Planar Laminated Sandstone

Sandstone beds are characterized by a peculiar planar lamination showing a subtle although perceptible undulation.

Planar laminated sandstone.

In geology lamination is a small scale sequence of fine layers laminae. Hence planar lamination has also been called horizontal lamination even lamination and parallel lamination. Consisting of several thin layers of. Lamina that occurs in sedimentary rocks laminae are normally smaller and less pronounced than bedding lamination is often regarded as planar structures one centimetre or less in thickness whereas bedding layers are greater than one centimetre.

Micaceous particles would fall more slowly owing to their shape thus aggregating on bedding. C d wrinkly laminations interbedded with isolated planar. Laminated light yellow to yellow colored parallel laminated sl sandstone in the middle and plannar cross stratified grayish white sandstone sp at the top chandimura section on lalmai hills. Covered with a thin layer of plastic to protect it.

The sedimentary structures which result are roughly horizontal units composed of inclined layers. The sandstone is planar laminated and in some places ripples can be seen. The term parallel lamination has also been used to describe laminae with parallel but nonplanar boundaries figure p11. The original depositional layering is tilted such tilting not being the result of post depositional deformation cross beds or sets are the groups of inclined.

Alternating episodes of deposition from high energy winds and. However structures from several millimetres to many centimetres. The horizontally bedded sandstone represents a damp sand sheet the surface of which would have been covered by a microbial mat. The planar laminated sandstone represents a dry sand sheet the surface of which would have been covered by granule wind ripples and climbing wind ripples.

B detail of wrinkled horizontal laminae. The origin of planar lamination in sands and sandstones. Typically the undulation shows no evidence of lateral accretion but only vertical aggradation and as a result most beds consist of a single laminaset. A laminated sandstone layer with tabular form interbedded with the cross stratified sandstone element ae1.

Spacing to height ratios of the undulation are generally 100 or more. Planar laminated sandstones popularly known. On parting surfaces through planar laminated sandstones parting lineation also called somewhat more precisely parting step lineation is characteristic presumably reflecting a tendency for flow parallel orientation of slightly elongated particles under upper flow regime conditions.