Test 2 (Lectures 4-8) Pt. 2 Flashcards
The process of making sedimentary rocks is called…
Diagenesis
What are sediments comprised of?
Loose fragments of rocks, minerals, shell, shell fragments, or mineral crystals that precipitate out of water
Sediment is produced through
Weathering
What are the 2 different types of weathering?
- Physical
- Chemical
What are the 4 different types of physical weathering?
- Jointing
- Frost wedging
- Root wedging
- Thermal expansion
What is jointing?
Natural cracks formed in rocks due to the expansion of a rock undergoing exhumation cooling and extraction
When does exfoliation occur?
When jointing develops in layers parallel to the surface due to pressure release
What is frost wedging?
When water freezes and forces a rock apart
What is root wedging?
When roots grow and force a rock apart
What is dissolution?
When minerals dissolve in water
What are some things that physical and chemical weathering work to do?
- Increase surface area (physical)
- Dissolve minerals and cements (chemicals)
- Alter hard minerals into soft minerals (chemicals)
What is oxidation?
A reaction where an element loses an electron
What is differential weathering?
When weathering occurs faster at the edges and corners than on a flat face
What part of the crust do sedimentary rocks occur in?
They occur in the uppermost part of the crust. They cover igneous and metamorphic base rocks.
What are the four sedimentary rock classes?
- Clastic
- Biochemical
- Organic
- Chemical
What do clastic sedimentary rocks consist of?
Mineral grains, rock fragments, and cementing material
What processes are clastic sedimentary rocks created by?
- weathering (generation of
detritus via rock disintegration) - erosion (removal of grains)
- transportation (dispersal of solid particles and ions by
gravity, wind, water, and ice) - deposition (settling out of the transporting fluid)
- lithification (transformation
into solid rock)
What is lithification?
Transforms a loose sediment into a solid rock
What cement glues the loose sediments together?
Minerals
As transport distance increase, grain size …
Decreases
Grain size is a measure of
The size of fragments or grains
Clasts may be comprised of
Individual mineral grains or rock fragments
Angularity is
The degree of edge or corner smoothness
Degree of sorting increases with
Transport distance
What is Breccia?
Course, angular rock fragments
What is conglomerate?
Rounded rock clasts
What is Arkose?
Sand and gravel with abundant feldspar
What is sandstone?
Clastic rock made of sand-sized particles
Fine clastics are composed of
Silt and clay
Biochemical sedimentary rocks are made up of
Sediments derived from the shells of once-living organism
Limestone are almost entirely made up of
Calcite and aragonite
What are some biochemical rocks?
- Chert
- Coal
- Oil shale
Chemical sedimentary rocks are comprised of minerals precipitated from….?
Water solution
What kind of texture do chemical sedimentary rocks have?
Crystal (interlocking) texture
Where are evaporite rocks derived from?
They are derived from evaporation of large volumes of sea or lake water
What are sedimentary structures?
Features that form when sediments were deposited
Why are sedimentary structures useful?
They provide strong evidence about conditions in the depositional environments
What are the prominent features of sedimentary rocks?
- Bedding
- Stratification
The boundary between two bed is referred to as
Bedding Plane
What does bedding reflect?
Changing conditions during deposition such as changes in sediment source, sediment composition, grain size, sorting, etc
Formations are
Rock units that are so unique that they can be recognized and mapped over large regions
Water flowing over loose sediments can create…
Bedforms
Cross beds are created by ___ and ____
Ripple; dune migration
Turbidity torrents occur under
Ocean landslides
What are depositional environments?
They are locations where sediments accumulate
What is transgression?
The process is which sea levels rise
What is regression?
The process in which sea levels fall
Coarse conglomerate is a characteristic of what setting?
Mountain stream environment
Rift basins form at what type of plate boundary?
Divergent
Foreland basins form on what side?
Craton side of collisional mountain belt
Intracontinental form on what side?
They form in the interior craton side, far from the continental margin or tectonic-plate boundaries
Passive margins are
Edges of continents that are not tectonic-plate boundaries
Sediment deposition is strongly linked to..
Sea level
