Formation of Highly Refractory Dunite by Focused Percolation of Pyroxenite-Derived Melt in the Balmuccia Peridotite Massif (Italy)

Mazzucchelli, Maurizio; Rivalenti, Giorgio; Brunelli, Daniele; Zanetti, A.; Boari, Elena

doi:10.1093/petrology/egn053

Cited by 48 publications

(59 citation statements)

References 53 publications

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“…This process is attested to by the strong orthopyroxene modal variability (Table 1, Figure 8) with several samples showing very low modal orthopyroxene and consequent locally high Cpx/Opx (Figure 8). The presence of four dunite samples can be interpreted as representative of the extreme terms of pyroxene dissolution due to channelling of silicaundersaturated melt at relatively low P [47]. Pyroxene instability is con rmed by petrographic examination that suggests a di use record of secondary olivine replacing orthopyroxene in olivine-rich peridotites.…”

Section: 24]mentioning

confidence: 92%

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

et al. 2015

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Cenozoic basalts carrying ultrama c mantle xenoliths occur in the Matilde, León and Chenque hills in the Paso de Indios region, Argentina. The mantle xenoliths from the Chenque and León hills mainly present porphyroclastic textures, whereas the Matilde hill xenoliths have coarse-grained to porphyroclastic textures. The equilibrium temperatures are in the range of 780 to 940• C, indicating a provenance from shallow sectors of the lithospheric mantle column that were subjected to a relatively low heat ux at Cenozoic Era. According to the modal compositions of xenoliths, the mantle beneath Matilde and León hills was a ected by greater than 22% partial melting, while less depleted peridotites occur in the Chenque suite (starting from 10% partial melting). Such an observation is con rmed by the partial melting estimates based on Cr# Sp , which vary from 8 to 14% for the selected Chenque samples and from 14 to 18% for the Matilde ones. The common melting trend is overlapped by small-scale cross cutting local trends that may have been generated by open-system processes, such as open-system partial melting and/or post partial-melting metasomatic migration of exotic Na-Cr-rich melts. The two main mineralogical reaction schemes are: i) the dissolution of pyroxenes and the segregation of new olivine in olivine-rich peridotites, and ii) the replacement of primary olivine by orthopyroxene±clinopyroxene in orthopyroxene-rich peridotites. These were produced by channelled and/or pervasive melt extraction/migration. Enhanced pyroxene dissolution is attributed to channelling of silica-undersaturated melts, whereas the replacement of primary olivine by orthopyroxene±clinopyroxene points to reaction with silica-saturated melts. Late disequilibrium reactions identi ed in the xenoliths comprise: the breakdown of orthopyroxene in contact with the host basalt, and (rarely) reaction coronae on orthopyroxene, clinopyroxene and spinel linked to glassy veins. Such features are apparently related to the injection of melt, likely during entrainment into the host basalts and ascent to the surface.

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Section: 24]mentioning

confidence: 92%

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

et al. 2015

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“…Refractory peridotites may be volumetrically significant (up to 30-40%), while the mafic layers generally do not exceed 5%. Several orogenic peridotites contain accessory lithologies resulting from the segregation and migration of partial melts or from the interaction between mantle rocks and melt/fluid (e.g., Bodinier et al, 1988Bodinier et al, , 1990Bodinier et al, , 2008Borghini et al, 2007;Boudier and Nicolas, 1977;Garrido and Bodinier, 1999;Gysi et al, 2011;Mazzucchelli et al, 2009;Obata and Nagahara, 1987). Rock types related to melt/fluid processes include a variety of dikes, veins, and veinlets representing magma conduits now filled with garnet and/or amphibole pyroxenites, hornblendites, glimmerites (mica-clinopyroxene), orthopyroxenites or gabbros, and diffuse facies of pyroxene-rich or amphibole (AEphlogopite)-bearing peridotites resulting from interactions between peridotites and percolating melt/fluid.…”

