Optionals IAS Mains Geology: Questions 50 - 54 of 113

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Question 50

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Appeared in Year: 2017

Write in Short

Short Answer▾

Write short notes on the followings (Paper-II)

Supergene alteration of sulphide deposits

Question 51

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Appeared in Year: 2017

Describe in Detail

Essay▾

What is the use of heavy minerals in sedimentology? (Paper-II)

To explain the usage of heavy minerals in sedimentology

Explanation

Heavy Minerals in Sedimentology

  • The heavy minerals are used in the study of diagenetic processes (conversion of sediments to sedimentary rocks by physical and chemical properties). The heavy minerals have specific gravity greater than 2.8 to 2.9.
  • The heavy minerals studies are required to know the provenance of sedimentary rocks. They are used in hyd

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Question 52

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Appeared in Year: 2017

Describe in Detail

Essay▾

Describe the difference between alluvial fan, flood plain and delta

To describe the difference between alluvial fan, flood plain and delta (Paper-II)

Explanation

Difference Between Alluvial Fan, Flood Plain and Delta

Introduction

The alluvial fan, flood plain and delta plain are formed from depositional environment of sediments.

Alluvial Fan

  • It is a triangular shaped deposit of gravel, sand, and sediments like silt. These are called as alluvium. They are formed when flowing water interacts with mountains, hills

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Question 53

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Appeared in Year: 2017

Describe in Detail

Essay▾

How can mineral assemblage of a basaltic rock be shown on a triangular ACF diagram? Explain the rationale behind the calculation of A in the ACF diagram. What is the maximum number of phases possible in a two component system according to the standard phase-rule?

To explain the mineral assemblage, number of phases in a phase rule and ACF diagram for a basaltic rock. (Paper-II)

Explanation

Mineral Assemblage

ACF is a simplified 3-C triangular diagram to illustrate the metamorphic mineral assemblage.

The mineral assemblage for ACF is provided as follows,

  • Rationale behind Calculation of A in ACF diagram,
  • The molecules do not occur separately but they exist with the feldspar. Hence the presence of Na and K in minerals are ignored as shown

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Question 54

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Appeared in Year: 2017

Describe in Detail

Essay▾

Describe the classification of sedimentary rocks based on grain size

To describe the classification of sedimentary rocks based on grain size (Paper-II)

Explanation

Classification of Sedimentary Rocks Based on Grain Size

Introduction

  • Texture is the size, shape and arrangement of grains in a rock.
  • Depending upon the size, particles of sediments are classified into pebbles, graves, sand, silt and clay. Each of these gives rise to a particular type of rock.
The Grain Size and Rock Type
GradeGrain sizeRock type
Pebble10 mm and aboveConglomerate

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