Gondwana dispersion and Asian accretion: Tectonic and palaeogeographic evolution of eastern Tethys

http://www.geo.umass.edu/petrology/Giordano%20et%20al_EPSL_2008_visc.pdf

Viscosity of magmatic liquids: A model

Late Jurassic–Cenozoic reconstructions of the Indonesian region and the Indian Ocean

Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie–Sulu orogen in China: implications for geodynamics and fluid regime

http://www2.ess.ucla.edu/~manning/pdfs/m04.pdf

The chemistry of subduction-zone fluids

Interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time, moderating atmospheric composition and maintaining a life-supporting planet. While volcanoes expel volatile components into surface reservoirs, subduction of oceanic crust is responsible for replenishment of mantle reservoirs. Many natural, 'superdeep' diamonds originating in the deep upper mantle and transition zone host mineral inclusions, indicating an affinity to subducted oceanic crust. Here we show that the majority of slab geotherms will intersect a deep depression along the melting curve of carbonated oceanic crust at depths of approximately 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle. Low-degree partial melts are alkaline carbonatites that are highly reactive with reduced ambient mantle, producing diamond. Many inclusions in superdeep diamonds are best explained by carbonate melt-peridotite reaction. A deep carbon barrier may dominate the recycling of carbon in the mantle and contribute to chemical and isotopic heterogeneity of the mantle reservoir.

/pdf/slab-melting-as-a-barrier-to-deep-carbon-subduction-1i5bz2ommq.pdf

Slab melting as a barrier to deep carbon subduction

A primary consequence of plate tectonics is that basaltic oceanic crust subducts with lithospheric slabs into the mantle. Seismological studies extend this process to the lower mantle, and geochemical observations indicate return of oceanic crust to the upper mantle in plumes. There has been no direct petrologic evidence, however, of the return of subducted oceanic crustal components from the lower mantle. We analyzed superdeep diamonds from Juina-5 kimberlite, Brazil, which host inclusions with compositions comprising the entire phase assemblage expected to crystallize from basalt under lower-mantle conditions. The inclusion mineralogies require exhumation from the lower to upper mantle. Because the diamond hosts have carbon isotope signatures consistent with surface-derived carbon, we conclude that the deep carbon cycle extends into the lower mantle.

https://science.sciencemag.org/content/sci/334/6052/54.full.pdf

Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions.

A multinuclear magnetic resonance study of the structure of hydrous albite glasses

Crystalline silica (mostly cristobalite) was produced by vapor-phase crystallization and devitrification in the andesite lava dome of the Soufriere Hills volcano, Montserrat. The sub–10-micrometer fraction of ash generated by pyroclastic flows formed by lava dome collapse contains 10 to 24 weight percent crystalline silica, an enrichment of 2 to 5 relative to the magma caused by selective crushing of the groundmass. The sub–10-micrometer fraction of ash generated by explosive eruptions has much lower contents (3 to 6 percent) of crystalline silica. High levels of cristobalite in respirable ash raise concerns about adverse health effects of long-term human exposure to ash from lava dome eruptions.

https://science.sciencemag.org/content/sci/283/5405/1142.full.pdf

Simon C. Kohn

Papers

Slab melting as a barrier to deep carbon subduction

Deep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions.

A multinuclear magnetic resonance study of the structure of hydrous albite glasses

Cristobalite in volcanic ash of the soufriere hills volcano, montserrat, british west indies

Structural controls on the solubility of CO2 in silicate melts: Part I: bulk solubility data