Chapter 12, Problem 1RQ

To determine

The way in which basic features of Wopmay orogen are typical of orogenic belts.

Answer to Problem 1RQ

The Wopmay orogen, which is typical of orogenic belts, was formed by the deposition of quartz sandstone, carbonate rocks, mudstone, and flysch deposits.

Explanation of Solution

The Wopmay system can be defined as the deformation of the body of rocks or mountain that has been leveled by the process of erosion. The Wopmay orogen occurred around 2 billion years ago. It is a great reservoir of sedimentary rocks. The basic features of Wopmay orogen that are typical of the orogen belt are described as follows:

(i) Quartz sandstones were the first sedimentary structure that was deposited in the Wopmay orogen. The thick deposit of the quartz sandstone was found in the Slave Craton.

(ii) Wopmay orogen is abundant in carbonate rocks. The carbonate rocks, which have the layers of stromatolites, have been deposited on the top of the quartz sandstone. These rocks help in the formation of carbonate platforms.

(iii) The carbonate platforms facilitate the deposition of transitional mudstones, which indicate the down wrapping of the platform for the formation of the foreland basin.

(iv) The deposition of flysch deposits (shale and turbidites ) occurred after the deposition of mudstones. The thickening of the Wopmay flysch increased with the deposition of plutonic rocks from westwards.

(v) The upward deposition of flysch grades into the beds of stromatolites and mudstones created the shallow-water environment. This also helped in shallowing the foreland basin.