Thrombolites and stromatalites (microbialites) are
“organosedimentary structures that are formed by benthic microbial communities which trap and bind detrital sediment and/or precipitate calcium carbonate” (Burne & Moore, 1987).
These structures are some of the earliest known life on Earth. Fossils of stromatolites have been found in the Pilbara region of Western Australia dating back 3500 Ma years (Grey et al. 2012).
The living thrombolites of Lake Clifton are of immeasurable scientific value and are classified as “HIGHLY ENDANGERED”
They will not survive changes to the groundwater level, increased nutrient levels, physical damage such as trampling or other environmental disturbances.
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Formation of Thrombolites
According to Konishi et al., “thrombolites and stromatolites are two forms of microbialites distinguished by their internal structure (Moore and Burne, 1994). Thrombolites are characterised by a micritic clotted internal fabric with fenestrations while stromatolites are typically comprised of fine, more or less planar, laminations (Kaldowsky, 1908; Konishi et al. 2001).
Stromatolites provide some of the best evidence for the earliest life on Earth. Stromatolite and microfossil sites in the Pilbara region of Western Australia contain some of the world’s most abundant and best preserved evidence for early life on Earth dating back to around 3426 -335 Ma, nearly 3500 years ago (Grey et al., 2012). The significance is that Early life on Earth provides an insight into any similar life that might exist or has existed on other planets in the solar system.
In 1987 Burne and Moore defined Microbialites as “organosedimentary structures that are formed by BMCs which trap and bind detrital sediment and/or precipitate calcium carbonate”. BMCs are Benthic Microbial Communities which lie in a mat at the bottom of water bodies. Particles of calcium carbonate from the bed rock are trapped by the mat of microbialites and a stromatolite or a thrombilite is formed somehow by these microbes. Konishi, Prince and Knott suggested that it might have been as a protection against later, more advanced, predators (Konishi et al. 2001).
Lake Clifton has the largest reef of living thrombolites in the southern hemisphere. Within the Yalgorup Lake System extinct microbialites are found round the margins of Lakes Pollard, South Newnham, South Preston Hayward and a large, distinct reef around Martin’s Tank Lake (Moore,L., 1998). It would appear from the reef around Martin’s Tank Lake that at one time the Lake water was much higher engulfing the microbialites. With the drying conditions the Lake level has receded leaving the reef high and dry with no sign of microbial activity.
It has been suggested that the cyanobacteria at Shark Bay (and presumably Lake Clifton) are perhaps the most slowly evolving organisms on Earth, and certainly now they are among the rarest.