Chapter 5, Problem 1QRD

(a)

To determine

The features in a sedimentary rock that might indicate that it was deposited in shallow marine environment.

Answer to Problem 1QRD

Mature sandstones and dark shales that contain shallow marine fossils constitute the shallow marine deposits.

Explanation of Solution

The marine realm is classified into shallow marine, continental slope, and deep marine environments.

A shallow ocean environment is formed adjacent to the shore by the continental shelves. They are considered as the submerged edges of the continents, and they have a clear continuity with the adjacent coastal plains. Continental shelves are nearly smooth and almost flat areas that fringe the continents and extend toward the sea from few kilometers to about 300 kilometers and at water depths from just centimeters up to 200 meters.

The type of sediment deposited on the shelves varies depending on the factors such as the nature of the source rock on adjacent landmasses, the elevation of source areas, the distance from shore, and the presence of carbonate‐secreting organisms. Since large particles are heavier than smaller ones, they have the ability to dropout soon after entering the ocean and thereby deposit near to shore. In addition, the finer particles are kept in suspension and transport them farther out to the sea due to the activity of shallow water currents and the action of waves. As a result, the sediment deposited on the shallow marine environment are coarser than material that were deposited in deeper parts of the ocean.

(b)

To determine

The features in a sedimentary rock that might indicate that it was deposited in deep marine continental rise environment.

Answer to Problem 1QRD

Dark shaley sandstone and dark shales that consist of deep marine trace and body fossils constitutes the deep marine continental rise environment.

Explanation of Solution

The marine realm is classified into shallow marine, continental slope, and deep marine environments.

Most of the sediments that were deposited at the ocean floor of the deep marine environment that is situated far away from the continents are very fine silt and clay, volcanic ash, and the siliceous and calcareous remnants of microscopic organisms.

(c)

To determine

The features in a sedimentary rock that might indicate that it was deposited in transitional deltaic environment.

Answer to Problem 1QRD

Immature sandstone and shales with mixed shallow marine and freshwater fossils constitute the transitional deltaic environment.

Explanation of Solution

The marine realm is classified into shallow marine, continental slope, and deep marine environments. A transition zone is present between the marine and continental depositional environment. It is referred to as the shore.

The deposition of sediment that occurs where a stream flows into a body of relatively stagnant water such as the ocean or lake is referred as the delta. Even though the shape of delta is similar to the Greek alphabet letter delta, it changes depending on the volume of sediment it receives and the erosional removal of that sediment occurs by the action of waves, tides, and currents along the shoreline.

(d)

To determine

The features in a sedimentary rock that might indicate that it was deposited in a continental desert environment.

Answer to Problem 1QRD

Continental desert environment can be indicated by the presence of well-sorted sandstone and arkose that are red and lack fossils other than continental terrestrial trace fossils.

Explanation of Solution

Wind is also an energy that can cause erosion, transportation, or deposition of sediment in addition to the moving ice and flowing water. However, wind is very selective with regard to the size of particles, which it can transport. The desert regions are characterized by an abundance of the particles such as sand and silt, sparse plant cover, and strong winds.