Clastic Rock

Deposited sediments can harden into rock over time; next, it compacts the sediments. That is, by the weight of sediments on top of them, they are pressed together. Next, together, the sediments are cemented. In the gaps between the loose sediment particles, minerals fill up. From the water that passes through the sediments, these cementing minerals come. These sedimentary rock forms are referred to as “clastic rocks.” In reference to sedimentary rocks as well as particles in the transport of sediments, whether in suspension or as bedload and in sediment deposits, geologists use the term clastic. Actually, clastic rocks are rock particles which are compacted and cemented together.

Rocks consisting mainly of broken pieces or clasts of older weathered and eroded rocks are Clastic sedimentary rocks. Conglomerate and breccia are made of individual cemented stones. Clastic sediments or sedimentary rocks are graded on the basis of grain size, composition of the clast and cementing content (matrix) and texture. The classification factors are also helpful for assessing the deposition environment of a sample. The stones in the conglomerate are squared. The stones in Breccia are angular. Sandstone is constructed from particles that are sand-sized. Siltstone is composed of particles which are smaller. Silt is smaller but larger than clay than sand. The smallest grain size is shale. Most of the shale is made from clay-sized particles and hardened mud.

As dissolved materials precipitate from the solution, chemical sedimentary rocks form. Chert, some dolomites, flint, iron ore, limestone, and rock salt are examples. The chemical and mineralogical elements of the structure as well as the cementing content that make up these rocks form the composition of siliciclastic sedimentary rocks. They are classified into four groups by Boggs; main minerals, accessory minerals, fragments of soil, and chemical sediments. Based on their resistance to chemical decomposition, major minerals can be divided into subdivisions. Those with great resistance to decomposition are classified as stable, whereas those that are not considered less stable are classified as stable.

From the deposition of plant or animal waste, organic sedimentary rocks form. Chalk, lead, diatomite, some dolomites, and some limestone are examples. In silicate sedimentary rocks, quartz is the most common stable mineral (SiO2). Quartz makes up about 65 percent of the structural grains found in sandstones and about 30 percent of the shale’s average minerals. Accessory minerals are correlated with minerals whose existence in the rock is not explicitly related to the specimen classification. In contrast to quartz and feldspar, these typically occur in smaller quantities. In addition, heavy minerals or coarse grained mica are usually those that occur (both Muscovite and Biotite).

In the composition of siliccyclastic sedimentary rocks, rock fragments also occur and are responsible for around 10-15 percent of the sandstone composition. They usually make up most of the particles in conglomerates of the gravel scale, but contribute only a very small amount to the mudrock composition. Rock fragments are not necessarily sedimentary in nature, although they often are. They can also be igneous or metamorphic. In abundance, chemical cements differ but are primarily found in sandstones. Silicate based and carbonate based are the two main groups. Most silica cements are made of quartz, but chert, opal, feldspar, and zeolite may be included. Composition involves the single or varied fragments’ chemical and mineralogical composition and the cementing material (matrix) binding the clasts together as a rock. Pyroclastic volcanic rocks such as tuff, agglomerate and intrusive breccias, as well as some marginal eutaxitic and taxitic intrusive morphologies, are found in Clastic igneous rocks. By flow, injection, or explosive destruction of solid or semi-solid igneous rocks or lavas, Igneous clastic rocks are broken. Clastic metamorphic rocks include breccias, as well as some protomylonite and pseudotachylite, formed in faults. Occasionally, by hydrothermal fluids, metamorphic rocks may be fractured, creating a hydrofracture breccia. Identifying a clastic rock as an impact breccia involves recognizing shatter cones, tektites, spherulites, and impact crater morphology, as well as recognizing unique signatures of chemical and trace elements, particularly osmiridium, potentially.

Information Sources:

  1. worldofstones.com
  2. learnbps.bismarckschools.org
  3. wikipedia