cementation, in geology, hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces It is the last stage in the formation of a sedimentary rock
What does compaction and cementation mean?
cementation: When fluids deposit ions to create a cement that hardens loose sediments compaction: When sediments are squeezed together by the weight of sediments and rocks on top of them
What is an example of cementation?
The new pore-filling minerals forms “bridges” between original sediment grains, thereby binding them together In this way, sand becomes sandstone, and gravel becomes conglomerate or breccia Cementation occurs as part of the diagenesis or lithification of sediments
What type of rock is cementation?
At the same time the particles of sediment begin to stick to each other – they are cemented together by clay, or by minerals like silica or calcite After compaction and cementation the sedimentary sequence has changed into a sedimentary rock
What is the role of cementation?
Cementation reduces the porosity and permeability of a sand In some cases, however, solution of cement or grains can reverse this trend
What does cementation mean and in what type of rock does it occur?
Cementation, in geology, hardening and welding of clastic sediments (those formed from preexisting rock fragments) by the precipitation of mineral matter in the pore spaces It is the last stage in the formation of a sedimentary rock
What’s the difference between compaction and cementation?
Compaction happens when sediments are deeply buried, placing them under pressure because of the weight of overlying layers This squashes the grains together more tightly Cementation is where new minerals stick the grains together – just as cement (from a bag) binds sand grains in a bricklayer’s mortar
What is compact rock?
A rock so closely grained that no component particles or crystals can be recognized by the eye
What is cementation value?
The range of values for the cementation exponent is relatively small Most porous arenaceous sediments have cementation exponents between 15 and 25 (Glover et al, 1997) Values higher than 25, and as high as 5, are generally found in carbonates where the pore space is less well connected (Tiab and Donaldson, 1994)
What is non clastic sedimentary rock?
Non-clastic textures are found chiefly in rocks that have precipitated chemically from water (chemical sedimentary rocks), such as limestone, dolomite and chert Other non-clastic sedimentary rocks include those formed by organisms (biochemical rocks), and those formed from organic material, such as coal
What causes compaction and cementation?
1 Compaction occurs when the overlying sediments’ weight compacts the grains as tightly as possible 2 Cementation is the process whereby dissolved minerals in the water between the grains crystallize cementing the grains together
What are conglomerate rocks?
Conglomerate is a sedimentary rock made of rounded pebbles and sand that is usually held together (cemented) by silica, calcite or iron oxide It is a stone similar to sandstone but the rock particles are rounded or angular gravel rather than sand
What is calcite mineral used for?
Calcite is the mineral component of limestone which is used primarily as construction aggregates, and in production of lime and cement
How stratified rock is formed using cementation?
Sediments are squeezed together by the weight of overlying sediments on top of them This is called compaction Cemented, non-organic sediments become clastic rocks Fluids fill in the spaces between the loose particles of sediment and crystallize to create a rock by cementation
What do you mean by cementation Class 12?
Cementation process is the hardening of cement during the process of construction The process starts after adding water to the mixture of cement, sand and small stone pieces In this, a gel type of product is formed which gets thickened and hardened gradually So cementation is the process of gel formation
What will be the form of rocks when subjected to compaction and cementation?
Sedimentary – A rock formed as a result of the weathering process, either by compaction and cementation of rock mineral fragments, or the precipitation of dissolved minerals Metamorphic – These rocks form as existing rocks are subjected to intense heat and/or pressure, usually over long periods of time
What is fine grained rock?
Definition: Igneous rock in which the framework of the rock consists of crystals that are too small to determine mineralogy with the unaided eye; framework may include up to 50 percent glass A significant percentage of the rock by volume may be phenocrysts
What is cementation chemistry?
Cementation is a type of precipitation, a heterogeneous process in which ions are reduced to zero valence at a solid metallic interface The process is often used to refine leach solutions Copper ions in solution, often from an ore leaching process, are precipitated out of solution in the presence of solid iron
What is the difference between clastic and bioclastic sedimentary rocks?
Sedimentary Rock Formation Sediments are squeezed together by the weight of overlying sediments on top of them This is called compaction Cemented, non-organic sediments become clastic rocks If organic material is included, they are bioclastic rocks
What causes sediment to cement or glue together?
The weight of the sediments squeezes the particles together As more and more sediments are deposited the weight on the sediments below increases Waterborne sediments become so tightly squeezed together that most of the water is pushed out These minerals act as glue or cement to bind the sediments together
What do you call the compactness of minerals?
81 Density—A Measure of Compactness
What type of rock is produced if there is too much heat and pressure?
Metamorphic rocks form when rocks are subjected to high heat, high pressure, hot mineral-rich fluids or, more commonly, some combination of these factors
What compacted sediments?
In sedimentology, compaction is the process by which a sediment progressively loses its porosity due to the effects of pressure from loading When a layer of sediment is originally deposited, it contains an open framework of particles with the pore space being usually filled with water
What are metamorphic rocks short answers 7?
(vii) Metamorphic rocks are the rocks that get formed under great heat and pressure Igneous and sedimentary rocks, when subjected to heat and pressure, get transformed into metamorphic rocks For example, clay changes to slate and limestone into marble
Is Tuff intrusive or extrusive?
Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals Some cool so quickly that they form an amorphous glass These rocks include: andesite, basalt, dacite, obsidian, pumice, rhyolite, scoria, and tuff