Millennial storage of near-Moho magma

Mutch, E. J. F.; Maclennan, John; Holland, T. J. B.; Buisman, Iris

doi:10.1126/science.aax4092

Cited by 42 publications

(33 citation statements)

References 90 publications

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“…Some previous studies of the likely duration of basalt storage in the Icelandic crust are consistent with this time scale, but are poorly constrained [71,72]. Intriguingly, more detailed storage time scales have recently been obtained by the modelling of diffusion profiles in spinel inclusions from Borgarhraun, and indicate that crystals may be stored for about 1000 years in mushes prior to eruption [73].…”

Section: Sill Thickness Mush Thickness and Time Scalesmentioning

confidence: 86%

“…Diffusive exchange of Mg-Fe through the liquid and crystals of the mush pile may account for the olivine distributions. Recent diffusion chronometry results also indicate that spinel inclusions in crystalline nodules in Borgarhraun have been stored for ∼ 1000 years after their inclusion in a crystal framework [73].…”

Section: Synthesis: Evolution Of a Lower Crustal Sillmentioning

confidence: 99%

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Mafic tiers and transient mushes: evidence from Iceland

Maclennan

2019

Phil. Trans. R. Soc. A.

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One contribution of 15 to a Theo Murphy meeting issue 'Magma reservoir architecture and dynamics' .It is well established that magmatism is transcrustal, with melt storage and processing occurring over a range of depths. Development of this conceptual model was based on observations of the products of magmatism at spreading ridges, including Iceland. Petrological barometry and tracking of the solidification process has been used to show that the Icelandic crust is built by crystallization over a range of depths. The available petrological evidence indicates that most of the active rift zones are not underlain by extensive and pervasive crystal mush. Instead, the microanalytical observations from Iceland are consistent with a model where magmatic processing in the lower crust occurs in sills of decimetric vertical thickness. This stacked sills mode of crustal accretion corresponds to that proposed for the oceanic crust on the basis of ophiolite studies.A key feature of these models is that the country rock for the sills is hot but subsolidus. This condition can be met if the porosity in thin crystal mushes at the margins of the sills is occluded by primitive phases, a contention that is consistent with observations from cumulate nodules in Icelandic basalts. The conditions required for the stabilization of trans-crustal mushes may not be present in magmatic systems at spreading ridges.This article is part of the Theo Murphy meeting issue 'Magma reservoir architecture and dynamics'.

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Section: Sill Thickness Mush Thickness and Time Scalesmentioning

confidence: 86%

Section: Synthesis: Evolution Of a Lower Crustal Sillmentioning

confidence: 99%

Mafic tiers and transient mushes: evidence from Iceland

Maclennan

2019

Phil. Trans. R. Soc. A.

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“…The slow coupled diffusion of CaAl‐NaSi largely precludes erasing primary magmatic zonation within crystals this large, as Grove et al () found that it would take 250,000 years to erase CaAl‐NaSi oscillatory zoning at only 100 μm. Previous work on residence time of plagioclase crystals below mid‐ocean ridges suggests that they reside within the crust for tens (Costa et al, ) to thousands of years (Mutch et al, ). In addition, Lange et al () estimated the minimum ascent time from the MOHO to the crust for plagioclase megacrysts to be on the order of 2–10 days.…”

Section: Discussionmentioning

confidence: 99%

“…Geochemistry, Geophysics, Geosystems (Mutch et al, 2019). In addition, Lange et al (2013) estimated the minimum ascent time from the MOHO to the crust for plagioclase megacrysts to be on the order of 2-10 days.…”

Section: /2019gc008638mentioning

confidence: 99%

Trace Element and Isotopic Characteristics of Plagioclase Megacrysts in Plagioclase Ultraphyric Basalts (PUB)

Nielsen

Üstünışık

Lange

et al. 2020

Geochem Geophys Geosyst

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Major, trace, and isotopic compositions of plagioclase megacrysts from plagioclase ultraphyric basalts (PUB) from multiple mid‐ocean ridges were determined to characterize the liquid compositions from which they were derived. Large (up to 2 cm) plagioclase megacrysts exhibit homogeneous major element compositions, with variable degrees of trace element and isotopic heterogeneity. The pattern and degree of heterogeneity is itself variable between megacrysts, with some being homogenous and others exhibiting a wide range of trace element and isotopic zoning. Liquids calculated to be in equilibrium with the plagioclase megacrysts exhibit a range equivalent to lavas erupted from entire ridge segments. Many of the megacrysts may be considered to be cognate xenocrysts in that they are related to the same mantle material as the host lavas in which they were carried to the surface. The observed trace element patterns together with the isotopic diversity suggest a complex set of processes are active, that include mixing of distinct primitive melts, fractional crystallization, and diffusive reequilibration. The degree to which each process influences the megacrysts varies between individual crystals in each sample. Equally important is the range of composition we see within individual crystals. For example, Ba concentrations vary by as much as a factor of 5 but not systematically from core to rim.

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“…Our models utilize recent advances in numerical diffusion approaches that address diffusion anisotropy by allowing for high resolution investigation of diffusing species in three dimensions (c.f., Shea et al 2015aLynn et al 2017;Krimer and Costa 2017;Mutch et al 2019). Previous studies have used the slowest and/or fastest crystal directions to provide maximum or minimum timescale estimates when modeling in one dimension (1D; e.g., Pan and Batiza 2002;Longpré et al 2014;Thoraval and Demouchy 2014).…”

Section: Numerical Model Setupmentioning

confidence: 99%