Geology 2024 Paper II 50 marks Discuss

Q8

(a) What are the different layers in the Earth's interior ? How is the layered structure of the Earth determined ? Name two most abundant elements of each layer of the Earth. (15 marks) (b) Define major, minor and trace elements. Write briefly about the characteristics of lithophile, chalcophile, siderophile and atmophile elements with examples. Why are trace elements considered more efficient than major elements in understanding the Earth's processes ? (15 marks) (c) Discuss in detail the pollution of surface water and groundwater due to mining activities. (20 marks)

हिंदी में प्रश्न पढ़ें

(a) पृथ्वी की विभिन्न आंतरिक परतें कौन-सी हैं ? पृथ्वी की परतीय आंतरिक संरचना कैसे ज्ञात की जाती है ? पृथ्वी की प्रत्येक परत के दो सबसे प्रचुर तत्वों के नाम बताइए । (15 अंक) (b) मुख्य, गौण तथा सूक्ष्मात्रिक तत्वों की परिभाषा दीजिए । लिथोफाइल, चाल्कोफाइल, साइडरोफाइल व एट्मोफाइल तत्वों की विशेषताओं को उदाहरणों सहित संक्षेप में लिखिए । सूक्ष्मात्रिक तत्व, भूप्रक्रम को समझने में मुख्य तत्वों से ज्यादा प्रभावी क्यों माने जाते हैं ? (15 अंक) (c) खनन गतिविधियों के कारण भूपृष्ठ जल एवं भौमजल के प्रदूषण पर सविस्तार चर्चा कीजिए । (20 अंक)

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Directive word: Discuss

This question asks you to discuss. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'discuss' in part (c) demands critical examination with multiple perspectives, while parts (a) and (b) require descriptive clarity with definitions. Allocate approximately 25-30% time/words to part (a) (15 marks), 25-30% to part (b) (15 marks), and 40-45% to part (c) (20 marks) given its higher weightage and analytical demand. Structure: begin with Earth's layered architecture and geophysical determination methods, transition to elemental classification with Goldschmidt's geochemical affinity rules, then elaborate mining water pollution with case-specific mechanisms, remediation, and policy frameworks.

Key points expected

  • Part (a): Earth's interior layers (crust, mantle, outer core, inner core); determination methods including seismic wave analysis (P-wave/S-wave velocity changes, shadow zones), meteorite analogies, and geothermal/magnetic data; two most abundant elements per layer (e.g., O-Si in crust; Mg-Fe in mantle; Fe-Ni in core)
  • Part (b): Definitions of major (>1 wt%), minor (0.1-1 wt%), and trace (<0.1 wt%) elements; Goldschmidt's classification with characteristics—lithophile (O-loving, e.g., Al, Na), chalcophile (S-loving, e.g., Cu, Zn, Pb), siderophile (Fe-loving, e.g., Au, Pt), atmophile (gas-loving, e.g., N, noble gases); trace element efficiency due to sensitivity to fractionation processes, lower detection limits, and discriminatory power in petrogenetic modeling
  • Part (c): Surface water pollution mechanisms—acid mine drainage (AMD), heavy metal leaching (As, Cd, Pb, Hg), sediment loading, and tailings dam failures; groundwater contamination pathways—seepage from waste rock dumps, tailings ponds, pit lakes, and aquifer dewatering effects
  • Part (c): Specific Indian mining cases—coal mining in Jharia (Damodar basin pollution), iron ore in Goa/Odisha (sedimentation of Mandovi river), uranium in Jaduguda (radionuclide groundwater concerns), copper in Khetri, bauxite in Eastern Ghats; economic impacts on agriculture, fisheries, and public health costs
  • Integrated synthesis: Connection between geochemical principles (element mobility, Eh-pH controls) and environmental degradation; sustainable mining practices, Mine Water Utilisation Policy 2017, and SDG linkages

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Precise definitions of seismic discontinuities (Mohorovičić, Gutenberg, Lehmann); accurate Goldschmidt classification with correct affinity explanations; scientifically rigorous treatment of AMD chemistry (pyrite oxidation: FeS₂ + O₂ + H₂O → Fe²⁺ + SO₄²⁻ + H⁺) and heavy metal speciation; no confusion between lithophile/siderophile characteristicsBasic layer identification with minor errors in discontinuity naming; generic element classification without clear affinity mechanisms; superficial AMD description without chemical equations; some conflation of element categoriesFundamental errors (e.g., stating mantle is liquid, confusing siderophile with chalcophile); incorrect element abundance data; misunderstanding of seismic wave behavior; conflating surface and groundwater pollution mechanisms
Diagram / cross-section15%7.5Labeled schematic of Earth's interior with depth, pressure, temperature, and wave velocity variations; seismic wave behavior diagram showing P-wave refraction and S-wave shadow zone; mining pollution flowchart or cross-section showing surface water-groundwater interaction and contaminant plume migrationSimple layer diagram without scale or wave velocity data; basic AMD schematic without process arrows; minimal visual integration between partsNo diagrams; poorly labeled sketches with incorrect layer sequencing; diagrams unrelated to question content
Field evidence20%10Specific case studies: Damodar River Basin (coal mining, DVC reports), Mandovi-Zuari estuary (iron ore sedimentation, Goa Foundation studies), Jaduguda (UCIL tailings, health surveys), Singrauli (thermal power-mine complex); references to CPCB/WHO water quality standards (pH, TDS, heavy metal limits)Generic mention of Indian mining regions without specific data; vague references to 'river pollution' without naming water bodies; no quantitative water quality parametersNo Indian examples; purely theoretical treatment; incorrect attribution of cases (e.g., citing Jharia for uranium)
Quantitative reasoning20%10Seismic velocities (P-waves: ~6-8 km/s crust, ~8-13 km/s mantle, ~8-10 km/s outer core, ~11 km/s inner core; S-waves absent in outer core); element abundance data (e.g., Fe ~32%, O ~30% by mass in whole Earth); AMD generation rates (~5-20 kg H₂SO₄ per tonne pyrite); water quality thresholds (WHO: As 10 μg/L, Cd 3 μg/L; Indian standards for irrigation/industrial use)Approximate depth figures for discontinuities; rough percentage estimates without precision; qualitative 'high/low' metal concentrations without valuesNo numerical data; incorrect orders of magnitude; confusion between weight and volume percentages
Indian / economic relevance20%10Critical analysis of Mining Surveillance System, Sustainable Sand Mining Guidelines 2016, National Mineral Policy 2019; economic valuation of ecosystem services loss in mining areas; Mine Water Utilisation Policy for zero liquid discharge; community displacement and health burden (cancer clusters in Jaduguda, fluorosis in Rajasthan mines); SDG 6 (clean water) and SDG 12 (responsible consumption) linkagesMention of environmental clearance (EIA Notification 2006) without elaboration; generic sustainable mining rhetoric; superficial health impact mentionNo policy or economic context; purely academic geochemistry without environmental governance; no mention of mining's contribution to GDP or employment versus environmental cost

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