Which of the following is/are the evidences of the magmatic origin of granites ? A. Chilled margins of the granite Choose the correct answer from the options given below :
B. Perfect gradation between the country rocks and the granites
C. Presence of xenoliths of country rocks in the granites
D. Graphic texture
Granite Origin Evidence Analysis
This question asks to identify the geological features that strongly suggest granites formed from molten magma (magmatic origin).
Examining Evidences for Magmatic Origin
- Chilled Margins (A): The presence of fine-grained chilled margins around granite bodies indicates that hot magma intruded into cooler surrounding rocks, causing the magma at the contact to cool and solidify quickly. This is a typical sign of magmatic intrusion.
- Perfect Gradation (B): A perfect, gradual transition between granite and the country rock usually points towards metamorphic processes, like granitization, where the rock gradually changes composition in place, rather than magma physically intruding.
- Xenoliths (C): Xenoliths are fragments of the pre-existing country rock that have been broken off and incorporated into the moving magma. Their presence within the granite is a direct piece of evidence that the granite existed as a mobile, molten mass capable of engulfing rock fragments.
- Graphic Texture (D): This texture is characterized by the regular, intergrowth pattern of quartz and feldspar crystals. It is commonly observed in felsic igneous rocks and is thought to form during the crystallization of a granite magma.
Conclusion on Granite Formation Evidence
Based on the analysis, the features providing evidence for the magmatic origin of granites are:
- A. Chilled margins - Shows rapid cooling upon intrusion.
- C. Presence of xenoliths - Indicates magma assimilation.
- D. Graphic texture - A common crystallization texture in magmas.
Feature B (Perfect gradation) is generally associated with metamorphic or metasomatic origins rather than magmatic ones.
Therefore, the correct combination is A, C, and D.
Similar Questions
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Many natural disasters are caused by the volcanic activity occurring in the island arc systems.
Reason (R) : The fissure type volcanism causes the erupted lava to spread over wide areas.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Gypsum has lower density than anhydrite.
Reason (R) : Hydrated minerals tend to expand many times the original volume of the anhydrous minerals.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Drumlins show features opposite to those of Roches Moutonnees.
Reason (R) : The stoss side is steep and the lee side is roughened.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : In a hand specimen quartz can be easily distinguished from orthoclase.
Reason (R) : Orthoclase has lower refractive index than quartz.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : L waves are responsible for majority of the destructive earthquakes.
Reason (R) : They are the surface waves and develope in the immediate vicinity of the epicenter.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : All continents were united together in the past.
Reason (R) : The Gangamopteris and Glossopteris flora have been found on all the southern continents.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : A dip-slip fault can be a wrench fault.
Reason (R) : Along a dip fault, the net slip can be equal to strike-slip, dip-slip or oblique-slip.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : Chronostratigraphy is concerned with the mutual time relationship of strata.
Reason (R) : Formation, member and bed are units of chronostratigraphy.
In the light of the above statements, choose the most appropriate answer from the options given below :
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : The angle between any two faces of a crystal is termed as interfacial angle.
Reason (R) : The interfacial angles of corresponding faces of different crystals are constant if they have same chemical composition and measurements are taken at same temperature.
In the light of the above statements, choose the most appropriate answer from the options given below :
Match List - I with List - II.
List - I
Crystal SystemList - II
CharacteristicsA. Monoclinic I. 4 triads B. Tetragonal II. 3 diads C. Orthorhombic III. 1 tetrad D. Cubic IV. 1 diad Choose the correct answer from the options given below :
Important Questions from Mixed Topic (CUET PG)
- Kalpsutra, the illustrated canonical text is from:-
- The Harappan city almost exclusively devoted to craft production was-:
- Mohandas Karamchand Gandhi launched quit India movement after the failure of:-
- The "Objectives Resolution" was introduced in constituent assembly by:-
- Who among the following was not a member of the constituent assembly:-
