EARTH238 Lecture Notes - Lecture 4: Diagenesis, Pressure Solution
30 Aug 2016
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Lecture 4: diagenetic: due to compaction and not tectonism, differential compaction: laterally and vertically. The compaction of mud leads to a development of a preferred orientation of clay in the resulting shale bed: pressure solution: under pressure some minerals tend to dissolve. Styolite: structure formed due to dissolution of minerals that leave behind clays: penecontemporaneous folds and faults. Only occur locally and within a bed, does not affect bed boundary. Two adjacent beds might have folding but it will be individual. Slumping: original bedding more or less maintains cohesion. Primary igneous structures: magma formed either intrusive or extrusive, felsic and mafic, dykes: cross cuts pre-existing rocks. Importance of primary structures: serve as younging indicators. Deformation and strain: deformation can be homogeneous in 2d circles become ellipses and in 3d spheres become ellipsoids straight lines remain straight heterogeneous, strain. Change in the shape of a body (describes final shape in terms of the initial shape)
