The correct answer is option 3: 2 and 4 only.

Let`s dissect each statement to better understand:

1. Sediments of Gondwana System were deposited under marine conditions.

This statement is incorrect. Sediments of the Gondwana System were primarily deposited in freshwater and terrestrial environments, such as swamps and river deltas. Marine conditions were not prevalent during the deposition of Gondwana sediments. Therefore, option 1 is incorrect.

2. Rocks of Gondwana System are fossiliferous.

This statement is correct. The rocks of the Gondwana System are known for their abundance of fossils. They contain the remains of various plant and animal species, providing valuable information about the Earth`s past. Therefore, option 2 is correct.

3. Rocks of Gondwana System contain metallic mineral deposits.

This statement is incorrect. The Gondwana rocks do not contain significant metallic mineral deposits. They are primarily composed of non-metallic minerals and sedimentary deposits. Therefore, option 3 is incorrect.

4. Gondwana deposition took place in a downfaulted trough.

This statement is correct. The Gondwana deposition occurred in rift basins or downfaulted troughs formed due to t