Chemistry, origin, and evolution of mineralized granites in the Lachlan fold belt, Australia; the metallogeny of I- and S-type granites

Blevin, Phillip L.; Chappell, B. W.

doi:10.2113/gsecongeo.90.6.1604

Cited by 192 publications

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“…The Ordovician volcano-intrusive complexes are one of four main components of the LFB in New South Wales, the others being Cambrian greenstones, Ordovician to early Silurian quartz turbidites, and Silurian to early Devonian volcanic and sedimentary rocks (Suppel et al 1998). Silurian to early Devonian granitoids occur throughout the belt, and S-type intrusions are locally associated with Sn and minor W, while I-type intrusions are associated with Mo and Cu mineralisation (Blevin and Chappell 1995). The LFB as a whole is interpreted to have formed by complex accretionary processes from mid Cambrian to Carboniferous times, related to the closure of a back-arc basin (the Wagga Marginal Basin; Fig.…”

Section: Regional Setting and Deposit Stylesmentioning

confidence: 99%

Porphyry gold-copper mineralisation in the Cadia district, eastern Lachlan Fold Belt, New South Wales, and its relationship to shoshonitic magmatism

Holliday

Wilson

Blevin

et al. 2002

Mineralium Deposita

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The Cadia porphyry gold-copper district is the largest hydrothermal, intrusion-related gold deposit in eastern Australia. Discovered in 1992 by Newcrest Mining Limited, pre-mine resources in the district were in excess of 585 t Au and 2.35 Mt Cu. The Cadia district lies within shoshonitic subaqueous volcanic rocks of the Late Ordovician Molong Volcanic Belt in the eastern Lachlan Fold Belt (LFB) of New South Wales. An island arc tectonic setting is envisaged for the formation of these volcanic rocks, but the nature of the arc basement and geometry of the subduction zone(s) is debated. Mineralisation occurs in four principal porphyry deposits (Cadia Hill, Cadia Ridgeway, Cadia East/Cadia Far East and Cadia Quarry) as sheeted and stockwork quartz-sulfide veins, and locally as broadly stratabound disseminated mineralisation (Cadia East) and skarn (Big Cadia and Little Cadia). All of the porphyry deposits show a close spatial association with shoshonitic monzodiorite to quartz monzonite dykes and stocks of the Cadia Intrusive Complex (CIC). Gold-copper mineralisation is hosted by these intrusions and also by the enclosing Forest Reefs Volcanics (FRV) wall rocks. Hydrothermal alteration associated with mineralisation is potassic, which is overprinted by selectively pervasive propylitic and silica-albite assemblages. Petrological studies and major and trace element analysis of rocks of the CIC and FRV, as well as of other intrusions in the Cadia district that appear unrelated to mineralisation, have been conducted. Unaltered samples from the CIC are characterised by high K 2 O contents (up to 6.5 wt%) and molecular K/Na ratios consistently >1, confirming the alkalic and shoshonitic nature of the complex. The CIC samples also fall just within the shoshonite field on Ce/Yb-Ta/Yb and Th/Yb-Ta/Yb plots, although immediately adjacent to the calc-alkaline field. The FRV are geochemically similar to the CIC, although lower in P 2 O 5 and Ce (LREE). Dacitic and hornblende porphyry intrusions from within the district, but spatially unrelated to mineralisation, have a distinctive geochemical signature and are not shoshonitic in composition. The close spatial association between gold-copper mineralisation and the shoshonitic, monzonitic CIC argues strongly for a genetic link between the two. A similar association occurs at the economic Goonumbla porphyry gold-copper deposits in the eastern LFB, while sub-economic gold-copper mineralisation at Cargo and Copper Hill is associated with calc-alkaline quartz diorite and dacitic intrusions. The Cadia district is considered to be an excellent example of the association of alkaline, potassic magmas and gold-copper porphyry style mineralisation.

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Section: Regional Setting and Deposit Stylesmentioning

confidence: 99%

Porphyry gold-copper mineralisation in the Cadia district, eastern Lachlan Fold Belt, New South Wales, and its relationship to shoshonitic magmatism

Holliday

Wilson

Blevin

et al. 2002

Mineralium Deposita

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“…Cu and Au de pos its are re lated to more mafic gran ites. Tung sten min er ali sa tion is cor re lated with granitic mag mas of tran si tional char ac ter and Mo-W-Sn with fel sic and frac tion ated gran ite (Blevin and Chappell, 1995). Ox i dation state of mag mas is of par a mount im por tance in con trol ling the na ture of many ore el e ments, and it al lowed di vid ing the gran ites into two con trast ing gran ite types (Chappell andWhite, 1974, 2001;Frost and Frost, 2011) and fur ther into the il men ite and mag ne tite se ries (Ishi hara, 1981).…”

