A dacite is the volcanic equivalent of which plutonic rock?

A dacite is the volcanic equivalent of which plutonic rock?

• A. Granite
• B. Granodiorite
• C. Diorite
• D. Gabbro

Answer: (B)

Dacite is a felsic volcanic rock with a high silica content and a mineral mix dominated by plagioclase and quartz, with some alkali feldspar and little to no mafic minerals. The plutonic rock that forms in the same magmatic system and matches this composition most closely is granodiorite, which also contains quartz plus a blend of plagioclase and alkali feldspar. This volcanic–plutonic pairing reflects how rapid cooling in the volcanic environment yields a finer-grained rock that mirrors the coarser-grained plutonic counterpart with similar mineralogy. Gabbro is too mafic, diorite lacks quartz, and granite is more alkali-feldspar–rich, making granodiorite the best match for dacite.

Dacite is a felsic volcanic rock with a high silica content and a mineral mix dominated by plagioclase and quartz, with some alkali feldspar and little to no mafic minerals. The plutonic rock that forms in the same magmatic system and matches this composition most closely is granodiorite, which also contains quartz plus a blend of plagioclase and alkali feldspar. This volcanic–plutonic pairing reflects how rapid cooling in the volcanic environment yields a finer-grained rock that mirrors the coarser-grained plutonic counterpart with similar mineralogy. Gabbro is too mafic, diorite lacks quartz, and granite is more alkali-feldspar–rich, making granodiorite the best match for dacite.