The Coquina Rock Diagenesis, and Sedimentary Rocks

Type of Rock The rock coquina is originally a sedimentary rock. Sedimentary rocks are made up of sediments. The sediments are formed by the mechanical or chemical activities of the natural activities like running water, blowing wind, glaciers etc. this which causes disintegration and decomposition of the pre-existing rocks. The products of decay are transported to some depositional sites by the natural agencies, where they get deposited and with subsequent compaction form sedimentary rocks (Hefferan, O’Brien, 2010). . The sedimentary rocks usually accumulate under a great variety of conditions. This shows the variation in rock, chemical structure as well as in texture. Weathering is the most important process that operates in the†¦show more content†¦Rock Composition The most common chemical sedimentary rock is limestone. Composed mostly of the mineral calcite (CaCO3), limestones are formed by biochemical processes in shallow seawater (Jahnert, 2012). Coral and algae are especially important limestone builders. Coquina is a form of biochemical limestone. It is an allochemical rock, meaning it is made up of mostly broken down shells, skeletal remains, and gravel (sand). Most coquinas are composed of invertebrate seashells, usually mollusks, and shells of saltwater organisms but freshwater versions exist as well (Schmidt, 1979). Other variations of limestone result from the deposition and cementation of calcium†rich shells, shell fragments, corals, algae, and the remains of tiny marine organisms. (Hefferan, O’Brien, 2010). ). Coquina contains little to no matrix (cement) and what matrix does exist is composed of firm microcrystalline calcite. Under the Folk Classification, coquina contains allochmes. Allochems are types of fossils with sparite cement which would make it biosparite. Coquina rock has the ability to absorb large amounts of water. This absorption of water makes the surface of the coquina constantly damp. According to the Dunham Classification, which is a produced classification of carbonate rocks, coquina falls under grain-supported and lacks mud. Everything that keeps the rock held together is mostly the shells themselves. Every rock has specific mineral properties that