#astrobleme

astrobleme [ as-truh-bleem ] - an erosional scar on the earth's surface, produced by the impact of a cosmic body, such as a meteorite.

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A collab between @vavoom-sorted-art and me. Next page coming out over on her Blog on Sunday!

Check #astroblemecomic for updates!

Part 63 Coming Soon!

Largest asteroid ever to hit Earth was twice as big as the rock that killed off the dinosaurs

The destructive space rock was somewhere between 12.4 and 15.5 miles wide and hit the Earth 2 billion years ago. The large scar left by the asteroid in present-day South Africa, can be easily spotted from space.

astrobleme [ as-truh-bleem ] - an erosional scar on the earth's surface, produced by the impact of a cosmic body, such as a meteorite.

Beginning - Previous - Next

A collab between @vavoom-sorted-art and me. Next page coming out over on her Blog on Sunday!

Check #astroblemecomic for updates!

Part 65 Coming Soon!

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Vredefort Granophyre

You did not want to be around on the day this rock formed. The Vredefort Granophyre is an igneous rock found in certain parts of an area of South Africa called the Vredefort dome (http://tmblr.co/Zyv2Js1gYAvFm). The Vredefort structure is part of the remnant of an ancient impact crater – a gigantic hole in the ground formed from an asteroid impact just over 2 billion years ago.

The impact of the asteroid delivered a huge amount of energy to the target rocks – so much energy that some of them actually melted. The target rocks were a mixture of metamorphic gneisses and basaltic lava, with minor components of shale, carbonates, and metamorphosed quartz-rich sandstone.

A granophyre is a fine-grained igneous rock with quartz and feldspar as the main minerals. That mineralogy actually makes sense – add up the ingredients that melted to make the rock and the end result is something like this molten rock.

The granophyre is found filling a series of large cracks called dikes that form a swarm around the center of the crater. The large chunks in it were pieces of shattered rock broken by the impact that were picked up by the melt as it was injected. Although the impact super-heated the rocks that melted, by the time it picked up these chunks it had cooled enough that there wasn’t enough heat left to melt them. As the melt migrated through the cracks and cooled, it picked up and partially melted different components, leading to some variation in the chemistry of the rocks from one side of a dike to the other.

The extremely violent processes recorded in this rock – shattering and melting of target rocks – are typical of high-energy, giant impacts on Earth and elsewhere.

-JBB

Image credit: https://flic.kr/p/oxjhQj