pet-basic elements of geology

Pet-518 Elements of Geology ( Lecture I)

Pet-518 Elements of Geology

Department of Petroleum Technology University of Karachi

Course content

• Definition, significance and basic disciplines.• Earth as a dynamic terrestrial planet:• Its shape, composition, surface relief, origin and age.• Introduction to minerals, rocks and fossils. • Definitions, method of study , description and classification of rock

forming minerals and major rock types, rock cycle.• Weathering and Soil.• Sedimentary rocks and their classification.• Basic concept of stratigraphy and sedimentation.• Sedimentary environment and stratigraphic sequences.• Basic concepts in geodynamics; interior model of earth. • lithosphere and plate tectonic.• Deformation of rocks: • Classification of Fold, Fault and Unconformities.• Geological Time Scale and significance of Fossils•



Course content

1. An Introduction to Geology2. Matter and Minerals3. Earth's Interior4. Kind of Rocks and Rock Cycle5. Igneous & Metamorphic rocks6. Weathering , Mass Wasting and Soil7. Sedimentary Environments8. Sedimentary Rocks9. Principles of Stratigraphy and Sedimentation10. Crustal Deformation including Plate Tectonics11. Deformational features of rocks12. Classification of Fold Fault and Unconformities.13. Geological Time Scale14. Fossils and Fossilization15. Mountain Building and the Evolution of Continents


• Definition of Geology:

• Geology is classically defined as the study of the Earth.

• Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them.

• It also includes the study of the organisms which inhabit our planet.

• A very important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time.

• .


View of the Planet Earth



Some Discipline of Geology

• Mineralogy - formation, chemical and physical properties, and classification of minerals

• Petrology - formation, properties, and classification of rocks• Sedimentology - genesis, transport, and deposition of

sediment, and the formation of sedimentary rocks• Structural geology - deformation of earth materials and

resulting geologic structures• Tectonics - regional to global-scale deformation and structures

resulting from interactions among pieces of the Earth's rigid outer layer, or lithosphere

• Geomorphology - processes of landform evolution and landscape development

• Hydrogeology - interrelationships of water and geologic materials and processes



The two broad areas of the science of geology

• (1) Physical geology,

is the study of Earth materials and structures; the processes and forces that act upon them; and how these materials, structures, processes, and forces have changed over time.

• (2) Historical geology,

which seeks to understand the origin of Earth and its development through time.

The relationship between people and the natural environment is an important focus of geology.

This includes natural hazards, resources, and human influences on geologic processes



Physical geology

• Earth materialsatoms, chemicals, metals, oil, gas, rocks, minerals, salt, gems, coal, sand, gravel, clay, soil, atmosphere, hydrosphere, organisms, etc. How do Earth materials affect people?building materials, fuels, soil to grow food, salt for food, jewelry, we are made of Earth materials

• Earth processesearthquakes, volcanic eruptions, floods, continental drift, weather, climate, landslides, subsidence and collapse, tides, geysers, erosion, etc. Any geologic processes recently in the news? How do these processes affect people?


• How old is the Earth?

• 4.5 to 4.6 billion years (4,500,000,000 to 4,600,000,000 years) Determined through radiometric dating (Uranium, Thorium). Using an instrument called a mass spectrometer.

• Multicellular life• did not appear until about 1 billion years

ago. Before this, 3 billion years ago single celled life only.

• Hard parts like shells don't appear until 600 million years ago. (Trilobites)


Historical Geology



Earth at a Glance



Introduction to Historical Geology

• Historical Geology is the study of changes to Earth and life in time and space.

• I. Time• A. How much time? • Oldest meteorites and oldest moon rocks are 4.6 billion years

old,4,600,000,000 years.

•Oldest rocks found so far on Earth are zircon grains from a sandstone in western Australia, dated at 4.1 to 4.2 bilion years old.

• Previously, the oldest Earth rocks were 3.96 billion years old, from the Northwest Territories of Canada.

• B. How do we know? • Radioactive materials serve as geologic clocks.•




• C. What happened on the Earth during this long period of time?

• Many natural events:

– meteorite impacts volcanic eruptions and lava flows– mountain building earthquakes erosion– slow movement of continents (plate tectonics)– formation and destruction of ocean basins

(plate tectonics)– glaciations climatic changes

• All of these natural events are still going on today -• We see evidence in the rock record that these events have been

occurring for a long time. • Geologists call this uniformitarianism. • The physical laws governing the universe operate uniformly through

time.




• James Hutton (1726-1797) believed that• "the past history of our globe must be explained by what can be seen to be

happening now."

