Hydrous metasomatism of oceanic sub-arc mantle, Lihir, Papua New Guinea: petrology and geochemistry of fluid-metasomatised mantle wedge xenoliths

McInnes, Brent; Grégoire, Marilaure; Binns, R. A.; Herzig, Peter; Hannington, Mark D.

doi:10.1016/s0012-821x(01)00306-5

Cited by 266 publications

(112 citation statements)

References 31 publications

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“…The major and trace element contents of the Monglo orthopyroxenes are also very similar to those of Lihir (Table 1; Fig. 6 and Table 2 of McInnes et al, 2001). On the other hand, their major element contents (lower Al and Ca and higher Si) are different from those of the orthopyroxenes produced during the Pinatubo dacite-peridotite interaction experiments of Prouteau and Scaillet (2003).…”

Section: Dunite Metasomatism By Adakitic and Other Slab-related Meltssupporting

confidence: 62%

Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

Grégoire

Jégo

Maury

et al. 2008

Lithos

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somatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines). Lithos, Elsevier, 2008, 103 (3-4) AbstractThe Monglo adakite contains mafic and ultramafic xenoliths, which probably originated from the mantle section of an Early Cretaceous supra-subduction zone ophiolitic complex located within the Luzon arc crust. Spinel-bearing dunites are dominant among this xenolith collection and display evidence for three episodes of subduction-related melt percolation. The first one is evidenced by an undeformed clinopyroxene characterized by convex-upwards REE pattern. This clinopyroxene crystallized from a calc-alkaline basaltic magma, likely formed in the Cretaceous supra-subduction setting of the ophiolite. Then, two metasomatic events, evidenced by orthopyroxene-rich and amphibole-rich secondary parageneses, respectively, affected most of the spinel dunites. The opx-rich paragenesis is related to the circulation within the dunitic upper mantle of hydrous slab-derived melts similar to those affecting the mantle peridotite xenoliths from Papua New Guinea and Kamchatka. Finally the amphibole-rich veins are related to the interaction between the studied dunite xenoliths and the host adakite or an adakitic melt similar to it.

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Section: Dunite Metasomatism By Adakitic and Other Slab-related Meltssupporting

confidence: 62%

Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

Grégoire

Jégo

Maury

et al. 2008

Lithos

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“…Partial melting of young oceanic crust of the Indo-Australian Plate beneath the Solomon Arc exerts a strong control on erupted magma chemistry (Johnson et al, 1987;König et al, 2007). Metasomatic enrichment of the mantle wedge by the stalled Pacific slab has been suggested to be an important control on the composition of magmas in Papua New Guinea (McInnes et al, 2001;Müller et al, 2001;Richards et al, 1990), and may also be significant for magma generation in the Solomon Islands.…”

Section: Geology and Tectonic Setting Of Savomentioning

confidence: 99%

Anomalous alkaline sulphate fluids produced in a magmatic hydrothermal system — Savo, Solomon Islands

et al. 2010

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In magmatic-hydrothermal and associated geothermal systems, acidic magmatic-derived fluids (pH<3) commonly discharge from springs proximal to the vent of active (degassing) volcanoes and more alkaline (pH>5) geothermal fluids are typically limited to lateral outflows some distance from the main vent. Here we describe an unusual hydrothermal system associated with Savo volcano, a recently active (1830-40) trachyte-dominated island arc stratovolcano in the Solomon Islands. Hot springs (~100°C) near to the volcanic crater discharge alkaline waters instead of the more commonly recognised acidic fluids. 2The hydrothermal system of Savo dominantly discharges sinter and travertine-forming alkaline sulphate (pH 7-8) waters at hot springs on its upper flanks, in addition to a small number of lower discharge acid sulphate springs (pH 2-7). Alkaline sulphate springs discharge dilute, chloride-poor (<50 mg/l), sulphate-(>600 mg/l) and silica-rich (>250 mg/l) fluids. They have restricted δ 34 S SO4 (5.4 ± 1.5‰) and δ 18 O H2O values (−4‰; local nonthermal groundwater is −8‰). Acid sulphate springs discharge low chloride (<20 mg/l), high sulphate (300-800 mg/l) waters, with variable silica (100-300 mg/l) and distinctly lower δ 34 S SO4 values (−0.6 ± 2.5‰) compared to the alkaline sulphate fluids. They also display high δ 18 O H2O and δD H2O relative to non-thermal groundwater.Geochemical modelling shows that water-rock reaction and dilution in the presence of secondary anhydrite, pyrite and quartz leads to chloride being diluted to low concentrations, whilst maintaining high sulphate and silica concentrations in the fluid. Strontium, oxygen and hydrogen isotopes confirm water-rock reaction and mixing with groundwater as primary controls on the composition of the alkaline sulphate springs.The highly unusual dilute chemistry of all discharges at Savo is a consequence of high regional rainfall, i.e. climatic control, and results from open system mixing at depth between hydrothermal and meteoric waters.

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“…Slab melts and aqueous fluids from subducted slabs can enrich the mantle by metasomatism Kepezhinskas et al 1995;McInnes et al 2001;Pearce and Peate 1995;Rapp et al 1999). At low melt/rock ratios, slab melts enrich the mantle wedge with mobile elements, and particularly with Na (Kepezhinskas et al 1995;Xiong et al 2006), rather than ascending to the surface as pristine adakites or mantlehybridised high magnesian andesites (HMAs; Kepezhinskas et al 1995;Rapp et al 1999).…”

Section: Sodic Magmas At Savomentioning

confidence: 99%

The petrogenesis of sodic island arc magmas at Savo volcano, Solomon Islands

Smith

Petterson

Saunders

et al. 2009

Contrib Mineral Petrol

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Savo, Solomon Islands, is a historically active volcano dominated by sodic, alkaline lavas and pyroclastic rocks with up to 7.5 wt % Na 2 O, and high Sr, arc-like trace element chemistry. The suite is dominated by mugearites (plagioclase-clinopyroxene-magnetite ± amphibole ± olivine) and trachytes (plagioclaseamphibole-magnetite ± biotite). The presence of hydrous minerals (amphibole, biotite) indicates relatively wet magmas. In such melts, plagioclase is relatively unstable relative to iron oxides and ferromagnesian silicates; it is the latter minerals (particularly hornblende) that dominate cumulate nodules at Savo and drive the chemical differentiation of the suite, with a limited role for plagioclase. This is potentially occurring in a crustal "hot zone", with major chemical differentiation occurring at depth. Batches of magma ascend periodically, where they are subject to decompression, water saturation and further cooling, resulting in closed-system crystallisation of plagioclase, and ultimately the production of sodic, crystal and feldspar-rich, high-Sr rocks.The sodic and hydrous nature of the parental magmas is interpreted to be the result of partial melting of metasomatised mantle, but radiogenic isotope data (Pb, Sr, Nd) cannot uniquely identify the source of the metasomatic agent.

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Hydrous metasomatism of oceanic sub-arc mantle, Lihir, Papua New Guinea: petrology and geochemistry of fluid-metasomatised mantle wedge xenoliths

Cited by 266 publications

References 31 publications

Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

Metasomatic interactions between slab-derived melts and depleted mantle: Insights from xenoliths within Monglo adakite (Luzon arc, Philippines)

Anomalous alkaline sulphate fluids produced in a magmatic hydrothermal system — Savo, Solomon Islands

The petrogenesis of sodic island arc magmas at Savo volcano, Solomon Islands

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