Chronology of deformation within the turbidite‐dominated, Lachlan orogen: Implications for the tectonic evolution of eastern Australia and Gondwana

Foster, David A.; Gray, David; Bucher, Martin

doi:10.1029/1998tc900031

Cited by 156 publications

(143 citation statements)

References 97 publications

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“…The Lachlan belt exemplifies this type of orogen as it has undergone multiple cycles of contractional orogeny and extensional collapse involving HT metamorphism (Foster et al, 1999;Collins, 2002a,b;Gray and Foster, 2004;Fergusson et al, 2007). In MBL the elevated heat flow into the base of the continental crust may have arisen during subduction of hot oceanic lithosphere newly formed at the Phoenix-Pacific ridge (Figures 4 and 5b) (Bradshaw, 1989;Luyendyk, 1995), or due to back arc extension and lithospheric thinning ( Figure 5b and 5c) (Weaver et al, 1991Mukasa and Dalziel, 2000); or from basal heating in the presence of a postulated mantle plume .…”

Section: Discussionmentioning

confidence: 99%

Tectonics of the West Antarctic rift system: new light on the history and dynamics of distributed intracontinental extension

Siddoway¹

2007

Open-File Report

109

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Section: Discussionmentioning

confidence: 99%

Tectonics of the West Antarctic rift system: new light on the history and dynamics of distributed intracontinental extension

Siddoway¹

2007

Open-File Report

109

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“…It is currently held that the sequences of the Melbourne Zone were deposited on a low gradient shelf on the eastern margin of the Australian continental plate. In contrast, the sequences in eastern Victoria, New South Wales and Queensland were deposited on off-shore island-arc platforms many hundreds of kilometres from the mainland (Foster et al, 1999). It seems that although many trilobite groups were able to establish themselves in these settings, homalonotids (and acastids) were unsuccessful in dispersing from the continental margin.…”

Section: T (R) Ianae T (R) Rickardsi T (R) Sp (Uk)mentioning

confidence: 98%

Homalonotid trilobites from the Silurian and Lower Devonian of south-eastern Australia and New Zealand (Arthropoda: Trilobita: Homalonotidae)

Sandford¹

2005

MMV

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“…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. 1; Scheibner and Basden 1998) and associated collision of an oceanic-arc along the Pacific margin of Gondwana (Foster et al 1999). The Ordovician quartz turbidites and arc-related volcanic rocks of the eastern LFB were accreted during the early Silurian (Glen et al 1998), although the current geometry of the volcanic rocks (as four separate belts) is attributed to splitting of a single arc (the Macquarie Arc; 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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Chronology of deformation within the turbidite‐dominated, Lachlan orogen: Implications for the tectonic evolution of eastern Australia and Gondwana

Abstract: Abstract.Ar-Ar data from fabric-forming white mica in slates, syntectonic quartz veins and granitic mylonites constrain the timing of metamorphism, deformation, and exhumation in the Lachlan orogen, Australia. These data also help define the tectonic evolution of the Tasmanides

Cited by 156 publications

References 97 publications

Tectonics of the West Antarctic rift system: new light on the history and dynamics of distributed intracontinental extension

Tectonics of the West Antarctic rift system: new light on the history and dynamics of distributed intracontinental extension

Homalonotid trilobites from the Silurian and Lower Devonian of south-eastern Australia and New Zealand (Arthropoda: Trilobita: Homalonotidae)

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

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