Piecing together the puzzle of Pangea


Thick black and magenta lines show northern boundaries of India and Arabia and southern boundary of Eurasia. Dashed light-green line marks outer margin of Pangeides active margin. Dashed yellow line shows approximate boundary between active margin and arc of thick lithosphere. Dashed dark-green line outlines area underlain by thinner lithosphere that now underlies North Africa, Arabia, and western Europe. Inset shows same reconstruction without any lithospheric thickness contours. NA--North America;, Eu--Eurasia; SA--South America; Af--Africa; An--Antarctica; Au--Australia. Click image to expand.
MCKENZIE ET AL., GEOLOGY, GEOLOGICAL SOCIETY OF AMERICA

Scientists have pieced together the continent of Pangea (which mean "all land" in Greek) that existed 250 million years ago when all today's continents were joined together.

Their aim was to determine the pattern of plate thickness before Pangea broke up and to compare it to today's plate thickness of continents that varies from about 90 kilometres beneath places like California or Western Europe, to more than 200 kilometres beneath the older interiors of the U.S., Eastern Europe, and Russia.

Authors Dan McKenzie, Michael C. Daly, and Keith Priestley were surprised to find the thick parts of the plates all came together to form a boomerang-shaped arc.

The outside of the boomerang consisted of a subduction zone where oceanic plates were returned to the mantle.

The inside of the boomerang consisted of a plate with a thickness of about 100 kilometres which was strongly deformed and heated about 600 million years ago.

Pangea itself was assembled from a number of different plates. The continental deformation that took place during this assembly must have been controlled by the plate thickness, since it produced a continuous boomerang shaped region of thick plate.

Their research was published as The lithospheric structure of Pangea by the geological Society of America.

  1. http://www.crossref.org/iPage?doi=10.1130%2FG36819.1
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