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Earth Scienceor

GeologyFebruary-2015

n.k.agarwal

ex-Director, GSI

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Geology is the History of Earth

Geology is the Study of Earth

Geology

In its Most Simple Meaning :

How earth was formed ?

How old is earth ?

What is earth made up of ?

Why earth is called a unique planet ?

What are the biotic and a-biotic components of earth ?

What are Natural Resources ?

What is its Environment ?

How to manage Natural Resources ?

Interdisciplinary

Science

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Main Branches of Geology

1.Physical Geology

2.Geomorphology & Environmental Geology

3.Petrology

4.Stratigraphy

5.Paleontology

6.Structural Geology

7.Geochronology

8.Economic Geology Minerals Oil & Gas etc.

9.Seismo-Tectonics

10.Engineering Geology

11.Geochemistry

12.Geophysics etc. 4

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ENERGY and MASS TRANSFORMATION

The Big Bang~15 billion years ago

B

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Ma= Million Anum = 10x6 Ga= Giga Anum = 10x9

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V

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The Origin of the Earth

~15 billion years ago :The Earth and the other 8 planets and the

Sun accreted at about the same time from a

vast cloud of dust and gas (nebula).

~5 billion years ago :The nebula began to gravitationally contract,

began to rotate and flattened. Eventually, the

Sun ignited (fusion) and the newly formed

planets began to differentiate - heavier

elements and chemical components sank to

the center and rocky material formed the

crust. The newly formed planets and moons

released gas forming early atmospheres.

Making of Solar System

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Making of Solar System

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Solar System

Inner Planets Outer PlanetsAsteroids 9

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Earth From Outer Space

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http://ep.yimg.com/ca/I/spaceimages_2114_11521197

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Indian Sub-Continent from Outer Space

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Uttarakhand from Outer Space

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University of Petroleum and Energy Studies

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What's the first

thing that you

notice about

our planet

when you see

this image?

The Earth is composed

of several integrated

parts (spheres) that

interact with one

another:

Atmosphere

Hydrosphere

Solid earth (lithosphere)

Biosphere

Unique Planet - Earth

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Atmosphere:

The swirling clouds of the atmosphere represent the

very thin blanket of air that

covers our planet. It is not

only the air we breathe, but

protects us from harmful

radiation from the sun.

Hydrosphere:

The global ocean is the most prominent feature of

our (blue) planet. The

oceans cover ~71% of our

planet and represent 97% of

all the water on our planet.

Unique Planet - Earth

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The Earth

System

Biosphere:

Includes all life forms on Earth - concentrated on land,

water and air- Plants and

Animals.

Solid Earth:

Represents the majority of the Earth system. Most of

the Earth lies at inaccessible

depths.

Unique Planet - Earth

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Inside the Earth

Crust

Mantle

Liquid

Core

Solid

Core

Crust thickness varies

From 5-70 km

1216 km

3486 km

0

6357 km at Poles

Density (gm/cm3)

Earth 5.517

Continental Crust 2.80

Oceanic Crust 2.90

Mantle 4.53

Outer Core 9.71

Inner Core 16.0 18

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The Earth's interior is

characterized by a gradual

increase in temperature,

pressure and density with

depth.

At only 100 km depth, the

temp is ~1300C.

At the Earth's center, the

temperature is >6700C.

The pressure in the crust

increases ~280 bars for

every kilometer depth.

Earth's Internal Structure

Polar Radius ~6357 km

Equatorial Radius ~6378 km

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Depth wise the Earth consists of 3 major divisions marked by differences in chemical composition Crust, Mantle and Core

Crust: Outermost rigid layer - 2 types:

1. oceanic - 3-15 km thick and is composed

of basalt (igneous).

Young (3.8

billion years old).

Earth's Internal Structure (contd.)

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Mantle: comprises ~82% of the Earth by

volume (~2900 km).

The mantle is

characterized denser

rocks and is able to flow

(plastically) at very slow

rates.

Core: composed of iron, nickel and other

minor elements.

The outer core is liquid

capable of flow and

source of the Earth's

magnetic field (~2270km).

The inner core is solid

Fe-Ni (~1216km).

Earth's Internal Structure (contd.)

