Sedimetary Petrology (Intro) Flashcards
Pieces of broken down, pre-existing rocks at or near the Earth’s surface.
Sediments
Rocks that are made up of lithified sediments.
Sedimentary Rocks
A sub-branch of Petrology that focuses on the composition, characteristics, and origins of sedimentary rocks.
Sedimentary Petrology
A simple model of the processes responsible for the production of sedimentary rocks
Sedimentary Cycle
Area of uplifted rocks that will undergo weathering
Zone of Production
Area where sediments accumulate that will undergo diagenesis
Zone of Deposition
Enumerate the sequence of formation of Sedimentary Rocks.
- Weathering
- Erosion
- Transport
- Deposition
- Diagenesis
The process that breaks down rocks into sediments.
Weathering
The physical removal of material by mobile agents such as water, wind, ice, and gravity.
Erosion
The transfer of rock and soil downslope under the influence of gravity.
Mass Wasting
Factors, particularly temperature and moisture, are crucial to the rate of rock weathering.
Climate
Chemical traits of rocks, including mineral composition and solubility.
Rock Characteristics
Unequal weathering due to the rock’s composition.
Differential Weathering
A mixture of minerals, organic matter, water, and air.
Soil
The layer of rock fragments produced by weathering.
Regolith
The study of physical and chemical properties of soils and its formation.
Pedology
The source of the weathered mineral matter from which soils develop.
Parent Material
Strongly influences weathering by the length of the time that processes have been operating.
Time
Climactic elements, such as temperature and precipitation, that exert the strongest impact on soil formation
Climate
The types of abundance of organisms present have a strong influence on the physical and chemical properties of the soil.
Organisms
Variations in topography can lead to the development of a variety of localized soil types.
Topography
Zones of soil with varying composition, texture, and structure found at different depths.
Horizons
A vertical profile of all the soil horizons.
Soil Profile
Washing out of fine soil components.
Eluviation
Depletion of solube minerals from the upper horizons.
Leaching
Constitutes the O and A horizon.
Topsoil
Soil horizon that consists largely of organic material.
O Horizon
The zone beneath the O horizon that is largely mineral matter, with biological activity is high and humus generally present at up to 30% in some instances.
A Horizon
A light-colored layer, known as the Zone of Eluviation and leaching, that contains little organic material.
E Horizon
Also called as the subsoil, is the zone of accumulation where much of the material removed from the E horizon by eluviation is deposited.
B Horizon
Also called as the true soil, that constitutes the O, A, E, and B horizon.
Solum
The layer of partially altered parent material.
C Horizon
The unweathered parent material.
R Horizon
A system of soil classification based on the physical and chemical properties of the soil profile.
Soil Taxonomy
High-nutrient
Alfisol
Volcanic
Andisol
Desert
Aridosol
New
Entisol
Permafrost
Gelisol
Organic
Histosol
Young
Inceptisol
Prairie
Mollisol
Tropical Forest
Oxisol
Conifer Forest
Spodosol
Low-Nutrient
Ultisol
Swelling Clay
Vertisol
The physical breakdown (disintegration) and the chemical alteration (decomposition) of rocks at or near Earth’s surface.
Weathering
The physical breakdown or disintegration of rocks at or near the surface.
Mechanical Weathering
The chemical breakdown or decomposition of rocks at or near the Earth’s surface.
Chemical Weathering
The freeze-thaw action of water trapped within fractures of rocks that cause the expansion and contraction which would eventually disintegrate rocks.
Frost Wedging
A mode of weathering near coastlines where salt from seawater accumulate and grow through cracks and fracture them while growing.
Salt Crystal Growth
Rocks that are originally covered and are then exposed are relieved from pressure, causing an unloading action and expansion
Sheeting or Unloading
Organisms, such as plants, can burrow their roots through cracks which breaks down the rocks into pieces.
Biological Actions
The intrusions from beneath the surface induce pressure from below, fracturing the rock mass on the surface
Intrusions
A solution mixture of reactive components to specific rocks.
Solution
Chemical breakdown of minerals in rocks due to addition of water.
Hydrolysis
Chemical breakdown of rocks due to exposure to oxygen.
