Peloid

Peloid (Greek πέλος ( pelos ) = mud, εἶδος ( eidos ) = form ) is a term from the Karbonatpetrographie, the description of limestones in thin and polished section. However, the definition is not quite uniform. He called round, oval to slightly elongated, micritic or cryptocrystalline grains in the order of 50 to 500 microns, with or without interactivity structure ( depending on definition ). Peloids are due to their size and structure can be seen only in thin sections under the microscope. Larger entirely micritic Kalkkörner ( > 0.5 mm) are counted among the intraclasts.

Definition and naming

The term peloid dates back to ED McKee and RC Gutschick that have shaped him in 1969. As synonyms of peloid the terms Pelettoide apply ( depending on the author ), Schlammpeloide, Bahamite, Pseudoooide and Arrondide. It is roundish, oval to slightly elongated, micritic or crypto- crystalline, calcareous components in the order of 50 to 500 microns, with or without interactivity structure. " Peloid " i e p is basically a collective term for rock components, their origin or genesis is not sure what is very often the case. More recent work (eg, wing, 2004) also expect the so-called fecal pellets ( faecal pellets of snails and crustaceans ) also to the peloids, since they also consist of a micritic matrix and also the magnitude of the peloids have. Fecal pellets often have a low level of inter- structure and are in many cases a genetic interpretation to. However, they can also be structureless or have secondarily lost their Inter structure.

The absence of the Inter structure may be primary, or originally existing Internet structure has been lost by recrystallization. Next slightly rounded fragments of biogenic by the drilling activity of microorganisms ( Bohrpilze and Bohralgen ) can be completely mikritisiert, and thereby get the look of a peloid. Also Ooide ones could be completely mikritisiert and become peloids. As a rule, however, the origin of such peloids from original ooids will be detected by other evidence. Another possibility for the formation of peloids are formed with the participation of cyanobacteria sediment crumbs ( Algenpeloide ). Limestones, which consist predominantly of peloids are called depending on the matrix in the classification of limestones by Robert L. Folk as Pelmikrite or Pelsparite.

Similar components

The virtual absence of an inter- structure is in contrast to the ooids, roundish umkrusteten components with distinct layers. Onkoide are also layered, but usually constructed much larger and more irregular.

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