Final answer:
A pseudoporphyritic texture in metamorphic rocks features large mineral grains, known as porphyroblasts, surrounded by a fine-grained matrix. These porphyroblasts form during recrystallization under specific temperature and pressure conditions. Non-foliated metamorphic rocks, in contrast, show a massive texture with no preferred mineral alignment. The correct option is d.
Step-by-step explanation:
The term pseudoporphyritic refers to a texture in metamorphic rocks where porphyroblasts (large, distinct minerals) are surrounded by a fine-grained matrix. This mimics the porphyritic texture found in igneous rocks where large phenocrysts are embedded in a finer groundmass. During metamorphism, rocks may undergo recrystallization, where the size, shape, or composition of the minerals change without melting the rock due to changes in temperature and pressure. This can result in the growth of porphyroblasts such as garnet, staurolite, or kyanite, among others.
In a metamorphic context, minerals like chlorite, biotite, cordierite, garnet, staurolite, sillimanite, kyanite, and andalusite are markers of specific pressure-temperature conditions which can help geologists determine the metamorphic history of an area. For instance, the presence of kyanite and sillimanite indicates medium-pressure conditions often associated with continent-continent collisions. On the other hand, andalusite and sillimanite suggest low-pressure conditions perhaps related to divergent zones or particular types of ocean-continent collisions.
Non-foliated metamorphic rocks show a massive, structureless texture where mineral crystals grow in various directions without alignment, and such rocks may break across mineral grains. These characteristics are quite different from the oriented textures of foliated metamorphic rocks, like schist or gneiss, where minerals tend to be aligned due to directional pressure.
Hence, Option d is correct.