Insights into magma ocean dynamics from the transport properties of basaltic melt

Bajgain, S. K.; Ashley, Aaron; Mookherjee, Mainak; Ghosh, Debashri; Karki, Bijaya B.

doi:10.1038/s41467-022-35171-y

Cited by 22 publications

(19 citation statements)

References 107 publications

(223 reference statements)

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“…While the slope of Fe 2+ ‐bearing MgSiO 3 glass is 8% less than pure MgSiO 3 (Mashino et al., 2022; Murakami & Bass, 2011), 20.5 mol% of Al 2 O 3 ‐bearing SiO 2 glass shows almost 14% higher slope with respect to simplest SiO 2 glass (Murakami & Bass, 2010; Ohira et al., 2016) after the inflection pressure,which is evident that Al could make SiO 2 glass much stiffer with pressure. Our results support that Al acts as network former and undergoes the higher coordination (>6 + ) at much lower pressure than Si as predicted by various studies for different glasses/melts (Bajgain et al., 2015, 2022; Ghosh & Karki, 2018; Ohira et al., 2019; Solomatova & Caracas, 2019). So we could assume that when the pressure is increased from the inflection point, the fraction of 6 + in (Fe, Al)‐silicate glass is expected to increase faster than in MgSiO 3 glass because Si undergoes a CN change following Al, and Fe 2+ .…”

Section: Discussionsupporting

confidence: 90%

“…In fact very recent spin polarized calculations on pyrolite melt, the average CN of Fe‐O reaches 6 above 25 GPa and in the core‐mantle boundary (CMB) conditions it is 6–7 (Solomatova & Caracas, 2019). One experimental study on the Al 2 O 3 ‐SiO 2 glass showed an average Al‐O CN increase from 4 to 6 above 20 GPa, and from 6 to >6 ∼110 GPa (Ohira et al., 2019), while theoretical calculations on the model basaltic melt, pyrolite glass and melt a gradual increase is predicted with higher than 6 CN in the pressure range 60–80 GPa (Bajgain et al., 2015, 2022; Ghosh & Karki, 2018; Solomatova & Caracas, 2019) and reaching 7 toward the CMB conditions. It is therefore evident that both Fe‐O and Al‐O undergo the higher CN much earlier than Si‐O and have a large effect on the reduction of the inflection pressure.…”

Section: Discussionmentioning

confidence: 99%

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Ultrahigh‐Pressure Acoustic Velocities of Aluminous Silicate Glass up to 155 GPa With Implications for the Structure and Dynamics of the Deep Terrestrial Magma Ocean

Saha,

Murakami,

McCammon

et al. 2023

Geophysical Research Letters

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We have carried out in situ high‐pressure acoustic velocity measurements of (Fe2+, Al)‐bearing MgSiO3 glass up to pressures of 155 GPa, which confirmed a distinct pressure‐induced trend change in the transverse acoustic velocity (VS) profile around 98 GPa, likely caused by the Si‐O coordination number (CN) change from 6 to 6+. Although it has been reported that the substitution of Fe2+ in MgSiO3 glass induces almost linear velocity reduction up to ∼160 GPa, we revealed that the VS profile of (Fe2+, Al)‐bearing MgSiO3 becomes anomalously steeper above ∼100 GPa and eventually came to be equivalent to MgSiO3 glass above ∼125 GPa. This implies the incorporation of Al into Fe‐bearing MgSiO3 glass significantly facilitates making it far elastically stiffer and thus the densification under pressures well within the Earth's lower mantle. Our results indicate the possible presence of stiff and highly dense silicate melts in deep MOs in the rocky terrestrial planets.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Ultrahigh‐Pressure Acoustic Velocities of Aluminous Silicate Glass up to 155 GPa With Implications for the Structure and Dynamics of the Deep Terrestrial Magma Ocean

Saha,

Murakami,

McCammon

et al. 2023

Geophysical Research Letters

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“…As a result, we speculate that, upon decompression, melt polymerization may occur as a result of pressureinduced oxidation of Fe 2+ to Fe 3+ and the subsequent transition of Fe 3+ modifier to Fe 3+ O 4 5− former as Fe 3+ CN decreases, and that this melt polymerization should result in an increase in viscosity. Independent evidence for this comes from other AIMD simulations on basaltic melts, in which such liquids, at 2200 K, exhibit decreasing viscosities up to Frontiers in Earth Science frontiersin.org ~10 GPa before undergoing a drastic increase above these pressures (Bajgain et al, 2022). Such hypothesis is also in accord with the conclusions of Spice et al (2015).…”

Section: Structural Role Of Iron In Peridotite Glassessupporting

confidence: 53%

Atomic structure and physical properties of peridotite glasses at 1 bar

Losq

Sossi²

2023

Front. Earth Sci.