Section: Discussionmentioning

confidence: 93%

The auriferous ore mineralization and its zonal distribution around the Variscan Kłodzko-Złoty Stok granitoid pluton in the Sudetes (SW Poland) – an overview

Mikulski¹,

Speczik

2016

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1 Pol ish Geo log i cal In sti tute -Na tional Re search In sti tute, Rakowiecka 4, 00-975 Warszawa, Po land Mikulski, S.Z., Speczik, S., 2016. The au rif er ous ore min er ali sa tion and its zonal dis tri bu tion around the Variscan K³odzko-Z³oty Stok granitoid pluton in the Sudetes (SW Po land) -an over view. Geo log i cal Quar terly, 60 (3): 650-674, doi: 10.7306/gq.1284 Due to a low level of ero sion the Variscan (Carboniferous-Mississippian) K³odzko-Z³oty Stok (KZS) granitoid pluton and its meta mor phic rock cover are unique ex am ples of the ore min er ali sa tion dis tri bu tion pat tern around a pluton. The KZS pluton formed from I-type mag mas. It is com posed mostly of high-K, metaluminous, bi o tite-and hornblende-rich granitoids of var ious com po si tions rang ing from granodiorite to monzonite. The ore min er alisation in the KZS shows spe cific zonation that reflects in ter ac tion be tween post-mag matic min er al is ing flu ids and coun try rocks of dif fer ent com po si tion. In the KZS pluton and its sur round ings the min er alisation re veals high-tem per a ture Ti-W ox ides and As-Fe sul phide-ar sen ides plus Fe-ox ides which are re placed out wards by Cu-Fe-Pb-Zn sulphides and sub se quently, in the mar ginal parts of the pluton, by the Pb-Sb-Fe sul phide min er alisation. The spe cific el e ments and the iso to pic com po si tion of sul phur in ore min er als in di cate that the metal-bear ing postmagmatic-meta mor phic hy dro ther mal flu ids, de spite their strong af fin i ties to the KZS hy brid mag matic flu ids, show also an in flu ence of vari able com po si tion of coun try rocks. Vari able al ter ation pro cesses: hornfelsitisation, skarnisation, dolomitisation, serpentinitisation, pyroxenisation, biotitisation, K-feldspatisation, sili ci fi ca tion, berezitisation, carbonatisation, prehinitisation, chloritisation, epidotisation, sericitisation, albitisation and sulphidisation de vel oped along con tacts of var i ous rock types within the coun try rocks. In more frac tured zones, trans ported el e ments were pref er en tially trapped by cal car e ous (Ca-rich) meta mor phic rocks. More over, along the di rect con tact be tween granitoids and cal car e ous rocks a high tem per a ture au rif er ous skarns with mag ne tite-pyrrhotite or/and löllingite-ar seno py rite min er alisation were formed. There are pos i tive cor re la tions be tween or ganic mat ter and Fe 2 O 3 and MgO con tents in skarns, sug gest ing remobilization of or ganic mat ter by hy dro ther mal flu ids re leased dur ing serpentinisation. The or ganic mat ter and car bon ate sam ples have very vari able d 13 C and d 18 O val ues. Most prob a bly these are the re sult of iso to pic re-equil i bra tion be tween min er als un der high tem per a tures. On the in ti mate con tact of granitoids with less per me able amphibolitic hornfelses a high tem per a ture ti tan ite-schee lite min er alisation of veinlet-im preg na tion type oc curred, while ther mal and metasomatic al teration of the en vel op ing more per...

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“…Geology Surface geology of Australia, New South Wales-2nd edition 1:1,000,000 Surface geology of Australia, Victoria-3rd edition 1:1,000,000 Eastern Lachlan orogen geoscience database, version 2 NA Glen and others (2006) Chemistry, origin, and evolution of mineralized granites in the Lachlan fold belt, Australia: the metallogeny of I-and S-type granites Blevin and Chappell (1995) Intrusive metallogenic provinces in eastern Australia based on granite source and composition Blevin and others (1996) Mineral occurrences…”

Section: Theme Name or Title Scale Citationmentioning

confidence: 99%

Porphyry copper assessment of eastern Australia

Bookstrom¹,

Len²,

Hammarstrom³

et al. 2014

Scientific Investigations Report

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Chemistry, origin, and evolution of mineralized granites in the Lachlan fold belt, Australia; the metallogeny of I- and S-type granites

Cited by 192 publications

References 0 publications

Porphyry gold-copper mineralisation in the Cadia district, eastern Lachlan Fold Belt, New South Wales, and its relationship to shoshonitic magmatism

Porphyry gold-copper mineralisation in the Cadia district, eastern Lachlan Fold Belt, New South Wales, and its relationship to shoshonitic magmatism

The auriferous ore mineralization and its zonal distribution around the Variscan Kłodzko-Złoty Stok granitoid pluton in the Sudetes (SW Poland) – an overview

Porphyry copper assessment of eastern Australia

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