1. Using included fragments to estimate the age of a rock unit.
Pieces of granite were found in conglomerate (a) that gave a radiometric date of 320 Ma. Also, fragments of the rhyolite (b) and granite (c) were found in conglomerate (a). Given this information about included fragments in conglomerate (a), estimate the minimun & maximum age for this rock unit.
To estimate the minimum and maximum age for the rock unit that contains conglomerate (a), we can use the information about the included fragments.
1. Start by determining the minimum age:
Since the granite fragments found in conglomerate (a) gave a radiometric date of 320 Ma, we know that the conglomerate (a) cannot be younger than this age. Therefore, the minimum age for the rock unit containing conglomerate (a) is 320 Ma.
2. Next, determine the maximum age:
To estimate the maximum age, we need to consider the ages of the other included fragments, which are the rhyolite (b) and granite (c). If the rhyolite (b) and granite (c) fragments are older than 320 Ma, then the rock unit containing conglomerate (a) must also be at least that old.
3. Additional information is needed to determine the maximum age:
Unfortunately, the information provided does not include the radiometric dates for the rhyolite (b) and granite (c) fragments in conglomerate (a). Without this information, we cannot accurately estimate the maximum age for the rock unit.
In summary, based on the information provided, the minimum age for the rock unit containing conglomerate (a) is 320 Ma. However, without knowing the radiometric dates for the rhyolite (b) and granite (c) fragments, we cannot determine the maximum age.