Large-scale silicate liquid immiscibility during differentiation of tholeiitic basalt to granite and the origin of the Daly gap

Charlier, Bernard; Namur, Olivier; Toplis, Michael J.; Schiano, Pierre; Cluzel, Nicolas; Higgins, Michael D.; Auwera, Jacqueline Vander

doi:10.1130/g32091.1

Cited by 153 publications

(94 citation statements)

References 30 publications

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“…SI-13 (at 1,020°C) is saturated with plagioclase (An 36.7 ), olivine (Fo 43.2 ), augite, pigeonite, ilmenite, magnetite, and whitlockite. This is the same assemblage as that observed in cumulates crystallized from immiscible liquids in the Sept Iles layered intrusion (Namur et al 2010;Charlier et al 2011). The Mull composition (M-9; 1,020°C) has plagioclase (An 60.4 ), olivine (Fo 33.9 ), pigeonite, ilmenite, and magnetite on liquidus.…”

Section: 4supporting

confidence: 52%

Experiments on liquid immiscibility along tholeiitic liquid lines of descent

Charlier

Grove

2012

Contrib Mineral Petrol

204

165

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Crystallization experiments have been conducted on compositions along tholeiitic liquid lines of descent to define the compositional space for the development of silicate liquid immiscibility. Starting materials have 46-56 wt% SiO 2 , 11.7-17.7 wt% FeO tot , and Mgnumber between 0.29 and 0.36. These melts fall on the basaltic trends relevant for Mull, Iceland, Snake River Plain lavas and for the Sept Iles layered intrusion, where large-scale liquid immiscibility has been recognized. At one atmosphere under anhydrous conditions, immiscibility develops below 1,000-1,020°C in all of these compositionally diverse lavas. Extreme iron enrichment is not necessary; immiscibility also develops during iron depletion and silica enrichment. Variations in melt composition control the development of silicate liquid immiscibility along the tholeiitic trend. Elevation of Na 2 O ? K 2 O ? P 2 O 5 ? TiO 2 promotes the development of two immiscible liquids. Increasing melt CaO and Al 2 O 3 stabilizes a singleliquid field. New data and published phase equilibria show that anhydrous, low-pressure fractional crystallization is the most favorable condition for unmixing during differentiation. Pressure inhibits immiscibility because it expands the stability field of high-Ca clinopyroxene, which reduces the proportion of plagioclase in the crystallizing assemblage, thus enhancing early iron depletion. Magma mixing between primitive basalt and Fe-Ti-P-rich ferrobasalts can serve to elevate phosphorous and alkali contents and thereby promote unmixing. Water might decrease the temperature and size of the two-liquid field, potentially shifting the binodal (solvus) below the liquidus, leading the system to evolve as a single-melt phase.

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Section: 4supporting

confidence: 52%

Experiments on liquid immiscibility along tholeiitic liquid lines of descent

Charlier

Grove

2012

Contrib Mineral Petrol

204

165

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“…Plausible hypotheses to explain the data include a magmatic origin either by purely magmatic processes, such as liquid immiscibility that is thought to have formed Fe-Ti-P/V deposits in layered intrusions such as the Bushveld Complex, South Africa (VanTongeren and Mathez, 2012) and Sept Iles layered intrusion, Canada (Charlier et al, 2011), or by magmatichydrothermal processes similar to those that form porphyry copper deposits (e.g., Baker, 2002;Candela and Piccoli, 2005;Pollard et al 2006).…”

Section: Identification Of the Magnetites Origin At Los Coloradosmentioning

confidence: 99%

Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

Knipping

Bilenker

Simon

et al. 2015

Geochimica et Cosmochimica Acta

221

104

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. data demonstrate that a saline magmatic-hydrothermal ore fluid will scavenge significant quantities of metals such as Cu and Au from a silicate melt, and when combined with solubility data for Fe, Cu and Au, it is plausible that the magmatic-hydrothermal ore fluid that continues to ascend from the IOA depositional environment can retain sufficient concentrations of these metals to form iron oxide copper-gold (IOCG) deposits at lateral and/or stratigraphically higher levels in the crust. Notably, this study provides a new discrimination diagram to identify magnetite from Kiruna-type deposits and to distinguish them from IOCG, porphyry and Fe-Ti-V/P deposits, based on low Cr (< 100 ppm) and high V (>500 ppm) concentrations. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes

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“…Nonetheless, the resultant rock association from such a mechanism is prevalently composed of two rock types with contrasting chemical compositions, including low-Si, Fe-Ti-rich basic rocks and overlying coeval Si-rich felsic rocks. Furthermore, it is well documented that such magmatism generally results in the development of the Fe-Ti oxide-bearing mineralized zones near the bottom of the body (e.g., Zhou et al, 2005Zhou et al, , 2008aCharlier et al, 2011;Namur et al, 2012;VanTongeren and Mathez, 2012 and references therein). However, for the 1.21 Ga high Fe-Ti gabbros in the study area, no coeval felsic rocks or oxide deposits have been recognized.…”

Section: Mechanism Of Fe-ti Enrichmentmentioning

confidence: 99%

“…The mechanism of Fe-Ti enrichment in basic igneous rocks is still a controversial issue after so many years, and suggestions include: (1) silicate liquid immiscibility (e.g., Zhou et al, 2005Zhou et al, , 2008aCharlier et al, 2011;Namur et al, 2012;VanTongeren and Mathez, 2012 and references therein); (2) partial melting of peridotite with Fe-rich eclogitic streaks (e.g., Herzberg and Zhang, (Shaw, 1970) of peridotite in which the amount of melting that occurs in the presence of garnet varies from 0 to 100%. The light lines indicate the percentage of melt contribution from garnet-facies mantle (Garnet); e.g.…”

Section: Mechanism Of Fe-ti Enrichmentmentioning

confidence: 99%