• Some events which occurred in the past, and left a record in the rocks, ARE NOT OCCURRING TODAY, or have not occurred in the human lifespan:

• Huge meteorite imapcts• Large glacial ice sheets • Other events occur so slowly that they are difficult to measure:• Plate Tectonics - sea floor spreading, continental drift • Erosion of mountain ranges • Still other events are short lived but very catastrophic: • Volcanic eruptions • Earthquakes • Floods • Mudflows, avalanches, etc (mass wasting) • Evidence of all of these events is preserved in the geologic record.



Geologic record

• D. What do you mean by geologic record? • The geologic record consists of rock units, each of which

records some event or series of events that occurred in the past.

• What are rocks?– Rocks are defined as aggregates of one or more

minerals. • What are minerals?

– naturally occurring – inorganic – solids – definite chemical composition – characteristic internal crystal structure (arrangement of

atoms in lattice)



Course content

• E. How do rocks form? • By cooling, hardening, and crystallizing from hot, molten lava

– Igneous rocks • By forming from the compaction and cementation of sediments

– Terrigenous, clastic or detrital sedimentary rocks• By forming from the precipitation of dissolved chemicals in

water – Chemical and biochemical sedimentary rocks

• By forming from accumulated organic matter – Organic sedimentary rocks (coals)

• By the alteration of pre-existing igneous or sedimentary rocks by heat and pressure – Metamorphic rocks

Geologic record



Fundamental principles of Geology

• Most sedimentary rocks occur in the form of layers called beds or strata.

• Each layer is the result of the deposition of sediment during some natural event (such as a flood or storm).

• A. Steno's Laws Named for Nicholaus Steno

• Principle of Superposition • Oldest rocks on the bottom • Younger rocks on top • Principle of Original Horizontality • Sediments are deposited in flat layers • Principle of Original Lateral Continuity • Sediments are deposited over a large area in a continuous

sheet



Other basic principles of Geology

• Principle of intrusive relationships•• The intrusion is younger than the rocks it cuts.

• Principle of cross-cutting relationships• The fault is younger than the rocks it cuts. •

• Principle of components or inclusions

• Note the irregular erosional surface.• This is an unconformity. • The clasts (in the bed above the unconformity)• are derived from the underlying (older) bed. • The gravel clasts are older than the layer which contains them. • The layer containing the gravel must be younger than the layer from

which the clasts originate.


• Sometimes papers pile up on my desk for several weeks before I have time to put them away.

• The oldest papers are at the bottom of the pile, the most recent additions near the top.

• The lowermost objects must be placed first. Rocks are no different. This is simple idea behind the

principle of superposition.• When we examine a series of

undisturbed sedimentary rock layers we assume the rocks at the bottom of the stack are the oldest and the rocks at the top are the youngest (Fig. ).


Principle of Superposition



Principle of Original Horizontality

• Sedimentary rocks are deposited in nearly horizontal layers (beds; Fig. ). If layers are no longer horizontal they must have undergone deformation after formation. The majority of sedimentary rocks are deposited under water. They may be pushed above sea level and tilted during the formation of mountains. These processes expose rocks to weathering and erosion that serves to erase parts of the geologic record as rock units are worn away.



Course content

• Superposition: A lies below B so A must be the • oldest unit.

Original horizontality: A, B, and C must have been deposited as horizontal layers. Because they have the same orientation we can probably consider them a discrete group that experienced a similar geologic history

Original horizontality: Because A, B, and C are more steeply tilted than the overlying units they must have been uplifted and tilted early in the history of the region.

A, B, and C were subjected to weathering and erosion at Earth's surface. A relatively flat land surface was formed by erosion. A significant time interval may have passed while erosion occurred. This eroded surface is known as an unconformity and is the physical expression of a gap in time. An unconformity occurs when no beds are deposited or when part of the rock record is removed by erosion



Course content

• Superposition: D must have been deposited after C as it overlies B and C.Original horizontality: D was deposited as a horizontal bed.Cross-cutting: D must be younger than B and C because it cuts across the underlying layers.

Original horizontality: D is no longer horizontal so it must have been slightly tilted after formation. This would also have increased the inclination of layers A, B, and C.

Cross-cutting: All layers A through D are cut by the younger igneous pluton. The pluton contains inclusions of layers B and C, further indication that it must have formed subsequent to the deposition of those beds. We have no evidence to tell us whether E formed before or after D was tilted



Course content

• D and E were subjected to weathering and erosion at Earth's surface.

• A relatively flat land surface was formed by erosion.

• A second unconfomity surface is formed.

