Sedimentary Rocks (TERMS)

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Sedimentary rock
a type of rock that is formed by sedimentation of material at the Earth's surface and within bodies of water
Sedimentology
The scientific discipline that studies the properties and origin of sedimentary rocks
Clastic sedimentary rock
are composed of silicate minerals and rock fragments that were transported by moving fluids and were deposited when these fluids came to rest
Breccia
are composed of dominantly angular gravel.
Mudrock
are sedimentary rocks composed of at least 50% silt- and clay-sized particles. These
relatively fine-grained particles are commonly transported as suspended particles by turbulent
flow in water or air, and deposited as the flow calms and the particles settle out of suspension
Mudrock
all rocks composed dominantly of
mud.
Biochemical sedimentary rock
Are created when organisms use materials dissolve in air or water to build their tissue.
Chemical sedimentary rock
forms when mineral constituents in solution become supersaturated and inorganically precipitate.
Siliciclastic sedimentary rock
are dominantly composed of silicate minerals. The sediment that makes up these rocks was transported as bed load, suspended load, or by sediment gravity flows. Siliciclastic sedimentary rocks are subdivided into conglomerates and breccias, sandstone, and mudrocks.
Carbonate sedimentary rock
are composed of calcite (rhombohedral CaCO3), aragonite (orthorhombic CaCO3), dolomite (CaMg(CO3)2), and other carbonate minerals based on the CO32-ion. Common examples include limestone and dolostone.
Evaporite sedimentary rock
are composed of minerals formed from the evaporation of water. The most common evaporite minerals are carbonates (calcite and others based on CO3 2-), chlorides (halite and others built on Cl- ), and sulfates (gypsum and others built on SO4 2-). Evaporite rocks commonly include abundant halite (rock salt), gypsum, and anhydrite.
Organic-rich sedimentary rock
have significant amounts of organic material, generally in excess of 5% total organic carbon. Common examples include coal, oil shale, and other sedimentary
rocks that act as reservoirs for liquid hydrocarbons and natural gas.
Siliceous sedimentary rock
are almost entirely composed of silica (SiO2), typically as chert, opal, chalcedony or other microcrystalline forms
Iron-rich sedimentary rock
are composed of >15% iron; the most common forms are banded iron formations and ironstones
Phosphatic sedimentary rock
are composed of phosphate minerals and contain more than 6.5% phosphorus; examples include deposits of phosphate nodules, bone beds, and phosphatic
mudrocks
Diagenesis
all the chemical, physical, and biological changes,
including cementation, undergone by a sediment after its initial deposition, exclusive of surface weathering
Clasts
fabric of the rock
Beds/strata
a layer of rock that has a uniform lithology and texture
Parallel lamination
all sedimentary layering is parallel
Graded bedding
a structure where beds with a smaller grain size occur on top of beds with larger grains.
Sedimentary environment
The setting in which a sedimentary rock forms
Sedimentary basin
Places where large-scale sedimentation takes place
Rift basin
A type of basin formed by the moving apart of two pieces of a continent
Sag basin
When a piece of lithosphere that was heated and stretched cools again, its density rises, causing isostatic subsidence
Fanglomerate
When a series of conglomerates accumulates into an alluvial fan, in rapidly eroding (e.g. desert) environments, the resulting rock unit is often called...
Arkosic sand
is sand that is similarly rich in feldspar, and thus the potential precursor of arkose.
Quartz arenite
are made up almost entirely of quartz grains, usually well sorted and rounded.
Lithic sandstone
contain many lithic fragments derived from fine-grained rocks, mostly shales, volcanic rocks, and fine-grained metamorphic rocks
Graywacke
is a heterogeneous mixture of lithic fragments and angular grains of quartz and feldspar, and/or grains surrounded by a fine-grained clay matrix
Eolianite
a term used for a rock which is composed of sand grains that show signs of significant transportation by wind.
Karst topography
a landscape shaped by the dissolution of a layer or layers of soluble bedrock, usually carbonate rock such as limestone or dolomite
Pseudokarst
are similar in form or appearance to karst features, but are created by different mechanisms.
Lithographic limestone
is hard limestone that is sufficiently fine-grained, homogeneous and defect free to be used for lithography
Spring
Deposits form on emergence from a spring/seep (hahaha).
Braided channel
Deposits form within a fluvial channel, dominated by oncoids
Cascade
Deposits form at waterfalls, deposition is focussed here due to accelerated flow
Barrage
Deposits form as a series of phytoherm barrages (lol) across a channel, which may grow upto several metres in height
Lacustrine tufa
are generally formed at the periphery of lakes and build up phytoherms (freshwater reefs) and stromatolites
Calcareous sinter
formed from ambient temperature water can be considered a sub-type of tufa.
Speleothems
may be regarded as a form of calcareous sinter. They lack any significant macrophyte component due to the absence of light, for this reason they are often
morphologically closer to travertine or calcareous sinter.
Tufa columns
are an unusual form of tufa typically associated with saline lakes.
Fiorite
Botryoidal geyserite
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