Deep Carbon

I found this article at Science Direct very interesting:

We report from converted seismic waves, a pervasive seismically anomalous layer above the transition zone beneath the western US. The layer, characterized by an average shear wave speed reduction of 1.6%, spans over an area of ∼1.8×106 km2∼1.8×106 km2 with thicknesses varying between 25 and 70 km. The location of the layer correlates with the present location of a segment of the Farallon plate. This spatial correlation and the sharp seismic signal atop of the layer indicate that the layer is caused by compositional heterogeneity. Analysis of the seismic signature reveals that the compositional heterogeneity can be ascribed to a small volume of partial melt (0.5 ± 0.2 vol% on average). This article presents the first high resolution map of the melt present within the layer. Despite spatial variations in temperature, the calculated melt volume fraction correlates strongly with the amplitude of P–S conversion throughout the region. Comparing the values of temperature calculated from the seismic signal with available petrological constraints, we infer that melting in the layer is caused by release of volatiles from the subducted Farallon slab. This partially molten zone beneath the western US can sequester at least 1.2×1017 kg1.2×1017 kg of volatiles, and can act as a large regional reservoir of volatile species such as H or C.

Basically, what’s that saying is there’s a huge pool of something-or-other deep beneath the western United States. Could be hydrogen. Could be carbon. Could be methane or any number of other alternatives.

There are all sorts of possible reactions to that news. My immediate reaction was that it might present some great new opportunities for testing the abiogenic theory of the origins of petroleum. I know that deep deposits of this sort are one of the bits of evidence offered in support of the theory. I always thought it was a bit wacky but who knows?

Hat tip: the Daily Mail

3 comments… add one
  • Gray Shambler

    sure, I’m a layman, but the extreme depth of some petroleum reserves makes me wonder too.

  • The usual explanation for that is that it leaked down from above.

  • sam

    Might make the eruption of Yellowstone even worse than is thought. If that’s possible. (Viscosity of the magma.)

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