- First, through biochemical reactions, as a result of the activity of plants and animals in the water. Examples are very small plants that live in the ocean could reduce the degree of acidity of the surrounding water and thus precipitated calcium carbonate.
- Second, through inorganic reactions in water. When the water at eye-hot water cools, it will precipitate opal and calcite. Another example is the evaporation of sea water or lake, causing the concentration of dissolved materials and start upsalt.as deposition of chemical sediments.
Based on the composition of sedimentary rocks are grouped into a siliceous non-clastic, siliceous, containing silica and a carbonate, cabonaceous, the main composition of calcium carbonate.
Another frequently encountered sediments is the main composition of the remaining animals rombakan generated directly from the physiological activities of organisms called biogenic sediments. The remains of the hard end up into fragments, or clastic. Sediment is the main component of these fragments are called sediment bioklastik.
The important biogenic sediments are composed of calcium carbonate, which is widespread in the oceans. Calcium carbonate can be precipitated by chemical precipitation from seawater, but most of the carbonate sediment is the result of biogenic activity; especially on a warm surface sea water. Here carbonates separated by organisms while making the rest of her hard and calcite or aragonite mengendaplah. When the calcium ions and bicarbonate in the water combine to form a solid calcium carbonate, according to the reaction:
Ca2+ + (HCO 3) 1- -----> CaCO3 + H1+
Calcium ions bicarbonate ions Calcium carbonate bicarbonate Hydrogen
Many siliceous shaped colloidal precipitate; others are formed through chemical processes. Some of this sediment settles directly from the water, others are formed through the recrystallization process in the sediment during consolidation. Reference that is sure to distinguish the occurrence of these two deposits is minimal. A common form of nodules or concretion in limestone layers. Many of these nodules cored silikaan fossil material. This suggests that the occurrence of secondary processes.
Chert (chert or flint); issiliceous sedimentary rocks which are common, dense and hard. And is a form of quartz SiO2. The color ranges from white to dark gray. Same hardness, 7, shows the gloss (luster) such as glass (semi-vitreous). The nature of the outbreak is typical, flat and rounded parts (conchoidal fracture), very useful for early human tool-making.
Chert is found as layers or nodules in carbonate rocks or other sediments. Although it is an organic or inorganic deposits, some containing the remains of organisms silisious.
Siliceous sinter, is a chemical sediments that formed around the eyes, mineral water, geysers, also called geyserite. It is white or light-colored and porous.
Sediment carbonate (carbonaceous)
Non-clastic sediments consisting mainly of calcium carbonate minerals, calcite (CaCO3). carbonate sedimentary rocks are often found are limestone or limestone. Up to hundreds of meters thick and several square kilometers in extent. Most rocks are grouped in organic rock. In sea water contains many ions and carbonate kasium. In certain conditions of sea water saturated with these ions and sedimentation stone-limestone. These conditions include:
1. Warm water, where the ions are soluble in large quantities.
2. High evaporation, such as at the equator where the ions are concentrated near the surface when the amount of water is reduced.
3. Mixing water, triggering the occurrence of precipitation or precipitation.
In such conditions the occurrence of precipitation is possible, and if the water is formed mixing oolit , who grew up while the concentric layers of CaCO3 deposited thereon. In calm water, precipitated calcium carbonate with a needle-shaped crystals, lined with carbonate mud. This sediment after compaction crystallize back into a micro-crystalline limestone, with very fine crystals, which can only be viewed with a microscope with very high magnification. Limestones tend to have different physical properties, depending on its formation.
Travertine or tufa is limestone formed by the evaporation of the eye-water and rivers that contain calcium carbonate in solution. Sediment-water eyes or hot and cold water flow at the surface, resembling a sponge, porous, brittle-textured soil and sometimes branched, called tuff.
Caliche. limestone precipitate is formed in soils in semiarid regions berkomposisi carbonate rocks above. Capillarity draw ground water containing calcium carbonate in the solution above. On the surface of the water evaporates leaving the sediment as cement in the soil or as thin layers.
Dolomite or dolostone. The composition of calcium-magnesium carbonate (CaMg) CO3, rock solid texture such as sugar (sugary), gray and does not react with HCl acid. The formation of sedimentary dolomitecarbonate generally during recrystallization. The size of the calcium ions and is almost the same magnesium allowing calcium ions replace magnesium ions in the structure of calcite. Dolomitisasi fossils may be found, but no organism that form shells with dolomite.
Sediment organic
Sediment non-clastic other is formed from the remnants of micro-organisms whose life floating in the sea. After death, the remainder or the rigors of towing sink and accumulate to form sedimentary mud (Muddy sediment) are called deep-sea ooze. If it consists mainly of carbonate, called calcareous ooze.
Coral, algae and organime colonies growing on shallow seabed also precipitate kasium tropical coral reef or carbonate to form carbonate reef. Besides there are also siliceous calcareous ooze ooze, the main ingredient siliceous Remains.
Radiolarian ooze, derived from micro-protozoa, radioaria, groups of animals were single cells that form the shell of silica. His life was floating near the surface of the sea. After death his body sank to the seabed. And accumulate in large quantities and can form the majority of sediment deposition in areas of very slow pace, especially in the sea. Carbonate shell dissolved in cold water temperature and high hydrostatic pressure in the deep ocean, but silica remains stable; so that the shells of the radiolarians accumulated.
Diatomaceous, silisious plants that also are microscopic. Many forms, some are like the stem, rounded and circular. His life was floating on the surface of the sea, and concentrated in a number of extraordinary magnitude. Each plant contains a small drop of oil, which may be the main raw materials of petroleum. Rock the teridiri from the rest of this plant such as soil texture and appearance (earthy). Is loose, smooth, white powder, similar to chalk. Other organic sediment composition of carbonate in the form of primary fossilan limestone, lime (chalk) and marl.
Fossilan limestone. In general, limestone is formed by material derived from organic materials, including those consisting of shells of marine animals. The composition of the shell of the mineral calcite is taken from the sea water solution, where her life. After the animal dies, a number of shells accumulated on the sea or shallow sea, tersemen by calcite, silica or other materials and settles.
Limestone (chalk) is a limestone composed of shell fossilan protozoa (single cell animals had), especially those that form globular shell, rounded, its name Globigerina. Chalk white, light and soft, like chalk.
Marl (marl) consists of a mixture of shells and shell fragments with mud and sand. Is actually a limestone with impurities (impurity).
Salt deposits. In addition to limestone, found also salt and gypsum deposits, both of which are the result of evaporation. contains salts of mineral halite, NaCl composition, and Gypsum composition CaSO4.2H2O. Both exist as layers in a confined area.
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