List of top Questions asked in IIT JAM GG

In a sedimentary succession shown in the figure, the last occurrence of the fossil species Q (dated 50 Ma) and the first occurrence of the fossil species R (dated 30 Ma) are recorded at Y and X, respectively. The estimated rate of sedimentation is (assume constant rate of sedimentation).

Age of granitic rocks can be determined using Rb-Sr whole rock radioactive dating method and the following age equation, \[ (^{87}Sr/^{86}Sr) = (^{87}Sr/^{86}Sr)_0 + (^{87}Rb/^{86}Sr) (e^{\lambda t} - 1) \] For a suite of representative co-magmatic granitic rocks, the Rb-Sr whole rock isochron plot and relevant data are shown in the diagram. The age of granite is calculated at (1 Ga = 10⁹ yrs), (give answer in one decimal place).

Considering garnet chemical formula in 12 oxygen basis, the number of Mg cations in a garnet of chemical composition P (as shown in the figure) is (give answer in two decimal places).

The schematic map given below shows intersecting strike lines of the same lithological contact. In the map, AB and CD are 5 cm and 3.5 cm, respectively. The scale of the map is 1 cm = 100 m. The plunge of the fold axis is (give answer in one decimal place).

Shown below is an isobaric binary temperature-composition phase diagram in the system X-Y with complete miscibility between X and Y.

Which of the following statements is/are correct for crystallization of a starting melt of composition X₆₀Y₄₀ (the dot in the diagram)?

Match the earth layers (Group I) with corresponding approximate thicknesses (Group II).
\[ \begin{array}{|l|l|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline P. \ \text{Lithosphere} & 1. \ 2900 \text{ km} \\ Q. \ \text{Mantle} & 2. \ 2250 \text{ km} \\ R. \ \text{Outer Core} & 3. \ 1200 \text{ km} \\ S. \ \text{Inner Core} & 4. \ 100 \text{ km} \\ \hline \end{array} \]

Match the igneous bodies in Group I with their ages in Group II.
\[ \begin{array}{|l|l|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline P. \ \text{Singhbhum granite} & 1. \ \text{Neoproterozoic} \\ Q. \ \text{Malani rhyolite} & 2. \ \text{Cretaceous} \\ R. \ \text{Deccan volcanics} & 3. \ \text{Permian} \\ S. \ \text{Panjal Traps} & 4. \ \text{Archaean} \\ \hline \end{array} \]

Which one of the following sequences of silicate structures indicates an increasing degree of sharing of corners of \( (\text{SiO}_4)^{4-} \) tetrahedra?

Match the geological processes (Group I) with their examples in Indian stratigraphy (Group II).
\[ \begin{array}{|l|l|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline P. \ \text{Permo-Carboniferous glaciation} & 3. \ \text{Talchir Formation} \\ Q. \ \text{Cretaceous marine transgression} & 4. \ \text{Lameta Formation} \\ R. \ \text{Neogene fluvial sedimentation} & 2. \ \text{Siwalik Group} \\ S. \ \text{Cretaceous inter-trappean sedimentation} & 1. \ \text{Ariyalur Group} \\ \hline \end{array} \]

Match the sedimentary features in Group I with the corresponding sedimentary environments of their formation in Group II.
\[ \begin{array}{|l|l|} \hline \textbf{Group I} & \textbf{Group II} \\ \hline P. \ \text{Point Bar} & 2. \ \text{Meandering fluvial channel} \\ Q. \ \text{Barchan} & 3. \ \text{Aeolian} \\ R. \ \text{Dropstone} & 4. \ \text{Glacial} \\ S. \ \text{Herring-bone cross stratification} & 1. \ \text{Tidal} \\ \hline \end{array} \]