Granulite

About: Granulite is a research topic. Over the lifetime, 6763 publications have been published within this topic receiving 268925 citations.

Pressure-Temperature and Fluid Evolution of Quartzo-Feldspathic Metamorphic Rocks with a Relic High-Pressure, Granulite-Facies History from the Central Erzgebirge (Saxony, Germany)

Abstract: by (1) high-pressure (HP) equilibration, followed by near-isothermal The Gneiss–Eclogite Unit is a composite tectonometamorphic unit decompression at high temperatures, during which rocks from different within the Variscan Erzgebirge mega-antiform. It comprises migdepths were amalgamated, and (2) extensive hydration and rematitic paraand orthogneisses, high-temperature (HT) mylonites, equilibration at medium pressures, followed by rapid cooling during kyanite-bearing granulites, eclogites and garnet peridotites. Four continued uplift, when the entire unit came into contact with cooler, different quartzo-feldspathic assemblages are recognized, in which now overand underlying units. This scenario is attributed to maximum conditions of up to 830°C and 21 kbar were determined. continent collision, orogenic collapse and disintegration of the HP The assemblages are characterized by the nearly complete prograde unit during continuing collision, crustal stacking and uplift controlled breakdown of biotite, by high grossular content (23–47 mol %) by extension. of garnet in the presence of albite, and high Si contents of phengite [3·3–3·4 per formula unit (p.f.u.)]. Water activities at this stage are variable and range from 0·4. The maximum pressures indicated for individual rock volumes may vary considerably between 12 and 24 kbar at 700–800°C, so that non-coherency

Influence of Fluid and Deformation on Metamorphism of the Deep Crust and Consequences for the Geodynamics of Collision Zones

Abstract: A survey of natural transitions from igneous rocks, amphibolite, and granulite, to eclogite demonstrates that the transitions may take place over cm-scale distances parallel to fluid fronts. Rocks ranging in composition from basaltic to granitic show incomplete reactions over the whole range of high pressure to ultrahigh-pressure conditions (500°C and 1.2 GPa to 800°C and >3.0 GPa), indicating overstepping of reaction boundaries of 1 GPa. When fluid becomes available metastable crust may react forcefully and release earthquakes as indicated by occurrence of eclogite-facies pseudotachylite.