Which mountain-building process involves the formation of plutons and batholiths from partial melting or intense heat?

Which mountain-building process involves the formation of plutons and batholiths from partial melting or intense heat?

• A. Precipitation of carbonate material by organisms
• B. Formation of plutons and batholiths from partial melting or intense heat
• C. Weathering and erosion of sediment that accumulate near mountain fronts
• D. Metamorphism of existing rocks

Answer: (B)

During mountain building, intrusive igneous activity can occur when rocks melt or are heated enough to form magma that moves upward and crystallizes below the surface. This process creates plutons—irregular intrusions of igneous rock—and, on a larger scale, batholiths, which are large complexes of such intrusions. These features are classic evidence of tectonic thickening and heating that accompany orogeny. Other processes mentioned involve surface sedimentation, weathering, or metamorphism that doesn’t produce these large intrusive bodies, so the formation of plutons and batholiths from partial melting or intense heat best captures this mountain-building path.

During mountain building, intrusive igneous activity can occur when rocks melt or are heated enough to form magma that moves upward and crystallizes below the surface. This process creates plutons—irregular intrusions of igneous rock—and, on a larger scale, batholiths, which are large complexes of such intrusions. These features are classic evidence of tectonic thickening and heating that accompany orogeny. Other processes mentioned involve surface sedimentation, weathering, or metamorphism that doesn’t produce these large intrusive bodies, so the formation of plutons and batholiths from partial melting or intense heat best captures this mountain-building path.