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Q31. Nickel ores are NOT associated with
Nickel is a heavy metal often found mixed with dense, iron-rich (ultramafic) volcanic rocks, or concentrated in deeply weathered tropical soils (laterites) and ocean floor lumps (nodules). 'Skarns' are a different type of rock formed when hot fluids bake limestone, and they usually hold copper, zinc, or iron, but rarely nickel.
Q32. The correct hierarchy of the given stratigraphic units is
Geologists organize rock layers into categories, just like biologists organize animals (Kingdom, Phylum, Class). The largest distinct rock grouping is a 'Group'. This is broken down into smaller 'Formations'. Formations are broken down into 'Members', and the smallest individual layer is a 'Bed'.
Q33. The crystal form ‘dome’ contains
In crystallography, different 3D shapes have specific names. A 'dome' refers to an open shape consisting of exactly two faces that are not parallel to each other. Instead, these two faces lean into each other and are perfectly symmetrical, acting as if there is a 'mirror' reflecting one side to create the other.
Q34. The mineral assemblage found in a granulite facies metabasalt is
'Granulite facies' refers to rocks that have been baked under extreme heat and pressure deep underground. When basalt (a volcanic rock) experiences these intense conditions, it transforms into a new set of high-temperature minerals, most notably orthopyroxene, garnet, plagioclase, and clinopyroxene.
Q35. The name of an igneous rock having a modal composition of 55% olivine, 40% orthopyroxene and 5% plagioclase, as per the IUGS classification scheme, is
Rocks are named based on the percentages of specific minerals they contain. An 'ultramafic' rock with a lot of olivine (over 40%) is generally called a peridotite. Specifically, when it is mostly a mix of olivine and orthopyroxene, geologists classify it as a 'Harzburgite'.
Q36. The plate tectonic setting of Benioff-Wadati zone is
The Benioff-Wadati zone is a deep, slanted area of earthquakes. It happens where one huge piece of Earth's crust (a plate) is being pushed underneath another plate deep into the mantle. This specific crashing and sinking process is called a 'subduction zone'.
Q37. The saturated thickness of an unconfined aquifer is defined by the distance between
An 'unconfined aquifer' is an underground layer of sponge-like rock filled with water. The top of the water is called the 'water table'. The bottom of the water rests on a solid, waterproof rock base called a 'confining layer'. So, the actual thickness of the water-filled (saturated) zone is the distance between the water table and that solid bottom layer.
Q38. The sedimentary structure formed by unidirectional current is
When water flows strongly in one direction (unidirectional), like a river, it pushes sand along the bottom to form dunes. As these dunes migrate forward, they leave curved, scoop-shaped layers of sand behind. This structure is called 'trough cross-bedding'.
Q39. The suture of a cephalopod having smooth saddles and crenulated lobes is called
Extinct shelled squids (cephalopods like ammonites) have zig-zag lines on their shells where the internal walls meet the outer shell, called 'sutures'. The humps pointing forward are 'saddles' and the dips pointing backward are 'lobes'. If the saddles are smooth and round, but the lobes are frilly or jagged (crenulated), it is called a 'ceratitic' suture pattern.
Q40. The symbols , {100} and (100) in a crystal represent the sequence
Geologists use different brackets to describe parts of a crystal's shape. Square brackets [ ] describe a specific direction or 'line'. Curly braces { } describe a family of identical faces, known as a 'form'. Standard parentheses ( ) describe one single, specific flat surface or 'face'.