Lecture 6 Flashcards
Plutons:
Shape:
Orientation
Tabular, massive
Discordant, concordant
Tabular:
Massive:
Discordant:
Concordant:
Tabular: Stock
Massive: Batholith (>100 square km)
Discordant: Dike
Concordant: Sill, Laccolith
Laccolith vs lopolith
Mushroom-like roof – laccolith
Upo: lopolith
Mechanical (breaking):
Chemical:
Sediments
Dissolved ions
Agents of weathering
Water, wind, ice
Mechanical Weathering Types
Frost wedging – freezing and thawing of ice Salt crytal growth Dessication cracks Sheeting/unloading Biological activity
Chemical weathering types
Dissolution,
Chemical weathering stability series
Goldich Stability series (inverted Bowen’s reaction series)
Rates of weathering
Climate & Relief
Arid and high relief
Humid and low relief
Arid: less chemical weathering, more physical weathering
Humid: enhanced chemical weathering
Layer of rock and mineral fragments produced by weathering
Regolith
Combination of decomposed and disintegrated rock (mineral matter) ) and organic matter (humus), water, and air, portion of regolith that supports plant life
Soil
Controls of soil formation
Climate and topography (slope)
Parent material and biological factors (plants, animals)
time
Soil O,A,E,B,C,R
Organic matter A –mineral + some humus E-luvation/leaching B- accumulation of different materials C – partially altered parent material R – bed rock – unweathered parent material
Top soil, subsoil, regolith, true soil
Top soil: O and A
Subsoil: O – B
Regolith : R na may unting C
True soil: Subsoil
Incorporation and transportation of material by a mobile agent such as gravity, wind, water, ice or fauna
Erosion
Maximum sediment grain size an agent of erosion can transport
Competence
Maximum load of sediments of an agent of erosion
capacity
process where sediments, soil, and rocks are added to a land mass such as when
• When *and * slows down and as glacial ice melts
• When chemical/temperature changes causes *
• When decayed * piles up
Deposition
wind, water currents
precipitation
organic material
Deposition
- Wind and water currents; melting glacier
- chemical/ temperature changes
- undecayed organic materials pile up
- solids
2. dissolved materials
Sum of physical and chemical processes by which sediments are lithified into sedimentary rocks
Diagenesis (formation of sedimentary rock)
Burial by succeeding sedimentation/
compacting sediments together
Compaction
Precipitation of the cement (‘glue”) around dusts from pore waters (gluing sediments to form sedimentary rocks)
Cementation
Unstable crystals to more stable counterparts
Recrystallization
Dissolution of unstable to be replaced by a more stable mineral
Replacement
post-diagenesis, Burrowing animals that leave marks
Bisturbation
physical breakdown (disintegration) and chemical alteration (decomposition) of rocks at or near the Earth’s surface. products:
• Weathering
sediments, dissolved ions
structures that result from emplacement of igneous materials at depth.
plutons
massive, >100 sq. km in outcrop area, and granitic. It is the largest intrusive igneous bodies
batoliths
smaller than batholiths and granitic
stock
Discordant, cuts across bedding surfaces in the host rock
dikes
nearly horizontal, concordant bodies
sill
- concordant pluton with dome or mushroom-like roof and planar base, injected between sedimentary strata
Laccolith
igneous intrusion associated with a structural basin, with contacts that are parallel to the bedding of the enclosing rocks.
Lopolith
TYPES OF WEATHERING
- Mecanical
* Chemical
AGENTS OF WEATHERING
- Wind
- Water
- Ice
process in which big rocks are broken increasingly into smaller pieces.
Mechanical Weathering-
Types of mechanical weathering
• *- freezing and thawing of ice
• *- evaporation of saline water leaving salt
• *- thermal expansion/contraction of water normally due to alternating dry and wet season.
• *- exfoliation, joints( linear but indicates movement)
• *
Frost wedging Salt Crystal Growth Dessication Cracks Sheeting/Unloading Biological Activity
- Frost wedging- * and * of ice
- Salt Crystal Growth- *of saline water leaving *
- Dessication Cracks- thermal * of water normally due to *dry and wet season.
- Sheeting/Unloading- *, joints( *but indicates movement)
- Biological Activity
freezing , thawing
evaporation, salt
expansion/contraction, alternating
exfoliation, linear
*- breaks down * and internal structure of minerals producing more *constituents. • Hydration • * • Reduction • *
Chemical Weathering, rocks component, stable
Oxidation
Dissolution
Chemical Weathering- breaks down rocks component and * of *producing more stable constituents. • * • Oxidation • * • Dissolution
internal structure, minerals
Hydration
Reduction
RATES OF WEATHERING
- : joints and fractures
- : Goldich Stability Series
Structure
Composition
RATES OF WEATHERING
Structure: *
Composition:*
joints and fractures
Goldich Stability Series
Process in seawater
• Dissolved and suspended load- *and *on the shallow parts
• *- jumping of sediments
• *- sediments are dragged to the surface
dissolution, suspension
Saltation
Traction
Process
• *- dissolution and suspension on the shallow parts
• Saltation- *of sediments
• Traction- sediments are *to the *
Dissolved and suspended load
jumping
dragged, surface
