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GENERAL GEOLOGY
1. Importants Part of Earth Interior:
Based on chemical properties Depthkm Based on physical properties Depthkm Crust 40 Lithosphere (cool, rigid) 100 Asthenosphere (hot, plastic) 350 Mantle (^2883) Mesosphere (hot but strong due to high pressure) 2883 Outer Core Liquid Outer Core (Liquid NiFe) Inner Core
Solid Inner Core ( Solid NiFe)
2. Major Features of the Earth: - Shield Areas - Stable Platforms - Folded Mountains - Ocean Floor a. The Oceanic Ridge b. The Abyssal Floor c. Seamounts or Volcanic Mounts d. Trenches e. Continental Margins 3. Percentage of the most abundant Element in Earth: Elements Symbol Percentage Oxygen O 46. Silicon Si 27. Aluminum Al 8. Iron Fe 5. Calcium Ca 3. Sodium Na 2. Potassium K 2. Magnesium Mg 2. Titanium Ti 0. Hydrogen H 0. Phosphorous P 0. Manganese Mn 0. Sulfur S 0. Carbon C 0. 4. Mohos Scale of Hardness: Hardness Mineral Scratched ability 1 Talc 2 Gypsum
Scratched by a Finger Nail
3 Calcite 4 Fluorite Scratched by a Copper Coin 5 Apatite Scratched by a Knife 6 Feldspar Scratched by a Glass 7 Quartz 8 Topaz 9 Corundum
Steel File
10 Diamond No Scratched
5. Rock forming Mineral: S.No Mineral Groups Mineral 1 Oxides Quartz, Hematite. 2 Carbonates Calcite, Dolomite, Magnesite, Ankarite. 3 Sulfides Pyrite, Galena 4 Sulfates Gypsum, Anhydrite, Hexahydrite, Polyhalite. 5 Chlorites Rock Salt, Sylvite, Bischoffite, Carnallite. 6 Silicates Feldspars, Mica, Hornblende, Augite, Olivine 6. Crystal System: System Axes Mineral Example Isometric 3 axes, at 90 Garnet, Fluorite, Pyrite, Sphalerite, Halite Tetragonal 3 axes at 90, 2 hori = but 2 ver is short or long Zircon, Cassiterite Hexagonal 4 axes, 3 = hori axes at 60, 1 axes vertical s l Qurtz, Apatite, Calcite, Beryl Orthorhombic 3 axes of differ length at 90 Olivine, Topaz Monoclinic 3 unequal axes, 2 axes at 90 3 is inclined Orthoclase, Mica, Augite, Gypsum Triclinic 3 unequal axes, none at 90 Plagioclase, Axinite 7. Geological Time Scale:
Era Eon Periods Epoch
Well Known Names
Developments of Plants and animals
Duration in Ma
Ma ago Quaternary Holocene^ Human age^ Human^ 0. Pleistocene Ice age Modern Plants 1.6 1. Neogene Pliocene^ 3.7^ 5. Miocene Mammals 18.4 23. Oligocene 12.9 36. Eocene Mollusks 21.2 57.
C^
e n o z o i c T^ e r t i a r yPaleogene Paleocene
Age of Mammals
Extinction of (^) 8.6 66. Cretaceous 1st Flowering Plant 78 144 Jurassic First Bird 64 208
M^
e s o z o i c Triassic
Dinosaurs and other species Age of Reptiles
Dinosaurs dominant Extinction of^37 Permian Trilobites 41 286 Pennsylvanian 1st Reptiles 34 320 Carboniferous Mississipian
Age of Amphibians (^) Large Coal swamps and amphibians abundunt 40 360 Devonian 1st Insect fossils 48 408
Silurian
Age of Fishes 1st Land Plants and Fishes dominant 30 438 Ordovician 1st Fishes 67 505
P^
h a n e r o z o i c
P a l e o z o i c
Cambrian
Age of Invertebrates 1st organisms with shells and Trilobites dominant 65 570 Late 1st Multi celled Organisms 330 900
Middle 700 1600 P r o t e r o z o i c Early 900 2500
Late 1st One celled organism 500 3000 Middle 400 3400 A^
r c h e a n Early Age of Oldest Rock 400 3800
P^
r e c a m
b r i a n
Haden Origin of Earth 1200+ 4600
9. Igneous Rock: Bowen Reaction Series: High Temperature Olivine Calcic Feldspar (Early) Pyroxene
Amphibole Sodic Feldspar
Biotite
Potassium Feldspar
Muscovite (Late) Low Temperature Quartz
Igneous Rock Classification: “On the Basis of Silica Content” Acidic Si >65% Light
Intermediate Si 65-55% Medium Sub Acidic Sub Basic
Basic Si 55-45% Dark
Ultrabasic Si <45% V.Dark
