Adrian P. Jones, Author at Elements Magazine

Meteorite Impacts as Triggers to Large Igneous Provinces

Large Igneous Provinces: Origin and Environmental Consequences, Thematic Articles / Adrian P. Jones

Ameteorite impacting on the surface of the Earth produces not only a crater but also, if the impactor is sufficiently large, high melt volumes. Computer simulations suggest that, in addition to shock- induced melting produced by impact, additional decompression melting of the hot target mantle beneath the crater can produce melt volumes comparable to those found in large igneous provinces (LIPs). The coincidence between the expected frequency of such impact events combined with the similarity in magma volumes of LIPs suggests that large meteorite impacts may be capable of triggering LIPs and mantle hotspots from a point source which is subsequently buried. Can the impact model explain any LIP? What are the distinctive macroscopic criteria predicted from an impact model, and how may they be recognised or rejected in the geological record of the Earth?

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Earth Catastrophes and Their Impact on the Carbon Cycle

Perturbations to Deep Carbon Cycle, Thematic Articles / Celina A. Suarez

Carbon is one of the most important elements on Earth. It is the basis of life, it is stored and mobilized throughout the Earth from core to crust and it is the basis of the energy sources that are vital to human civilization. This issue will focus on the origins of carbon on Earth, the roles played by large-scale catastrophic carbon perturbations in mass extinctions, the movement and distribution of carbon in large igneous provinces, and the role carbon plays in icehouse–greenhouse climate transitions in deep time. Present-day carbon fluxes on Earth are changing rapidly, and it is of utmost importance that scientists understand Earth’s carbon cycle to secure a sustainable future.

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Carbonatitic Melts and Their Role in Diamond Formation in the Deep Earth

Carbonatites, Thematic Articles / Suzette Timmerman

Carbonatitic high-density fluids and carbonate mineral inclusions in lithospheric and sub-lithospheric diamonds reveal comparable compositions to crustal carbonatites and, thus, support the presence of carbonatitic melts to depths of at least the mantle transition zone (~410–660 km depth). Diamonds and high pressure–high temperature (HP–HT) experiments confirm the stability of lower mantle carbonates. Experiments also show that carbonate melts have extremely low viscosity in the upper mantle. Hence, carbonatitic melts may participate in the deep (mantle) carbon cycle and be highly effective metasomatic agents. Deep carbon in the upper mantle can be mobilized by metasomatic carbonatitic melts, which may have become increasingly volumetrically significant since the onset of carbonate subduction (~3 Ga) to the present day.

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Author name: Adrian P. Jones

Meteorite Impacts as Triggers to Large Igneous Provinces

Earth Catastrophes and Their Impact on the Carbon Cycle

Carbonatitic Melts and Their Role in Diamond Formation in the Deep Earth