Section: Orogenic Peridotite Massifsmentioning

confidence: 99%

“…The Baldissero and Balmuccia peridotite bodies, exposed at the southern tip and in the middle part of the Ivrea zone, respectively, are dominantly composed of fertile spinel lherzolites with subordinate harzburgites and dunites (Hartmann and Wedepohl, 1993;Lensch, 1968Lensch, , 1971Mazzucchelli et al, 2009Mazzucchelli et al, , 2010Sinigoi et al, 1980). The massifs also contain mafic layers, among which two suites were distinguished by Shervais (1979) in Balmuccia: (1) a Cr-diopside suite in chemical equilibrium with the host peridotite and (2) an Al-augite suite in disequilibrium with the peridotite.…”

Section: Alpsmentioning

confidence: 99%

“…To account for their distinctive characteristics, several authors (notably Peter Kelemen) suggested the formation of the layered refractory peridotites by olivine-forming, meltrock reactions, leading to the evolution of 'porous-flow channels' Gervilla and Remaïdi, 1993;Kelemen, 1990;Kelemen and Dick, 1995;Kelemen et al, 1990Kelemen et al, , 1992Kelemen et al, , 1997Mazzucchelli et al, 2009;Suhr, 1999;Takazawa et al, 1992). However, as pointed out by Suhr et al (2003), the interpretation of these channels as high melt flux, feeder conduits for MORB is questionable in several instances, and alternatives such as the formation of melt accumulation horizons due to compaction waves (e.g., Rabinowicz and Ceuleneer, 2005) must be considered.…”

Section: Interpretationsmentioning

confidence: 99%

“…To explain the isotopic enrichment observed in refractory peridotites, Bodinier et al (1991) and Downes et al (1991) suggested an interpretation involving focused percolation of enriched (plume-derived) melts in refractory porous-flow channels Mazzucchelli et al, 2009;Suhr, 1999;Takazawa et al, 1992). In Lanzo, this process was tentatively ascribed to a 'prerift' stage of the opening of the Liguro-Piemontese ocean basin -see also Piccardo et al, 2007b.…”

Section: Interpretationsmentioning

confidence: 99%

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Orogenic, Ophiolitic, and Abyssal Peridotites

Bodinier

Godard

2014

Treatise on Geochemistry

181

148

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Crustal Metasomatism at the Slab‐Mantle Interface in a Continental Subduction Channel: Geochemical Evidence From Orogenic Peridotite in the Sulu Orogen

Chen

Zheng

et al. 2018

JGR Solid Earth

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To understand crust‐mantle interactions in a continental subduction channel, we carried out a combined study of whole‐rock elements and Sr‐Nd isotopes, mineral elements, and whole‐rock and mineral O isotopes in orogenic peridotite and its host gneiss from the Sulu orogen in China. The results indicate that the peridotite originated from highly depleted subcontinental lithospheric mantle beneath the North China Craton and underwent three episodes of metasomatism via crustally derived fluids. The peridotite was offscraped from the subcontinental lithospheric mantle wedge base and experienced petrographic transformation from a spinel peridotite to a garnet peridotite during continental subduction from forearc to subarc depths. The peridotite underwent the first episode of metasomatism via aqueous solutions at high‐pressure conditions. Afterward, the peridotite underwent a second episode of metasomatism by carbonate melts at ultrahigh‐pressure conditions and a third episode of metasomatism by aqueous solutions at high‐pressure conditions. While the aqueous solution was derived from the metamorphic dehydration of the subducting/exhuming continental crust at the forearc depths, the carbonate melts were produced by partial melting of the ultrahigh‐pressure metasedimentary rocks in the exhuming continental crust at subarc depths. These metasomatic agents did not originate from the gneiss directly hosting the peridotite but from another part of the deeply subducted continental crust that was not in direct contact with the peridotite. Therefore, the orogenic peridotite recorded the geochemical transfer from the subducting crust into the mantle in the continental subduction zone.

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Formation of Highly Refractory Dunite by Focused Percolation of Pyroxenite-Derived Melt in the Balmuccia Peridotite Massif (Italy)

Cited by 48 publications

References 53 publications

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

Short-scale variability of the SCLM beneath the extra-Andeanback-arc (Paso de Indios, Argentina): Evidence from spinel-faciesmantle xenoliths

Orogenic, Ophiolitic, and Abyssal Peridotites

Crustal Metasomatism at the Slab‐Mantle Interface in a Continental Subduction Channel: Geochemical Evidence From Orogenic Peridotite in the Sulu Orogen

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