Granodiorite Syenite Diorite Gabbro Peridotite
Granite Dunite
P^
L^
U^
T^
O^
N^
I C
Pyroxenite
Andulite Monzonite Trachysite
Syeno Gabbro Pegmatite Granite Porphry
Syenite Porphry
Diorite Porphry
Dolerite
H^
Y^
P^
A^
B^
Y^
S S A
L
Trachy Basalt
Rhyolite Trachyte (^) GabbroAlkali
Obsidian
Alkali Basalt
“ O
n
t h e
B
a s i s
o f
T^
e x t u r e
a n d
m
o d e
o f
o c c u r r e n c e ”
V^
O^
L^
C^
A^
N^
I C
Pitchstone
Andesite
Basalt
Min Comp
Quartz Orthoclase
Orthoclase
+-Plagio
Plagio >+- Orthoclase
Plagio +Augite
Olivine Pyroxene Occurrence: Sill => intrusive body parallel to strata Dyke => intrusive body perpendicular to strata Batholith => Large magmatic basin Lapolith => Funnel shape Laccolith => Umberalla shape (plano-convex) Phacolith => crests and trough under folded strata Stock => small batholith Boss => Circular shape Volcanic Neck or Plug => plug type intrusive body Lawa flows
10. Metamorphic Rock: Agents of Metamorphism: - Temperature - Pressure - Chemical Fluids Types of Metamorphism: - Thermal Metamorphism - Dynamothermal Metamorphism (Regional Metamorphism) - Cataclastic Metamorphism - Plutonic Metamorphism - Metasomatism Zones of Metamorphism: Metamorphic Zones
Temperature Pressure Metamorphism Types
Example
Epizone or Upper Zone Low (300)^ High dp^ Cataclastic^ Phyllites Mesozone or Intermediate Zone 300 – 500^ High dp^ Dynamothermal^ Schists Katazone or Lower Zone
500 – 800+ High up Plutonic Gneiss
Structures of Metamorphic Rocks:
- Schistose Structure
- Gneissose Structure
- Granulose Structure
- Slaty Structure 11. Sedimentary Rocks: Terminologies of grains: Sorting Shapes Sphericity Angularity Roundness Transporting Agency
Very well sorted Well sorted Moderately sorted Poorly sorted Very poorly sorted
Equant Rod like Tabular Discoidal
High Low
Very Angular Angular Sab Angular
Sub rounded Rounded Well rounded
Glacier => Glacial deposites. Water => River = Alluvial deposites Lakes = Lacustrine deposites Sea = Marine deposites Wind => Aeolian/ Eolian deposites.
Classification of Sedimentary Rocks: Rudaceous Rocks Boulder deposit e.g, Conglomerate Arenaceous Rocks Sandy Rocks e.g, Sandstone
Mechanically Formed (based on physical behaviour) Argillaceous Rocks
Clayey Rocks e.g, Shale C^ l a s t i c Calcarious Rocks^ Limestone
R
o c k s
Organically Formed (due to accumulation animals and plant remains)
Carbonaceous Rocks Coal Seams Carbonate Rocks Limestone, Dolostone
Sulfate Rocks Gypsum rock
N^
o n
C
l a s t i c R^
o c k s
(^) Chemically Formed (due to precipitation accumulation of soluble constituents) (^) Chlorite Rocks Rock Salt
Sedimentary Environment: Major Categories
General Environments
Specific Environments Channel and Bar Overbank, high energy (levee) Overbank, low energy (swamp)
Fluvial (River)
Alluvial Fan Desert Playa Erg Sub glacial Englacial Supraglacial Cryolacustrine Proglacial fluvial
Glacial
Proglacial Aeolian Cryolacusrine Lacustrine Playa Lake (salina) Fresh water lacustrine Intra Paludal
C^
o n t i n e n t a l
Paludal (Swamp) Deltaic Paludal Channel Bar Overbank crevasse splay Deltaic paludal Deltaic lacustrine Prodelta
Coastal Deltaic
Delta front Eustrine Eustrine-Lagoon Lagoonal Slat marsh Beach forshore Beach backshore Beach dune (bern) Tidal channel
T^
r a n s i t i o n a l
Littoral beach
Tidal flat Low energy open Shelf shallow sea Low energy restricted High energy Glaciomarine Reefal Fore reef
Reef
Rreef lagoon Open Slope Open Rise Slope Basin
Submarine Canyon, Slope and Rise Submarine Fans Pelagic Basinal or Abbysal Plain Oceanic Plateau Trench Slope Trenc Slope Basin Trench Floor
Trench
Submarine fan
M
