Sedimentary Petrology Flashcards
study of the processes of formation, transport, and deposition of material that accumulates as sediment in continental and marine environments and eventually forms sedimentary rocks.
Sedimentology
study of processes that erode, transport, and deposit sediments
Sedimentology
the study of the characteristics and origin of sedimentary rocks
Sedimentary Petrology
the study of the origin, relationship, and extent of rock layers (strata)
Stratigraphy
the study of rocks to determine the order and timing of events in Earth’s history: it provides the time frame that allows us to interpret sedimentary rocks in terms of dynamic evolving environments.
Stratigraphy
formed at low temperatures and pressure compared to igneous and metamorphic rocks.
Sedimentary rocks
rocks which form at or near the earth’s surface primarily through: Deposition of weathered material by water, wind, or ice (detrital, clastic, terrigenous), Direct inorganic chemical precipitation from water, or Precipitation by organic processes.
Sedimentary rocks
Sedimentary rocks are rocks that form at or near the earth’s surface primarily through?
Deposition of weathered material by water, wind, or ice (detrital, clastic, terrigenous)
Direct inorganic chemical precipitation from water
Precipitation by organic processes.
the physical breakdown (disintegration) and chemical alteration (decomposition) of rocks at or near the Earth’s surface.
Weathering
2 types of weathering
Physical / Mechanical weathering
Chemical weathering
These are processes that break the solid rock into pieces and may separate the different minerals without involving any chemical reactions.
Physical weathering
The most important agents in physical weathering
Freeze-thaw action
Temperature change
Salt dome intrusion
Root wedging
Wetting and drying
Organic activity
Unloading
Physical / Mechanical weathering prevails in?
cold climates, high altitudes, dry regions
repeated cycles of freezing and thawing, the expansion force of water as it freezes is sufficient to split any mineral or rock.
Frost wedging
Differences in temperature in a rock give rise to differential expansion (heating) and contraction (cooling).
Heating and cooling
The disruption of soil results in the swelling and contracting of soil particles.
Wetting and drying
The action of organisms, including animals and plants, reduces the size of rocks and minerals.
Organisms
the removal of thick layers of sediments overlying deeply buried rocks by erosion or uplift.
Unloading
Factors controlling weathering
Source Composition
Climate
Topographic Relief
Weathering where the dissolving of a solid in a liquid
Dissolution
Weathering where combination of a solid mineral or element with water.
Hydration
Weathering where both the chemical combination of oxygen with a compound and the change in the oxidation number of some chemical elements. it is usually used in mineral weathering
Oxidation and Reduction
the chemical process in which electrons are gained
Reduction
involves the transfer of charged atoms (ions) of calcium, magnesium, sodium, and potassium between waters rich in one of the ions and a mineral rich in another. This most effective in clay.
Ion-exchange
The removal of material by mobile agents such as water, wind, ice, or man
Erosion
Arrangement of minerals in Goldich Stability Series (from least to highest resistance)
Olivine, Ca-Felds, Pyroxenes, Amphibole, Na-feldspar, Biotite Mica, K-feldspars, Muscovite Mica, Quartz
Difference between Bowen’s reaction series and Goldich Stability Series?
Bowen’s shows
Transport media of Erosion
Air, Water, Ice, Gravity
Mode of Transport in Erosion
Rolling, Saltation, Saltation, Suspension
the clasts move by rolling along at the bottom of the
air or water flow without losing contact with the bed surface
Rolling
the particles move in a series of jumps, periodically
leaving the bed surface, and carrying short distances within the body of the fluid before returning to the bed again.
Saltation
turbulence within the flow produces sufficient upward motion to keep particles in the moving fluid more or less continually.
Suspension
Particles being carried by rolling and saltation are referred to as _____________ and the material in suspension is called _________________.
Bedload; Suspended load
Flow where all molecules within the fluid move parallel to each other in the direction of transport.
Laminar flows
Flow where
heterogeneous fluids are thoroughly mixed
turbulent flows
Flow where molecules in the fluid move in all directions but with a net movement in the transport direction.
Turbulent flows
Flow where a heterogeneous fluid with almost no mixing.
Laminar flows
a dimensionless quantity that indicates the extent to which a flow is laminar or turbulent.
Reynolds number(Re)
Reynolds number is obtained by relating the
following factors:
the velocity of flow (y), the ratio between
the density of the fluid and viscosity of the fluid (n– the fluid kinematic viscosity) and a ‘characteristic length’ (l – the
diameter of a pipe or depth of flow in an open channel)
These are the products of volcanic eruptions or the result of the breakdown of volcanic rocks.
Volcaniclastic sediments
This is material that is made up of particles or clasts derived from pre-existing rock
Terrigenous clastic material
makeup 20–25% of the sedimentary rocks in the stratigraphic record
Sandstones and conglomerates
makeup 60% of the sedimentary rocks in the stratigraphic record
mudrocks
any sedimentary rock containing over 50% calcium carbonate (CaCO3).
limestone
These are deposits formed by the
precipitation of salts out of water due to evaporation
Evaporites
what are the other sediments and sedimentary rocks
sedimentary ironstone,
phosphate sediments
organic deposits (coals and oil shales)
cherts (siliceous
sedimentary rocks).
A widely used classification chat/ grade scale for classifying the diameters of sediments
Uden-Wentworth grain size scale
in udden-Wentworth scale, φ ______ as diameter ________.
increase; decrease
size of boulder in udden-Wentworth grain size scale
> 256 mm , -8 phi
size of cobbles in udden-wentworth grain size scale
16-128 mm; -4 - -8phi
size of silt in udden-wentworth grain size scale
0.063 to 0.0039 mm; 4 to 8 phi
size of pebbles in udden-wentworth grain size scale
4-16 mm; -2 to -4phi
size of granules in udden-wentworth grain size scale
2-4mm ; -1 to -2phi
size of sand in udden-wentworth grain size scale
2-0.063 mm ; -1 to 4 phi
Sedimentary rocks made of silt- and clay-sized
particles. it is the most abundant
Mudrocks
Rock name for sedimentary rocks that is composed of gravel size (>2) sediments
Rudite
Rock name for sedimentary rocks that is composed of sand (0.065-2) size sediments
Aranite
Rock name for sedimentary rocks that is composed of Mud (<0.065) size sediments
