Cretaceous metamorphism, magmatism and shearing in the Waipuna Valley, directly south of the Reefton Goldfield

Ritchie, T.; Scott, James M.; Muhling, Janet R.; Kennedy, Allen

doi:10.1080/00288306.2014.992444

Cited by 10 publications

(5 citation statements)

References 51 publications

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“…9B). This conclusion is supported by the similarity in zircon U-Pb ages of the Broughton Granodiorite and Snares Granite with Rahu Suite plutons found in Westland Waight et al 1997;Ritchie et al 2015). However, although Snares Granite has similar major element concentrations to Rahu Suite Buckland Granite at equivalent SiO 2 (Table 2), it has distinctly lower Sr and Ba and higher Y, Nb and Rb.…”

Section: Rb-sr and Sm-nd Whole-rocksupporting

confidence: 45%

Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

Scott

Turnbull²,

Sagar

et al. 2015

New Zealand Journal of Geology and Geophysics

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The first comprehensive geological map, a summary of lithologies and new radiogenic isotope data (U-Pb, Rb-Sr) are presented for crystalline rocks of the Sub-Antarctic Snares Islands/Tini Heke, 150 km south of Stewart Island. The main lithology is Snares Granite (c. 109 Ma from U-Pb dating of zircon), which intrudes Broughton Granodiorite (c. 114 Ma from U-Pb zircon) on Broughton Island. Rafts of schist within Snares Granite are common on the outlying Western Chain islets, and rare on North East and Broughton islands. Zircon grains extracted from one schistose raft on Broughton Island are prismatic and yield an essentially unimodal age population of c. 116 Ma that is within error of the granodiorite. These properties suggest that the dated raft represents a meta-igneous rock despite its mica-rich nature. Some schistose rocks on the Western Chain contain coarse relict plagioclase phenocrysts and appear to have an igneous protolith. No conclusive metasedimentary rocks have been identified, although sillimanite-bearing mica-rich schist occurs on Rua. Deformation of the crystalline rocks occurred after Snares Granite intrusion and before cooling below muscovite K-Ar closure at 400 ± 50°C at 95 Ma. This period overlaps the age of extensional ductile shear zones on Stewart Island. The discovery of several basaltic dykes, which cut across fabrics and are unmetamorphosed, indicates that volcanic rocks are associated with all Sub-Antarctic island groups. The larger of the islands are overlain by peat, which on North East Island also contains gravel deposits.

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Section: Rb-sr and Sm-nd Whole-rocksupporting

confidence: 45%

Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

Scott

Turnbull²,

Sagar

et al. 2015

New Zealand Journal of Geology and Geophysics

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“…The two terranes are separated by the Anatoki Fault (Cooper 1979(Cooper , 1989 and were merged prior to 354 Ma (Tulloch et al, 2009b) or even 371 Ma (Jongens, 2006;Turnbull et al, 2013Turnbull et al, , 2016. Metasedimentary rocks of the Buller Terrane (predominantly Greenland Group) are early Ordovician fore-arc turbidites (Laird, 1972;Cooper, 1974) regionally metamorphosed in the late Ordovician to greenschist facies (Adams, 2004) and locally to higher grades (Scott et al, 2011a;Mortimer et al, 2013;Palmer et al, 2015;Ritchie et al, 2015). The adjacent Takaka Terrane consists of an amalgamation of a Cambrian volcanic-volcaniclastic arc assemblage and an Ordovician-Devonian passive margin sequence (e.g.…”

Section: Geological Settingmentioning

confidence: 99%

“…Further inboard, the coeval to younger metaluminous amphibole-bearing I-type to evolved two-mica I/S-type granites of the Rahu Suite are found in the Victoria and Paparoa Ranges (White, 1987;Tulloch, 1988), Hohonu Ranges and Lake Kaniere region (Waight et al, 1997(Waight et al, , 1998b and in valleys cutting intervening low lying areas (e.g. Ritchie et al, 2015) as well as in Fiordland (Allibone et al, 2007). The Rahu Suite is characterized by more crustal (evolved) isotopic signatures than the Separation Point and Darran suites and was likely intruded following crustal over-thickening that initiated at >126 Ma in a tectonic regime of orogenic collapse that peaked at $110 Ma (e.g.…”

Section: Geological Settingmentioning

confidence: 99%

“…Tulloch & Kimbrough, 1989;Kula et al, 2009). In Westland, these include the Paparoa Metamorphic Core Complex (Tulloch & Kimbrough, 1989;Spell et al, 2000;Sagar & Palin, 2011;Schulte et al, 2014) and mylonitic fabrics suggesting the existence of core complexes in the Victoria (Tulloch & Challis, 2000;Ritchie et al, 2015) and perhaps the Bonar Ranges (Jongens, 2006;Ring & Bernet, 2010;Scott et al, 2011a;van der Meer et al, 2013).…”

Section: Geological Settingmentioning

confidence: 99%

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Magmatic Evolution during the Cretaceous Transition from Subduction to Continental Break-up of the Eastern Gondwana Margin (New Zealand) documented by in-situ Zircon O–Hf Isotopes and Bulk-rock Sr–Nd Isotopes

