ASBOG Practice Exam

What is referred to as a paraconformity?

1. Unconformity with complex erosion surfaces

2. Unconformity with strata that are parallel

3. Unconformity caused by tectonic forces

4. Unconformity resulting from sediment compaction

The correct answer is: Unconformity with strata that are parallel

A paraconformity is specifically described as an unconformity that exists between two parallel layers of sedimentary rock, which indicates a hiatus in deposition without any significant erosion of the strata involved. The parallel nature of the layers distinguishes paraconformities from other forms of unconformities. This suggests a period during which deposition has ceased, but there has been minimal or no apparent erosion, allowing the original bedding planes to remain intact. In contrast, unconformities that involve complex erosion surfaces do not maintain this parallel relationship and often show irregular surfaces where sediments have been worn away. Tectonic forces can lead to various modifications of rock layers, but they do not directly define paraconformities. Lastly, while sediment compaction can affect the characteristics of rock layers, it is not the defining process that results in a paraconformity. Hence, the uniqueness of a paraconformity lies in the preservation of parallel strata despite a significant lapse of time in sediment deposition.