This website is made to help students prepare for their competitive exams with ease and confidence.
Q111. The following diagram represents the prograde sequence of metamorphic zones that develop during Buchan-type of metamorphism (<4 kbar) of typical pelites. Identify the zones labelled P, Q and R.
The correct answer is P - Biotite zone; Q - Cordierite zone; R - Andalusite zone. Buchan-type metamorphism occurs under characteristically low-pressure but high-temperature conditions. As a mudrock (pelite) heats up from the Chlorite zone, it enters the Biotite zone (P). At higher temperatures under low pressure, Cordierite (Q) typically forms instead of high-pressure garnet. Finally, it reaches the extremely hot Andalusite zone (R), rather than the high-pressure Kyanite or Sillimanite zones seen in Barrovian metamorphism.
Q112. The host rock of Pb-Zn deposit at Zawar is
The correct answer is dolomite. The Zawar mines in Rajasthan, India, are incredibly famous and ancient sources of Lead (Pb) and Zinc (Zn). These precious metals did not form in hard quartz or baked gneiss. Instead, hot, metal-rich fluids pushed their way into thick, chemically reactive beds of carbonate rocks—specifically 'dolomite'—where the metals precipitated out and became trapped.
Q113. The igneous body with dome or mushroom-like shape is known as a
The correct answer is laccolith. When thick, viscous magma forces its way between flat layers of underground rock, it pushes the rock layers above it upward into a distinct dome or mushroom shape while the floor beneath it remains perfectly flat. This specific blister-shaped intrusion is called a Laccolith. A sill is completely flat on both top and bottom, and a lopolith sags downward into a bowl shape.
Q114. Which among the following is the only possible plunge for a lineation located on the foliation plane striking 20° N and dipping 40° southeasterly?
The correct answer is 20° SE. In geology, a line drawn on a tilted ramp (foliation plane) can never be steeper than the ramp itself. The ramp dips at a 40° angle, so a 45° plunge is physically impossible. Furthermore, since the ramp is tilting specifically towards the Southeast (SE), any line drawn on that surface MUST also point downwards in the Southeast quadrant. It cannot miraculously point Northwest (NW). Therefore, 20° SE is the only mathematically and physically valid option.
Q115. Which is the shallowest among the marine environments listed below?
The correct answer is Littoral. The ocean is divided into depth zones. The 'Littoral' zone is the absolute shallowest; it is simply the beach where the tide washes in and out. The 'Neritic' zone is slightly deeper, covering the submerged continental shelf. The 'Bathyal' zone drops steeply down the dark, deep ocean slope. Finally, the 'Abyssal' zone is the pitch-black, freezing, deepest ocean floor plains, making it the complete opposite.
Q116. Which one of the following crystal forms DOES NOT belong to the di-tetragonal pyramidal class?
The correct answer is Tetragonal dipyramid. The di-tetragonal pyramidal class (symmetry 4mm) lacks a horizontal mirror plane. Because it lacks this mirror, it cannot form closed shapes that perfectly mirror top-to-bottom like a 'dipyramid'. Instead, crystals in this class are 'hemimorphic', meaning their top half looks different from their bottom half (often ending in a flat pedion). Therefore, the fully symmetrical dipyramid form is impossible here.
Q117. Which one of the following represents the compositional change in plagioclase during the crystallization of mafic magma?
The correct answer is Na/Ca ratio increases; Al/Si ratio decreases. As hot mafic magma cools, high-temperature calcium-rich plagioclase (Anorthite: CaAl2Si2O8) crystallizes first. As cooling continues, the remaining liquid is enriched in sodium and silica, so later plagioclase becomes sodium-rich (Albite: NaAlSi3O8). Because the crystal shifts from Calcium to Sodium, the Na/Ca ratio increases. Because Albite has 3 Silicon atoms and only 1 Aluminum, the Al/Si ratio mathematically decreases.
Q118. Which one of the following statements is FALSE?
The correct answer is Juvenile water is derived from sediment diagenesis. 'Juvenile water' is brand-new water that has never been part of the Earth's water cycle before; it is created deep underground by magma and spewed out of volcanoes. Water squeezed out of normal dirt turning into rock (sediment diagenesis) is called 'connate water', not juvenile. The other statements are true: aeration is the dry dirt above the soggy saturation zone, and aquifuges/aquicludes block water.
Q119. Which one of the following statements is FALSE?
The correct answer is Echinoids have genal spines. 'Genal spines' are the sharp, sweeping horns located on the back corners of the head shield (cephalon) of ancient sea bugs called Trilobites. Echinoids (sea urchins) do not have a head shield, so they cannot possess genal spines. Ammonites do have wavy septa, brachiopods do use a fleshy pedicle stalk to attach to rocks, and trilobites do have a tail section called a pygidium.
Q120. Which one of the following stratigraphic units belongs to the Cretaceous?
The correct answer is Lameta Formation. In Indian stratigraphy, the Lameta Formation is a legendary sequence of rocks laid down right at the very end of the Cretaceous period, famous globally for its rich deposits of dinosaur bones and eggs. The Talchir Boulder Bed is much older (Permian). The Fenestella Shale is Carboniferous, and the Kasauli Formation is much younger (Tertiary).