The temperature of the <scp>I</scp>celandic mantle from olivine‐spinel aluminum exchange thermometry

Matthews, Simon; Shorttle, Oliver; Maclennan, John

doi:10.1002/2016gc006497

Cited by 83 publications

(168 citation statements)

References 81 publications

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“…On Figure 2, I compared the calculated trends with the observed variation in Icelandic basalts produced in the rift zones at the coasts (GEOROC database). Consistent with the calculations, magma production in this context is thought to reflect a passive plate spreading alone (Brown andLesher, 2014, Shorttle et al, 2014) and T P = 1480 °C is in agreement with the most recent estimated potential mantle temperature beneath Iceland (Matthews et al, 2016). Calculated crust thicknesses are in fact similar to the estimated crustal thicknesses in Iceland's rift zones (Darbyshire et al, 2000).…”

Section: Implications For the Nature Of The Mantle Heterogeneity Benesupporting

confidence: 74%

No direct contribution of recycled crust in Icelandic basalts

Lambart¹

2017

Geochem. Persp. Let.

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Using Melt-PX to model the decompression melting of a heterogeneous mantle, I investigated the role of major-element composition of the lithologies present in the source on magmatic productivity, and trace element and isotopic melt compositions, independently of the bulk mantle composition. My calculations demonstrate that the volume of magma produced is not significantly affected by the nature of the lithological heterogeneity, but depends on the bulk mantle composition. However, an isochemical bulk mantle can produce contrasting trace element and isotopic melt compositions depending on the major-element compositions of the lithologies present in the source. Results show that the observed crust thickness of the Icelandic rift zones is consistent with about 10 % of recycled crust in the source, but also demonstrate there is no need to involve the contribution of melts derived from a recycled basalt component to explain the compositional variability of the Icelandic basalts in rift zones, and rather advance the contribution of olivine-bearing hybrid lithologies formed by solid-state reactions between the recycled crust and the peridotite.

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Section: Implications For the Nature Of The Mantle Heterogeneity Benesupporting

confidence: 74%

No direct contribution of recycled crust in Icelandic basalts

Lambart¹

2017

Geochem. Persp. Let.

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“…An alternative suite of constraints comes from analyses of mid‐ocean ridge basalt geochemistry. A variety of petrologic and geochemical studies yield similar estimates for ambient mantle potential temperatures (e.g., 1250–1350°C: Katsura et al, ; 1280–1400°C: Herzberg et al, ; 1314–1464°C: Dalton et al, ;

1318_{- 32}^{+ 44}^{\circ}

C: Matthews et al, ). Geochemical and geophysical arguments are therefore in reasonable agreement for ambient potential temperatures of T = 1340 ± 60°C.…”

Section: Modeling Strategymentioning

confidence: 84%

Reassessing the Thermal Structure of Oceanic Lithosphere With Revised Global Inventories of Basement Depths and Heat Flow Measurements

Richards

Hoggard

Cowton³

et al. 2018

JGR Solid Earth

154

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Half‐space cooling and plate models of varying complexity have been proposed to account for changes in basement depth and heat flow as a function of lithospheric age in the oceanic realm. Here, we revisit this well‐known problem by exploiting a revised and augmented database of 2,028 measurements of depth to oceanic basement, corrected for sedimentary loading and variable crustal thickness, and 3,597 corrected heat flow measurements. Joint inverse modeling of both databases shows that the half‐space cooling model yields a mid‐oceanic axial temperature that is >100°C hotter than permitted by petrologic constraints. It also fails to produce the observed flattening at old ages. Then, we investigate a suite of increasingly complex plate models and conclude that the optimal model requires incorporation of experimentally determined temperature‐ and pressure‐dependent conductivity, expansivity, and specific heat capacity, as well as a low‐conductivity crustal layer. This revised model has a mantle potential temperature of 1300 ± 50°C, which honors independent geochemical constraints and has an initial ridge depth of 2.6 ± 0.3 km with a plate thickness of 135 ± 30 km. It predicts that the maximum depth of intraplate earthquakes is bounded by the 700°C isothermal contour, consistent with laboratory creep experiments on olivine aggregates. Estimates of the lithosphere‐asthenosphere boundary derived from studies of azimuthal anisotropy coincide with the 1175 ± 50°C isotherm. The model can be used to isolate residual depth and gravity anomalies generated by flexural and sub‐plate convective processes.

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“…It is useful to compare estimates of T P with the potential temperature of ambient convecting mantle. Estimates of this ambient value vary depending upon methodology (e.g., Dalton et al, ; Herzberg et al, ; Katsura et al, ; Matthews et al, ). Throughout this section, we exploit the adiabatic melting models of McKenzie and Bickle () and Katz et al ().…”

Section: Magmatismmentioning

confidence: 99%

Neogene Uplift and Magmatism of Anatolia: Insights From Drainage Analysis and Basaltic Geochemistry

McNab

Ball

Hoggard

et al. 2018

Geochem Geophys Geosyst

102

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It is agreed that mantle dynamics have played a role in generating and maintaining the elevated topography of Anatolia during Neogene times. However, there is debate about the relative importance of subduction zone and asthenospheric processes. Key issues concern onset and cause of regional uplift, thickness of the lithospheric plate, and the presence/absence of temperature and/or compositional anomalies within the convecting mantle. Here, we tackle these interlinked issues by analyzing and modeling two disparate suites of observations. First, a drainage inventory of 1,844 longitudinal river profiles is assembled. This database is inverted to calculate the variation of Neogene regional uplift through time and space by minimizing the misfit between observed and calculated river profiles subject to independent calibration. Our results suggest that regional uplift commenced at 20 Ma in the east and propagated westward. Second, we have assembled a database of geochemical analyses of basaltic rocks. Two different approaches have been used to quantitatively model this database with a view to determining the depth and degree of asthenospheric melting across Anatolia. Our results suggest that melting occurs at depths as shallow as 60 km in the presence of mantle potential temperatures as high as 1400°C. There is evidence that temperatures are higher in the east, consistent with the pattern of subplate shear wave velocity anomalies. Our combined results are consistent with isostatic and admittance analyses and suggest that elevated asthenospheric temperatures beneath thinned Anatolian lithosphere have played a first‐order role in generating and maintaining regional dynamic topography and basaltic magmatism.

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The temperature of the Icelandic mantle from olivine‐spinel aluminum exchange thermometry

Cited by 83 publications

References 81 publications

No direct contribution of recycled crust in Icelandic basalts

No direct contribution of recycled crust in Icelandic basalts

Reassessing the Thermal Structure of Oceanic Lithosphere With Revised Global Inventories of Basement Depths and Heat Flow Measurements

Neogene Uplift and Magmatism of Anatolia: Insights From Drainage Analysis and Basaltic Geochemistry

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