Question

Which of the following rock and texture combinations is/are CORRECT?

• A. Komatiite and Spinifex
• B. Gabbro and Ophitic
• C. Marble and Granoblastic
• D. Basalt and Porphyroblastic

Hint:

When identifying textures in rocks, remember that certain textures, like Spinifex, Ophitic, and Granoblastic, are characteristic of specific rock types such as komatiite, gabbro, and marble.

Answer 1

The Correct Option is A, B, C

Evaluating the rock and texture combinations:

✅ Komatiite and Spinifex: Komatiite is an ultramafic volcanic rock known for its high-temperature origin. Spinifex texture, featuring long, skeletal olivine crystals, is characteristic of this rock type.

✅ Gabbro and Ophitic: Gabbro is a coarse-grained mafic intrusive rock. Ophitic texture—where plagioclase laths are enclosed by larger pyroxene crystals—is commonly observed in gabbros.

✅ Marble and Granoblastic: Marble, a metamorphic rock derived from limestone, typically exhibits a granoblastic texture, which results from recrystallization under metamorphic conditions forming equigranular interlocking grains.

❌ Basalt and Porphyroblastic: Basalt is a fine-grained extrusive igneous rock, and does not exhibit porphyroblastic texture. Porphyroblastic texture is a metamorphic feature characterized by large crystals (porphyroblasts) set in a finer matrix.

Conclusion:
The incorrect combination is Basalt and Porphyroblastic.