Emplacement depths of Paleozoic‐Mesozoic plutons from western New Zealand estimated by hornblende‐AI geobarometry

Tulloch, A. J.; Challis, G. A.

doi:10.1080/00288306.2000.9514908

Cited by 70 publications

(36 citation statements)

References 55 publications

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“…Reconnaissance thermobarometry using the garnetÁbiotite thermometer (Ferry & Spear 1978;Kleeman & Reinhardt 1994) and the garnetÁbiotiteÁmuscoviteÁplagioclase geobarometer (Ghent & Stout 1981;Hoisch 1990) yields conditions of c. 5808C and palaeo-pressures of c. 0.4 Mpa (these results should be considered indicative and provisional only). This pressure is approximately the same as the emplacement depth of the Paringa Granodiorite (Tulloch & Challis 2000).…”

Section: Conditions Of Metamorphismsupporting

confidence: 53%

Regional metamorphism of the Early Palaeozoic Greenland Group, South Westland, New Zealand

Mortimer

Nathan

Jongens

et al. 2013

New Zealand Journal of Geology and Geophysics

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Early Palaeozoic basement rocks in South Westland consist of regionally metamorphosed Greenland Group of probable Ordovician depositional age. Correlative and formerly contiguous Gondwana margin rocks are also found in Antarctica and eastern Australia. Major protoliths are variably foliated sandstone and mudstone, with rare scattered calcareous lenses. Field, petrographic and electron microprobe data reveal a progressive, regional, southeast-wards increase in metamorphic grade in a 2600 km 2 area between Martins Bay and Fox Glacier. We define new chlorite, biotiteÁalbite, biotiteÁcalcic plagioclase and sillimaniteÁmicrocline zones. Minerals such as cordierite and andalusite, along with semi-schistose textures, indicate a low P/T (pressure/temperature) Buchan style of regional metamorphism spanning the lower greenschist to upper amphibolite facies. This contrasts with medium to high P/T metamorphism in the Haast Schist east of the Alpine Fault. In South Westland, peak metamorphism is loosely constrained as Devonian to Carboniferous (330Á375 Ma) in age; the present-day isograd pattern was mostly established by the Late Cretaceous and has not been strongly influenced by Alpine Fault deformation.

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Section: Conditions Of Metamorphismsupporting

confidence: 53%

Regional metamorphism of the Early Palaeozoic Greenland Group, South Westland, New Zealand

Mortimer

Nathan

Jongens

et al. 2013

New Zealand Journal of Geology and Geophysics

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“…Al-in-hornblende geobarometry indicates that the Walkers Pluton was emplaced at pressures between 4 and 6.5 kbar in the mid crust (Allibone & Tulloch 2008), similar to emplacement depths of some other WFO plutons in northwest Fiordland (bradshaw 1989a; clarke et al in press). Further likely correlatives of the WFO include retrograde two-pyroxene granulite facies rocks on the northwest side of the Alpine Fault in the c. 123 Ma glenroy Metamorphic complex (Tulloch 1981;Tulloch & campbell 1993;Tulloch & challis 2000).…”

Section: Correlatives Of the Wfo Outside Western Fiordlandmentioning

confidence: 99%

Plutonic rocks of Western Fiordland, New Zealand: Field relations, geochemistry, correlation, and nomenclature

