Question

How would a metamorphic quartzite differ from a sedimentary quartzite (i.e. quartz sandstone)?

1. metamorphic quartzite would be more likely to contain well preserved fossils
2. the quartz grains in the metamorphic quartzite would be more tightly interlocking, leaving less pore space
3. metamorphic quartzite would be more likely to have a layered texture
4. metamorphic quartzite would be more likely to show cross bedding
5. metamorphic quartzite would be more likely than sedimentary quartzite to be found in the presence of shale and limestone

Answer 1

Metamorphic quartzite has tightly interlocked quartz grains and lacks the sedimentary structures, such as cross bedding, found in quartz sandstone due to the high heat and pressure of metamorphism.

Step-by-step explanation:

The quartz grains in metamorphic quartzite are more tightly interlocking compared to those in sedimentary quartzite (quartz sandstone), resulting in less pore space. This tight interlocking is due to the high temperature and pressure conditions that metamorphic rocks undergo, which re-crystallize and fuse the grains together.

In sedimentary rocks like quartz sandstone, it is common to find features such as cross-bedding, mud cracks, ripple marks, or even fossils because these are formed in environments where deposition occurs, often preserving these structures. In a metamorphic quartzite, however, these features would generally be obliterated due to the extreme conditions that re-crystallize and deform the original sedimentary structures.

Lastly, metamorphic rocks, including quartzite, are commonly found associated with other types of metamorphic and igneous rocks, such as gneiss and granite, as well as sedimentary rocks like shale and limestone, since they are all part of the geological processes that transform rocks over time.