Shelly limestone is a highly fossiliferous

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms w ...

, composed of a number of fossilized organisms such as

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

s, bryozoans, crinoids,

sponge Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate throu ...

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

s and

mollusk Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is e ...

s. It varies in color, texture and hardness.

Coquina Coquina () is a sedimentary rock that is composed either wholly or almost entirely of the transported, abraded, and mechanically sorted fragments of the shells of mollusks, trilobites, brachiopods, or other invertebrates. The term ''coquin ...

is a poorly

indurated Friability ( ), the condition of being friable, describes the tendency of a solid substance to break into smaller pieces under duress or contact, especially by rubbing. The opposite of friable is indurate. Substances that are designated hazardous, ...

form of shelly limestone. Shelly limestone is a sedimentary rock because it is made up of fragments. To be shelly, it is full of broken shells which are "glued" together with

calcite Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratc ...

. Calcium carbonate often makes up around 10% of the volume, whilst many varied sized shells from granular to very large pebbles. Its color is gray.

Formation

Each shelly limestone is unique in its own way, where every stone of this type is composed of different fossilized organism and shell fragments. Shelly limestones are mainly found near where marine life live or where marine life once occupied. The unique qualities of a shelly limestone are formed with the help of calcite, acting as a sticking agent for small shell fragments, dead marine organism and other minerals. Typically, the rock is composed of approximately 10 percent calcium carbonate. The appearance of shelly limestones can differ in color, composition, hardness and texture depending on where the stone is formed. Generally, however, shelly limestones have noticeable shell fragments in various sizes. Shelly limestone is considered a carbonate rock because the stone is mainly composed primarily of carbonate minerals. In detail, shelly limestones are formed when rocks containing different minerals get weathered down then get transported to a standing body of water. From here organisms that precipitate carbon, phosphate, and silicate materials (which forms the rock's shelly texture) combine with the minerals and go through a process called deposition, where the minerals and organic components sort by size and density. Once sorted, the fragments go through diagenesis, where the fragments compress and cement together, and over time will form a shelly limestone. Shelly limestone can be found dating back to Precambrian and Cambrian times.

Applications

Shelly limestone can be found worldwide and are used to help identify the time period the limestone was formed, different types of organism that were alive in a specific time period, as well as, conditions of the environment based on its mineral composition. These fossil shells can also contain elements and geochemical details that can help determine changes in the climate.Benton, M. J, and D. A. T Harper. Introduction to Paleobiology and the Fossil Record. Wiley-Blackwell, 2009. Other applications of limestone include being used to produce cement for roads and other foundations. Due to the stones high calcium carbonate content, it can also be used in the agricultural industry as an agent that helps reduce acidity in soil.

Bibliography

* Matthews, SC, and Missarzhevsky, VV. (1975). "Small Shelly Fossils of Late Precambrian and Early Cambrian Age: A Review of Recent Work." ''Journal of the Geological Society'' 131.3: 289–303. https://doi.org/10.1144/gsjgs.131.3.0289 * Brasier, MD. (1984). "Microfossils and Small Shelly Fossils from the Lower Cambrian Hyolithes Limestone at Nuneaton, English Midlands." ''Geological Magazine'' 121.3: 229–53. https://doi.org/10.1017/S0016756800028296 * Jago, JB, Zang, Wen-Long, Sun, Xiaowen, Brock, GA, Paterson, JR, and Skovsted, CB. (2006). "A Review of the Cambrian Biostratigraphy of South Australia." ''Palaeoworld.'' 15.3-4: 406–23. https://doi.org/10.1016/j.palwor.2006.10.014 * Mohammed Haneefa, K, Santhanam, Manu, and Parida, FC. (2013). "Review of Concrete Performance at Elevated Temperature and Hot Sodium Exposure Applications in Nuclear Industry." ''Nuclear Engineering and Design'' 258: 76–88. https://doi.org/10.1016/j.nucengdes.2013.01.018 * Evans, KR, and Rowell, AJ. (1990). "Small Shelly Fossils from Antarctica: An Early Cambrian Faunal Connection with Australia." ''Journal of Paleontology'' 64.5: 692–700. https://doi.org/10.1017/S0022336000018928

Notes

{{Reflist

References

Shelly limestone
Limestone

Formation

Applications

Bibliography

See also

Notes

References