ERTH 2406 Study Guide - Midterm Guide: Metamorphic Rock, Unconformity, Metamorphism
11 Feb 2016
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Primary structures bedding and lamination in sedimentary rocks; igneous layering (low banding), tabular intrusions(dykes) Secondary structures- faults, fractures, joints, cleavage, foliation, axial planes of folds. Foliation pervasive, penetrative, closely spaced, nearly parallel surfaces in a rock, preferred orientation of platy grains or aggregates of grains/ discontinuities such as micro fracture, intersection of foliation plane with a surface creates a line. Lineation any linear feature that occurs penetrative throughout a body of rock such as elongated minerals, aggregates of minerals of deformed objects ex. Fold hinge-center of the fold, area of maximum curvature. Axial plane-imaginary surface which bisects the two limbs of the fold. Axial trace- the line of intersection of the axial plane and the surface. Axial planar foliation foliation which is (sub) parallel to the axial trace of a fold, formed during folding event. Anticline- fold with older rocks in the core. Similar folds- orthogonal thickness changes systematically such that the thickness stays constant.
