Tectonic overpressure

In tectonic pressure is a concept from the geology . Normally, pressure data obtained from minerals are converted into a depth assuming a purely lithostatic pressure. So it is assumed that the pressure only comes together through the loading rocks.

However, since the pressure results from the average of the three normal stresses σ ₁ , σ ₂ and σ ₃ , other possible factors have an influence on the pressure. Therefore, the depths calculated using the lithostatic pressure can be falsified by lateral compression or tension . A compression leads to tectonic overpressure, a tension to tectonic underpressure

Sketch of a strain ellipsoid with the three normal stresses

The pressures achieved in this way can make up ± 100% of the lithostatic pressure and reach into the GPa . However, there are also authors who are of the opinion that the pressure contribution cannot be more than 1 GPa. Therefore, according to these authors, a tectonic overpressure alone cannot trigger an ultra-high pressure metamorphism .

The exact contribution to the pressure depends on the tectonics and the rock parameters ( rheology ).

Individual evidence

1. ↑ Li, Gerya, castle: Influence of tectonic overpressure on P-T paths of HP-UHP rocks in continental collision zones: thermomechanical modeling. In: Journal of Metamorphic Geology. Volume 28, 2010, pp. 227-247, doi: 10.1111 / j.1525-1314.2009.00864.x
2. ↑ ^{a b} Gerya: Tectonic overpressure and underpressure in lithospheric tectonics and metamorphism. In: Journal of Metamorphic Geology. Volume 33, No. 8, 2015, pp. 785-800
3. ↑ Qingchen Wang, Jingbo Liu, Bolin Cong, 1999, Could tectonic overpressure cause ultrahigh-pressure metamorphism ?, Chinese Science Bulletin, Volume 44, Issue 24, pp. 2295-2298