What Is A Granitic Magma

Granitic or rhyolitic magmas and andesitic magmas are generated at convergent plate boundaries where the oceanic lithosphere the outer layer of earth composed of the crust and upper mantle is subducted so that its edge is positioned below the edge of the continental plate or.

What is a granitic magma.

Other articles where granitic magma is discussed. The parental granitic magma underwent the mixing of mantle derived mafic magma and crustal felsic magma coupled with fractional crystallization during magma ascent before emplacement. Granitic magma has high levels of potassium and sodium while basaltic magma has very low levels of these minerals. Granitic magma must make room for itself or be intruded into other rocks in order to form an intrusion and several mechanisms have been proposed to explain how large batholiths have been emplaced.

The fracture network in granitic magmas consists of through going backbone mafic and silicic composite dykes and smaller dangling granitic dykes locally generated in the magma chamber. Emplacement is defined here as the switch from upward to horizontal flow and. Granitic magmas commonly ascend tens of kilometres from their source terranes to upper crustal emplacement levels or to the earth s surface. A good deal of research has shown that dyking is the only viable mechanism by which granitic magmas can be transported vertically through large thicknesses of crust to allow high level emplacement of magma in a largely liquid state clemens and mawer 1992 clemens 1998 petford et al 1993 mcnulty et al 1996 baker 1998 de saint.

Apart from its obvious bearing on the interpretation of the geology and geochemistry of felsic igneous rocks the magma ascent mechanism critically affects any modelling of the metamorphic evolution of the upper lithosphere as well as its rheology. Curve representing li f granitic magma and red referring to general granitic magma. The emplacement of granitic magma within the continental crust marks the final stage in the granite forming process. Stoping where the granite cracks the wall rocks and pushes upwards as it removes blocks of the overlying crust.