Source of the Cenozoic Volcanism in Central Asia

Cenozoic intraplate volcanism in central Asia is characterized by individual small volcanic provinces spread over three broad regions, whose origin remains controversial. This chapter explores whether the Big Mantle Wedge hypothesis is a viable candidate for explaining volcanism in regions B, C, and in particular A. Using numerical models, it investigates which mechanism would generate the geomorphological features of the surface volcanism in the Cenozoic. Geological field data suggest that the detailed distribution of the volcanic cones at the surface is compatible with a regular spacing of about 200 km. The chapter shows that such a pattern spontaneously emerges from the instability of a ~20-km thick layer of randomly distributed partially molten diapirs, and only such a cluster would be able to rise to the surface and win equilibration. Finally, the chapter discusses the implications of another hypothesis for the circulation of carbonates and hydrous rocks in the transition zone.