Foliations

Question 1

Origin of gneissic layering

Answer 1

1. Inheritance of compositional contrast from the protolith
2. ## Transposition
3. Differentiation
   -generation of new layering during deformation/metamorphism
   -higher pressure in zones of shearing
   -solubility of certain materials increases
   -shearing happens oblique or perpendicular to original orientation
4. Lit-par-lit (layer-by-layer) intrusion of sills
   -layers intruded

Question 2

transposition

Answer 2

What is it?
Rotation of a pre-existing foliation (e.g., bedding) by folding into an orientation approximately parallel to the axial plane of the folds
 development of a new orientation of bedding in such a way that bedding, as seen in small outcrops, no longer provides information concerning stratigraphy or gross distribution of
stratigraphic horizons.