(Ruby—Sapphire)—Chromian Mica—Tourmaline Rocks from Westland, New Zealand

Grapes, Rodney; Palmer, K.

doi:10.1093/petrology/37.2.293

Cited by 32 publications

(18 citation statements)

References 20 publications

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“…3b). Cr-rich ruby is rare and found worldwide in the Brazilian São Luiz alluvial deposit and in the Juina kimberlite (Hutchinson et al, 2001(Hutchinson et al, , 2004Watt et al, 1994), the Moses Rock Dike kimberlite in Utah (Padovani and Tracey, 1981), the metagabbros of Karelia in Russia (Bindeman and Serebryakov, 2011), and in the serpentinite at Hokitika in New Zealand (Grapes and Palmer, 1996); (a3) The field of sample CO3 is comparable to the chemical composition of ruby-bearing garnetite xenolith in garnet peridotite from Sulu terrane in China (Zhang et al, 2004).…”

Section: The Rubies From Mbuji-mayimentioning

confidence: 96%

Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo, and the Changle alkali basalt, China

Giuliani¹,

Pivin

Fallick

et al. 2015

Comptes Rendus. Géoscience

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Section: The Rubies From Mbuji-mayimentioning

confidence: 96%

Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo, and the Changle alkali basalt, China

Giuliani¹,

Pivin

Fallick

et al. 2015

Comptes Rendus. Géoscience

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“…In this case, the difference in Na 2 O contents of actinolite and bulk nephrite is not considered to be the result of analytical error and so must result from the presence of a discrete Na-bearing solid phase. One possibility is Na-bearing margarite with between 1.3Á4.2 wt % Na 2 O in margarite coexisting with Crmuscovite in metasomatic corundum-rich rocks derived from the Pounamu ultramafics (Grapes & Palmer 1996) ). Amphibole nomenclature after Leake et al (1997). nephrite.…”

Section: Chemical Variationmentioning

confidence: 99%

Geochemistry of a New Zealand nephrite weathering rind

Grapes

Yun

2010

New Zealand Journal of Geology and Geophysics

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A dark-green nephrite boulder collected from Pleistocene glacial outwash gravels, West Coast of New Zealand, has a 6.1 cm thick weathering rind composed of an inner pale-green-white bleached zone (3.5 cm) and an outer brown oxidised zone (2.6 cm). The primary mineralogy of the boulder is monomineralic actinolite with small amounts of secondary Al-substituted goethite within the weathering-rind. ) aq . Assuming that alumina was immobile during weathering, isocon analysis indicates a mass decrease of (24% and a volume change of (26% in the bleached zone and a mass decrease of (52% and volume change of (58% in the oxidised zone with 7Á84% depletion of all elements except Fe ' values between Â2.38 and 2.55 wt % is probably related to incipient dissolution and cation loss as well as lower amounts of Fe-hydroxide formation. Depending on the deposition age of the gravels from which the nephrite boulder was derived, the weathering rind may be the result of 360Á250 ka of weathering. The intensity of the green colouration of the nephrite reflects total iron content and oxidation ratio (mol.2Fe 2 O 3 )100/[2Fe 2 O 3 'FeO]). Combined with compositional data of other West Coast nephrites, a colour change from green or dark-green (unweathered) to pale-green-white (weathered) occurs where the oxidation ratio is !7; a change to brown colour occurs where oxidation ratios are !17.

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“…Margarite, talc, and corundum(?) (Grapes & Palmer 1992), which are rare in the Alpine Schist (Cooper 1976(Cooper , 1995Koons 1981;Grapes & Palmer 1996), also occur within the Makawhio mylonites. A noteworthy aspect of these occurrences is that minerals unique to the Makawhio mylonites are not restricted to a single rock type; kyanite occurs in kyanite-orthoamphibole hornblendite and kyanite-plagioclase schist, and scapolite in kyaniteplagioclase schist and hornblende-diopside-scapolite calcschist float boulders.…”

Section: Protolith Of the Makawhio Mylonitesmentioning

confidence: 99%

“…Some or all of this weak fabric development in the kyanite-orthoamphibole hornblendite may reflect metasomatic recrystallisation outlasting peak deformation (cf. Grapes & Palmer 1996). Alternatively, the progressive eastward trend of foliation from the kyaniteorthoamphibole hornblendite outward into enveloping quartzofeldspathic mylonite could reflect significant strain localisation within the mylonites, during which a laminar flow has been repartitioned to form zones where deformation is essentially coaxial (kyanite-orthoamphibole hornblendite), separated by zones in which the deformation is intensely non-coaxial (chlorite-hornblende schist).…”

Section: Localisation Of Strain Within the Alpine Fault Mylonitesmentioning

confidence: 99%

Geochemistry, mineralogy, and metamorphic history of kyanite‐orthoamphibole‐bearing Alpine Fault mylonite, South Westland, New Zealand

McClintock

Cooper

2003

New Zealand Journal of Geology and Geophysics

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Mylonite outcropping in the Alpine Fault Zone at Makawhio River, South Westland, shows mineralogy unlike rocks found elsewhere in the Haast Schist. The Makawhio mylonites comprise kyanite-orthoamphibole hornblendite, garnet amphibolite, chlorite-hornblende schist, kyanite-plagioclase schist, and talc-tremolite rocks, are characterised by ultrabasic to intermediate chemistry, show extreme enrichment in Cr and Ni, and collectively include kyanite, margarite, fuchsite, scapolite, and the first reported occurrence of gedrite and anthophyllite from the Eastern Province. These unusual mylonites form a pod-like body enveloped by chlorite-hornblende schist within Torlessederived metasediments. The geochemistry and mineralogy of the Makawhio rocks suggests an origin as a veined ophiolitic rock metasomatised before or during upper amphibolite facies Alpine Schist metamorphism and mylonitisation, resulting in a localised occurrence of rocks atypical of the Haast Schist overall.These kyanite-bearing, metasomatised mylonites are juxtaposed with quartzofeldspathic and calc-silicate mylonites, and with amphibolites derived from ocean-floor basalt, within the Alpine Fault Zone. The Makawhio River kyanite-bearing mylonites and associated rocks probably represent a tectonised sliver of the Pounamu Ultramafic Belt ophiolite, which is exposed to the north and south as part of the imbricated basement to the Torlesse Terrane along the western margin of the Southern Alps. The range of lithologies and unusual nature of the mylonites at Makawhio River may also represent an extension of the Torlesse Caples Terrane boundary incorporated into the plate boundary zone during oblique convergence and dextral shear on the Alpine Fault.

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(Ruby—Sapphire)—Chromian Mica—Tourmaline Rocks from Westland, New Zealand

Cited by 32 publications

References 20 publications

Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo, and the Changle alkali basalt, China

Geochemical and oxygen isotope signatures of mantle corundum megacrysts from the Mbuji-Mayi kimberlite, Democratic Republic of Congo, and the Changle alkali basalt, China

Geochemistry of a New Zealand nephrite weathering rind

Geochemistry, mineralogy, and metamorphic history of kyanite‐orthoamphibole‐bearing Alpine Fault mylonite, South Westland, New Zealand

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