pet-518 elements of geology

8/14/2019 Pet-518 Elements of Geology

1/28

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
http://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503530-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503530-,00.html


2/28



Course content

1. An Introduction to Geology 2. Matter and Minerals3. Earth's Interior 4. Kind of Rocks and Rock Cycle5. Igneous & Metamorphic rocks6. Weathering , Mass Wasting and Soil7. Sedimentary Environments8. Sedimentary Rocks 9. Principles of Stratigraphy and Sedimentation

10 . Crustal Deformation including Plate Tectonics 11. Deformational features of rocks

12. Classification of Fold Fault and Unconformities.13. Geological Time Scale

14. Fossils and Fossilization15 . Mountain Building and the Evolution of Continents
http://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503256-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503256-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503329-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504371-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503397-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503465-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503530-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503672-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503607-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503808-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504223-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504302-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504433-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504509-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504599-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504599-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504509-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504433-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504302-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504223-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503808-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503607-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503672-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503530-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503465-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503397-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,504371-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503329-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503256-,00.htmlhttp://wps.prenhall.com/esm_tarbuck_earth_7/0,6431,503256-,00.html


3/28


Definition of Geology :

Geology is classically defined as the studyof the Earth .

Geology is the study of the Earth, thematerials of which it is made, the structureof those materials, and the processes acting

upon them.

It also includes the study of the organismswhich inhabit our planet.

A very important part of geology is the studyof how Earths materials, structures,processes and organisms have changedover time.

.


View of the Planet Earth


4/28



Some Discipline of Geology

Mineralogy - formation, chemical and physical properties, andclassification 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 rigidouter layer, or lithosphere

Geomorphology - processes of landform evolution andlandscape development Hydrogeology - interrelationships of water and geologic

materials and processes


5/28



The two broad areas of the science of geology

(1) P hysical geology ,

is the study of Earth materials and structures; theprocesses and forces that act upon them; and how thesematerials, structures, processes, and forces have changedover time.

(2) Historical geology , which seeks to understand the origin of Earth and its

development through time.The relationship between people and the naturalenvironment is an important focus of geology.This includes natural hazards, resources, and humaninfluences on geologic processes


6/28



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?


7/28


How old is the Earth ?

4.5 to 4.6 billion years (4,500,000,000 to4,600,000,000 years) Determined throughradiometric dating (Uranium, Thorium).Using an instrument called a massspectrometer.

Multicellular life did not appear until about 1 billion years

ago.Before this, 3 billion years ago singlecelled life only.

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


Historical Geology


8/28



Earth at a Glance


9/28



Introduction to Historical Geology

Historical Geology is the study of changes to Earth and lifein 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 sandstonein western Australia, dated at 4.1 to 4.2 bilion years old.

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

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


10/28



Introduction to Historical Geology

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

time .


11/28



Introduction to Historical Geology 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.


12/28



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 thepast.

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)


13/28



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 inwater Chemical and biochemical sedimentary rocks

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

By the alteration of pre-existing igneous or sedimentary rocksby heat and pressure Metamorphic rocks

Geologic record


14/28


15/28



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.


16/28


Sometimes papers pile up on mydesk for several weeks before I have

time to put them away. The oldest papers are at the bottom

of the pile, the most recentadditions near the top.

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

principle of superposition . When we examine a series of

undisturbed sedimentary rocklayers we assume the rocks at thebottom of the stack are the oldestand the rocks at the top are theyoungest (Fig. ).


Principle of Superposition


17/28



Principle of Original Horizontality

Sedimentary rocks are deposited in nearly horizontallayers (beds; Fig. ). If layers are no longer horizontal theymust have undergone deformation after formation.The majority of sedimentary rocks are deposited under

water. They may be pushed above sea level and tiltedduring the formation of mountains. These processesexpose rocks to weathering and erosion that serves toerase parts of the geologic record as rock units are wornaway.


18/28



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

Original horizontality: A, B, and C must have beendeposited as horizontal layers.

Becausethey have the same orientation we can probablyconsider them a discrete group that experienced asimilar geologic history

Original horizontality: Because A, B, and C are more steeplytilted than the overlying units they must have been upliftedand 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 byerosion. A significant time interval may have passed whileerosion occurred. This eroded surface is known as anunconformity 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

l f l


19/28



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 Cbecause it cuts across the underlying layers.

Original horizontality: D is no longer horizontal so it

must have been slightly tilted after formation. Thiswould also have increased the inclination of layers A,B, and C.

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

P 518 El f G l


20/28



Course content

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

A relatively flat land surface was formed byerosion.

A second unconfomity surface is formed.

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

P 518 El f G l


21/28


Fossils occur in a consistentvertical order in sedimentaryrocks all over the world.

(William"Strata Bill" Smith, late1700's, England).

This principle is valid and does

not depend on any pre-existingideas of evolution.

(In fact, Charles Darwin's ideason evolution did not appear until50 years later - 1858).

Geologists interpret fossilsuccession to be the result of evolution - the naturalappearance and disappearanceof species through time.


Principle of fossil succession

P 518 El f G l


22/28



Geological time Scale

P t 518 El t f G l


23/28



The Rock Cycle and Geological Cycle

P t 518 El t f G l g


24/28



Course content

P t 518 El t f G l g


25/28



Course content

Pet 518 Elements of Geology


26/28


PRESENT IS KEY TO THE PAST

The " present is key to thepast" is a simple butimportant statement inpaleontology . Paleontologists look atpresent day organisms tohelp interpret fossils."Paleo" means old and"onto" means life .

Present day organismshelp us to understand thelife and environment of past organisms.


PRESENT IS KEY TO THE PAST



27/28



Kinds of Rocks

Pet 518 Elements of Geology


28/28

Pet-518 Elements of GeologyCourse content

pet-518 elements of geology

Documents