Oxidation
Enumerate the rock forming silicate minerals according to their resistance to chemical weathering. (From least resistant to most resistant)
- Olivine
- Ca-Feldspars
- Pyroxenes
- Amphiboles
- Na-Feldspars
- Biotite Mica
- K-Feldspars
- Muscovite Mica
- Quartz
Enumerate the weathering products from the rock forming silicates. (Clay Minerals)
Kaolinite, Illite, Montmorillonite, and Chlorite
The removal of materials or sediments by mobile agents such as water, ice, wind, or humans.
Erosion
Enumerate the 4 transport medias of sediments.
Air, Water, Ice, and Gravity
Mode of Transport: (BEDLOAD)
Sediments rolling along the surface of the bed.
Rolling
Mode of Transport: (BEDLOAD)
A series of jumping movement of sediments.
Saltation
Mode of Transport: (SUSPENDED LOAD)
Sediments suspended in the transporting media.
Suspension
The volume of void spaces in a sedimentary rock.
Porosity
Porosity associated with the original depositional texture of the sediment.
Primary Porosity
Porosity that developed after deposition and burial of the sediment in the sedimentary basin.
Secondary Porosity
The measure of how much water can move through pore spaces which also describes how water easily flows.
Permeability
A property of curve being tortous, or twisted, having many turns.
Tortuosity
Occurs when transportation ceases and sediments accumulate on Earth’s surface by collective deposition processes.
Deposition
Encompasses a variety of low-temperature processes that affect sediments after their accumulation, typically after burial.
Diagenesis
Process of lithification that results from the expulsion of intergranular fluids caused by increases in confining pressure during progressively deeper burial.
Compaction
Process of lithification that occurs when subsurface fluids precipitate minerals in the spaces between grains, binding or cementing grains together.
Cementation
The minerals that commonly form cement include:
- The most abundant type is quartz, often occurs as syntaxial quartz overgrowths, where it precipitates from pore solutions and nucleates on a pre-existing detrital quartz grain.
Silica minerals
The minerals that commonly form cement include:
- Its most abundant cements are sandstones and gravel stones. where calcite is the most common mineral cement.
Carbonate minerals
The minerals that commonly form cement include:
- Third most common cementing agents in sedimentary rocks. hematite, goethite, and limonite being its chief cements.
Iron Oxides and Hydroxides
The minerals that commonly form cement include:
- Occurs in feldspar-rich detrital sedimentary rocks like arkosic sandstones and gravel stones.
Feldspars
The minerals that commonly form cement include:
- Found in some detrital sedimentary rocks. their stabilities are strongly controlled by temperature and pH. And can also act as a cementing agent, especially in shales.
Clay minerals
The formation of new quartz crystals that grow on the surface of existing quartz grains during diagenesis. These overgrowths occur in sedimentary rocks and are part of the cementation process.
Syntaxial quartz overgrowths
Stages in Diagenesis:
- Early, shallow diagenesis, occurs shortly after burial.
EODIAGENESIS
Stages in Diagenesis:
- Later, deeper diagenesis.
MESODIAGENESIS
Stages in Diagenesis:
- Still later, shallow diagenesis occurs as sedimentary rocks approach the surface due to erosion.
TELODIAGENESIS
What are the two main categories of sedimentary rocks?
Clastic and non-clastic
Formed from the accumulation and cementation of fragments of other rocks or minerals.
Clastic sedimentary rocks
Rocks formed from volcanic debris.
Volcaniclastic
Rocks formed from fragments of continental rocks.
Terrigenous clastic
Three category of Terrigenous clastic includes:
- Fine-grained rocks made of clay minerals.
Mudrocks
Three category of Terrigenous clastic includes:
- Medium-grained rocks made of sand-sized particles.
Sandstones
Three category of Terrigenous clastic includes:
- Coarse-grained rocks made of gravel-sized particles.
Conglomerate or Breccia
Formed by chemical precipitation or the accumulation of organic material.
Non-clastic sedimentary rocks
Example of Volcaniclastic
Tuff and Ignimbrites
Rocks composed primarily of carbonate minerals, such as limestone and dolomite.
Carbonates
Rocks formed from the evaporation of mineral-rich waters, such as halite (salt) and gypsum.
