Heat-pipe tectonics

[1][2] Io is a rocky body that is internally extremely hot; its heat is produced by tidal flexing associated with its eccentric orbit.

[2][6][7] Its crust is a single thick, dense and cold outer shell made up of layers of volcanic materials, whose rigidity and strength supports the weight of high mountains.

[3][2][8] Observations suggest that similar processes occurred in the early history of other terrestrial planets in the Solar System, i.e. Venus, the Moon, Mars, Mercury and Earth, indicating they may preserve fossil heat-pipe evidence.

[9] In heat-pipe tectonics, volcanism is the major heat transport mechanism in which melts of rock are transferred to the surface by localised vents.

[11][12] When melts reach surface via vertical vents, they cool down and solidify forming mafic or ultramafic rocks which are rich in iron and magnesium.

[1][9] This vertical advection of volcanic materials causes compression of the lithosphere, because interior spherical shells of planets are progressively becoming smaller at increasing depths.

[2][6][7] And the composition of the lava is interpreted to be mainly sulfur and silicates from the high eruption temperature of at least 1200 K.[3] In addition to extensive volcanism, mountain ranges are the second observation on Io's surface.

[2] Thus, Io requires a thicker lithosphere to bear the overwhelming stresses imposed by globally distributed mountains.

The theory explains the globally distributed volcanic materials on the surface; the development of thick lithosphere; and the formation of contractional mountains.

[3][2] Research in 2017 suggested that all terrestrial planets may possibly undergo volcanism to cool down in their early development when they were much hotter inside than at present.

[1][9][13] In the Solar System, Mars, the Moon, Mercury, Venus and Earth show evidence of past heat pipe tectonics, while not undergoing it at present.

[9] - Large scale volcanism dominated the heat transfer mechanism until 4 billion years ago, smoothing out the surface.

[1][24] - Extensional - Subduction - Volcanism New observations in Barberton, South Africa and Pilbara, Australia show no evidence of periods of non-diapiric deformation that lasted more than 300 million years.

- Upward inverse-drip shaped intrusion metamorphose the volcanic layers into TTG (Tonalite - trondhjemite - granodiorite).

[1] - Tectonism-induced structure found right after 3.2 billion years ago: Pilbara: Rifting and arc production Barberton: Collisions and intrusion.

[1] As time goes by, terrestrial planets cool down as internal heat production reduces and the surface temperature becomes lower.

Figure 1: Volcanic Resurfacing. Melts rise through vent reaching the surface and forms layers of volcanic materials constantly. As such, the newly deposited materials bury the older layers, pushing the older layers downwards. Besides, intrusions, e.g. diapir or sill, may occur at the bottom of the lithosphere.
Figure 2: Contractional Mountain. Downward advection of volcanic layers occurs under ongoing volcanic resurfacing. As the older layer is compressed to a smaller sphere, contraction occurs on the layer causing shortening, either in form of fault or fold.
Left: Heat-pipe tectonics develops a thicker and colder lithosphere by repetitive volcanic resurfacing. The lithosphere remains at low temperature, i.e. 600 degree Celsius, in great depth. Right: Plate tectonics develops a thinner and hotter lithosphere that it raises to 1500 degree Celsius at shallow depth. (Modified from Moore & Webb, 2013; Arevalo, McDonough & Luong, 2009)