page_title: Lithosphere–asthenosphere boundary
section_title: Beneath oceanic lithosphere
hierarchical_section_title: Lithosphere–asthenosphere boundary / Measuring the LAB depth / Beneath oceanic lithosphere
caption_attribution_description: English: Colors indicate age of oceanic lithosphere, lines represent tectonic plates, world map.Français&#160;: Carte monde indiquant l'âge de la lithosphère océanique en fonction de la couleur. Les différentes plaques tectoniques sont séparées par les lignes.
context_page_description: The lithosphere–asthenosphere boundary represents a mechanical difference between layers in Earth's inner structure. Earth's inner structure can be described both chemically and mechanically. The lithosphere–asthenosphere boundary lies between Earth's cooler, rigid lithosphere and the warmer, ductile asthenosphere. The actual depth of the boundary is still a topic of debate and study, although it is known to vary according to the environment.
context_section_description: Beneath oceanic crust, the LAB ranges anywhere from 50 to 140 km in depth, except close to mid-ocean ridges where the LAB is no deeper than the depth of the new crust being created. Seismic evidence shows that oceanic plates do thicken with age. This suggests that the LAB underneath oceanic lithosphere also deepens with plate age. Data from ocean seismometers indicate a sharp age-dependent LAB beneath the Pacific and Philippine plates and has been interpreted as evidence for a thermal control of oceanic-lithosphere thickness.
caption: Age of oceanic lithosphere.
exif: {}