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ATMOSPHERE

HYDROSPHERE

BIOSPHERE

SOLID EARTH

EARTH A UNIQUE PLANET

Only Planet known to have Life Supporting

Conditions

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Biotic and A-Biotic Constituents

Rocks and Minerals

Soil

Water

Gases

All Life Forms

Plants

Animals

Terrestrial

Land

Fresh Water

Marine

Most of Solid Biotic

Constituents are

Made up of Minerals

and Rocks

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What is Mineral ?

It is a Natural Inorganic Solid Substance with a

Definite Range of Chemical Composition,

Atomic Structure and Measurable Properties.

What about Coal, Oil, Water

Coral etc. ?

Loose Definition of Mineral !

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How Many Minerals are known ?

> 3500 are Identified

About 100 are Commonly found

About 30 are important

rock forming minerals.

Rock forming minerals

are composed of the most

abundant elements found

in the earths crust

Abundance of elements

in earths crust (% Wt.)

1 Oxygen 46.71

2 Silicon 27.69

3 Aluminum 8.07

4 Iron 5.05

5 Calcium 3.65

6 Sodium 2.75

7 Potassium 2.58

8 Magnesium 2.08

9 Titanium 0.62

10 Hydrogen 0.14

11 Phosphorus 0.13

12 Carbon 0.094

13 Manganese 0.09

14 Sulphur 0.002

15 Barium 0.050

Rest 0.244

Total 100.0

15 elements constitute 99.75 %

of Earths crust25

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Rocks and Minerals Raw MaterialLife Revolves around Rocks & Minerals

Needle

Tooth paste

Talcum Powder

Utensils

Electronics

Appliances

Fertilizers

Agriculture - Soil

Energy Fuels (Coal, Oil & Gas)

Energy Nuclear

Ornaments and Gem Stones

Soil

Forest

Direct Useable

Minerals & Rocks

Indirect Useable

Minerals & Rocks

Gold, Silver

Clay

Sand

Gravel, boulder

Lime

Gem Stones

Glass

Copper, Zinc, Lead, Steel

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Important Mineral Compositions

S.No. Composition

1 Oxides

2 Silicates

3 Carbonates

4 Phosphates

5 Sulphides

6 Nitrates

7 Borates

8 Hydrocarbon Compounds

9 Mixed

10 Native

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Common Rock Forming Minerals (simplified)

S.N. Name S.N. Name

1 Quartz* 9 Montmorinillonite*

2 Orthoclase

Microcline

Albite etc.

10 Chromite

Hematite*

Magnetite*

Pyrolusite*

Psilomelane*

3 Muscovite, Biotite, Chlorite 11 Garnet

4 Calcite*

Dolomite*

Magnesite*

12 Epidote

Sillimanite*

Kyanite*

5 Amphiboles 13 Pyrite*

Chalcopyrite*

Pyrrhotite*

6 Pyroxenes 14 Peat, Lignite, Coal,

7 Olivine 15 Apatite*

8 Kaolin* 16 Gold**, Silver** etc.

* - Also forms mineral deposits ; ** - Occurs in small quantities in some rocks.28

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Soils

Alluvium Indo Gangetic Brahmaputra Plains Terraces along valleys

Coastal Plains

Lateritic Laterite, Bauxite, Clays etc. Sand Rock, Silica Sand

Weathering and Erosion of Rocks

Generates Soils Transported

Residual

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Natural Resources

Mineral Resources

Water Resources

Plant & Animal Resources

Rocks & Minerals

Soil

Water Bodies

Ground Water

Forest & Wild Life etc.

Renewable & Non-Renewable Resources

Finite Resources30

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Environment

Total biotic & a-biotic components surrounding us

Mutual relation and interrelation

Sustainability

Man is Unique pest, parasite and predator

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Natural Resource Management

Quality of Life

Resilience

Over Exploitation

Conservation

New Resources & Replacement

Global Climate Change

Environment Protection

Sustainable Development32

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To Understand Use of Geology in Oil &

Gas Exploration

Our Main Concern

All Oil & Gas Exploration and Exploitation

revolves around Geology

To Understand What is Oil & Gas Exploration

or

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Understanding of Geology tells us where to

search for Oil & Gas and How to Exploit it

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What is Applied Geology

?In most simple meaning : It is the

application of the knowledge of Geology

for the benefit of mankind Improving the

Quality of Life

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This chapter helps you in understanding :

1) What is Geology & Applied Geology?

2) How Mineral Resources including Oil & Gas

related to the knowledge of Geology?

3) Relation between Knowledge of Geology and

Sustainable Development

Summary :

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