What Is The Origin Of Sedimentary Basins Of Pakistan?

The sedimentary basins in Pakistan originated in the same ways that other sedimentary basins do across the world.

There are three main ways that sedimentary basins can form; lithospheric stretching, lithospheric compression and strike-slip deformation. Each of these formation methods contribute towards creating the sedimentary basins found on Earth.

A sedimentary basin is a term used to refer to a geographical feature that has subsidence and consequent infilling that is found in the form of sedimentation. The sediments are buried and the increasing pressure triggers the beginning of the formation process. Some basins experience inversion, resulting in many of the oil reserves found across the world. The three formation methods are detailed below.

• Lithospheric stretching

This occurs when the lithosphere is forced to stretch horizontally. This stretching takes place because of mechanisms such as trench pull or ridge push. The lower part of the lithosphere flows away from the main area that is being stretched. The upper, brittle crust will begin to crack and fracture. These two mechanisms cause the land to subside and infill with water and sediments.

• Lithospheric compression

The lithosphere will flex like an elastic plate if a load is placed upon it. The imposed load and the flexural rigidity of the lithosphere has a function of the magnitude of the flexure and the wavelength of the flexure is a function of the flexural rigidity.

• Strike - slip deformation

This formation method occurs because of near horizontal maximum and minimum principal stresses. These subsidence zones that appear as a result are referred to as strike slip or pull apart basins. Where a vertical fault plane curves, basins are formed through strike slip action.

Sedimentary basins can be formed in one of the three ways mentioned above, these formation methods occur all over the world, including Pakistan.