Why Is So Much Mafic Magma Erupted Along Mid-Ocean Ridges

question 77

Multiple Choice

Why is so much mafic magma erupted along mid-ocean ridges?

• A)Basaltic mantle under the ridge is hot enough to completely melt if seawater is added.
• B)Lowered pressures decrease the temperatures at which mafic magma can partially melt from massive, extensive, rising plumes of mantle peridotite.
• C)The subducting, oceanic slab sinks so deep that eventually it melts, producing massive quantities of mafic magma.
• D)The mantle beneath the ridges is enriched in thorium, uranium, and potassium, causing strong heating due to energy from radioactive decay.

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Definitions:

Pigouvian Subsidies

Financial incentives given by the government to encourage activities that have positive external effects on society.

Government Transfers

Payments by the government to individuals for which no good or service is provided in return.

Deadweight Loss

Deadweight loss is the decrease in total surplus (both consumer and producer surplus) that occurs when a market is not in perfect competition, typically due to inefficiencies like taxes, subsidies, or monopolies.

Disposable Income

The amount of money that households have available for spending and saving after income taxes have been accounted for.