A calcareous deposit, secreted by calcareous algae in the form of laminated domes and columns. Occurs in many cenotes (qv).
A composite, flat-to-domed structure composed of successive mineral layers. Some are known to be produced by the action of bacteria in salt or fresh water, and some ancient ones are considered to be evidence for early life on the earth.
layered sedimentary rock formations bound by colonial bacteria
Reef formation composed of mats of photosynthetic bacteria and sediments.
The most common usage is: a laminated, relief-forming structure of biogenic, specifically microbial, origin. Usually they are found in carbonate sediments, particularly Precambrian sediments. It is usually very difficult to demonstrate a biological origin, and care should be taken not to assume a biological origin for all "laminated, relief-forming structures" in carbonates.
A geological feature formed by the conversion of loose, unconsolidated sediment into a coherent layer, as a result of the growth, movement, or activity of microorganisms; e.g., blue-green algae. Microfossils associated with stromatolite formation are an important form of evidence for early life on Earth, and thus a search for stromatolites could be undertaken on other planets in sites where liquid water might have accumulated. A to F | G to L | M to R | S to Z
A layered, mound-like sedimentary structure formed by the trapping of fine sediments by primitive algae. These algae represent some of the first life in the oceans and were responsible for production of our oxygen-rich atmosphere. (Image) (Image)
A mound-shaped fossil that forms from the repetitious layering of algal mat covered by trapped sediment particles.
Layered mounds of sediment formed by cyanobacteria; cyanobacteria secrete a mucuous-like substance to which sediment sticks, and as each layer of cyanobacteria gets buried by sediment, it colonizes the surface of the new sediment, building a mound upward.
A layered (usually mineralised) flat, dome-shapes or columnar formations, sometimes reaching the sise of a reef, created by the activities of bacterial communities (mostly cyanobacteria). Common in the Precambrian shallow water basins. Much rare today (salt marshes, sabkhas etc.).
Precambrian fossils formed by mats or clumps of algae that trapped sediment.
a calcareous rock structure consisting of deposits of blue-green algae. [AHDOS
Layered structures built by colonies of microorganisms which are commonly found in the Archean and Proterozoic fossil records. Modern examples can be found in sites such as Shark Bay in Western Australia.
Stromatolites (from Greek strÅma, mattress, bed, stratum, and lithos, rock) are defined as "attached, lithified sedimentary growth structures, accretionary away from a point or limited surface of initiation." A variety of stromatolite morphologies exist including conical, stratiform, branching, domal, and columnar types. Stromatolites are commonly thought to have been formed by the trapping, binding, and cementation of sedimentary grains by microorganisms, especially cyanobacteria (formerly known as blue-green algae).
