The Zagros Mountains in Iran formed from the ongoing collision of two continental plates-the Arabian and Eurasian Plates. This setting creates intense pressure and heat, generating magma deep underground. Despite this, the region lacks widespread volcanic activity. Scientists study the geologic processes that explain why magma often remains trapped in such environments. Which explanation best describes the absence of surface eruptions?
Answer
A
The thick, buoyant continental crust prevents magma from rising, despite conditions that generate it.
B
Subduction in the region forces magma deep into the mantle, where it is absorbed by surrounding rock.
C
Surface volcanism is blocked because crustal plates slide past each other, preventing magma from pooling near faults.
D
The plates are diverging, creating thin crust that causes magma to cool before reaching the surface.
Explanation
The Arabian and Eurasian Plates are colliding, so the setting can generate heat and magma, but the thick continental crust can make it difficult for magma to rise all the way to the surface. Magma may remain trapped or cool within the crust rather than erupting. Choice A, “The thick, buoyant continental crust prevents magma from rising,” best explains the limited surface volcanism; the other choices describe different plate-boundary settings.
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