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

<p>Most magmatism occurring on Earth is conventionally attributed to passive mantle upwelling at mid-ocean ridges, slab devolatilization at subduction zones, and mantle plumes. However, the widespread Cenozoic intraplate volcanism in northeast China and the peculiar petit-spot volcanoes offshore the Japan trench cannot be readily associated with any of these mechanisms. Furthermore, the seismic tomography images show remarkable low velocity zones (LVZs) sit above and below the mantle transition zone which are coincidently corresponding to the volcanism. Here we show that most if not all the intraplate/petit-spot volcanism and LVZs present around the Japanese subduction zone can be explained by the Cenozoic interaction of the subducting Pacific slab with a hydrous transition zone. Numerical modelling results indicate that 0.2-0.3 wt.% H<sub>2</sub>O dissolved in mantle minerals which are driven out from the transition zone in response to subduction and retreat of a stagnant plate is sufficient to reproduce the observations. This suggests that critical amounts of volatiles accumulated in the mantle transition zone due to past subduction episodes and/or delamination of volatile-rich lithosphere could generate abundant dynamics triggered by recent subduction event. This model is probably also applicable to the circum-Mediterranean and Turkish-Iranian Plateau regions characterized by intraplate/petit-spot volcanism and LVZs in the underlying mantle.</p>

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The origin of Cenozoic basalts from central Inner Mongolia, East China: The consequence of recent mantle metasomatism genetically associated with seismically observed paleo-Pacific slab in the mantle transition zone

Lithos ◽

10.1016/j.lithos.2015.11.010 ◽

2016 ◽

Vol 240-243 ◽

pp. 104-118 ◽

Cited By ~ 37

Author(s):

Pengyuan Guo ◽

Yaoling Niu ◽

Pu Sun ◽

Lei Ye ◽

Jinju Liu ◽

...

Keyword(s):

Transition Zone ◽

Inner Mongolia ◽

Mantle Metasomatism ◽

East China ◽

Mantle Transition Zone ◽

Pacific Slab

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Theoretical modeling of the regular olivine intergrowths in the mimetic paramorphosis after ringwoodite and wadsleyite

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2018-4-3-12 ◽

2018 ◽

pp. 3-12

Author(s):

B. B. Shkursky

Keyword(s):

Transition Zone ◽

Theoretical Modeling ◽

Mantle Transition Zone ◽

Misorientation Angles

Theoretical modeling of regular olivine grains misorientations in mimetic paramorphoses after ringwoodite and wadsleyite, the formation of which during the ascension of matter from the Mantle Transition Zone is expected, has been carried out. The coordinates of the misorientation axes and the misorientation angles, characterizing 10 operations of alignment in the pair intergrowths of olivine grains, eight of which are twins, are calculated. Possible conditions for the formation of mimetic paramorphoses predicted here, and the chances of their persistence are discussed. The calculated orientations are compared with the known twinning laws of olivine.

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