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Thrombolites have a clotted structure without the laminae of stromatolites.Each clot within a thrombolite mound is a separate cyanobacterial colony.The clots are on the scale of millimetres to centimetres and may be interspersed with sand, mud or sparry carbonate. [1]
Thrombolites are poorly laminated or non-laminated clotted structures formed by cyanobacteria, common in the fossil record and in modern sediments. [18] There is evidence that thrombolites form in preference to stromatolites when foraminifera are part of the biological community. [33]
Oncolites are very similar to stromatolites, but, instead of forming columns, they form approximately spherical structures. [1] The oncoids often form around a central nucleus, such as a shell fragment, [ 2 ] and a calcium carbonate structure is deposited by encrusting microbes .
Ancient giant stromatolites used to be widespread in Earth’s Precambrian era, which encompasses the early time span of around 4.6 billion to 541 million years ago, but now they are sparsely ...
Zones of stromatolites and thrombolites (non-laminated algal mounds) occur in several formations in the Bertie Group, [39] along with numerous desiccation cracks. [38] During the Hercynian orogeny in the Devonian, many of the Silurian sediments were eroded to the south in the Appalachians, while north of the mountains the Silurian units were ...
"Spongiostromata" is an antiquated form taxon that refers primarily to fossil cyanobacteria. "Spongiostromate" is also used to describe stromatolites and oncolites that do not preserve clear tubules or other cellular microstructure.
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