Evaporites
What other variety of non-clastic rocks includes?
- coal
- ironstones
- phosphates
- siliceous deposits
What are the four main principal components of sedimentary rocks?
Mineral grains, lithic fragments, biogenic material, and chemical precipitates
Give examples of mineral grains found in sedimentary rocks.
Quartz, mica, feldspar, calcite
These are individual mineral crystals that make up the rock.
Mineral grains
These are fragments of other rocks that have been eroded and transported to the depositional environment.
Lithic fragments
These are organic materials derived from living organisms
Biogenic material
These are minerals that have precipitated from solution in water
Chemical precipitates
Examples of Chemical precipitates
- carbonates
- chlorides
- sulfates
- silica
Examples of Biogenic material
- shells
- skeletal material
- plant debris
- algae
- bacteria
- bone
Examples of Lithic fragments
- limestone
- mudrock
- volcanic rock
- metamorphic rock
Examples of Mineral grains
- quartz
- mica
- feldspar
- calcite
Refers to the size of the individual particles that make up the rock. It can be classified using a variety of scales, but one of the most common is the phi scale.
Grain size
a logarithmic scale that expresses grain size in terms of its diameter (d)
Phi scale
Formula of Phi scale?
Phi = -log₂(d)
Coarse fraction, includes particles from sand to gravel
Clasts
Fine fraction, includes mud-sized particles.
Matrix
Used to represent the typical particle size in a population.
Central measure
BAR graph showing the weight percentage of clasts at different phi values.
Histogram
LINE graph showing the weight percentage of clasts at different phi values.
Frequency curve
Line graph showing the cumulative weight percentage of all particles coarser than a given phi value.
Cumulative curve
Most abundant particle size.
Mode
Average size of the particles, calculated as the sum of all particle sizes divided by the number of particles.
Mean
Average diameter of the particles, calculated using a formula involving the 16th, 50th, and 84th percentiles of the particle size distribution.
Graphic geometric mean (GM)
Method of determining the grain size distribution of sediments by passing them through a series of stacked sieves with different mesh sizes.
Sieving
Provides information about the nature and maturity of the grains.
Grain Shape
Factors affecting shape?
- Lithology (the type of rock the grains came from)
- Hardness
Spheroid particles with similar dimensions in all directions.
Equant
Rod-shaped particles with an elongated cylindrical shape.
Prolate
Disk-shaped particles with a flattened cylindrical or disk-like shape.
Oblate
Particles that have a flattened shape where the three axes (length, width, and thickness) have significantly different lengths.
Bladed
Distribution of grain sizes present within a sedimentary rock.
Sorting
Quick method of determining the phi size value for any percentile.
Sorting coefficient
More complicated measure of sorting that involves finding values that are one and two standard deviations above and below the mean.
Inclusive graphic standard deviation
Volume of void space in a sedimentary rock, expressed as a percentage.
Porosity
Arrangement of grains in a rock.
Packing density
Loose arrangement with 48% porosity.
Cubic packing
Denser arrangement with 26% porosity.
Rhombohedral packing
Ability of a rock to allow fluids to pass through it. It is influenced by factors such as grain size, sorting, and porosity.
Permeability
2 Ways to Measure Maturity:
- Textural
- Compositional
Measures how much a sedimentary rock has been transported and eroded, based on its physical characteristics.
Textural maturity
Degree of maturity that measures the amount of components present
Compositional maturity
Soils that are derived from broken down ultramafic rock.
Laterites
The sequence of formation of Soil Horizons.
- R
- C
- O
- A
- E
- B
Frost action characterized by lateral movements.
Frost Wedging
Frost action characterized by vertical movements.
Frost Heaving
Description of the layers that formed when a surface is exposed through sheeting or unloading.
Onion Layers
Occurs when glaciers pulverizes the rock beneath it.
Rock Flour
The point before metamorphism.
Diagenesis
During frost action, water expands by ____ %.
9%
Term for the “Soil” from the moon.
Lunar Regolith
The most effective transport media
Water
The strongest transport media
Ice
A process of cementation wherein the minerals precipitate surrounding the sediment particles, instead of the void spaces.
Syntaxion
