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Geology 2021 Paper II 50 marks 150 words Compulsory Calculate

Paper II — Q5

Answer the following questions in about 150 words each: (a) Lead (Pb) mineralization zone is drawn in the given diagram with…

Answer the following questions in about 150 words each:

(a)

Lead (Pb) mineralization zone is drawn in the given diagram with nomenclature. The related data is also provided in the table. Calculate the average grade of lead (Pb) in percentage.

Scale : 1"=10'

Sample No. | Zone of Influence, L (ft) | Width, W (ft) | W × L (ft²) | % Pb S-1 | 6·0 | 3·5 | 21·00 | 7·1 S-2 | 7·5 | 2·5 | 18·75 | 7·5 S-3 | 10·0 | 3·0 | 30·00 | 6·9 S-4 | 12·5 | 3·5 | 43·75 | 8·9

(b)

Describe the geological nature of coal deposits of Jharia (Jharkhand) and comment on their economic potential.

(c)

What are geophysical methods of exploration? How is gravity method useful in mapping the metallic ores?

(d)

Define 'trace element'. Discuss the possible ways that a trace element can enter into a mineral structure.

(e)

State the sea level changes in Late Pleistocene period with possible causes. Add a note on anthropogenic causes occurred in last two centuries.

हिंदी में प्रश्न पढ़ें

निम्नलिखित प्रश्नों में से प्रत्येक का लगभग 150 शब्दों में उत्तर दीजिए :

(a)

नामकरण के साथ दिए गए आरेख में सीसा (Pb) खनिजीभवन क्षेत्र दर्शाया गया है। इससे सम्बन्धित आँकड़े भी तालिका में दिए गए हैं। प्रतिशत में सीसे (Pb) के औसत ग्रेड की गणना कीजिए।

पैमाना : 1"=10'

नमूना संख्या | प्रभाव-क्षेत्र, L (ft) | चौड़ाई, W (ft) | W × L (ft²) | सीसा % S-1 | 6·0 | 3·5 | 21·00 | 7·1 S-2 | 7·5 | 2·5 | 18·75 | 7·5 S-3 | 10·0 | 3·0 | 30·00 | 6·9 S-4 | 12·5 | 3·5 | 43·75 | 8·9

(b)

झरिया (झारखण्ड) के कोयला निष्क्षेपों की भूवैज्ञानिक प्रकृति का वर्णन कीजिए तथा उनकी आर्थिक क्षमता पर टिप्पणी कीजिए।

(c)

अन्वेषण की भूभौतिक विधियाँ क्या हैं? धात्विक अयस्कों के मानचित्रण में गुरुत्वाकर्षण विधि किस प्रकार उपयोगी है?

(d)

'सूक्ष्मात्रिक तत्व' को परिभाषित कीजिए। उन सम्भावित तरीकों पर चर्चा कीजिए, जिनसे एक सूक्ष्मात्रिक तत्व खनिज संरचना में प्रवेश कर सकता है।

(e)

प्लीस्टोसीन काल के अन्त में समुद्र की सतह में होने वाले परिवर्तनों को सम्भावित कारणों सहित समझाइए। पिछली दो शताब्दियों में मानवजनित कारणों पर टिप्पणी कीजिए।

Q5 of the 2021 UPSC Mains Geology Paper II, as printed
The question as printed in the 2021 Geology paper
Model answer coming soon See all 2021 Geology questions

The figure this question refers to, in words

The question paper is a scan and the diagram did not survive as text. This is the figure as read from the original page — every component, value and label — so the question can be worked from the text below.

(a) Sample No. | Zone of Influence, L (ft) | Width, W (ft) | W x L (ft2) | % Pb S-1 | 6.0 | 3.5 | 21.00 | 7.1 S-2 | 7.5 | 2.5 | 18.75 | 7.5 S-3 | 10.0 | 3.0 | 30.00 | 6.9 S-4 | 12.5 | 3.5 | 43.75 | 8.9

What "Calculate" is asking you to do

Apply the standard formula or schedule to data the question has already supplied — a table of readings, cost records, a balance sheet — and produce the number. The method is rarely in doubt; the marks sit in the named intermediate quantities, each of which has to appear as a labelled line.

