Transcript From: “Sedimentary Rocks”

Sediment - particulate material transported and deposited
by wind, water, or ice, chemically precipitated from
solution, or secreted by organisms, that forms in layers
in loose, unconsolidated form.
Unconsolidated material - A sediment that is loosely arranged or
unstratified, or whose particles are not cemented
together, occurring either at the surface or at depth.
Sedimentary rock - A layered rock resulting from the consolidation
of sediment.
And
Sedimentary
Rocks
Metamorphic
Rocks
Erosion
Heat and Pressure
Magma
Sediment
Igneous
Rocks
Material (such as gravel, sand, mud, and
lime) that is transported by wind, water, ice,
or gravity;
Material that is precipitated from solution;
Deposits of organic origin (such as coal
and coral reefs).
Rock formed by the
accumulation and
consolidation of sediment.
-unconsolidated particles
created by
1. The weathering of rock
2. The secretions of organisms
or decomposition of organic
matter
3. Chemical precipitation
Composed of lithified sediments
- by compaction
- by cementation
Two Classifications
- clastic
-nonclastic
Clastic Sedimentary Rocks
Organic Sedimentary Rocks
Chemical Sedimentary Rocks
Skeletal (Bioclastic) Sedimentary Rocks
Clastic
Sedimentary
Rocks
Composed of
fragments of
older rocks that
have been
deposited and
consolidated
Chemical
Sedimentary
Rocks
Biochemical
Sedimentary
Rocks
Form when
Composed of
minerals
accumulations of
precipitate from
organic debris
ions dissolved in (they are included
water (an aqueous
in chemical
solution)
sedimentary
rocks)
From: “Sedimentary Rocks”
1. Clastic
2. Biogenic
3. Chemical
1. Clastic – broken fragments of
rock produced by weathering.
Range in size from largest boulder
to smallest clay particle.
Classified according to size.
Found everywhere on the Earth.
Texture - Size, shape, and distribution
of particles that collectively make up a
rock
•Size
•Rounding
•Sphericity
•Sorting
Roundness – the shape of sediment
grains.
Related to the distance a sediment has
been transported.
Sphericity - how close to a
spherical shape a grain is or will be.
Sorting – separation of sediments
by grain size and density.
Poorly sorted – sediment with a
wide range of grain sizes.
Well sorted – sediment with a
small range of grain sizes.
Sorting - a function of transported
1. Water
2. Wind
3. Glaciers
Udden-Wentworth Scale
Fluid Dynamics
Modes of Transport
Suspended Load
Bed Load
Saltation
Progressive Sorting
Graded Beds
Fining
up
Compaction
Compaction - reduction in bulk volume or
thickness of fine-grained sediments,
owing to increasing weight of overlying
material that is continuously being
deposited, or to pressures resulting from
earth movements. Tighter packing of
sedimentary particles results in a
decrease in porosity.
Cementation
Cementation - the process by which clastic
sediments are converted into rock by
precipitation of a mineral cement
among the grains of the sediment.
Cement - chemically precipitated mineral
material that occurs in the spaces
among the grains of a sedimentary
rock, thus binding the grains into a
rigid mass. The most common cements
are silica, carbonates, and iron oxides.
Crystallization
Crystallization - the development and growth
of crystals by precipitation from
solution at or near the Earth's surface.
Bioclastic and Chemical Sedimentary
Rocks
Carbonates
Evaporites
Organic Sedimentary Rocks
Clastic Sedimentary Rocks - Examples
Conglomerate
Sandstone
Siltstone
Graywacke
Shale
Breccia
Bedforms
Mudcracks
In general, as transport distance
increases, rounding and sorting
increase.
Examples:
Breccia – cemented close to source
Conglomerate – transported then
cemented
Size and Mode of Transport
Transport-Related Properties
Cross-Bedding
Tidal Flat Deposit
Stream Deposit
Large Clasts
Small Clasts
Rock Type
Sediment Grain Size
Shale
Clay
less than 0.001 mm
Siltstone
Silt
.001-0.1 mm
Sandstone
Sand
.01-1 mm
Conglomerate Gravel
1mm +
Sedimentary rocks made of silt- and claysized particles are collectively called
mudrocks, and are the most abundant
sedimentary rocks.
Strata
Stratum
Stratigraphy
Stratigraphic
Formation –
smallest mappable
unit
Almost Always Present in Sedimentary
Rocks
Originally Horizontal
Tilting by Earth Forces Later
Variations in Conditions of Deposition
Size of Beds (Thickness)
• Usually 1-100 Cm
• Can Range From Microscopic to 50m
Evaporites -Water
Soluble
• Halite
• Gypsum
• Calcite
Precipitates
Example: Ca(sol'n) +
SO4 (Sol'n) = CaSO4
• Gypsum
• Limestone
• Iron Formations
Alteration After
Deposition
• Dolomite
Biogenic Sediments
• Limestone - Shells,
Reefs, Etc.
Organic Remains
• Coal
• Petroleum
Chemical Sedimentary Rocks - Evaporites
Rock salt
NaCl
Anhydrite
CaSO4
Rock gypsum
CaSO4. H2O
Bioclastic Sedimentary Rocks - Carbonates
(Limestones)
Coquina
Chalk
Coraline limestone
2. Biogenic – composed of
remains of plants or animals.
