EARTH331 Lecture Notes - Lecture 4: Feldspathoid, Eutectic System, Olivine
13 Apr 2016
School
Department
Course
Professor
Document Summary
Mode: actual mineral composiion of a rock, based on observed volume % Norm: idealized mineralogy calculated from chemical composiion of a rock, exaggerates the denser minerals compared to the mode. Caion norm: expresses normaive minerals on an atomic basis. Silica-oversaturated: contains quartz (or another silica polymorph) in the mode as a stable phase. Silica-undersaturated: contain mineral incompaible with quartz, such as olivine or feldspathoid. Primary magmas: derived directly by parial meling of some source no characterisics that relect efects of difereniaion source presumed to be mantle (also called primiive magmas) Evolved magmas: experienced some sort of chemical difereniaion (also called derivaive magmas) Parental magma: most primiive rock found in an area magma from which the others are derived. Alkaline rocks: richer in alkalis, commonly silica undersaturated. Peralkaline: al2o3 content is less than (na2o + k2o) Peraluminous: al2o3 content is greater than (cao + na2o + k2o) Metaluminous: al2o3 content is less than (cao + na2o + k2o) but,
