oncolite

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Related to Oncoids: Peloid, Ooids

oncolite

[′äŋ·kō‚līt]
(geology)
A small, variously shaped (often spheroidal), concentrically laminated, calcareous sedimentary structure resembling an oolith; formed by accretion of successive, layered masses of gelatinous sheaths of blue-green algae.
References in periodicals archive ?
Oncoids show rounded or slightly elliptical sections and are 0.
The fact that oncoid laminae are mostly discontinuous indicates that oncoids remained static under calm periods, allowing microbial mats and/or encrusting organisms to colonize the surface of the oncoid that was not in contact with the sediment.
It also contains pisoids, intraclasts, oncoids, and porous micrite.
Matrix is dominated by peloids, but contains tuberoids, other intraclasts, oncoids, thin-shelled bivalves, benthic foraminifera, smooth-walled ost racodes, echinoid spines, and gastropods, in approximate order of decreasing abundance.
At a distance of 5 m from the lamproite contact the new crystals form a continuous mass among the oncoids (Fig.
In SEM images, oncoids and Rothpletzella accumulations floating in the matrix are built by tubes filled with sparitic cement (Fig.
The Lower Unit is constituted by microbialites formed by subspherical to ellipsoidal oncoids that can reach several centimetres in diameter.
crinoids, brachiopods, Between wave base and gastropods, and oncoids storm base.
This unit includes the local development of coral-microbial reef buildups which coexisted with sediments showing a large variety of non-skeletal components such as ooids, peloids, intraclasts and oncoids.
Intraclast-oncoid grainstone (al) is a poorly sorted fabric dominated by variously shaped small micritic intraclasts (20-35%) with a wide range of sizes, micritized aggregate grains or lumps (5%) and oncoids (5-10%).
A sharp-based bed with small, subspherical oncoids of up to 2 cm occurs in the lower part of the Calcarenite Member (Fig.