Thomas Sheldrick

What drove Mongolian Mesozoic Magmatism: was it crustal or mantle processes?

Thomas SheldrickSupervisors: Dr Tiffany Barry (University of Leicester), Dr Daniel Smith (University of Leicester), Dr Batulzii Dash (Mongolian University of Science) and Dr Douwe van Hinsbergen (Utrecht University).

Project Overview/Outline

There is a large amount of Mesozoic basaltic-intermediate volcanism in Mongolia, Russia and China. A quick approximation suggests the surface extent of Mesozoic volcanism in Mongolia alone exceeds 9800 Km2. Furthermore, there are also large pockets of diffusive Ceneozoic basaltic volcanism in Mongolia too1. However, Mongolia is far away from subduction zones and is in an intraplate setting. Such long-lived intraplate volcanism creates some fascinating questions, such as:

  • How can Mongolia, in an intraplate setting, have such prolonged, intermittent periods of volcanism?
  • Is the magmatism in Mongolia, Russia and China related to a common geological process?

There are a number of models to try and explain the magmatism in Russia and China. However, with the magmatism in Mongolia still being poorly understood these models are yet to have been vigorously tested. Current models include:

  1. post-orogenic diffuse extension2;
  2. eastward lithospheric delamination resulting in mantle upwelling and underplating3;
  3. slab breakoff leading to upwelling of the asthenosphere;
  4. bi-directional delamination, back-arc extension and mantle upwelling induced by mantle avalanches4; and finally,
  5. increased geothermal gradients due to a mantle plume5.

Dr Tiffany Barry and I have collected a large suite of volcanic samples from across eastern and southern Mongolia. My research will involve using isotopes and trace element geochemistry coupled with precise Ar-Ar dating to help test and develop current geological models.

Get geochemical plots

I also update my website which allows you to download geochemical templates. You can access this website at www.geoplotters.com

References

1: Barry et al. (2003) J.Pet. 44, 55-91. 2: Fan et al. (2003) JVGR 121, 115-135. 3: Wang et al. (2006) EPSL 251, 179-198. 4: Dash et al. (2015) Gond. Res, 27, 281-299. 5: Yarmolyuk & Kovalenko, (2001) In: Tectonics, Magmatism and Metallogeny of Mongolia.

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