Flood basalts

A recent television programme dealt with the possible link between these vast outpourings of lava, whose remnants now show as stacked-up layers of basalt, such as India’s Deccan Traps and America’s Columbia River province, and at least some of the great mass extinctions.

Keep a look-out for doming – it could be an omen
Of a mantle plume coming our way.
They rise a great distance with thermal assistance,
Like a lava lamp’s globby display.

But now hear the worst: they erupt in a burst,
Huge volumes of basalt flood out.
Kilometres cubed, by the million, are spewed
All over the land round about.

When flood basalts outpoured, palaeontologists record
Mass extinctions near contemporaneously;
Looks like cause and effect, but let’s not neglect
Other things that occurred simultaneously:

Mantle plumes do much more, they affect spreading sea floor,
Volcanism, sea levels and rifts.
Did any of these cause catastrophes
By triggering environment shifts?

Or was a rogue asteroid by the heavens deployed
To drive species over the brink?
Could either recur? How could we prepare?
Who knows – but it sure makes you think.

See also The pressure-pulse hypothesis

[Artist’s impression: geo.mtu.edu/kabrna.com]
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