Solubility of Sphene in Siliceous Melts

Ayers, John C.; Flanagan, D. M.; Miller, Calvin F.; Watson, E. Bruce; Ryerson, Frederick J.

doi:10.1130/abs/2018am-320568

Cited by 3 publications

(2 citation statements)

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“…Using the resulting modal abundances of each solid phase and melt, we then conducted trace element partitioning calculations using the composition-dependent partition coefficient data set of Keller (2021), compiled via the Geochemical Earth Reference Model (GERM) Partition Coefficients Database (https://kdd.earthref.org /KdD/). With these melt trace element compositions and temperatures, we then applied the zircon saturation model of Boehnke et al (2013), the apatite saturation model of Harrison and Watson (1984), the sphene model of Ayers et al (2018), and the monazite saturation model of Montel (1993). Because the saturation of several of these accessory phases depends on trace elements that also partition into other accessory phases, bulk solid-melt partition coefficients and melt trace element compositions were updated iteratively after adding each accessory phase.…”

Section: Zircon Trace Element Geochemistrymentioning

confidence: 99%

Multi-scale, open-system magmatic and sub-solidus processes contribute to the chemical and isotopic characteristics of the Jurassic Guadalupe Igneous Complex, Sierra Nevada, California, USA

Ratschbacher,

Ardill,

Keller

et al. 2024

Geosphere

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The chemical and isotopic characteristics of a solidified pluton represent the integration of magmatic and sub-solidus processes operating across a range of spatial and temporal scales during pluton construction, crystallization, and cooling. Disentangling these processes and understanding where chemical and isotopic signatures were acquired requires the combination of multiple tools tracing processes at different time and length scales. We combine whole-rock oxygen and Sr-Nd isotopes, zircon oxygen isotopes and trace elements, and mineral compositions with published high-precision U-Pb zircon geochronology to evaluate differentiation within the bimodal Guadalupe Igneous Complex, Sierra Nevada, California (USA). The complex was constructed in ~300 k.y. between 149 and 150 Ma. Felsic magmas crystallized as centimeter- to meter-sized segregations in gabbros in the lower part of the complex and as granites and granophyres structurally above the gabbros. A central mingling zone separates the mafic and felsic units. Pluton-wide δ18O(whole-rock), δ18O(zircon), and Sr-Nd isotopic ranges are too large to be explained by in situ, closed-system differentiation, instead requiring open-system behavior at all scales. Low δ18O(whole-rock) and δ18O(zircon) values indicate assimilation of hydrothermally altered marine host rocks during ascent and/or emplacement. In situ differentiation processes operated on a smaller scale (meters to tens of meters) for at least ~200 k.y. via (1) percolation and segregation of chemically and isotopically diverse silicic interstitial melt from a heterogeneous gabbro mush; (2) crystal accumulation; and (3) sub-solidus, high-temperature, hydrothermal alteration at the shallow roof of the complex to modify the chemical and isotopic characteristics. Whole-rock and mineral chemistry in combination with geochronology allows deciphering open-system differentiation processes at the outcrop to pluton scale from magmatic to sub-solidus temperatures over time scales of hundreds of thousands to millions of years.

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Section: Zircon Trace Element Geochemistrymentioning

confidence: 99%

Multi-scale, open-system magmatic and sub-solidus processes contribute to the chemical and isotopic characteristics of the Jurassic Guadalupe Igneous Complex, Sierra Nevada, California, USA

Ratschbacher,

Ardill,

Keller

et al. 2024

Geosphere

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“…To do this, we applied Perple_X thermodynamic modeling and free energy minimization software (Connolly, 2009(Connolly, , 2005 to model major-element chemistry and major-phase equilibria of a cooling and differentiating magma using the internally consistent thermodynamic database of Holland and Powell (2011), solid solution models based on the thermodynamic data of Tajčmanová et al (2009), Green et al (2016), and Jennings and Holland (2015), and the melt model of Holland et al (2018). After running major-element calculations with Perple_X, we assessed accessory phase stability using saturation models for sphene (Ayers et al, 2018), zircon (Boehnke et al, 2013), apatite (Harrison and Watson, 1984;Bea et al, 1992), monazite (Montel, 1993), and xenotime (Rusiecka and Baker, 2019), though the latter did not saturate. Finally, we partitioned trace elements among all major and accessory phases using partition coefficients compiled and averaged from the literature (including via the GERM database, https:// earthref.org /GERM) in the registered Julia package StatGeochem.jl (doi.org/10.17605/osf.io/tjhmw), which was also used to automate our Perple_X calculations (code available in File 4, see footnote 1).…”

Section: Zircon Trace-element Modelingmentioning

confidence: 99%

Volcano-pluton connections at the Lake City magmatic center (Colorado, USA)

et al. 2022

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Exposed at the Lake City caldera (Colorado, USA) is the ca. 23 Ma reversely stratified (rhyolite to trachyte) Sunshine Peak Tuff and post-collapse syenite and monzonite resurgent intrusions. Existing models for this system suggest that the rhyolites are related to the trachyte and resurgent syenite through fractional crystallization, separation, and remobilization (crystal mush model), and that multiple magma batches were involved in the system (Hon, 1987; Kennedy et al., 2016; Lubbers et al., 2020). We use U-Pb zircon CA-ID-TIMS-TEA and zircon trace-element modeling to further probe age and geochemical relationships between the extrusive and intrusive units. Zircon ages and compositions from the erupted units and the syenite overlap, suggesting these magmas were related and may have mixed prior to eruption. Results from the monzonite suggest it was a contemporaneous but distinct magma batch that mixed with parts of the larger system. Trends in zircon geochemistry are decoupled from time, reflecting a complex history of accessory mineral saturation and mixing of magma batches, and a distinct high-Hf population of zircon grains hints at the existence of an additional, independent batch of rhyolitic magma in the system. The new ages we present shorten the lifetime of the Lake City magmatic system from 80 to 300 k.y. (Bove et al., 2001) to 60 to 220 k.y. and suggest the high-silica rhyolite magma crystallized over a minimum of ~160 k.y. This latter timescale likely reflects a protracted history that includes differentiation of a parent melt prior to extraction of eruptible high-silica rhyolite magma.

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