Supercontinent on EARTH Magazine

Frogs fill in post-Gondwana picture

Wed, 13 Feb 2019 16:29:47 -0500

Land connections, bridges and corridors may have enabled the dispersal of plants and animals, including frogs, among the landmasses around the Indian Ocean after the breakup of Gondwana. Credit: Seshadri.K.S., CC BY-SA 3.0

The positions of landmasses after the breakup of Gondwana during the late Mesozoic and early Paleogene are highly debated, especially the configurations of the Indian and Australian plates around the newly opening Indian Ocean. In a new study, the paleogeographic and genetic distributions of a group of frogs called Natatanurans were used to test the various post-breakup models — and the results bring additional clarity to the post-Gondwana puzzle.

Ocean tide size linked to supercontinent cycle

Thu, 06 Sep 2018 14:54:16 -0400

Daily tides are driven primarily by Earth’s rotation and the gravitational force of the moon on oceans. However, in a new study in Geophysical Research Letters, researchers suggest that tidal magnitudes are also influenced, on longer timescales, by the size and shape of the ocean basins, and are therefore driven by plate tectonics.

Piecing together the puzzle of Pannotia

Tue, 03 Jul 2018 11:30:46 -0400

Researchers have found evidence that a supercontinent, Pannotia, existed between 650 million and 600 million years ago, forming after Rodinia and before Pangea. Credit: Nance and Murphy, Geological Society Special Publications, March 2018.

Earth’s landmasses have joined together into supercontinents and then split apart again as many as six times in the planet’s history. Pangea is the most famous supercontinent, but at least five pre-Pangean supercontinents — Rodinia, Columbia, Kenorland, Ur and Vaalbara — have been widely championed, mainly based on paleomagnetic data. Now, a new study offers a panoply of evidence for an often-overlooked supercontinent thought to have formed after Rodinia and before Pangea, called Pannotia, whose existence has long been in question.

Breakup of Pangea led to thicker oceanic crust

Thu, 06 Apr 2017 10:09:41 -0400

This map, created by researchers at the University of Texas at Austin, depicts the ages of ocean crust in millions of years before present (Ma). Warm shades represent younger crust and cool shades represent progressively older crust. Modern mid-ocean spreading ridges are indicated by yellow lines. Credit: Harm Van Avendonk.

Oceanic crust formed at mid-ocean spreading centers, like the Mid-Atlantic Ridge, is recycled back into the mantle at subduction zones. Aside from isolated chunks that might be even older, the oldest crust found on Earth today is thought to be about 200 million years old. This old crust, portions of which are found along the outer margins of the Atlantic, Pacific and Indian oceans, is much thicker than the crust being produced today — in some places by almost 2 kilometers — according to a new study, a finding that may suggest that Earth’s supercontinent cycle affects how Earth’s interior cools.

Rethinking Pangea? Ancient ocean crust challenges supercontinent theory

Tue, 20 Dec 2016 21:19:32 -0500

Scientists deploy equipment to collect magnetic information about crust underlying the eastern Mediterranean Sea. Credit: Roi Granot.

The oldest piece of undisturbed oceanic crust ever discovered has been found beneath the eastern Mediterranean Sea, hidden under more than 10 kilometers of sediment. This ancient crust — estimated at up to 100 million years older than the oldest oceanic crust previously known — could reshape our view of global tectonics and the supercontinent cycle.

Chemical clues reveal ancient geography

Thu, 05 Jan 2012 06:41:58 -0500

Reconstructing the history of supercontinents requires careful detective work. A variety of geological processes wipes the evidence clean, like a burglar who smears away his fingerprints. Yet even the most cautious criminals leave clues behind — and so do supercontinents.