Granodiorites of the South Mountain Batholith (Nova Scotia, Canada) derived by partial melting of Avalonia granulite rocks beneath the Meguma terrane: Implications for the heat source of the Late Devonian granites of the Northern Appalachians

Shellnutt, J. Gregory; Dostál, J.

doi:10.1016/j.tecto.2015.06.001

Cited by 8 publications

(1 citation statement)

References 58 publications

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“…There is a similarly continuous covariance of trace incompatible (Rb, Ta, U, Li, F, Sn, W) and compatible (Ba, Sr, Zr, V, Hf, Sc, REE) elements (MacDonald, 2001). Model results indicate that the observed range of major element and trace element compositions is consistent with a combination of assimilation and fractional crystallization (AFC) processes (Clarke et al 2004;Shellnutt and Dostal, 2012;2015). In addition to abundant quartz and feldspars, SMB samples contain varied abundances of biotite, muscovite, aluminosilicates (sillimanite or andalusite), cordierite, garnet and tourmaline, reflecting the peraluminous nature of the SMB-forming magmas.…”

Section: Geological Setting and Overview Of The South Mountain Batholithmentioning

confidence: 69%

Geochemical variation in biotite from the Devonian South Mountain Batholith, Nova Scotia: Constraints on emplacement pressure, temperature, magma redox state and the development of a magmatic vapor phase (MVP)

Brenan,

Maciag,

Hanley

2023

American Mineralogist

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Here we report the composition of biotite from the peraluminous Devonian South Mountain Batholith (SMB) of southwestern Nova Scotia (Canada), the largest intrusive body within the Appalachian orogen. The batholith was emplaced in two phases: an early (379-375 Ma) granodioritemonzogranite suite (Stage 1), and a later (375-372 Ma) more evolved monzogranite-leucogranite suite (Stage 2). Biotite analyses (major and minor elements) were obtained on 55 unmineralized samples representing 11 plutons. Regardless of the stage of pluton emplacement, biotite is commonly interstitial to alkali feldspar, quartz and plagioclase, indicating similar timing of biotite saturation. This suggests that biotite chemistry records conditions at similar extents of magma evolution for the chosen suite of samples. Biotite compositions are Fe-rich, with Fe/(Fe+Mg) ranging from 0.6 to 0.98, and Al-rich, with IV Al ranging from 2.2 to 2.9 atoms per formula unit (apfu; 22 oxygen basis), the latter reflecting the coexistence of other Al-rich phases, such as muscovite, garnet, aluminosilicates and cordierite. Biotite anion sites are dominated by OH (>3 apfu), followed by F (~0.3 apfu) and Cl (< 0.02 apfu), with a general trend of decreasing OH, increasing F and a marked decrease in Cl, with increasing differentiation. Pressure (P) is estimated from the Al content of biotite to be between 280-430 MPa, consistent with a range of 240 to <470 MPa derived from phase equilibria and fluid inclusion microthermometry combined with mineral thermobarometry. Temperature (T) calculated from the Ti content of biotite ranges from 603-722 o C. Comparison of P-T estimates with water-saturated granite phase relations suggest minimum water contents of 6-7 wt% for the SMB magmas. The redox state of the SMB was estimated by comparing biotite Fe#-Ti relations with compositions calculated using the MELTS thermodynamic model, as experiments have shown that biotite Fe# increases with decreasing fO2 at a given extent of crystallization. Results of MELTS modelling for the most primitive magmas of the SMB sample suite indicate that the observed biotite Fe#-Ti variation is consistent with crystallization at FMQ to FMQ-1, with more oxidizing conditions suggested for the most strongly differentiated samples.To constrain the origin of the biotite anion site variation, a quantitative model using biotite-melt exchange coefficients (KD) derived from existing experimental data was used to track the change in 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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Section: Geological Setting and Overview Of The South Mountain Batholithmentioning

confidence: 69%

Geochemical variation in biotite from the Devonian South Mountain Batholith, Nova Scotia: Constraints on emplacement pressure, temperature, magma redox state and the development of a magmatic vapor phase (MVP)

Brenan,

Maciag,

Hanley

2023

American Mineralogist

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Record of Permian–Early Triassic continental arc magmatism in the western margin of the Jiamusi Block, NE China: petrogenesis and implications for Paleo-Pacific subduction

Wang

Yang

et al. 2016

Int J Earth Sci (Geol Rundsch)

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An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U–Pb–Hf isotopic constraints and paleogeographic implications

Keppie

Shellnutt

Dostál

et al. 2017

Int J Earth Sci (Geol Rundsch)

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Granodiorites of the South Mountain Batholith (Nova Scotia, Canada) derived by partial melting of Avalonia granulite rocks beneath the Meguma terrane: Implications for the heat source of the Late Devonian granites of the Northern Appalachians

Cited by 8 publications

References 58 publications

Geochemical variation in biotite from the Devonian South Mountain Batholith, Nova Scotia: Constraints on emplacement pressure, temperature, magma redox state and the development of a magmatic vapor phase (MVP)

Geochemical variation in biotite from the Devonian South Mountain Batholith, Nova Scotia: Constraints on emplacement pressure, temperature, magma redox state and the development of a magmatic vapor phase (MVP)

Record of Permian–Early Triassic continental arc magmatism in the western margin of the Jiamusi Block, NE China: petrogenesis and implications for Paleo-Pacific subduction

An autochthonous Avalonian basement source for the latest Ordovician Brenton Pluton in the Meguma terrane of Nova Scotia: U–Pb–Hf isotopic constraints and paleogeographic implications

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