CIVILS MAINS 2013 GEOLOGY PAPER II
Maximum Marks: 250

QUESTION PAPER SPECIFIC INSTRUCTIONS
Please read each of the following instructions carefully before attempting questions.
There are EIGHT questions divided into two SECTIONS and printed both in HINDI and in ENGLISH.
Candidate has to attempt FNE questions in all. Question No.1 and 5 are compulsory and out of the remaining, THREE are to be attempted choosing at least ONE from each section.
The number ofmarks carried by a question/part is indicated against it.
Answers must be written in the medium authorized in the Admission certificate which must be stated clearly on the cover ofthis Question-cum-Answer booklet in the space provided. No marks will be given for answers written in medium other than the authorized one.
Word limit in questions, wherever specified, should be adhered to.
Diagrams/ sketches, wherever required, may be drawn in the space provided for answering the question itself
Attempts of questions shall be counted in chronological order. Unless struck off, attempt of a question shall be counted even if attempted partly. Any page or portion ofthe page left blank in the answer book must be clearly struck off.

SECTION

1.Attempt the following questions with suitable sketches wherevernecessary. IOx5=50
1.(a)Explain how the radius ratio ofcation to anion influences coordination in minerals. Cite examples oftwo commoncoordination in rock fOJining minerals.

1.(b)Define the Gibbs phase rule and calculate the variance ofthe assemblage containing enstatite+ forsterite Mg-spinel Mg-cordierite corundum in the appropriate chemical system.
1.(c)With suitable examples, enumerate the essential difference between regional dynamothermal metamorphism and contactmetamorphism.

1.(d)Explain why in any igneous rock, primary forsterite and quartz cannot stably coexist.
1.(e)Describe the critical differences betweenporosity and permeability. Add a note on how these two properties ofsediments are determined.
2.(a)With theoretical details, discuss optical indicatrix, and determination ofsign ofelongation of uniaxial minerals. 15

2.(b)With suitable examples, discuss the causes behind and effects of pleochroism and birefringence in minerals. 15
2.(c)Derive Bragg's law for X-ray diffraction. Calculate the inter-planar spacing in a crystal for a plane that gives a sharp reflection at20= 50° for CuKaradiation 1·5418 in a powder X-ray diffraction experiment. 10+10=20


3.(a)Thin sections ofthree basaltic rocks contain phenocrysts ofCa-rich plagioclase in diopside matrix, phenocrysts ofdiopside in Ca-rich plagioclase matrix, and coexisting phenocrysts of both Ca-rich plagioclase and diopside. On the basis ofphase diagram in the diopside-anorthite system, describe the initial melt composition and temperatures, along with crystallization behavior ofthe above rocks. 20
3.(b)By suitable reactions, discuss various mineralogical and mineral-chemical changes that take place during metamorphism ofa basaltic rock at the greenschist-amphibolite facies transition. 15
3.(c)In a P-T diagram show the domains ofvarious metamorphic facies and briefly explain these facies. 15
4.(a)What are turbidites? With a neat sketch, show different units ofa Bouma cycle and the flow regimes under which they are formed.
4.(b)With neat sketches, describe the primary depositional sedimentary structures, with emphasis on their application in determining paleocurrent directions. 15
4.(c)With the help ofa neat sketch, briefly discuss the classification ofsandstone. What is the general tectonic environment in which quartz arenites are found? 15+5=20

SECTION

5.Attempt the foIlowing questions with suitable sketches wherevernecessary. 10x5=50
5(a).Describe the relationship between average crustal abundance ofmetals and their content in ore deposits. Add a briefnote on tonnage, grade and cut-offgrade oforedeposits.
5(b)What are the sources for the formation of coal and petroleum deposits? Briefly discuss the process ofcoalification.
5(c)Briefly enumerate the various sampling methods in mineral exploration and mining.
5(d)From the first and the second laws ofthermodynamics and assuming reversible process, derive the expression dD TdS PdV; where P and V respectively stand for internal energy, entropy, temperature, pressure and volume.
5.(e)Discuss the various causes and environmental impacts ofacid mine drainage.
6.(a)Explain the ore forming processes that result in chromite and Ni-Cu sulphide deposits hosted by ultramafic rocks. 15
6.(b)With schematic sketches, show and elucidate the zones ofhydrothermal alteration in a porphyry copper deposit, emphasizing their mineralogy and temperature ofalteration. Explainwhy the ore zone is localized at the boundary between two specific alteration zones.15
<img src='./qimages/179-6c.jpg'> <br><br>Mark the location of following mineral and coal
deposits in the outline map of India and write a
brief description of each of these deposits:
Khetri copper belt, Hutti gold deposit,
Jharia coal field, and NeIlore mica belt.
10+10=20
7(a)Explain how ore concentrates are produced from run-offmine by mineral beneficiation, with the help ofexamples oftwo different beneficiation processes. 15
7(b)With suitable examples, define indicator and pathfinder elements in geo-chemical prospecting. Discuss mobility ofelements in near surface environment. 10+10=20
7(c)Compare and contrast the corrections used in gravity and magnetic methods of mineral prospecting.· 15
8(a)Discuss the mineralogical and chemical compositions ofvarious meteorites, with a note on how meteorites furnish evidence about planetary interiors. 15
8(b)Discuss the effects ofriver flooding and response to flood hazards. 15
8(c)Explain the role ofwater in slope stability and add a note on types ofslope failure. 10+10=20