Structure that answers it

Data as given → formula or standard treatment, named → substitution → each intermediate, labelled → result with units

Where marks are lost

Omitting an intermediate the marking scheme pays for separately, or rounding at an intermediate line so the final figure drifts. In commerce and accountancy, any figure in a statement that no numbered working note supports is treated as unearned.

All UPSC directive words, compared →

How this answer will be evaluated

Approach

(a) calculate: given > formula > substitution > result with units > interpretation | (b) describe: define > structure or process in order > labelled diagram > significance | (c) explain: definition/context > points in order > small example > short close | (d) define: precise definition > the distinguishing feature > one example | (e) enumerate: list the items in order > one line each > no commentary Full marks: Precise calculations, specific Indian examples, clear mechanisms, and accurate historical data.

Key points expected

  • Sum of W×L areas (113.5 ft²)
  • Sum of (Area × %Pb) products
  • Final division to get average grade
  • Result stated as percentage
  • Stratigraphic position (Barakar/Barren Measures)
  • Tectonic setting (Raniganj syncline)
  • Coal rank (bituminous) and thickness
  • Economic potential (reserves/production)

Evaluation rubric

Each sub-part is marked on its own, against the marks and word limit printed on the paper.

  1. (a) Weighted average grade of Pb using area-weighted method.  · 150 words

    calculate— given → formula → substitution → result with units → interpretation

    Must cover

    • Sum of W×L areas (113.5 ft²)
    • Sum of (Area × %Pb) products
    • Final division to get average grade
    • Result stated as percentage

    Loses marks

    • Using simple arithmetic mean of grades
    • Arithmetic errors in multiplication

    Earns more

    • Explicit formula for weighted average
    • Correct arithmetic for each sample

    Extra mark

    • Mention of area-weighted vs simple average
  2. (b) Geology of Jharia coal and its economic value.  · 150 words

    describe— define → structure or process in order → labelled diagram → significance

    Must cover

    • Stratigraphic position (Barakar/Barren Measures)
    • Tectonic setting (Raniganj syncline)
    • Coal rank (bituminous) and thickness
    • Economic potential (reserves/production)

    Loses marks

    • Generic coal description without Jharia specifics
    • Missing stratigraphic context

    Earns more

    • Mention of specific seams (e.g., 1, 2, 3)
    • Reference to Jharia coalfield area

    Extra mark

    • Mention of specific mining hazards (fire/flood)
  3. (c) Geophysical methods and gravity's role in ore mapping.  · 150 words

    explain— definition/context → points in order → small example → short close

    Must cover

    • Definition of geophysical methods
    • Principle of gravity method (density contrast)
    • Application to metallic ores (high density)
    • Interpretation of gravity anomalies

    Loses marks

    • Confusing gravity with magnetic method
    • No mention of density contrast

    Earns more

    • Mention of Bouguer correction
    • Example of specific ore (e.g., chromite)

    Extra mark

    • Comparison with magnetic method
  4. (d) Definition of trace element and modes of entry.  · 150 words

    define— precise definition → the distinguishing feature → one example

    Must cover

    • Definition (<1% by weight)
    • Substitution (isomorphous replacement)
    • Interstitial inclusion
    • Surface adsorption

    Loses marks

    • Confusing trace with major elements
    • Missing mechanism of entry

    Earns more

    • Example of specific trace element (e.g., REE)
    • Mention of ionic radius similarity

    Extra mark

    • Mention of fluid inclusions
  5. (e) Late Pleistocene sea level changes and anthropogenic causes.  · 150 words

    enumerate— list the items in order → one line each → no commentary

    Must cover

    • Glacial-interglacial cycles (Milankovitch)
    • Sea level rise/fall magnitudes
    • Anthropogenic causes (CO2, deforestation)
    • Recent (20th-21st century) rise

    Loses marks

    • Ignoring anthropogenic component
    • No mention of glacial cycles

    Earns more

    • Mention of specific glacial periods (e.g., Wisconsin)
    • Reference to thermal expansion

    Extra mark

    • Mention of specific sea level data (e.g., 120m)

Model answer coming soon

Every evaluation on this site is marked against a verified model answer. This question's answer is still being written; evaluation opens the moment it lands.

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