Terestrial Sediments - mainly plant matter
Marine Sediments - mainly carbonates
Corals - Large components of reefs.
Bivalves, Gastropods, Foraminifers Whole or partial skeletons form sand and
gravels.
Algae, Crinoids, Echinoderms, Bryozoans
- disintergrate to form some sand particles
and lime mud.
Diatoms, Radiolaria – Bedded chert SiO2
3. Chemical – formed by minerals
precipitating from solution.
Inorganic process, no biological
activity involved.
1. Terestrial - Evaporites:
Gypsum - CaSO4 . H2O
Anhydrite - CaSO4
Halite - NaCl
2. Marine Carbonates - CaCO3
Clastic Rock – composed of
fragments of pre-existing rocks.
Nonclastic Rock – composed of
chemical precipitates or biogenic
matter.
Inorganic theories
• carbides of iron, calcium etc.. When contacted with
water
• action of hot water on limestone, CaCO3 and gypsum
Organic theories
• Animal theories: due to decomposition of marine
animals - fishes, oysters, other microscopic organisms.
• Vegetal theories: due to decomposition of plants –
seaweeds
• Land plants such as those in swamps: coal beds, oil
• Microscopic plants: Diatoms and Non-fossil organisms
- planktons
Likely scenario: oil
=
ancient animal + plants:
paraffinic base - vegetal origin
asphaltic base - animal origin
SEA/FRESH WATER
Water prevents
rapid oxidation of
organic material
Plants and animals
Source rock – mostly shales
Final accumulation of oil – sandstones,
limestones, fractured shales
Trapped hydrocarbons
Limestone/sandstone Secondary
Regional flow
of water
Shale
10’s – 100’s km
primary
Anticlines
Faults
Stratigraphic
Salt domes
Combination
Anticlinal/fault
traps
Overlap on beds flanking
the basement rock
Shore
Offshore
SEA LEVEL RECEDING
Shoreface
Near shore/Shallow Marine
Offshore/Deep Marine
Coarse grain sediments
Coarse grain with clay
Fine grain sediments
Fine grains with
clay
SEA LEVEL ADVANCING
Sedimentary rocks:
Source rock:
old sedimentary
Wind + water
+ igneous
+ organisms +
chemical action
Compaction/
Cementation:
Broken down
sediments
Deltas, shore
face, valley fills
Sandstones
Sandstones: compacted quartz sands – fragments of rock crystals
Limestones: Skeletons of lime-secreting organisms, corals etc..
Diatomaceous shales: Diatoms and other microscopic plants
Gypsum/Anhydrides/Limestones: Chemical dissolution of
rocks, followed by evaporation and crystallization
Conglomerates:
Loose aggregate of rounded pebbles – gravels
when cemented – conglomerates.
Porosity due to differential cementation
Oil fields in Pennsylvania, Texas, Oklahoma
Sand, Sandstones:
Finer sediments – yet noticeable, angular
Sands cemented by calcite – sandstones
silica – quartzite
Porosity due to voids and inter-grain spaces also
differential cementation
Pools in California, Alberta, Gulf Coast, Texas
Clays, shales: Fine grained particles – aluminous materials,
trapped water
Deep ocean sediments :
Compaction yields shales
Porosity in cracks and fissures
Some pools in Santa Maria Basin, California, Gas in
Kentucky
Limestone: Principally CaCO3, hard and crystalline rock,
Marl, chalk, dolomites – other forms
Porosity due to weathering and solution – vugs
Many pools in mid-continent, Alberta, Middle east, Saudi
Arabia
Cherts: Chemically pure silica – cryptocrystalline –
crystals visible only under magnification
• Occurrence as small nodules or large masses
parallel to bedding plane
• Porosity due to fractures
• Major pool – Offshore California, Monterey cherts
Grain Size - Power of Transport
Medium
Grading - Often Due to Floods
Rounding } Transport, Reworking
Sorting
Cross-bedding - Wind, Wave or Current
Action
Fossils
• Salt Water - Corals, Echinoderms
• Fresh Water - Insects, Amphibians
• Terrestrial - Leaves, Land Animals
Color And Chemistry
• Red Beds - Often Terrestrial
• Black Shale - Oxygen Poor, Often Deep
Water
• Evaporites – Arid Climates
Dimension stone can be defined as natural rock
material quarried for the purpose of obtaining
blocks or slabs that meet specifications as to size
(width, length, and thickness) and shape. Color,
grain texture and pattern, and surface finish of
the stone are normal requirements. Durability is
mainly based on mineral composition and
hardness and past performance.
Although a variety of igneous, metamorphic, and sedimentary rocks
are used as dimension stone, the principal rock types are granite,
limestone, marble, sandstone, and slate. Other varieties of
dimension stone may be used. They are normally considered to be
special minor types which include alabaster (massive gypsum),
soapstone (massive talc), and various products fashioned from
natural stone.
may be defined as:
the extraction of building stone or slate from
an open surface quarry.Quarrying plays a
very important role in the use of dimension
stone. Dimension stone is stored in a
‘quarry’ until it is needed by it’s
manufacturer. Dimension stone may be used
for many purposes. It can be, and often
times is used in the construction of
buildings and cemeteries.
Sedimentary rocks is the
most abundant type of
rocks in Canada.
Also, Hamilton and
surrounding area lay
mostly on sedimentary
rocks.
Natural Resources Canada, 2004