Ka-RUNCH!

“Kareem, will you ever actually tell me what’s going on with the volcanoes in Italy and Greece and Turkey? And do it quick, I gotta start getting ready for the lunch trade.”

“Eddie, you’re the one who keeps asking the side questions. Sy, I see you’re carrying Old Reliable.”

“I always travel ready for action, Kareem.”

“You got the GPlates system loaded in there? It’s a go‑to tool in our Geophysics lab.”

“Matter of fact, I do, but I’ve not had time to start playing with it. Here, show us what it can do.”

“I’ve got a particular display in mind, give me a minute. <busy‑fingers pause> There. What you’re looking at is Planet Earth as we think it was 195 million years ago.”

“Is that Pangaea?”
 ”Is that Pangaea?”

“Sure is. Most of Earth’s high‑silica slag had sutured together in one big supercontinent that stretched from pole to pole.”

“What’s on Earth’s other side?”

“Mostly a huge ocean, which is why I colored it flat blue. There were probably seamounts and rifts and stuff scattered around the seabottom but all that high‑density low‑silica structure is long gone, shoved below by the continents that rode over it. This is a snapshot at the time when Pangaea was just beginning to come apart — you can see where South America is ripping away from Africa at their southern juncture, and North America’s just started to move off to the west.”

“What’s the difference between the light blue and the darker blue?”

“Good eyes, Eddie, and it’s important. The light blue is the continental shelf.”

“It’s not part of the continent?”

“Oh, it is. The shelf’s the flooded margin, partly ancient consolidated rock and partly sediments that have washed down over the ages. There’s usually a steepish drop‑off from the shelf down to the abyssal bottoms. My hero Wegener is the guy who realized that when you’re putting the jigsaw puzzle together, the shelf is the border you need to pay attention to.”

“What’s the yellow-line kite shape?”

“It ties together some points that’ll help answer Eddie’s Italy‑Greece‑Turkey question. Let me put the video in motion…”

Earth from 195 million years ago to the present
rendered using the GPlates system
and configuration data from Müller, et al., 2019, doi.org/10.1029/2018TC005462

“I see you’ve got Africa in the center instead of the usual New World axis.”

“Why not? Anyway it’s convenient for Eddie’s volcanoes. See that fragment at the kite’s eastern corner? I marked it with dark circle. Watch what happened to it about 55 million years ago, and where it went after that.”

“It banged into what’s gonna be Turkey!”

“Mm-hm, and the land crinkled up and that’s the origin of Turkey’s volcano belt that I’ve marked purple. GPlates calls that chunk the Kirsehir plate. No connection with the vulcanism further west.”

“Wait. That little thing is a plate?”

“The definition depends on who you’re talking to and what about. Officially we’ve got cratons, major plates, minor plates, microplates and terranes, but there’s fuzzy lines between them. GPlates ‘plate’ list contains about a thousand chunks that have moved around independently and are big enough to pay attention to.”

“I can see why you called it the Africa‑Eurasia nutcracker, Kareem. It crunches right down on that continental shelf north of Africa.”

“That’s the planet’s oldest bit of seafloor, Sy, maybe 300 million years old, half again older than anywhere else. Maybe the rock got brittle with age, but the collision region’s faults and folds are incredibly complex.”

“It’s a hot mess, HAW!”

“Can’t say you’re wrong, Eddie. Anyway, south and west of Turkey there’s a whole series of trenches where north‑bound seafloor crust dives under south‑bound structures. The sunken material melts, puffs up and pushes up against what’s above it. All of that leaves beaucoodles of weak spots for magma to leak upwards and you get volcanoes throughout the red‑marked area.”

“One thing I get from this, Eddie, is that it’s not one long arc from Italy through Turkey. Kareem’s pointed out two different formation periods, 50 million years apart.”

“I get that, too, Sy. It’s amazing what you can see when you look close.”

“And when hundreds of researchers gather data over two centuries.”

“Thanks, Kareem. Gotta go.”

~~ Rich Olcott

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.