Types of Sedimentary Rocks

Several different types of sedimentary rocks can be distinguished according to the source of rock materials that form them  

Name of Particle Size Range (mm) Loose Sediment Consolidated Rock 

Source Adapted from Fichter, L.S., Sedimentary Rocks, James Madison University, Harrisonburg, VA, 2000 (http //csmres.jmu.edu/geollab/fichter/SedRx/). 

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As in the case of igneous processes, the sedimentary processes of rock formation lead to the formation economic mineral deposits. Many valuable mineral deposits of iron, manganese, copper, phosphorus, sulfur, zirconium, the rare Earths, uranium and vanadium owe their origin to sedimentary processes. Some of these constitute special types of sedimentary rocks, while others form important constituents of sedimentary rocks. 

Coal is Interspersed as individual beds within other types of sedimentary rock beds, including sandstones, limestones, clays, shales, and mixtures of these materials. The plant material that ultimately became coal deposits was accumulated in upland bogs, coastal or near-coastal swamps, or della plains. It is envisioned that the conditions were somewhat similar to the conditions existing today in the Okefenokce Swamp in Georgia or the Everglades of Florida. These areas may have varied from a few acres in several hundreds of square miles (hectares/square kilometers). Hence, the variation in ihe occurrence of coal as we find it today. 

Sedimentary rocks with the highest arsenic concentrations largely consist of materials that readily sorb or contain arsenic, such as organic matter, iron (oxy)(hydr)oxides, clay minerals, and sulfide compounds. Arsenian pyrite and arsenic-sorbing organic matter are especially common in coals and shales. Ironstones and iron formations are mainly composed of hematite and other iron (oxy)(hydr)oxides that readily sorb or coprecipitate arsenic. Iron compounds also occur as cements in some sandstones. Although almost any type of sedimentary rock could contain arsenic-rich minerals precipitated by subsurface fluids (Section 3.6.4), many sandstones and carbonates consist almost entirely of minerals that by themselves retain very little arsenic namely, quartz in sandstones and dolomite and calcite in limestones. 

When a portion of the rock is well-cemented while the material around it is not, this can result in differential erosion as the weaker material is worn away. Concretions are masses of well-cemented sediment that often form around a core, sometimes a fossil or a fragment of rock. These structures are often spherical or rounded and occur in many different types of sedimentary rocks. 

Certainly, CO2 evolved during late diagenesis must ultimately return to the atmosphere/ocean. It also seems clear that transport of major components such as silicon and potassium between sandstones and shales at a scale of a few meters is required and can perhaps be accomplished by diffusion (Thyne et ai, 2001). New data, especially for shales, must be obtained before simultaneous quantitative balances can be proposed for the reactions in Table 1. The speciation of aluminum in pore fluids, the initial and final quantities of the reactants and products in both sandstones and shales, and the precise volumes of sandstones and shales in the sequences in question are key data needed to ascertain the scale of mobihty for the major elements in late diagenesis. Our abihty to answer basic questions about the rock cycle falls short, in large part, for lack of information about the major mineral components of shale, the most common type of sedimentary rock. 

Background on Primary Petroleum Products. Petroleum is a natural resource found in many types of sedimentary rock formations. Naturally occurring petroleum is a complex mixture of gaseous, liquid, and solid hydrocarbons. Entire industries have grown up around the activities required to produce the crude oil, transport it to refineries, and convert the natural petroleum into a variety of end... 

The abundance of analcite in certain types of sedimentary rocks and the general rarity of gmelinite suggests that sodic gmelinite is generally unstable with respect to analcite plus water. 

Briefly, sedimentary rocks are formed by the accumulation of sediments. There are three basic types of sedimentary rocks (1) clastic sedimentary rocks, such as breccia, conglomerate, sandstone, and shale, which are formed from mechanical weathering debris, (2) chemical sedimentary rocks, such as rock salt and some limestone rocks, which form when dissolved materials precipitate from solution, and (3) organic sedimentary rocks, such as coal and some limestone rocks, which form from the accumulation of plant or animal debris. 

Because coal is a type of sedimentary rock, 100 or so mineral can occur in coal however, only about 15 are abundant enough to have high importance. It must be noted that minor impurities commonly substitute for the major cations as well as some anions which account for a considerable fraction of the minor and trace elements reported in coals. 

Although graded bedding occurs in several different types of sedimentary rock, it is characteristic of greywacke. As the name suggests, the sedimentation unit exhibits a grading from coarser grain size at the bottom to finer at... 

Natural CaCOs constitutes the most frequently occurring type of sedimentary rock on our planet It covers about 1 % of the earth s crust Natural CaCOs occurs in three major geological modifications. Chalk was and is formed in the oceans through biomineralization and the reactions of calcium salts with the CO2 in the air. By geological transformation (pressure) and thermal metamorphosis (heat and pressure), it is modified into limestone and marble. 

Ionic compounds occur throughout Earth s crust as minerals. Examples include limestone (CaC03), a type of sedimentary rock gibbsite [Al(OH)3], an aluminum-containing mineral and soda ash (Na2C03), a natural deposit. We can also find ionic compounds in the foods that we eat. Examples include sodium chloride (NaCl), which is table salt calcium carbonate (CaCOs), a source of calcium necessary for bone health and potassium chloride (KCl), a source of potassium necessary for fluid balance and... 

Evaporate sediments are a special type of sedimentary rock that is formed from the concentration of dissolved salts through evaporation (for example rock salt/haHte). 

With respect to the velocity and its behaviour, there are two types of sedimentary rocks ... 

The most detailed studies of mixed-layer minerals have been made in sedimentary materials, and it is desirable to refer briefly to these, because the minerals in such materials have often been better characterized than in soils, and further, mixed-layer minerals in soils may, in some cases, have been inherited from the parent materials. The classical work on this is Weaver s [1957] study of the clay petrology of sediments, which is referred to in Section DI2. He has found mixed-layer minerals in various types of sedimentary rocks varying in age from Devonian-Ordovician to Upper Ordovician. 

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