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Earth’s mantle, whose bulk composition is broadly peridotitic, likely experienced periods of extensive melting in its early history that formed magma oceans and led to its differentiation and formation of an atmosphere. However, the physical behaviour of magma oceans is poorly understood, as the high liquidus temperatures and rapid quench rates required to preserve peridotite liquids as glasses have so far limited their investigation. In order to better characterize the atomic structure and estimate the physical properties of such glasses, we examined the Raman spectra of quenched peridotite melts, equilibrated at 1900 °C ± 50 °C at ambient pressure under different oxygen fugacities (fO2), from 1.9 log units below to 6.0 log units above the Iron-Wüstite buffer. Fitting the spectra with Gaussian components assigned to different molecular entities (Q-species) permits extraction of the mean state of polymerisation of the glass. We find that the proportions of Q1 (0.36–0.32), Q2 (0.50–0.43), and Q3 (0.16–0.23) vary with Fe3+/FeTOT (FeTOT = Fe2+ + Fe3+), where increasing Fe3+/FeTOT produces an increase in Q3 at the expense of Q2 at near-constant Q1. To account for the offset between Raman-derived NBO/T (2.06–2.27) with those determined by assuming Fe2+ exists entirely as a network modifier and Fe3+ a network former (2.10–2.44), ∼2/3 of the ferric iron and ∼90% of the ferrous iron in peridotite glasses must behave as network modifiers. We employ a deep neural network model, trained to predict alkali and alkaline-earth aluminosilicate melts properties, to observe how small variations in the atomic structure of peridotite-like melts affect their viscosity. For Fe-free peridotite-like melts, the model yields a viscosity of ∼ −1.75 log Pa s at 2000 °C, similar to experimental determinations for iron-bearing peridotite melts. The model predicts that changes in the peridotite melt atomic structure with Fe3+/FeTOT yield variations in melt viscosity lower than 0.1 log Pa s, barely affecting the Rayleigh number. Therefore, at the high temperatures typical of magma oceans, at least at 1 bar, small changes in melt structure from variations in oxidation state are unlikely to affect magma ocean fluid dynamics.

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“…In contrast, low-viscosity melts form wide, shallow intrusions, such as sills and laccoliths. The melt viscosity also influences the intrusive patterns, e.g., multiple parallel dikes in case of highviscosity, whereas large, single intrusives for low-viscosity conditions (Bajgain et al, 2022;Petford et al, 2000;Tobias Schmiedel et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

Wall Fracturing versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights from Laboratory Experiments

Biswas

Mitra

Mandal

2023

Preprint

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Igneous dike intrusion is a primary crust-forming process at the Earth’s plate boundaries. Understanding its mechanism is thus crucially important in lithospheric studies. Our present article combines experimental and field observations to investigate the problem of dike emplacement from a mechanical perspective. We performed scaled laboratory experiments by injecting immiscible liquids into visco-elastic and visco-elasto-plastic host materials at varying volumetric flow rates (VFR = 0.100 ml/sec to 1.670 ml/sec). Another set of experiments used different injecting liquid–host combinations to set their viscosity ratios (η*) at low (105), moderate (106), and (iii) high (109) values. These two lines of experiments allow us to recognize three principal mechanisms of liquid pathways: 1) tensile fracturing of the host, 2) wave instability at the liquid-host interface and coupled fracturing-wave instability process. The three mechanisms give rise to a wide variation in intrusion geometry, ranging from planar structures with elliptical outlines to typical bulbous geometry, with intermediate patterns characterized by in-plane and off-plane wavy interfaces with the host. We use the experimental data to constrain the VFR conditions that determine the fracturing versus wave instability-controlled mechanisms. It is also shown from the experiments that η* can significantly influence the evolution of three-dimensional intrusive geometry. The Chotonagpur Granite Gneiss Complex in eastern India is chosen as our study area to validate our laboratory findings using a 2D shape analysis of the intrusive boundaries in terms of their fractal dimensions (D) and skewness-kurtosis estimates.

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Insights into magma ocean dynamics from the transport properties of basaltic melt

Cited by 22 publications

References 107 publications

Ultrahigh‐Pressure Acoustic Velocities of Aluminous Silicate Glass up to 155 GPa With Implications for the Structure and Dynamics of the Deep Terrestrial Magma Ocean

Ultrahigh‐Pressure Acoustic Velocities of Aluminous Silicate Glass up to 155 GPa With Implications for the Structure and Dynamics of the Deep Terrestrial Magma Ocean

Atomic structure and physical properties of peridotite glasses at 1 bar

Wall Fracturing versus Mechanical Instability as Competing Intrusion Mechanisms of Dikes: Insights from Laboratory Experiments

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