a r i n e
Rift Fracture Zone
Sedimentary Structure:
Rock Type (^) Depositional Erosional Deformational Diegenatic Bedding Channels Soft-sediment folds Concretions Cross Bedding Tool marks Slumps or slide scars Stylolites Ripple Marks Rip-up Breccias Sand crystals Salt crystal casts Trails and tracks
Sandstone Dikes Liesegang bands
Laminations Flute cast Sandstone Sills Liesegang rings Cross Laminations Load cast Flame Structures Graded bedding Burrows Fluid Escape channels Ice wedge casts Ball and pillow structure Panecontemporanous faults Slump or Slide cast Sand volcanoes Convolute Laminations Dish structures Organic escape structures
S a n d s t o n e
Root cast and molds Bedding Channels Soft-sediment folds Concretions Cross Bedding Tool marks Desiccation cracks Viens Ripple Marks Burrows Breccias Stylolites Stromatolites Trails and tracks
Tepees Breccias
Laminations Flute cast Load cast Liesegang bands Cross Laminations Flame Structures Liesegang rings Graded bedding Panecontemporanous faults Nodules Pellets Convolute Laminations Vugs Reefs Stromatactis Oncolites Hardgrounds Grapestones Fenestrae Mounds Pisolites
C^
a r b o n a t e s
Fensetrae Bedding (II, ~, I~) Mud cracks Mud volcanoes Concretions Lamination (II, ~, I~) Tool marks Flame Structures Escape structure Parallel stratification Burrows Load cast
Ripple Marks Trails andtracks Crystal casts Salt crystal casts Flute cast Color banding Laminations Rain prints Bioturbatted bedding Cross Laminations Convolute bedding Graded bedding Soft-sediment folds Sole Marks Soft-sediment faults
M
u d
R^
o c k s
Slickenside Lime Mud: G < ssp Sparite: G > 0.004 mm
Micrite: G < 0.004mm Microsparite: G b/w 0.004 – 0.06mm Macrosparite: G < 0.06mm Allochems: Transport Fragements of Precipetated material
Intraclast: fragments of preexist rock Oids: (oolith, oolites) c = p (G b/w 0.25-0.02mm) Pellets: G < 0.25mm , Grapestones, Skeletal Fragment Biolithic Elements: Oncolites: G < 10cm By precipitation by organisms Stramatolites: by Organic precipitation Test, Skeleton
Some Fold Concepts:
Recognition of Unconfirmity:
- Difference in structure.
- Fossil record.
- Fossil soil.
- Enviornament or time change.
- Rock type change.
The Core:
- The Core of the earth is about 1,800 miles (2,900 km) below the earth's surface.
- The core is a dense ball of the elements iron and nickel.
- It is divided into two layers, the inner core and the outer core.
- The inner core - the centre of earth - is solid and about 780 miles (1,250 km) thick. The inner core
may have a temperature up to about 13,000°F (7,200°C = 7,500 K), which is hotter than the surface
of the Sun. The inner core (which has a radius of about 750 miles (1,228 km) is solid.
- The outer core is so hot that the metal is always molten. The outer core is about 1370 miles (2,
km) thick. Because the earth rotates, the outer core spins around the inner core and that causes the
earth's magnetism. The outer core is in a liquid state and is about 1,400 miles (2,260 km) thick.
- The Earth has an iron-nickel core that is about 2,100 miles in radius.
- The core is earth's source of internal heat because it contains radioactive materials which release heat
as they break down into more stable substances.
The Mantle:
- The layer above the core is the mantle which is about 1,800 miles (2,900 km) thick and makes up
nearly 80 percent of the Earth's total volume.
- It begins about 6 miles (10 km) below the oceanic crust and about 19 miles (30 km) below the
continental crust.
- It is composed of olivine-rich rock mainly silicon, oxygen, magnesium, iron, aluminum, and
calcium.
