Concepts
Asthenosphere
as-THEN-uh-sfeer
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The mechanically weak and ductile region of Earth's upper mantle, lying below the lithosphere from a depth of about 80 to 200 kilometers and extending as deep as 700 kilometers, its lower boundary not well defined. It is almost solid, with a slight amount of melting, less than a tenth of a percent of the rock, contributing to its weakness; where it wells upward, more extensive decompression melting makes it the most important source of magma on Earth, feeding the mid-ocean ridges.
Facts
Origin YearThe term first appears in the geological literature in Joseph Barrell's 1914 paper on isostatic movements and a sphere of weakness beneath the crust. Cross-Tradition Connections
Associated With
The asthenosphere lies directly below the lithosphere; the rigid shell rides on the weak layer.
Decompression melting of upwelling asthenosphere is the source of mid-ocean ridge basalt.
In Discipline
Sources
1. Asthenosphere (Wikipedia)
Wikimedia FoundationLead sectionQuote, Lead section
The asthenosphere (from Ancient Greek asthenos 'without strength') is the mechanically weak and ductile region of the upper mantle of Earth.
1. Asthenosphere (Wikipedia)
Wikimedia FoundationHistory and etymologyQuote, History and etymology
Barrell, J. (1914). The strength of the crust, Part VI. Relations of isostatic movements to a sphere of weakness - the asthenosphere.
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