Igneous Petrology PART 1

Petrology

the study of rocks, their composition, classification, origin and their relationship with geological processes/history.

Petrogenesis

concerned with the interpretation of the origin of rocks

Petrography

gives emphasis to the descriptive rock science including their texture, mineralogy, and chemical composition.

EXPLAIN THE ROCK CYCLE

EXPLAIN THE CHEMICAL LAYERS OF THE EARTH

Continental Crust

Thicker that oceanic crust

20-90 km

Thickness of Continental Crust ranges from _______

35km

Average thickness of Continental Crust

Granodiorite

Main Composition of Continental crust

Lithospheric Plates

a massive, irregularly shaped slab of solid rock generally composed of continental and oceanic lithosphere

Basaltic

Main Composition of Oceanic crust

Olivine

Main Composition of Upper Mantle

Bridgmanite

Main Composition of Lower Mantle

LOW

Upper Mantle has _____ velocity

HIGH

Lower Mantle has _____ velocity

Transition Zone

where velocity increases RAPIDLY

Lower Mantle

where velocity increases GRADUALLY

Fe-Ni Alloy

Composition of CORE

Siliceous Rocks

From mantle to crust, the dominant types or rocks are _____

EXPLAIN THE RELATIONSHIP OF GEOTHERM AND MANTLE MELTING CURVE

Whole Earth
Iron
Oxygen
Silicon

Earth's Crust
Oxygen
Silicon
Aluminum

Elemental composition of the earth

ROCK

Oxygen+Silicon=______

EXPLAIN PLATE BOUNDARIES

10km

Thickness of Oceanic Crust

NSPAEAA

North American
South American
Pacific
African
Eurasian
Australian-Indan
Antarctic

These are the major plates

CNPACSJ

Caribbean
Nazca
Philippine
Arabian
Cocos
Scotia
Juan de Fuca

These are the Minor Plates

Divergent Boundaries

Also known as constructive Margin, where 2 plates move away from each other resulting into the upwelling of hot material from the mantle to create new seafloor

Divergent Boundaries

Also known as spreading centers

Oceanic Ridges

Elevated areas of the seafloor characterized by high heat flow and volcanism

The Global Ridge System

Longest topographic feature on earth surface (70km)

80 million years

it takes about _____ for the temperature of the crust to stabilize and contraction to cease.

Volcanic Island Arc

Oceanic-oceanic convergence results in what type of landform?

Continental Volcanic Arcs

Oceanic-continental convergence results in what type of landform?

Mountain Ranges

Continental-Continental convergence results in what type of landform?

RE-READ PPT on
OCEANIC RIDGES

Rift Valley

A deep down faulted structure

this structure is evidence that tensional forces are actively pulling apart the oceanic crust at the ridge crest

Rift Valley

this structure is evidence that tensional forces are actively pulling apart the oceanic crust at the ridge crest

Seafloor Spreading (5cm/year)

a mechanism that operates along oceanic ridge to create new sea floor

Continental Rifting

Where opposing tectonic forces act to "pull apart the lithosphere"

East African Rift

Birthplace of human race

East African Rift

where remians of homo habilis and homo erectus where discovered by louis and mark leakey and now considered as the birthplace of human race

Subduction

Occurs because the density of the descending plate is greater than the density of underlying plate

Deep-Ocean Trenches

this is a "surface manifestation" produced as oceanic lithosphere descends into the mantle

Deep-Ocean Trenches

large linear depressions

Subduction

The sideways and downward movement of the edge of the earth's crust into the mantle beneath another plate

Obduction

the "overthrusting" of oceanic lithosphere at a convergent plate boundary where the continental lithosphere is being subducted beneath oceanic lithosphere

MIIABOM
Mid-ocean ridges
Intracontinental rift
Island arcs
Active continental margin
Back-arc basin
Ocean island Basalts
Miscellaneous Intracontinental Activities

These are the Environments where we can find igneous rocks (igneous genesis)

Fracture Zone

Prominent Linear Breaks in the sea floor

Magma

entire assemblage or mixture of melt suspended crystals and dissolved volatiles

Melt

refers to the molten state of its own excluding any solid material suspended to it

Magma

the totality which is composed of 3 components known as crystal,melts and gas bubbles

Melt

liquid portion of magma

Groundmass

Solidified form of Magma

Phenocryst

Solidified form of Crystal

Vesicles

Solidified form of Gas bubbles

"PETRA"

is a Greek word which means Rock

"LOGOS"

is a Greek word means explanation

Igneous Rocks

these are primary rocks where the source is magma

Sedimentary Rocks

secondary rocks

Metamorphic Rocks

this rocks came from the changed of forms of ignx and Sed due to temp, pres and chemical fluids

"IGNIS"

means FIRE

Igneous Rocks

Rocks that directly solidify from molten or partially molten material

"SEDIMENTUM"

Means Settling or Sinking Down

Sedimentary Rocks

are rocks that resulted from the:
consolidation of sediments
precipitating chemicals from as sol'n or
organic rock from remains of plants and animal

DETRITAL (CLASTIC) SEDIMENTARY ROCKS
CHEMICAL SEDIMENTARY ROCKS

two types of sedimentary rocks

INTRUSIVE IGNX RX
EXTRUSIVE IGNX RX

two types of igneous rocks

METAMORPHOSIS

Means change in form

Metamorphic Rocks

Rocks derived from pre-existing rock due to mineralogical, chemical and structural changes

Foliated
Non-foliated

two groups of met rx

Foliated are more abundant than non foliated

Volcanic Tuff

(seds because it involves transportation)

is a rock that is either igneous or sedimentary

Serpentine

(formation is caused by contact metamorphism)

is a rock that is either igneous or metamorphic

Outcrop Characteristics
General Texture
Mineral Assemblage Present

How to classify rock in general terms?

Iron- 35%
Oxygen- 30%
Silicon- 15%

Abundant element and there percentages in terms of the whole earth system

Oxygen-46%
Silicon-28%
Aluminum-8%

Abundant element and there percentages in terms of the earth's CRUST