Question

Match the rock types in Group I with their characteristic mineral assemblages in Group II.

Group I		Group II
P	Diorite	1	plagioclase-orthopyroxene clinopyroxene
Q	Tole	2	olivine-orthopyroxene-clinopyroxene
R	Norite	3	plagioclase-homblonde + quartz
S	Lherzolite	4	quarte-plagioclase K-feldspar

• A. P4, Q-3, R-2, S-1
• B. P-2, Q-1,R-3,S-4
• C. P-3, Q-4, R-1, S-2
• D. P-1, Q-3, R-4,S-2

Answer 1

The Correct Option is C

To accurately match the rock types in Group I with their characteristic mineral assemblages in Group II, we need to understand the typical mineral composition associated with each rock type.

1. Diorite: Diorite is typically composed of plagioclase feldspar along with hornblende and sometimes quartz. Therefore, the corresponding mineral assemblage in Group II is plagioclase-hornblende + quartz. This matches with option 3.
2. Tole: Generally, Tole is not a recognized rock type in geological terms. Given the options, it seems to have been intended as a typographical error or misinterpretation. However, no other option seems to match a common rock from Group I. So, based on typical rock composition, the closest match could be with an assemblage involving feldspars and quartz, though this is a hypothesis to illustrate the importance of clear identification in geology.
3. Norite: Norite is characterized by plagioclase along with orthopyroxene and clinopyroxene. This matches with the mineral assemblage containing plagioclase-orthopyroxene-clinopyroxene, which corresponds to option 1.
4. Lherzolite: Lherzolite is a type of peridotite, predominantly composed of olivine, orthopyroxene, and clinopyroxene. The corresponding mineral assemblage is olivine-orthopyroxene-clinopyroxene, which matches with option 2.

From the analysis, we find that the correct matching is:

• P (Diorite) - 3: plagioclase-hornblende + quartz
• Q (Tole) - 4: Contains an error in identification, typically rocks such as granites or similar feldspar-rich types include quartz which cannot be determined correctly from given data.
• R (Norite) - 1: plagioclase-orthopyroxene-clinopyroxene
• S (Lherzolite) - 2: olivine-orthopyroxene-clinopyroxene

Therefore, the correct answer is P-3, Q-4, R-1, S-2.