Physicochemical conditions and timing of rodingite formation: evidence from rodingite-hosted fluid inclusions in the JM Asbestos mine, Asbestos, Québec

Normand, Charles; Williams‐Jones, Anthony E.

doi:10.1186/1467-4866-8-11

Cited by 35 publications

(19 citation statements)

References 47 publications

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“…This is in accordance with the liquidus T at 6 kbar modelled by software at 1280 ∘ C and is lower with respect to Italian primitive kamafugites, which are associated with carbonatites [40]. Mineralogy of 1631 deposits suggests that evolved 1631 magma rested in a magma chamber where low-pressure phases, such as leucite and vesuvianite can crystallise (max 2.5 kbar) [41,42]. Coexistence of K-feldspar and leucite in the 1631 deposits constrains the temperature of the magma chamber at~1090 ∘ C, based on the classical experimental phase equilibria results of [43] for the system NaAlSi3O8-KAlSi3O8-H2O.…”

Section: Petrogenesissupporting

confidence: 56%

Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

et al. 2017

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Vesuvius is a high-risk volcano and the 1631 Plinian eruption is a reference event for the next episode of explosive unrest. A complete stratigraphic and petrographic description of 1631 pyroclastics is given in this study. During the 1631 eruption a phonolite was firstly erupted followed by a tephritic phonolite and finally a phonolitic tephrite, indicating a layered magma chamber. We suggest that phonolitic basanite is a good candidate to be the primitive parental-melt of the 1631 eruption. Composition of apatite from the 1631 pyroclastics is different from those of CO 2 -rich melts indicating negligible CO 2 content during magma evolution. Cross checking calculations, using PETROGRAPH and PELE software, accounts for multistage evolution up to phonolite starting from a phonolitic basanite melt similar to the Vesuvius medieval lavas. The model implies crystal settling of clinopyroxene and olivine at 6 kbar and 1220 ∘ C, clinopyroxene plus leucite at a pressure ranging from 2.5 to 0.5 kbar and temperature ranging from 1140 to 940 ∘ C. Inside the phonolitic magma chamber K-feldspar and leucite would coexist at a temperature ranging from from 940 to 840 ∘ C and at a pressure ranging from 2.5 to 0.5 kbar. Thus crystal fractionation is certainly a necessary and probably a sufficient condition to evolve the melt from phono tephritic to phonolitic in the 1631 magma chamber. We speculate that phonolitic tephrite magma refilling from deeper levels destabilised the chamber and triggered the eruption, as testified by the seismic precursor phenomena before 1631 unrest.

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Section: Petrogenesissupporting

confidence: 56%

Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

et al. 2017

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“…This model can explain the high Ca contents and light Mg isotopic compositions in rodingites observed in this study. The external source of Ca is also consistent with mineral reactions [ Colemen , ; Li et al , , ; Normand and Williams‐Jones , ; Schandl and Mittwede , ] (Text S3). Based on the mineral and whole‐rock data, the generation of hydrogrossular in the Xigaze rodingites likely requires the involvement of Ca 2+ .…”

Section: Discussionsupporting

confidence: 72%

Deep carbon cycle recorded by calcium‐silicate rocks (rodingites) in a subduction‐related ophiolite

Dai

Wang

Liu

et al. 2016

Geophysical Research Letters

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Carbon cycling in subduction zones remains poorly constrained due to the lack of relevant geological records. Here we report magnesium isotope data (δ26MgDSM3) from calcium‐silicate rocks (rodingites) from the Xigaze ophiolite, southern Tibet, which is thought to represent remnants of Neo‐Tethyan oceanic lithosphere. Behaviors of immobile trace elements in rodingites resemble those of their mafic dike protoliths, showing subduction‐related signatures. The majority of rodingites exhibits low δ26Mg values of −0.72‰ to −0.33‰ with a weighted average of −0.47 ± 0.11‰ (2 SD), significantly lighter than that of their protoliths (−0.31 ± 0.03‰). This difference likely reflects the interaction of the protolith with isotopically light carbonate fluids. Modeling indicates that this hypothesis requires the input of 5 to 15 wt % carbonates during rodingitization. Our study suggests that rodingite may represent a previously unrecognized reservoir of dissolved Ca from subducted carbonates.

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“…Note that at 300 C the epidote-ss is predicted to be dominant while at 200 C it is predicted to be absent. Field observations of alteration sequences in rodingitized diorite from the JM Asbestos Mine in Québec reveal alteration patterns closely resembling the 300 C model, which is consistent with results from fluid inclusion analysis (Normand and Williams-Jones 2007). Remarkably, biotite is predicted to only occur between the zone of rodingitization and the prehnite-rich zone in the model calculated for 200 C and 1 kbar.…”

Section: Rodingitization Of Gabbro During Serpentinization Of Abyssalsupporting

confidence: 74%

Metasomatism Within the Ocean Crust

Bach

Jöns

Klein

2012

Lecture Notes in Earth System Sciences

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From ridge to trench, the ocean crust undergoes extensive chemical exchange with seawater, which is critical in setting the chemical and isotopic composition of the oceans and their rocky foundation. Although the overall exchange fluxes are great, the first-order metasomatic changes of crustal rocks are generally minor (usually <10% relative change in major element concentrations). Drastic fluid-induced metasomatic mass transfers are limited to areas of very high fluid flux such as hydrothermal upflow zones. Epidotization, chloritization, and serizitization are common in these upflow zones, and they often feature replacive sulfide mineralization, forming significant metal accumulations below hydrothermal vent areas. Diffusional metasomatism is subordinate in layered (gabbroicdoleritic-basaltic) crust, because the chemical potential differences between the different lithologies are minor. In heterogeneous crust (mixed mafic-ultramafic lithologies), however, diffusional mass transfers between basaltic lithologies and peridotite are very common. These processes include rodingitization of gabbroic dikes in the lithospheric mantle and steatitization of serpentinites in contact to gabbroic intrusions. Drivers of these metasomatic changes are strong across-contact differences in the activities of major solutes in the intergranular fluids. Most of these processes take place under greenschist-facies conditions, where the differences in silica and proton activities in the fluids are most pronounced. Simple geochemical reaction path models provide a powerful tool for investigating these processes. Because the oceanic crust is hydrologically active throughout much of its lifetime, the diffusional metasomatic zones are commonly also affected by fluid flow, so that a clear distinction between fluid-induced and lithology-driven

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Physicochemical conditions and timing of rodingite formation: evidence from rodingite-hosted fluid inclusions in the JM Asbestos mine, Asbestos, Québec

Cited by 35 publications

References 47 publications

Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

Magma evolution inside the 1631 Vesuvius magma chamber and eruption triggering

Deep carbon cycle recorded by calcium‐silicate rocks (rodingites) in a subduction‐related ophiolite

Metasomatism Within the Ocean Crust

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