Evidence for silicate liquid immiscibility in recharging, alkali-rich tholeiitic systems: The role of unmixing in the petrogenesis of intermediate, layered plutonic bodies and bimodal volcanic suites

Lino, Lucas Martins; Carvalho, Paulo Roberto Antonacci; Vlach, Sílvio Roberto Farias; Quiroz-Valle, Francy Roxana

doi:10.1016/j.lithos.2023.107193

Cited by 3 publications

(1 citation statement)

References 62 publications

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“…As shown earlier (Andreeva et al, 2020), the separation of a FeO-enriched (up to 15 wt%) melt into immiscible Fe-rich and Si-rich liquids occurs at the late stages of basalt crystallization upon cooling. Similar processes were described by Lima and Esposito (2023) and Lino et al (2023). The presence of Si-rich glass in ferrocarbonates suggests that ferrocarbonate mineral Frontiers in Earth Science frontiersin.org 13 crystallization occurred during the final stages of the basalt formation in the Wangtian'e shield volcano upon the magma cooling.…”

Section: Silicate-carbonate Immiscibilitysupporting

confidence: 66%

Mechanism of carbonate assimilation by intraplate basaltic magma and liquid immiscibility: example of Wangtian’e volcano (Changbaishan volcanic area, NE China)

Andreeva,

Dubinina,

Andreeva

et al. 2023

Front. Earth Sci.

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The balance of CO2 during abundant basaltic magma production is an important factor of volcanic hazards and climate. In particular, this can be explored based on CO2-rich mantle-derived magmas or carbonate assimilation by basaltic melts. To reconstruct the origin of Fe-rich carbonates hosted by Cenozoic basalts from Wangtian’e volcano (northeast China), we studied elemental compositions of melt, crystalline and fluid inclusions in magmatic minerals as well as the oxygen and carbon isotope compositions of the plagioclase and carbonates from basalts. The crystallization of basaltic magmas occurred in shallow chamber (∼4 km) at temperatures of 1,180°C–1,200°C and a pressure of 0.1 ± 0.01 GPa. Stable Fe-rich carbonates occur in the Wangtian’e tholeiite basalts as groundmass minerals, crystalline inclusions in plagioclase and globules in melt inclusions, which suggests that they crystallized from a ferrocarbonate melt. The values of δ18О and δ13С in the minerals analyzed by laser fluorination method are in line with the sedimentary source of Fe-rich carbonates, indicating assimilation and partial decomposition of carbonate phases. The parent ferrocarbonate melt could be produced during interactions between the basaltic magma and the crustal marbles. The phase diagram and thermodynamic calculations show that the ferrocarbonate melt is stable at a temperature of 1,200°C and a pressure of 0.1 GPa. Our thermodynamic calculations show that carbonate melt containing 73 wt% FeCO3, 24 wt% MgCO3 and 3 wt% CaCO3 is in thermodynamic equilibrium with silicate melt in agreement with our natural observations. The proposed mechanism is crustal carbonate sediment assimilation by the intraplate basaltic magma resulting in the melt immiscibility, production of the ferrocarbonate melt and the following Fe-rich carbonate mineral crystallization during magma residence and cooling.

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Section: Silicate-carbonate Immiscibilitysupporting

confidence: 66%

Mechanism of carbonate assimilation by intraplate basaltic magma and liquid immiscibility: example of Wangtian’e volcano (Changbaishan volcanic area, NE China)

Andreeva,

Dubinina,

Andreeva

et al. 2023

Front. Earth Sci.

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Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia

Nosova,

Lebedeva,

Vozniak

et al. 2024

Petrology

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Fenner trend and the role of fractional crystallisation and ferrobasaltic magma immiscibility in granophyre petrogenesis: the case of the mesoproterozoic Valaam sill in the Ladoga graben, Karelia

Nosova,

Lebedeva,

Vozniak

et al. 2024

Petrologiâ

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Petrographic, mineralogical, geochemical, isotope-geochemical studies of granophyres and host ferrogabbro, quartz ferromontsogabbro, quartz montsodiorites, and quartz monzonites in the Mesoproterozoic Valaam sill in the Ladoga Graben on the Karelian craton have been carried out. The sill is poorly layered: ferrogabbros are common in the lower part of the sill, the middle part consists of quartz gabbro-monzonites and quartz monzonites, granophyres form a network of veins mainly in the upper part of the sill. Geochemical features of ferrogabbro, iron-rich composition of olivine and pyroxene, low Ca composition of plagioclase indicate evolution along the Fenner trend. Granophyres have petro- and geochemical characteristics of anorogenic alkaline granites, are characterised by negative Eu/Eu* = = 0.15–0.49 and REE distribution similar to those of granophyres of layered intrusives. All rocks of the sill are characterised by a similar isotopic composition of Sr (87Sr/86Sr)T= 0.7043–0.7066, andεNdvalues ranging from –9.6 to –11.2. Model calculations show that fractional crystallisation can lead the initial ferrogabbro melt into immiscibility. Ilmenite-magnetite-silicate microstructures have been identified in ferrogabbro and ferromontzogabbro from the sill; similar microstructures in layered intrusives are considered evidence for immiscibility of Fe-enriched and Si-enriched liquids (Holness et al., 2011; Dong et al., 2013). The segregation of the high-silica melt may have occurred in a crustal chamber at around 350 MPa and 960oC; the sill formation at around 70 MPa injected magma in the form of a crystalline mush through which acidic melt migrated. This melt underwent fractional crystallisation and reacted with host minerals. At the level of sill formation, it crystallised under supercooling into granophyre aggregates. The example of the Valaam sill shows that after fractionation according to the classical Fenner trend reaches the final composition – ferrogabbro, its continuation with a conjugate decrease in SiO2and Fe contents can be associated with incomplete separation and mixing of iron-rich melts and separated acidic melt. Such a mechanism can be realised during the formation of the mafic part of AMCG-type massifs.

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Evidence for silicate liquid immiscibility in recharging, alkali-rich tholeiitic systems: The role of unmixing in the petrogenesis of intermediate, layered plutonic bodies and bimodal volcanic suites

Cited by 3 publications

References 62 publications

Mechanism of carbonate assimilation by intraplate basaltic magma and liquid immiscibility: example of Wangtian’e volcano (Changbaishan volcanic area, NE China)

Mechanism of carbonate assimilation by intraplate basaltic magma and liquid immiscibility: example of Wangtian’e volcano (Changbaishan volcanic area, NE China)

Fenner Trend and the Role of Fractional Crystallization and Ferrobasaltic Magma Immiscibility in Granophyre Petrogenesis: the Case of the Mesoproterozoic Valaam Sill in the Ladoga Graben, Karelia

Fenner trend and the role of fractional crystallisation and ferrobasaltic magma immiscibility in granophyre petrogenesis: the case of the mesoproterozoic Valaam sill in the Ladoga graben, Karelia

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