A pelite is a detrital sedimentary rock with very fine grains (<10 μm) containing, among other things, clay minerals, quartz, etc. It often has laminae.
A trachy-andesite is a volcanic rock of the alkaline series. Generally gray in color, it contains phenocrysts of feldspar, pyroxene and / or amphibole. Trachy-andesites result either from the differentiation of alkaline basalts by fractional crystallization, or from mixtures of alkaline basalt with trachyte or rhyolite.
Trachy-andesites are found especially in intraplate volcanism.
A sill (or seam layer) is a layer of often horizontal magmatic rock that has infiltrated between older layers of sedimentary rock, volcanic rock or along the foliation of a metamorphic rock, which differentiates it from the vein .
A dike, or dike, is a vein of rock that has been injected into a fracking of the country. As a result, a dyke intersects the other rocks it crosses (unlike a sill). The dyke is an intrusive phenomenon in a transverse opening crack. According to the principles of stratigraphy, its age is therefore always younger than that of the surrounding rocks.
Most dykes consist of magmatic rocks, which have been injected in the liquid state.
Contact metamorphism occurs in the host rock in contact with intrusive formations (hot magma pluton). It is a kind of firing of land located in direct contact or near this intrusion that generates, as soon as its volume is important, a metamorphic halo of variable width (from a few tens of meters to several kilometers) . This metamorphism is mainly related to temperature rise, which is why it is also called thermometamorphism.