SilMush: A procedure for modeling of the geochemical evolution of silicic magmas and granitic rocks

Hertogen, Jan; Mareels, Joyce

doi:10.1016/j.gca.2016.04.044

Cited by 5 publications

(4 citation statements)

References 73 publications

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“…The continuous compositional trends and ver-tical zoning from relative primitive charnockite to more evolved, orthopyroxene-free granite may suggest incremental fractiona-tion, which means that magma may have crystallized in a so-lidification front, which incrementally advanced from the first cooled magma chamber margin into its later cooled center (i.e. in situ fractional crystallization, see box-model and Table S1 in supplementary file 1; Langmuir, 1989;Nishimura and Yanagi, 2000;Hertogen and Mareels, 2016). Some early solidification fronts may still contain melt when most of the original magma chamber was solid-rich given that significant near-solidus crys-tallization (cotectic, eutectic, or minimum crystallization) will buffer temperature across most of the system (cf.…”

Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

“…Free parameters used in the modeling are the solidification zone mass fraction (0.1-0.2, cf. Hertogen and Mareels, 2016), the critical crystallinity for melt ex-traction (0.4-0.5, cf. Bachmann and Bergantz, 2004), and the poros-ity of the cumulate pile.…”

Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

“…The higher the critical crystallinity and porosity values, the more felsic is the composition of the modeled cumulate pile, while the choice of solidification zone mass fraction only determines the coarseness of the modeling (e.g. see also Hertogen and Mareels, 2016). Further details of the modeling are provided in supplemen-tary file 1, while the results are given in supplementary file 3 and summarized in Fig.…”

Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

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Thermodynamic modeling for an incrementally fractionated granite magma system: Implications for the origin of igneous charnockite

Zhao

Erdmann

2018

Earth and Planetary Science Letters

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Understanding fractionation of silicic magma is crucial to advance our knowledge of differentiation of continental crust, enrichment of elements of economic interest, and plutonic-volcanic connection. Microstructural records afford critical appraisals for silicic magma fractionation, yet are rarely reported in granite plutons. Here we combine detailed microstructural observations and thermodynamic modeling to quantify the components and the conditions of silicic magma fractionation using the peraluminous Jiuzhou pluton (South China) as an example. The pluton shows compositional gradients from primitive orthopyroxene-bearing granite (charnockite) at stratigraphically low levels to relatively evolved orthopy-roxene-free granite at stratigraphically high levels. Deviation of whole-rock compositions from metasediment-sourced experimental melts, and stepzoned plagioclase and alkali feldspar crystals in the exposed rocks suggest open-system fractionation by melt extraction, partial dissolution, and subsequent crystallization from trapped minimum melt. Crystal cluster and chain fabrics and viscous deformation are more abundant in the charnockites than in the overlying orthopyroxene-free granites, suggesting that gravitational, compaction-driven fractionation increased towards the bottom of the pluton. Field observations, thermodynamic modeling and petrographic studies further demonstrate that gravitational compaction reduces the trapped melt fraction of a crystal mush with thickness of ≥100 m from ∼30 wt% at the upper level to ∼10 wt% at the lower level of the pluton.Significant melt extraction restricted back-reaction with high-temperature phases during progressive crystallization, which preserved orthopyroxene during the solidification of granitic magma. The compositional, mineralogical and textural zoning of the Jiuzhou pluton suggests that incremental fractionation of granite systems may be an important process that produces compositionally zoned cumulate. Incremental fractionation may occur in many zoned granite plutons worldwide, causing their whole-rock composition to deviate from their primary melt composition. Detailed microstructural examination for these granite plutons may provide insights into the mechanism(s) for melt extraction and crystal accumulation of silicic magma, providing key insights towards quantifying fractionation of magma systems.

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Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

Section: Possible Fractionation In Solidification Frontsmentioning

confidence: 99%

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Thermodynamic modeling for an incrementally fractionated granite magma system: Implications for the origin of igneous charnockite

Zhao

Erdmann

2018

Earth and Planetary Science Letters

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“…Here, we model the continuous compositional variation trend for the Yunlu charnockite based on an in situ (incremental) fractional crystallization process (Nishimura and Yanagi 2000;Hertogen and Mareels 2016;Zhao et al 2018). In the modeling, the incremental fractionation with cumulate formation and melt extraction in a solidification front is considered by mass balance calculation (see details in supplementary material).…”

Section: Modeling the Geochemical Variation Of The Yunlu Charnockitementioning

confidence: 99%

Crystallization and melt extraction of a garnet-bearing charnockite from South China: Constraints from petrography, geochemistry, mineral thermometry, and rhyolite-MELTS modeling

Zhang

Xia

et al. 2021

American Mineralogist

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It is common for granitic rocks in high-grade terranes to undergo amphibolite-granulite facies metamorphic overprint, thus recovering magmatic records from the metamorphic modification remains a major challenge. Here, we report an early Paleozoic, garnet-bearing Yunlu charnockite, which outcropped in the Yunkai terrane of the Cathaysia block from South China, and underwent amphibole-grade metamorphic overprint in the late Devonian. Field observation, micro-texture and mineral geochemistry combining with diffusion modeling constrain that the metamorphic overprint with extremely short-duration of ~0.2-0.5 Ma only influences a narrow rim of < 100 μm for most minerals. The magmatic information is able to be retrieved combining with rhyolite-MELTS modeling, mineral thermobarometry using mineral core compositions to quantitatively estimate magmatic pressure, temperature and melt H 2 O contents. Rhyolite-MELTS modeling results are evaluated by comparison with experimentally-determined phase relations for a peraluminous granite with ~69.83 wt.% SiO 2 at a pressure of ~500 MPa. The comparison results suggest that the modeling reproduces phase relationships of feldspars and quartz within 20-60 °C below 7.0 wt% melt H 2 O, but fails to work properly for all phases at melt H 2 O contents higher than 7.0 wt%. The modeling results using reconstructed primary magma composition of the Yunlu charnockite combining with the orthopyroxene-garnet-plagioclase-quartz thermobarometry and fluid inclusion analyses suggest that the magma was emplaced at pressure of ~600 MPa, temperature of >900 °C, and initial H 2 O content This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

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Magmas and their sources: A special issue honoring Frederick A. Frey

Garcia

Rhodes

Huang

et al. 2016

Geochimica et Cosmochimica Acta

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SilMush: A procedure for modeling of the geochemical evolution of silicic magmas and granitic rocks

Cited by 5 publications

References 73 publications

Thermodynamic modeling for an incrementally fractionated granite magma system: Implications for the origin of igneous charnockite

Thermodynamic modeling for an incrementally fractionated granite magma system: Implications for the origin of igneous charnockite

Crystallization and melt extraction of a garnet-bearing charnockite from South China: Constraints from petrography, geochemistry, mineral thermometry, and rhyolite-MELTS modeling

Magmas and their sources: A special issue honoring Frederick A. Frey

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