Question

The contact between the Talchir Formation and the underlying Precambrian basement is

• A. an angular unconformity
• B. a disconformity
• C. a paraconformity
• D. an unconformity

Answer 1

The Correct Option is D

The question is related to the geological contact between the Talchir Formation and the underlying Precambrian basement. Understanding this requires knowledge of geological unconformities and stratigraphy. The options present various types of unconformities, each representing different geological processes:

1. An angular unconformity is when younger sedimentary layers are deposited on tilted or folded older rocks, indicating significant geotectonic activity.
2. A disconformity is an unconformity between parallel layers of sedimentary rocks that indicates a period of erosion or non-deposition.
3. A paraconformity is an unconformity in which strata are parallel, and no obvious discontinuity is noticeable, but deposition has not been continuous.
4. An unconformity is a broader term that refers to a surface of contact between two groups of unconformable strata.

For the Talchir Formation, which is the lowest formation of the Gondwana sequence resting over the older Precambrian rocks, the contact is characterized as an unconformity. This general term indicates a significant time gap between the deposition of the Precambrian basement and the overlying Talchir rocks, without specifying the nature (parallel, angular, etc.) of the strata involved.

Conclusion: The correct answer is an unconformity because the Talchir Formation lies unconformably over the Precambrian basement due to the significant time and depositional gap, but it does not specify the detailed nature of the unconformity, whether angular or parallel.