oncolite


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Related to oncolite: pisolite

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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
(3a) 0.15 m--brownish-grey, bioturbated, argillaceous dolowackestone with varigrained biodetritus, rare oncolites, some DSs, tongue of the Anikaitse Beds in the lower part.
(3b) 0.30 m--light brown, varigrained biodetrital dolopackstone to grainstone with oncolites and small stromatolites on the lower distinct smooth DS in the upper part.
Oncolites: are seen as separate unattached elliptical and ovoid grains showing concentric laminae with microbial remains around a nucleus commonly of micrite aggregates (Fig.
The combination of an aphanitic, mottled, matrix-supported structure with scattered peloidal fabrics and with the overall increase in the proportion of microbial carbonates in the form of oncolites and floating porostromate problematica in the carbonate buildup at Whitman's Hill may suggest that the bulk of the buildup framework was leiolitic (Schmid 1996).
0.15 m--Buff-grey, skeletal packstone or grainstone with pellets, skeletal psammite, pebbles, and oncolites; a thin (1 cm) domerite intercalation is at the base and a sharp discontinuity surface at the top.
Wavy-bedded, skeletal grain- to wackestones (packstone dominating) with numerous rounded skeletons of stromatoporoids, corals, and rare calcareous algae, oncolites, gastropods, and lepertitide ostracodes.