[{"@context":"http:\/\/schema.org\/","@type":"BlogPosting","@id":"https:\/\/wiki.edu.vn\/en\/wiki43\/automicrite-wikipedia\/#BlogPosting","mainEntityOfPage":"https:\/\/wiki.edu.vn\/en\/wiki43\/automicrite-wikipedia\/","headline":"Automicrite – Wikipedia","name":"Automicrite – Wikipedia","description":"Limestone constituent Automicrite is autochthonous micrite, that is, a carbonate mud precipitated in situ (no transporting) and made up of","datePublished":"2020-04-08","dateModified":"2020-04-08","author":{"@type":"Person","@id":"https:\/\/wiki.edu.vn\/en\/wiki43\/author\/lordneo\/#Person","name":"lordneo","url":"https:\/\/wiki.edu.vn\/en\/wiki43\/author\/lordneo\/","image":{"@type":"ImageObject","@id":"https:\/\/secure.gravatar.com\/avatar\/c9645c498c9701c88b89b8537773dd7c?s=96&d=mm&r=g","url":"https:\/\/secure.gravatar.com\/avatar\/c9645c498c9701c88b89b8537773dd7c?s=96&d=mm&r=g","height":96,"width":96}},"publisher":{"@type":"Organization","name":"Enzyklop\u00e4die","logo":{"@type":"ImageObject","@id":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","url":"https:\/\/wiki.edu.vn\/wiki4\/wp-content\/uploads\/2023\/08\/download.jpg","width":600,"height":60}},"image":{"@type":"ImageObject","@id":"https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/3797bbca4cf6bc08a12f7355c6a30d4024fbf28a","url":"https:\/\/wikimedia.org\/api\/rest_v1\/media\/math\/render\/svg\/3797bbca4cf6bc08a12f7355c6a30d4024fbf28a","height":"","width":""},"url":"https:\/\/wiki.edu.vn\/en\/wiki43\/automicrite-wikipedia\/","wordCount":2345,"articleBody":"Limestone constituentAutomicrite is autochthonous micrite, that is, a carbonate mud precipitated in situ (no transporting) and made up of fine-grained calcite or aragonite micron-sized crystals. It precipitates on the sea floor or within the sediment as an authigenic mud thanks to physicochemical, microbial, photosynthetic and biochemical processes. It has peculiar fabrics and uniform mineralogical and chemical composition.[1]Environments where automicrite is formed[edit]Automicrite deposits are found in different environments, as lakes, tidal flats, or the aphotic zone of marine slopes and basins. However, the environment where automicrite is most common is in carbonate mud mounds, a type of carbonate platform. In this kind of carbonate platform, common in the geological past but nearly absent today, automicrite deposits made carbonate structures of many tens to hundreds of metres of relief called “mud mounds”. Automicritic mud mounds seemed to form more easily in areas of low sedimentation rate of siliciclastic extrabasinal sediment.[2]Usually, the presence of mud in sedimentary rocks is an indicator of low-energy conditions in a depositional system, so in high-energy conditions it is nearly impossible to find mud. Instead, automicrite can precipitate internally in cavities and sediment pores below the sediment\u2013water interface, also in sediments that are formed in high-energy condition. Automicrite can also crystallize in suspension within cavities and then deposit on the cavity bottom. Usually, this process forms peloids, a kind of carbonate grains make by automicrite.[3]Features[edit]In present carbonate platforms, automicrite is composed by aragonite needle-shaped crystals which have dimension of 1- 5 \u03bcm. Instead, in old limestones micrite is composed by \u03bcm-size calcite crystals.[3]Formation[edit]Knowledge of the automicrites generation processes allow to make paleo-environmental interpretations, so it can become good instrument for basin analysis. Carbonate mud or micrite may originate through several processes, including the abiotic precipitation from highly supersaturated seawater or precipitation induced by microbial activity.[4]1. Abiotic micrites precipitation[edit]There are two kinds of \u201cinorganic\u201d micrite:[3]– Internal micrite which precipitates inside cavities and inter-granular pores of sediments. It is a pore-filling micrite which has peloidal or clotted textures, and when it is found in limestones it may prove that marine lithification occurred.– Seafloor micrite which precipitates at the sediment\u2013water interface.The equilibrium relationship for CO2,CaCO3{displaystyle {ce {CO2, CaCO3}}}in water is:"},{"@context":"http:\/\/schema.org\/","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/wiki43\/#breadcrumbitem","name":"Enzyklop\u00e4die"}},{"@type":"ListItem","position":2,"item":{"@id":"https:\/\/wiki.edu.vn\/en\/wiki43\/automicrite-wikipedia\/#breadcrumbitem","name":"Automicrite – Wikipedia"}}]}]