- The mantle is to divide into the lower mantle and the upper mantle.
- The upper mantle is rigid and is part of the lithosphere (together with the crust).
- The lower mantle flows slowly, at a rate of a few centimeters per year. The asthenosphere is a part
of the upper mantle that exhibits plastic properties. It is located below the lithosphere (the crust and
upper mantle), between about 100 and 250 kilometers deep.
- Convection (heat) currents carry heat from the hot inner mantle to the cooler outer mantle. The
mantle gets warmer with depth, the highest temperatures occur where the mantle material is in
contact with the heat-producing core and is about 4,000-6,700° F (2,200-3,700° C) while the top of
the mantle is about 1,600° F (870° C).
- The Gutenberg discontinuity separates the outer core and the mantle.
- The steady increase of temperature with depth is known as the geothermal gradient. The geothermal
gradient is responsible for different rock behaviors and the different rock behaviors are used to
divide the mantle into two different zones. Rocks in the upper mantle are cool and brittle, while
rocks in the lower mantle are hot and soft (but not molten).
The Core The Mantle
The Crust:
- The Crust lies above the mantle and is the earth's hard outer shell which is composed of silicon,
aluminum, calcium, sodium and potassium.
- The crust is divided into continental plates which drift slowly (only a few centimeters each year)
atop the less rigid mantle.
- There are two different types of crust. The Oceanic crust underlies the ocean basins and is thin (6-
km thick); this is where new crust is formed. The Continental crust is about 25-90 km thick. The
lithosphere is defined as the crust and the upper mantle, a rigid layer about 100-200 km thick.
- The thin oceanic crust is composed of primarily of basalt and the thicker continental crust is
composed primarily of granite. The low density of the think continental crust allows it to "float" in
high relief on the much higher density mantle below.
- The Mohorovicic discontinuity is the separation between the crust and the upper mantle.
Crust Type:
1. Oceanic Crust
2. Continental Crust
The Atmosphere
- It is the all kind of gaseous layer which is covered the earth.
- It is the essential part on earth for life, without this atmosphere life on earth isn't possible.
- It gives us air, water, warmth and is protecting us against harmful rays of the sun and against
meteorites.
- This layer around the earth is a colourless, odourless, tasteless 'sea' of gases, water and fine dust.
- The atmosphere is made up of different layers with different qualities. It consists of 78% nitrogen,
21% oxygen, 0.93% argon, 0.03% carbon dioxide and 0.04% of other gases.
- The Troposphere is the layer where the weather happens; above this layer is the Stratosphere. Within
the Stratosphere is the Ozone layer that absorbs the Sun's harmful ultraviolet rays. Above the
Stratosphere is the Mesosphere, the Thermosphere - in which the Ionosphere - and the Exosphere.
The atmosphere is about 500 miles (800 km) thick.
Divergent Plate Boundaries:
- Divergent plate boundaries are locations where plates are moving away from one another. This
occurs above rising convection currents.
- The rising current pushes up on the bottom of the lithosphere, lifting it and flowing laterally beneath
it. This lateral flow causes the plate material above to be dragged along in the direction of flow.
- At the crest of the uplift, the overlying plate is stretched thin, breaks and pulls apart.
- Two Types are as:
1. Oceanic to Oceanic Divergent Plate Boundary
2. Continental to Continental Divergent Plate Boundary
Transform Boundary:
- Transform Plate Boundaries are locations where two plates slide past one another.
- The fracture zone that forms a transform plate boundary is known as a transform fault.
- Most transform faults are found in the ocean basin and connect offsets in the mid-ocean ridges.
- Transform faults can be distinguished from the
typical strike-slip faults because the sense of
movement is in the opposite direction.
- A strike-slip fault is a simple offset; however, a
transform fault is formed between two different
plates, each moving away from the spreading center
of a divergent plate boundary.
- A smaller number of transform faults cut continental
lithosphere. The most famous example of this is the
San Andreas Fault Zone of western North America. The San Andreas connects a divergent boundary
in the Gulf of California with the Cascadia subduction zone. Another example of a transform
boundary on land is the Alpine Fault of New Zealand.
- Transform faults are locations of recurring earthquake activity and faulting. The earthquakes are
usually shallow because they occur within and between plates that are not involved in subduction.
Volcanic activity is normally not present because the typical magma sources of an upwelling
convection current or a melting subducting plate are not present.