Allibone¹,

Jongens

Turnbull

et al. 2009

New Zealand Journal of Geology and Geophysics

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This paper provides a comprehensive description of the plutonic rocks of western Fiordland between breaksea and Sutherland Sounds. The area is dominated by the early cretaceous Western Fiordland Orthogneiss (WFO), but also includes smaller bodies of Paleozoic and cretaceous granitoid. Plutonic rocks of western Fiordland intrude metasediments of the Western Province, many of whose age and terrane affinities remain undefined.Paleozoic granitoids in western Fiordland include the Pandora Orthogneiss (c. 500 Ma) and widespread related sills within Paleozoic metasedimentary rocks; the All Round Pluton (c. 340 Ma); the Deas cove granite (c. 372 Ma); and possibly the Straight River granite. The Pandora Orthogneiss is one of the oldest plutons yet found in the Median batholith. correlatives include the Jaquiery granite gneiss in central Fiordland and orthogneiss in Doubtful Sound. Plutonism of Ross/Delamarian age is therefore widespread in those parts of Fiordland where cambrian or older Western Province metasedimentary rocks form basement. The All Round Pluton and Deas cove granite are correlatives of the S-type Ridge and A/i-type Foulwind Suites, respectively.The c. 125-116 Ma WFO includes at least seven major dioritic and monzodioritic plutons in western Fiordland, one in central Fiordland, and one in central Stewart island. Plutons which compose the WFO are distinguished by differences in their age, petrography, structural and metamorphic histories, and geochemistry. The WFO in northern Fiordland and the correlative Walkers Pluton on Stewart island were emplaced in the mid crust (4-9 kbar) at depths comparable with some Separation Point Suite plutons of similar age. WFO plutons in southern Fiordland were emplaced at greater depths (10-18 kbar). WFO plutons have been variably recrystallised to eclogite; omphacite-, garnet-, two-pyroxene-, and hornblendegranulite; and hornblende-amphibolite facies assemblages, reflecting different PTX conditions during metamorphism of each body. Some parts of the WFO remain undeformed and unmetamorphosed. evidence of up to c. 6 kbar loading after emplacement is limited to WFO plutons in northern Fiordland and adjacent country rocks. extensional ductile shear zones previously shown to locally separate the WFO from adjacent rocks are discontinuous later features, commonly localised along earlier intrusive contacts between WFO plutons and metasedimentary country rocks. They do not form a regionally extensive detachment between the upper and lower plates of a metamorphic core complex.The WFO has previously been included in the Separation Point Suite since both units share a high Sr/Y (HiSY) chemistry and were emplaced at broadly the same time. However, the WFO and Separation Point Suite have distinct chemistries. Separation Point Suite rocks generally contain greater Sr, Na, and Al, and have lower Sr/Rb ratios, rare earth element and Y contents, than WFO rocks with comparable amounts of SiO 2 . Many aspects of the WFO chemistry (aside from its HiSY character) are similar to that o...

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“…This value is consistent with the average pressure estimated with reactions R1 and R2 (0.45-0.67 GPa). The amphibole structural formulae were generally computed following the criteria proposed by Holland and Blundy (1994) and in many other papers that discuss amphibole geobarometers (e.g., Ague, 1997;Tulloch and Challis, 2000). However, in the case of the Nkambe samples, Fe (Table 4).…”

Section: Pressure-temperature Estimations and Discussionmentioning

confidence: 99%

Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

Tetsopgang¹,

Enami²,

Njonfang³

2011

Journal of Mineralogical and Petrological Sciences

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Biotite -and amphibole -bearing monzogranite, quartz monzonite, and tonalite intrude into the biotite granitoids and biotite -hornblende gneisses of the Pan -African belt in the Nkambe area, northwestern Cameroon. The common mineral assemblage in these rocks is amphibole + biotite + plagioclase + K -feldspar + quartz + zircon + apatite; however, their modal composition varies in each rock -type. Most amphibole grains are relatively homogeneous and locally have slightly Al -rich rims. They are mostly ferro -edenite or ferropargasite, and in a tonalite sample, there is magnesiohornblende with less aluminous and more magnesian composition. The amphibole + biotite + plagioclase + K -feldspar + quartz assemblage was affected by several pressure -sensitive and H 2 O -free reactions. The ferro -edenite -and/or ferropargasite -bearing samples show similar pressure -temperature (P -T) ranges of 0.46 -0.50 GPa/655 -690 °C and 0.43 -0.69 GPa/675 -705 °C. In contrast, the magnesiohornblendebearing tonalite records lower temperature conditions of 0.77 GPa/610 °C, which is attributed to subsolidus reequilibration during cooling. The P -T estimates for the biotite -amphibole granitoids in this and previous studies suggest that relatively high -pressure granitoids are widespread in the Nkambe area.

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Emplacement depths of Paleozoic‐Mesozoic plutons from western New Zealand estimated by hornblende‐AI geobarometry

Cited by 70 publications

References 55 publications

Regional metamorphism of the Early Palaeozoic Greenland Group, South Westland, New Zealand

Regional metamorphism of the Early Palaeozoic Greenland Group, South Westland, New Zealand

Plutonic rocks of Western Fiordland, New Zealand: Field relations, geochemistry, correlation, and nomenclature

Emplacement P-T conditions of Pan-African biotite-amphibole granitoids in the Nkambe area, Cameroon

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