Superposition: Layers F and G must have been deposited after E because they lie atop all other units.Original horizontality: F and G were deposited as horizontal beds.Cross-cutting: F must be younger than D and E because it cuts across the underlying units. The river carved a valley through the upper part of G.


• Fossils occur in a consistent vertical order in sedimentary rocks all over the world.

• (William"Strata Bill" Smith, late 1700's, England).

• This principle is valid and does not depend on any pre-existing ideas of evolution.

• (In fact, Charles Darwin's ideas on evolution did not appear until 50 years later - 1858).

• Geologists interpret fossil succession to be the result of evolution - the natural appearance and disappearance of species through time.


Principle of fossil succession


PRESENT IS KEY TO THE PAST

• The "present is key to the past" is a simple but important statement in paleontology.Paleontologists look at present day organisms to help interpret fossils. "Paleo" means old and "onto" means life. Present day organisms help us to understand the life and environment of past organisms.


PRESENT IS KEY TO THE PAST



Geological time Scale

PET-Elements of Geology

DEPARTMENT OF PETROLEUM TECHNOLOGY UNIVERSITY OF KARACHI

Pet-518 Elements of Geology ( Lecture I)



Course content

• Definition, significance and basic disciplines.• Earth as a dynamic terrestrial planet:• Its shape, composition, surface relief, origin and age.• Introduction to minerals, rocks and fossils. • Definitions, method of study , description and classification of rock forming

minerals and major rock types, rock cycle.• Weathering and Soil.• Sedimentary rocks and their classification.• Basic concept of stratigraphy and sedimentation. • Sedimentary environment and stratigraphic sequences.• Basic concepts in geodynamics; interior model of earth. • lithosphere and plate tectonic.• Deformation of rocks: • Classification of Fold, Fault and Unconformities.• Geological Time Scale and significance of Fossils•



Course content

1. An Introduction to Geology2. Matter and Minerals3. Earth's Interior4. Kind of Rocks and Rock Cycle5. Igneous & Metamorphic rocks6. Weathering , Mass Wasting and Soil7. Sedimentary Environments8. Sedimentary Rocks9. Principles of Stratigraphy and Sedimentation10. Crustal Deformation including Plate Tectonics11. Deformational features of rocks12. Classification of Fold Fault and Unconformities.13. Geological Time Scale14. Fossils and Fossilization15. Mountain Building and the Evolution of Continents


• Definition of Geology:

• Geology is classically defined as the study of the Earth.

• Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them.

• It also includes the study of the organisms which inhabit our planet.

• A very important part of geology is the study of how Earth’s materials, structures, processes and organisms have changed over time.

• .


View of the Planet Earth



Some Discipline of Geology

• Mineralogy - formation, chemical and physical properties, and classification of minerals

• Petrology - formation, properties, and classification of rocks• Sedimentology - genesis, transport, and deposition of

sediment, and the formation of sedimentary rocks• Structural geology - deformation of earth materials and

resulting geologic structures• Tectonics - regional to global-scale deformation and structures

resulting from interactions among pieces of the Earth's rigid outer layer, or lithosphere

• Geomorphology - processes of landform evolution and landscape development

• Hydrogeology - interrelationships of water and geologic materials and processes



The two broad areas of the science of geology

• (1) Physical geology,

is the study of Earth materials and structures; the processes and forces that act upon them; and how these materials, structures, processes, and forces have changed over time.

• (2) Historical geology,

which seeks to understand the origin of Earth and its development through time.

The relationship between people and the natural environment is an important focus of geology.

This includes natural hazards, resources, and human influences on geologic processes



Physical geology

• Earth materialsatoms, chemicals, metals, oil, gas, rocks, minerals, salt, gems, coal, sand, gravel, clay, soil, atmosphere, hydrosphere, organisms, etc. How do Earth materials affect people?building materials, fuels, soil to grow food, salt for food, jewelry, we are made of Earth materials

• Earth processesearthquakes, volcanic eruptions, floods, continental drift, weather, climate, landslides, subsidence and collapse, tides, geysers, erosion, etc. Any geologic processes recently in the news? How do these processes affect people?

Interactions in Earth’s Subsystems

Gases from respiration

Transport of seeds and

spores

Atmosphere

Biosphere


Wind erosion, transport of water vapor for

precipitation

Mountainsdivert air

movements

Atmosphere

Lithosphere

Source of sediment and dissolved

material

Water and glacial

erosion, solution of minerals


Earth’s Differentiation

• Differentiation = segregated into layers of differing composition and density

• Early Earth was probably uniform

• Molten iron and nickel sank to form the core

• Lighter silicates flowed up to form mantle and crust

Earth’s Interior Layers

• Crust - 5-90 km thick– continental and

oceanic

• Mantle– composed

largely of peridotite

– dark, dense igneous rock

– rich in iron and magnesium• Core

– iron and a small amount of nickel

Forming the Earth-Moon System

• Most of the lunar material – came from the

mantle of the colliding planetesimal

• The material cooled – and crystallized – into lunar layers


• How old is the Earth?

