Transport of Volatile-rich Melt from the Mantle Transition Zone via Compaction Pockets: Implications for Mantle Metasomatism and the Origin of Alkaline Lavas in the Turkish–Iranian Plateau

Abstract

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Hybrid local and teleseismic P-wave tomography in North Tanzania: role of inherited structures and magmatism on continental rifting

“…The presence of melt in the lithosphere (Vp ≥ 10% in Figs. 9 and 10, as proposed by Soltanmohammadi et al, 2018) is favoured by the hydration (Baptiste et al, 2015) and carbonation of the lithosphere in this region (Muirhead et al, 2019), both decreasing the solidus (Foley 2008). The presence of a metasomatized mantle may have promoted the production of carbonated melt (Rudnick et al, 1993;Soltanmohammadi et al, 2018).…”

“…9 and 10, as proposed by Soltanmohammadi et al, 2018) is favoured by the hydration (Baptiste et al, 2015) and carbonation of the lithosphere in this region (Muirhead et al, 2019), both decreasing the solidus (Foley 2008). The presence of a metasomatized mantle may have promoted the production of carbonated melt (Rudnick et al, 1993;Soltanmohammadi et al, 2018). This thermochemical erosion eases the process of lithospheric thinning and can explain its higher value (~60 km) compared to crustal thinning (~10 km) in the case of the NTD (Fishwick, 2010;O'Donnell et al, 2013;Plasman et al, 2017;Tiberi et al, 2019;Accardo et al, 2020).…”

“…The craton becomes more stable against mantle erosion while its upper part of the cratonic lithosphere remains hydrated. In the first 100 km, the melt overtakes temperature effect (Tiberi et al, 2019, Soltanmohammadi et al, 2018 and migrates in pre-existing heterogeneities, explaining the highly 3D images in tomography. The cross-section tracks are localized Fig.…”

Phlogopite-Olivine Nephelinites Erupted During Early Stage Rifting, North Tanzanian Divergence

“…The low volumes of melts (<1%) is generally assume to be motionless in the mantle rocks due to their small permeability and wetting angle characteristics (Maumus et al, 2004). However, recent study based on physical properties and melt-rock reaction suggest that small volume of melts (i.e., 0.75%) could be extracted from the mantle (Soltanmohammadi et al, 2018). The extraction of low volume melt will be effective for a melt with high content in alkaline and volatile elements (Keller and Katz, 2016;Soltanmohammadi et al, 2018), the volatile content being a key parameter to enhance the melt extraction process due to their effect on the melt viscosity properties (Condamine and Médard, 2014;Gardès et al, 2020).…”

“…However, recent study based on physical properties and melt-rock reaction suggest that small volume of melts (i.e., 0.75%) could be extracted from the mantle (Soltanmohammadi et al, 2018). The extraction of low volume melt will be effective for a melt with high content in alkaline and volatile elements (Keller and Katz, 2016;Soltanmohammadi et al, 2018), the volatile content being a key parameter to enhance the melt extraction process due to their effect on the melt viscosity properties (Condamine and Médard, 2014;Gardès et al, 2020). In Labait and Kwahara lavas, early phlogopite crystallization suggests that the primary magmas have higher K content than the erupted lavas (nephelinites), and high volatile contents, especially in CO 2 , allowing low melt volume 0.5-1 vol% to be extracted from the mantle (Keller and Katz, 2016;Gardès et al, 2020).…”