ESS102H1 Midterm: GLG207-ESS222 Midterm Study Notes
Document Summary
Extrusion (eruption) = lavas, pyroclastic rocks: melting: If dihedral angles <60 , melt is extracted at low volume fractions - mantle melting to form basalt. If dihedral angle >60 , melt remains in situ - crustal melting to form granite: transport and emplacement: Transport = rapid ascent in dikes, slow ascent in diapirs. Emplacement = dikes, horizontal sheets (sills, laccoliths, lopoliths), batholiths (are these really just collections of sills?) Sills are concordant, more or less horizontal. If you can"t reasonable tell, then call it a dike. Appear to lack floors (probably most are actually sills) Layered intrusions - effectively, very large sills. If the dip toward the centre they are called lopoliths: crystallization, mixing, and assimilation. Heating of wall rocks leads to assimilation. Mingling of magmas may lead to mixing. Mafic minerals = usually colourful, high birefringence, dark coloured rocks. Extremely rapid = crystals cannot form, glass forms, i. e. holohyaline. Rapid = glass surrounds crystals, vitrophyre, spherulitic and related textures.
