Pile of sediments, characterized by repeated thrust faults, which accumulates on the oceanward side of a subduction zone. It grows due to sediment being scraped off the descending plate at a subductio [..]

Basalt containing normative nepheline and olivine.

Metamorphic rock consisting mainly of amphibole and plagioclase with little or no quartz.

A fine grained intermediate volcanic igneous rock characterised by the presence of oligoclase or andesine. Their chemistry and mineralogy are closely similar to those of the diorites. Porphyritic vari [..]

The earlier part of the Precambrian between 4000Ma and 2500Ma.

Partially molten layer below the lithosphere that is marked by low seismic wave velocities and high seimic attenuation.

Fine grained, dark, mafic igneous rock composed largely of plagioclase feldspar and pyroxene.

Group of high MgO (> 6 wt% MgO) andesites apparently restricted to fore arc regions, which suggests that rather special conditions are required for their generation. The most extensive occurences a [..]

Central part of the Earth extending from the Gutenberg discontinuity with the mantle at 2900km to the centre of the Earth at 6370km. The composition is predominantly iron and nickel. The outer core, f [..]

That part of the Earth lying above the Mohorovicic Discontinuity. It is divided into two shells, a lower continuous one - the sima (acronym of <silica and magnesia) - and an upper, discontinuous la [..]