What is/are one source of mineral deposits on the seafloor?
A. Coral reefs
B. Lagoons C
. Seafloor spreading
D. Volcanic vents
The correct answer and explanation is:
Correct Answer: D. Volcanic vents
Explanation:
One significant source of mineral deposits on the seafloor is volcanic vents, particularly hydrothermal vents. These are fissures on the ocean floor from which geothermally heated water is emitted. They are most commonly found along mid-ocean ridges, where tectonic plates are moving apart and magma rises to form new oceanic crust.
When seawater seeps into the oceanic crust through cracks, it becomes superheated by underlying magma. This hot water dissolves minerals from the surrounding rocks. As it re-emerges through hydrothermal vents and encounters cold ocean water, the minerals precipitate out, forming dense layers of metallic sulfides. These mineral-rich deposits include valuable elements like:
- Copper
- Zinc
- Gold
- Silver
- Iron
- Manganese
These accumulations are called polymetallic sulfide deposits, and they are considered a potential future source of metals, especially as land-based mineral resources become more difficult to extract.
Other features such as coral reefs (A) and lagoons (B) are not sources of metallic mineral deposits. They are mainly biological structures associated with carbonate sedimentation rather than metal enrichment.
Seafloor spreading (C) is a process — not a deposit source itself — although it creates the geologic setting (mid-ocean ridges) where hydrothermal vents form. So, while it plays an indirect role in mineral formation, it is not the direct source of the minerals.
In summary, volcanic vents, specifically hydrothermal vents, are the direct source of many mineral deposits on the seafloor. They represent one of the most geologically active and mineral-rich environments in the ocean, and are being explored for potential deep-sea mining.