Section A
Q1. Answer the following : 10× 4 = 40 Write symmetry elements shown by normal class in isometric system and
(a) that of orthorhombic system. Briefly write on the international system of crystallographic notation. 6+4=10 Using crystallization behaviour of basic magma with the help of albite-
(b) anorthite system, explain normal and oscillatory zoning in plagioclase. Write brief notes on cross-beddings and their significance. c ) Write notes on possible mineralogical changes observed during regional d ) metamorphism of aluminous shale. Write a brief note on textures and structures of metamorphic rocks. 2.
(a) How can 'hornblende' and 'augite' be distinguished based on their optical
(b) properties? Write the names of any three sulphide minerals and two carbonate minerals (with their chemical compositions). What is sedimentary facies? Narrate the important facies types that form in |c\rangle different parts of deltaic sedimentary environment. 2 + 8 = 10 Write briefly on the origin of alkaline rocks.
(d) Write a brief note on prograde metamorphism of basaltic rocks. 10 3.
(a) Give the classification scheme of limestone by Folk. Comment on the
(b) advantage and disadvantage of this classification. Write notes on porphyritic and poikilitic texture of igneous rocks (with suitable |c| labelled sketches). Comment on their petrogenetic significance. Discuss how X-ray diffraction patterns are used for identification of minerals.
(d) 4. Write a brief essay on diagenesis and lithification.
(b) Describe (with neat sketches) the following structures of igneous rocks :
(i) Pillow structure Rapakivi structure (ii) What do you mean by extinction angles of minerals? Give your answer with
(c) suitable sketches. What are the petrographic changes that take place when a basaltic magma assimilates a granite country rock? Write briefly on 'granulite terrains' of India.
(d) &-MM-9-8LF17 2
