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Would Large Igneous Provinces like the Deccan Traps have looked like ancient lunar Mare from space? Glowing lava oceans shinning in the night?

Are these two things similar in nature? Would smoke from these regions fill the atmosphere with a haze that would hide the view from space?

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I disagree with Michael about the "not as large as the lunar mare" part. Head and Wilson (1992) mention that the "total area of exposed mare deposits is about 6.3 millions km2" (17 % of the Moon's surface area). They estimated a total volume of 10 millions km3. The largest mare, Oceanus Procellarum, covers about 4 millions km2.

These values are quite comparable with Large Igneous Provinces (LIPs) in terms of area, and are even one order of magnitude lower in terms of volume. From the Encyclopedia of Volcanoes:

The composite Ontong-Java-Manihiki-Hikurangi plateau covers 3.5 million km2 with an estimated volume 59-77 million km3. [...] The Kerguelen plateau in the southern Indian Ocean is the second largest LIP, covering 2.3 million km2 with a volume of 15 million km3 [...] Not all LIPs are oceanic plateaus; for example, the North Atlantic volcanic province, derived from a hot spot presently centered beneath Iceland, has an area of 1.3 million km2 [...] Also notable are the Deccan traps in India (1.8 million km2/9.3 million km3).

If lunar maria seem that large from Earth, it's only because the Moon is small!

But to know if lunar maria or LIPs would have looked like "glowing lava oceans shinning in the night", we need to look at emplacement rates rather than just areas and volumes. From the same chapter, one can calculate LIP emplacement rates of ~3-13 km3 per year. It may seem quite low (for comparison, ocean ridges quietly produce ~20 km3 per year), but it is an average output rate over a few million years. As noted on largeigneousprovinces.org, their might be pulses of magmatic activity, with peaks in production rate. This is exactly what's been inferred for lunar maria by Wilson and Head (2017): even if the average output rate has been calculated at a very low 0.01 km3 per year, they found that some flows could have been emplaced with rates up to 106 m3s-1!

As to whether this would have been visible from space: define "from space"! From low Earth orbit like the ISS? From the Moon itself? :)

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  • $\begingroup$ Very interesting. When I say "seen from space" I imagine a view like the one from Geostationary satellites or the Moon. I know this would be clearly visible from the ISS since volcanic eruptions are usually visible, but I would like to know if LPIs would look like glowing red patches just as lunar marae looked a long time ago from Earth, or would the smoke block the view. $\endgroup$ – Swike Dec 11 '19 at 17:44
  • $\begingroup$ I guess it depends where the lava is emplaced. On barren land, where there is not much to burn, you could probably see lava glowing at night. But to witness a better show, you should probably go back in time to the Hadean and look at the magma ocean. $\endgroup$ – Jean-Marie Prival Dec 12 '19 at 8:37
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Yes, there would have been seas of lava glowing in the night, but not as large as the lunar mare. The lunar mare were caused by asteroids punching through the then thin lunar crust and releasing a flood of magma from below, as well as producing some magma of their own from the heat of impact. There is no evidence of anything of that nature causing the Deccan Traps or the Siberian Traps. There must have been some smoke and haze from both super-eruptions, but not enough to hide them from an observer in space in the unlikely event that there were any. Much of the incinerated trees and other vegetation were covered by sheets of lava, and therefore could not release much smoke and fumes.

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    $\begingroup$ In the case of the Siberian Traps, the rocks overlying the eruptions apparently contained large coal beds, which were set on fire by the eruptions. Also, you seem to be assuming one continuous super-eruption, rather than an ongoing series of eruptions lasting from 30 thousand to a couple of million years: en.wikipedia.org/wiki/Deccan_Traps en.wikipedia.org/wiki/Siberian_Traps $\endgroup$ – jamesqf Nov 10 '19 at 3:02
  • $\begingroup$ How did the oxygen needed to support the combustion get through many metres of lava? Anyway, the question refers specifically to the Deccan Traps. $\endgroup$ – Michael Walsby Nov 10 '19 at 9:15
  • $\begingroup$ @jamesqf If it were a series of eruptions instead of a continuous super-eruption what would the difference be in terms of the view from space? Less area covered with magma? Less spectacular than Lunar Mare? $\endgroup$ – Swike Nov 10 '19 at 13:57
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    $\begingroup$ @Swike: I don't think it would be really spectacular at all. It would be more like the Hawai'ian volcanos (with a more fluid lava that doesn't pile up) spread over a large area: occasional eruptions, but mostly nothing. Or maybe the Cascades: en.wikipedia.org/wiki/Cascade_Volcanoes Lots of volcanic activity on a million-year timescale, yet only two significant eruptions in a very long human lifespan. $\endgroup$ – jamesqf Nov 10 '19 at 17:45
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    $\begingroup$ @Swike: Almost certainly not, though I'm far from being an expert. It seems much more likely to have been built up by many eruptions over thousands or millions of years. $\endgroup$ – jamesqf Nov 11 '19 at 3:45

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