Q5
Answer the following questions in about 150 words each: (a) What do you understand by metallogenic epochs and provinces? Discuss any two major metallogenies in India. (10 marks) (b) Discuss the mode of occurrence, origin and distribution of gold deposits in India. (10 marks) (c) What do you understand by 'pathfinder' elements? What are the elements/ions used in the prospecting of sulphides of epigenetic origin, porphyry copper deposit and sulphide deposits in general? (10 marks) (d) Define gravitation. What are the corrections necessary to obtain the absolute value of gravity (g) while using gravity method in mineral exploration? (10 marks) (e) What are the major components of chondrites? Discuss the mineralogical and textural features, and significance of chondrites. (10 marks)
हिंदी में प्रश्न पढ़ें
निम्नलिखित में से प्रत्येक प्रश्न का उत्तर लगभग 150 शब्दों में दीजिए : (a) धातुजननिक युग व प्रान्तों से आप क्या समझते हैं? भारत के किन्हीं दो प्रमुख धातुजनन की विवेचना कीजिए। (10 अंक) (b) भारत के स्वर्ण भण्डारों की उपस्थिति शैली, उत्पत्ति एवं वितरण पर चर्चा कीजिए। (10 अंक) (c) 'खोजीय' तत्वों से आप क्या समझते हैं? कौन-से तत्व/आयन पश्चजनित सल्फाइड, पोरफिरी ताम्र निक्षेप और गन्धकीय निक्षेपों को खोजने में सहायक होते हैं? (10 अंक) (d) गुरुत्वाकर्षण को परिभाषित कीजिए। खनिज अन्वेषण में गुरुत्वाकर्षीय विधि में कौन-से सुधार आवश्यक होते हैं जिनसे गुरुत्व (g) का परिशुद्ध मान प्राप्त किया जा सके? (10 अंक) (e) कोंड्राइटों के प्रमुख अवयव कौन-से हैं? कोंड्राइटों के खनिजीय व गठनीय अभिलक्षणों की चर्चा करते हुए उनके महत्व पर प्रकाश डालिए। (10 अंक)
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
This multi-part question requires balanced coverage across five 10-mark sub-parts within 150 words each. For (a), define metallogenic epochs/provinces with two Indian examples (Dharwar, Singhbhum). For (b), cover lode gold, placer deposits and Kolar-Hutti fields. For (c), explain pathfinders with specific elements for each deposit type. For (d), define gravitation and list corrections (latitude, free-air, Bouguer, terrain). For (e), describe chondrule components, petrographic types and cosmochemical significance. Allocate ~30 words per sub-part, prioritizing precise terminology over elaboration.
Key points expected
- (a) Metallogenic epochs: time-bound mineralization events; provinces: spatially restricted areas with similar mineralization; Indian examples: Dharwar Craton (Au, Fe, Mn), Singhbhum Craton (Cu, U, Fe)
- (b) Gold occurrence: quartz veins/lodes (Kolar, Hutti), placer deposits (Subarnarekha); origin: hydrothermal, mesothermal-epithermal; distribution: Karnataka, Andhra Pradesh, Jharkhand
- (c) Pathfinder elements: mobile elements that migrate farther than ore elements, indicating proximity; epigenetic sulphides: As, Sb, Hg, Ba; porphyry Cu: Mo, Re, Ag; general sulphides: Cu, Pb, Zn, Ag, Cd
- (d) Gravitation: Newton's law of universal gravitation; corrections: latitude (normal gravity), free-air, Bouguer (slab and complete), terrain, tidal, drift corrections
- (e) Chondrite components: chondrules (olivine, pyroxene), matrix, CAIs, metal; types: E, H, L, LL, C; significance: primitive solar system composition, age dating, planetary differentiation models
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Precise definitions across all sub-parts: metallogenic epochs vs provinces distinguished correctly; Newton's law accurately stated; chondrule petrology uses correct terminology (PO, POP, BO textures); pathfinder concept clearly differentiated from direct indicators | Basic definitions correct but some confusion between related concepts (e.g., metallogenic province vs belt); minor errors in gravity correction sequence or chondrite classification | Fundamental misconceptions: conflates epochs with provinces, misstates gravity law, confuses chondrites with achondrites, or describes pathfinders as ore elements themselves |
| Diagram / cross-section | 10% | 5 | Sketches clear schematic diagrams where applicable: chondrite structure with labeled components, or simplified gravity correction geometry; neat, labeled illustrations enhance explanation | Mentions diagrams but execution is rough or labels incomplete; or describes diagrams textually without actual sketching | No diagrams where clearly needed (chondrite components, gravity measurement setup); or completely irrelevant illustrations |
| Field evidence | 20% | 10 | Specific field occurrences cited: Kolar schist belt greenstone-hosted gold, Hutti-Muski lodes, Khetri porphyry Cu pathfinders, specific meteorite falls (Allende, Murchison) for chondrite examples; links theory to observable features | General references to Indian fields without specific localities; mentions gold belts or cratons without naming specific mines or districts | No Indian field examples; purely theoretical treatment; or incorrect field associations (e.g., placing gold in Vindhyan sediments) |
| Quantitative reasoning | 15% | 7.5 | Gravity corrections listed with mathematical basis mentioned (Bouguer slab formula, free-air gradient ~0.3086 mGal/m); chondrite compositions include approximate percentages; pathfinder/ore ratios implied | Lists corrections qualitatively without gradients or values; mentions chondrite types without compositional data; no quantitative treatment | Incorrect quantitative statements; wrong units for gravity; confuses relative and absolute abundance measurements |
| Indian / economic relevance | 30% | 15 | Strong Indian focus: Dharwar/Singhbhum metallogenies with specific mineral wealth; Kolar-Hutti gold production significance; Indian chondrite falls (Nagpur, Piplia Kalan); economic importance of each deposit type for national mineral security; exploration applications of pathfinders in Indian terrain | Some Indian examples present but not integrated with economic significance; or foreign examples dominate with token Indian mention | No Indian examples; purely generic or foreign-centric treatment missing national relevance; ignores economic implications of gold, copper, or meteorite research |
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