Blue Schist Thin Section

Blueschist blueschist is a regional metamorphic rock formed under high pressure hp low temperature lt conditions.

Blue schist thin section. It is formed in the subduction zone environment with low geothermal gradients 4 14 c km 1 and is characterized by the presence of hp lt index minerals like glaucophane lawsonite aragonite jadeite and deerite fig 1. This is a somewhat haphazard collection of metamorphic textures and rocks seen in thin section with some discussion of the processes thought to have made them. Metamorphic rocks thin sections.

The thin section illustrates the folded metasedimentary banding with fine grained quartz muscovite and chlorite. There are also books of chlorite visible at the edges of the chloritoid infilling pressure shadows. 2000 is that the static metamorphism occurred under 7 8 kbar at a low geothermal gradient.

These rocks are not blueschists for the small porphyroblasts cannot be discerned nor suspected in outcrop and are seen only in thin section. Schist from the col de l iseran alps. All images have two views in plane and cross polarized light.

Tourmaline has no cleavage though cross fractures are common and has negative elongation. Blueschist signifies regional metamorphism at relatively high pressures and low temperatures but it isn t always blue or even a schist. This knowledge allows the interpretation that the sabah trench was located in the neighbourhood of telupid.

The black gray and white grains are mostly silt or smaller size grains of quartz and feldspar. Photomicrograph of a thin section of blueschist facies metamorphosed basalt from sivrihisar turkey blueschist ˈ b l uː ʃ ɪ s t also called glaucophane schist is a metavolcanic rock 1 that forms by the metamorphism of basalt and rocks with similar composition at high pressures and low temperatures 200 to 500 degrees celsius approximately corresponding to a depth of 15 to 30 kilometers. Rock with quartz garnet hornblende muscovite.

Plane cross polarized light field width is 0 6 mm. High pressure low temperature conditions are most typical of subduction where marine crust and sediments are carried beneath a continental plate and kneaded by changing tectonic motions while sodium rich fluids marinate the rocks. Tourmaline in a muscovite biotite schist.