• 4.5 to 4.6 billion years (4,500,000,000 to 4,600,000,000 years) Determined through radiometric dating (Uranium, Thorium).

Using an instrument called a mass spectrometer.

• Multicellular life• did not appear until about 1 billion years

ago. Before this, 3 billion years ago single celled life only.

• Hard parts like shells don't appear until 600 million years ago. (Trilobites)


Historical Geology




• Historical Geology is the study of changes to Earth and life in time and space.

• I. Time• A. How much time? • Oldest meteorites and oldest moon rocks are 4.6 billion years

old,4,600,000,000 years.

•Oldest rocks found so far on Earth are zircon grains from a sandstone in western Australia, dated at 4.1 to 4.2 bilion years old.

• Previously, the oldest Earth rocks were 3.96 billion years old, from the Northwest Territories of Canada.

• B. How do we know? • Radioactive materials serve as geologic clocks.•



Geologic record

• D. What do you mean by geologic record? • The geologic record consists of rock units, each of which

records some event or series of events that occurred in the past.

• What are rocks?– Rocks are defined as aggregates of one or more

minerals. • What are minerals?

– naturally occurring – inorganic – solids – definite chemical composition – characteristic internal crystal structure (arrangement of

atoms in lattice)



Course content

• E. How do rocks form? • By cooling, hardening, and crystallizing from hot, molten lava

– Igneous rocks • By forming from the compaction and cementation of sediments

– Terrigenous, clastic or detrital sedimentary rocks• By forming from the precipitation of dissolved chemicals in

water – Chemical and biochemical sedimentary rocks

• By forming from accumulated organic matter – Organic sedimentary rocks (coals)

• By the alteration of pre-existing igneous or sedimentary rocks by heat and pressure – Metamorphic rocks

Geologic record



Kinds of Rocks



Fundamental principles of Geology

• Most sedimentary rocks occur in the form of layers called beds or strata.

• Each layer is the result of the deposition of sediment during some natural event (such as a flood or storm).

• A. Steno's Laws Named for Nicholaus Steno

• Principle of Superposition • Oldest rocks on the bottom • Younger rocks on top • Principle of Original Horizontality • Sediments are deposited in flat layers • Principle of Original Lateral Continuity • Sediments are deposited over a large area in a continuous

sheet



Other basic principles of Geology

• Principle of intrusive relationships•• The intrusion is younger than the rocks it cuts.

• Principle of cross-cutting relationships• The fault is younger than the rocks it cuts. •

• Principle of components or inclusions

• Note the irregular erosional surface.• This is an unconformity. • The clasts (in the bed above the unconformity)• are derived from the underlying (older) bed. • The gravel clasts are older than the layer which contains them. • The layer containing the gravel must be younger than the layer from

which the clasts originate.


• Sometimes papers pile up on my desk for several weeks before I have time to put them away.

• The oldest papers are at the bottom of the pile, the most recent additions near the top.

• The lowermost objects must be placed first. Rocks are no different. This is simple idea behind the

principle of superposition.• When we examine a series of

undisturbed sedimentary rock layers we assume the rocks at the bottom of the stack are the oldest and the rocks at the top are the youngest (Fig. ).


Principle of Superposition



Principle of Original Horizontality

• Sedimentary rocks are deposited in nearly horizontal layers (beds; Fig. ). If layers are no longer horizontal they must have undergone deformation after formation. The majority of sedimentary rocks are deposited under water. They may be pushed above sea level and tilted during the formation of mountains. These processes expose rocks to weathering and erosion that serves to erase parts of the geologic record as rock units are worn away.


• Fossils occur in a consistent vertical order in sedimentary rocks all over the world.

• (William"Strata Bill" Smith, late 1700's, England).

• This principle is valid and does not depend on any pre-existing ideas of evolution.

• (In fact, Charles Darwin's ideas on evolution did not appear until 50 years later - 1858).

• Geologists interpret fossil succession to be the result of evolution - the natural appearance and disappearance of species through time.


Principle of fossil succession



The Rock Cycle and Geological Cycle



Course content

pet-basic elements of geology

Documents

historical geology

elements of geology

science of geology pet

study of earth materials

deformation of rocks

planet earth pet

earths materials

origin of earth