Lid tectonics, commonly thought of as stagnant lid tectonics or single lid tectonics, is the type of

tectonics Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

that is believed to exist on several silicate planets and moons in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, and possibly existed on Earth during the very early part of its history. The lid is the equivalent of the

lithosphere A lithosphere () is the rigid, outermost rocky shell of a terrestrial planet or natural satellite. On Earth, it is composed of the crust and the lithospheric mantle, the topmost portion of the upper mantle that behaves elastically on time ...

, formed of solid

silicate A silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used ...

minerals. The relative stability and immobility of the strong cooler lids leads to stagnant lid tectonics, which has greatly reduced amounts of horizontal tectonics compared with plate tectonics (which can also be described as mobile lid tectonics). The presence of a stagnant lid above a convecting mantle was recognised as a possible stable regime for convection on Earth, in contrast to the well-attested mobile plate tectonics of the current eon.

Formation

A lid tectonic regime arises when the cold upper lithosphere is too viscous to participate in the underlying flow of the mantle. The lid's

yield strength In materials science and engineering, the yield point is the point on a stress–strain curve that indicates the limit of elastic behavior and the beginning of plastic behavior. Below the yield point, a material will deform elastically and w ...

is high enough where the lid cannot brittlely fail. This relationship relies heavily on the ratio of lithospheric strength to natural convective stresses.O'Neill, C., Jellinek, A.M., Lenardic, A., 2007a. Conditions for the onset of plate tectonics on terrestrial planets and moons. Earth Planet. Sci. Lett. 261, 20–32. Hence, if lithospheric strength is greater than convective stresses, then there are stagnant lid tectonics.

Factors contributing to lid tectonics

Many characteristics of a planetary body influence the presence and degree of lid tectonics. The temperature of a body's

core–mantle boundary The core–mantle boundary (CMB) of Earth lies between the planet's silicate mantle and its liquid iron–nickel outer core, at a depth of below Earth's surface. The boundary is observed via the discontinuity in seismic wave velocities at that ...

, and the presence of water, strongly affect the rheological, composition, and thermal diagnostics of lid tectonics. The lid will not participate in the underlying convection of the mantle. At the base of the lithosphere, where the lid is in contact with less viscous material, melts will form at the thermal boundary layer and cause drips, believed to be of

peridotite Peridotite ( ) is a dense, coarse-grained igneous rock consisting mostly of the silicate minerals olivine and pyroxene. Peridotite is ultramafic, as the rock contains less than 45% silica. It is high in magnesium (Mg2+), reflecting the high pr ...

composition. This stagnant lid regime will not effectively mix a mantle.

Other planetary bodies

Stagnant lid regime is the most common tectonic style that exists in the

. Mercury, the

Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

Venus Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker ...

,Stern, R. J. (2005). Evidence from ophiolites, blueschists, and ultrahigh-pressure metamorphic terranes that the modern episode of subduction tectonics began in Neoproterozoic time. ''Geology'', ''33''(7), 557-560. and Io are all believed to have been dominated by lid tectonics for their entire history. In the mantle of both Mercury and the Moon, heat is mainly lost by conduction across the lid, leading to low heat flows. Solomatov and Moresi used the term "stagnant lid" when they characterized the tectonic style that was present on Venus in 1996.Solomatov, V. S., & Moresi, L. N. (1996). Stagnant lid convection on Venus. ''Journal of Geophysical Research: Planets'', ''101''(E2), 4737-4753. They stated that Venus had plumes similar to Earth, that would rise to the surface, and cold "drips" of lithosphere would sink back down. Mars is also believed to have stagnant lid tectonics, albeit, much slower in comparison to Venus.Breuer, D., & Spohn, T. (2003). Early plate tectonics versus single‐plate tectonics on Mars: Evidence from magnetic field history and crust evolution. ''Journal of Geophysical Research: Planets'', ''108''(E7).

References

{{Reflist Tectonics Planetary geology