Meer

Waight

Tulloch

et al. 2018

Journal of Petrology

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Major changes in tectonic style can lead to tapping of highly variable magma sources and potentially result in significant episodes of crustal growth. Here we focus on magmatism associated with a transition from arc magmatism to subsequent over-thickening and eventual orogenic collapse. This transition is associated with cessation of subduction and was followed by continental extension and finally continental break-up as recorded in the Cretaceous magmatic record of Zealandia. Orogenic collapse peaked at $110 Ma and is expressed through core complex formation and the intrusion of I-to evolved I/S-type Rahu Suite plutons that have widely varying chemical compositions but homogeneous whole-rock and zircon isotopic signatures that are intermediate between mantle and local upper crust values. The Rahu Suite is interpreted to be derived from differing degrees of melt extraction from a pre-existing lower crustal source and lacks a demonstrable juvenile component. This lower crustal source was likely formed by magmatic underplating and melt-crust hybridization during preceding arc volcanism (Separation Point and Darran suites), effectively smearing out a pulsed event of crust formation in the zircon record. Therefore, late orogenic I-and I/S-type suites do not have to equate to crustal growth and can be an expression of crustal re-melting. An abrupt change in magma sources in Zealandia occurred after 100 Ma during the onset of progressive crustal extension. A juvenile alkaline component (presumably derived from the lithospheric mantle) is suggested to have been present from >97 Ma. This component became more pronounced with time until the emplacement of granites and trachytes with isotopic signatures overlapping with coeval mafic mantle-derived dikes during bimodal rift-related magmatism. The juvenile alkaline component dictated the composition of the felsic magmas but did not represent a significant crustal growth event due to small total volumes.

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“…Two major pulses of plutonism occurred in the Late Devonian-Early Carboniferous (375-335 Ma) and in the Late Jurassic-Early Cretaceous (170-110 Ma), but Cambrian, Late Carboniferous, Late Permian and Late Triassic plutonic rocks are also known (Mortimer et al, 1999;Tulloch and Kimbrough, 2003;Tulloch et al, 2009a;McCoy-West, Mortimer and Ireland, 2014) In Fiordland, plutons as young as Early Cretaceous (as well as their host rocks) are metamorphosed to granulite facies orthogneisses. Devonian-Carboniferous and Cretaceous plutons form the amphibolite facies gneissic lower plate of the Paparoa Metamorphic Core Complexes (Tulloch and Kimbrough, 1989;Ritchie et al, 2015).…”

Section: Tuhua Intrusivesmentioning

confidence: 99%

Regional geological framework of New Zealands mineral deposits

Mortimer¹,

Christie²,

Brathwaite³

et al. 2019

Preprint

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New Zealand is the emergent part of a 4.9 Mkm 2 , mainly submerged continent in the SW Pacific Ocean that was formerly part of the Gondwana supercontinent. The geology can be described in terms of two main Cambrian-Early Cretaceous basement units (Western and Eastern provinces) and a Late Cretaceous-Holocene sedimentary and volcanic cover (Zealandia Megasequence and Rūaumoko Volcanics).The Early Paleozoic greywacke terranes and Cambrian-Early Cretaceous Tuhua Intrusives in the Western Province formed along strike from similar rocks in the Lachlan and New England orogens of Australia. The main mineral deposits in the Western Province are orogenic Au-quartz lodes in the Buller Terrane. Tuhua Intrusives host a variety of metalliferous deposits including granite-related Au and Mo, Ag±W porphyry Mo, vein and greisen W and Sn, magmatic Ni-Cu sulfide, Pt group element (PGE), and titanomagnetite-ilmenite.Mesozoic greywacke and schist terranes in the Eastern Province were assembled at a convergent accretionary margin in the Jurassic and Early Cretaceous. The Haast Schist represents the deeply exhumed part of the Torlesse-Caples-Waipapa terrane accretionary wedge. Greenschist facies schist in Otago and Marlborough contains widespread Au ± W ± Sb mineralisation in shear zones and quartz lodes, including the large Macraes deposit in east Otago. Volcanogenic massive sulfide Cu deposits and volcanogenic Mn-chert deposits occur in flanking schist and greywacke, and talc-magnesite lenses and nephrite jade (greenstone/pounamu) occur in ultramafic schists of the Southern Alps. A Permian ophiolite in the Eastern Province (Dun Mountain-Maitai Terrane) has associated Cu, chromite, PGE and chrysotile asbestos mineralisation. The older part of Zealandia Megasequence comprises Late Cretaceous (ca 105-85 Ma) syn-rift deposits (Momotu Supergroup), overlying transgressive non-marine and marine successions of the Haerenga Supergroup and Oligocene (ca 35-25 Ma) maximum marine inundation limestones of the Waka Supergroup. These Late Cretaceous to Oligocene sedimentary rocks contain most of New Zealand's economic petroleum, coal and limestone deposits.From latest Oligocene time (ca 25 Ma) another major tectonic and paleogeographic change took place in Zealandia related to re-initiation of subduction. In the North Island, allochthons were emplaced and the Northland-Coromandel volcanic arc erupted. All over New Zealand thick flysch-and molasse-like deposits of the Miocene Maui Supergroup overlie the Waka Supergroup limestones and are, in turn, succeeded by clastic dominated Pliocene-Holocene Pakihi Supergroup. Igneous rocks within Zealandia Megasequence have three separate origins. Whakaari Supersuite are subduction-related andesitic to rhyolitic lavas, Te Raupua Supersuite are the oceanic basin ophiolitic rocks in the Northland and East Coast allochthons and Horomaka Supersuite rocks are intraplate basaltic rocks.Economically important volcanic-hosted epithermal Au-Ag deposits occur in Miocene Whakaari Supersuite rocks in the Coromandel region....

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Cretaceous metamorphism, magmatism and shearing in the Waipuna Valley, directly south of the Reefton Goldfield

Cited by 10 publications

References 51 publications

Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

Geology and geochronology of the Sub-Antarctic Snares Islands/Tini Heke, New Zealand

Magmatic Evolution during the Cretaceous Transition from Subduction to Continental Break-up of the Eastern Gondwana Margin (New Zealand) documented by in-situ Zircon O–Hf Isotopes and Bulk-rock Sr–Nd Isotopes

Regional geological framework of New Zealands mineral deposits

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