Frae Wikipedia, the free beuk o knawledge
The
asthenosphere
(frae
Greek
asthen?s 'weak'
+ sphere) is the heichly viscous, mechanically waik
[1]
an
ductilely
-defurmin region o the upper
mantle
o the
Yird
. It lies belaw the
lithosphere
, at depths atween ~80 an ~200 km (~ 50 an 124 mile) ablo the surface. The lithosphere-asthenosphere boondary is uisually referred tae as LAB. Asthenosphere is generally solit altho some its regions coud be meltit (e.g. belaw
mid-ocean ridge
). The lawer boondary o the asthenophere is nae well defined. The thickness o the asthenosphere depends mainly on the temperatur. For some regions asthenosphere coud extend as deep as 700 km (430 mi). It is considered the soorce region o
mid-ocean ridge
basalt
(MORB).
[2]
- ↑
Barrel, J. The strength of the crust, Part VI. Relations of isostatic movements to a sphere of weakness - the astenosphere. J. Geol. 22, 655-683, 1914.
- ↑
Hofmann, A.W., 1997. Mantle geochemistry: the message from oceanic volcanism. Nature 385, 219-228.