Which rock is the coarse-textured, deep intrusive equivalent of basalt?

The correct answer is gabbro because it is the coarse-textured, deep intrusive equivalent of basalt. Both gabbro and basalt are composed primarily of similar minerals, predominantly pyroxene, plagioclase, and occasionally olivine. The key difference lies in their texture and formation; basalt forms from lava that cools rapidly on the Earth's surface, resulting in a fine-grained texture, while gabbro forms from magma that cools slowly beneath the surface, allowing larger crystals to develop and resulting in a much coarser texture.

Understanding the formation processes is crucial in differentiating between these rock types. The slow cooling of magma in the Earth's crust gives rise to gabbro's distinct coarse-grained characteristics, which are not found in basalt. Additionally, gabbro often occurs in large intrusions and is typically found in areas where continental crust is being formed or modified.

The other options, such as andesite, diorite, and granite, represent different compositions and cooling histories, making them unrelated to the direct comparison between basalt and gabbro. Andesite is typically an intermediate volcanic rock, diorite represents a different composition with a distinct mineralogy, and granite is a felsic intrusive rock that is distinctly