEaassttoonniiaann,, bbeettwweeeenn 445544 aanndd 445522 MMaa 22400mE 22800mE 23200mE MMaaggmmaattiissmm aanndd mmiinneerraalliissaattiioonn • Mineralisation and alteration was centred on monzonite pipes at Ridgeway, and dykes at Cadia East • Mineralisation occurred Ridgeway within larger monzonite Intrusive plutons at Cadia Hill and Complex Cadia Quarry • Quartz – sulfide – carbonate veins are the >0.2 g/t Au Weemalla predominant Formation mineralisation style >1.5 g/t Au (sheeted and stockwork) Ridgeway Section 11050E -unpubl. Cuison(2010) CCCaaadddiiiaaa dddiiissstttrrriiicccttt ––– lllooonnnggg ssseeeccctttiiiooonnn NNNWWW SSSEEE RRRiiidddgggeeewwwaaayyy CCCaaadddiiiaaa QQQuuuaaarrrrrryyy CCCaaadddiiiaaa HHHiiillllll CCCaaadddiiiaaa EEEaaasssttt 6000 RL Tertiary basalt Waugoola Group Upper FRV Lower FRV 5000 RL Weemalla Cadia Formation Intrusive Complex 4000 RL • The Cadia district has been dismembered by steeply-dipping faults, some with offsets of 100s of metres… • This has juxtaposed different levels of the magmatic- hydrothermal system, and disrupted the cover sequence SSSiiillluuurrriiiaaannn ssseeedddiiimmmeeennntttaaatttiiiooonnn aaannnddd lllaaattteeerrr dddeeefffooorrrmmmaaatttiiiooonnn EE WW IInnvveerrssiioonn aanndd rreeaaccttiivvaattiioonn ooff oolldd ssttrruuccttuurreess…… • Deformed Silurian sub-basins cover the dismembered Cadia Hill deposit • Scale of thrust-related movement differs between the basement and cover rocks Washburn (2008) CCaaddiiaa EEaasstt –– aa 3333 MMoozz ggoolldd rreessoouurrccee • Largest known gold deposit CCaaddiiaa in eastern Australia LLiittttllee HHiillll CCaaddiiaa • World’s sixth largest CCaaddiiaa porphyry deposit in terms of EEaasstt contained Au • Total resources of 2.3 billion tonnes at 0.44 g/t Au and 0.28 % Cu • Contains more than 70% of the Cadia district Au resource • Mineralised zone ~2 km long, 600 m wide and >1500 m in vertical extent • Significant variations in mineralisation and alteration styles with depth OOrree sshheellll pprroojjeecctteedd ttoo ssuurrffaaccee ffrroomm 55443300mmRRLL;; bbuullkk oorree ggrraaddee mmooddeellss ((ddaattaa ffrroomm NNeewwccrreesstt MMiinniinngg LLttdd..)) CCaaddiiaa EEaasstt –– GGeeoollooggyy Host rocks: 21,000 m N 21,500 m N 22,000 m N 22,500 m N • Polymict volcanic conglomerates and intermediate to basic lavas 6,000 m and associated autobreccia RL Pre-mineralisation intrusions: • Basaltic-andesite dikes and sills 5,500 m RL Mineralising intrusions: • Early Silurian (c. 437 Ma) alkalic monzonite – monzodiorite dikes 5,000 m RL surrounded by concentric zones of mineralisation and alteration Styles of mineralisation: 4,500 m RL • Deep-level W-NW- trending sheeted quartz-sulphide vein array • Shallow level, disseminated stratabound orezone CadiaEast section 15220mE; Fox et al., 2009
Description:The list of books you might like
