As defined, ganisters can either be created by either the cementation of quartzose by surficial soil-forming processes to form silicrete or by diagenetic cementation within the subsurface.
22.
Sediments deposited under oxic or anoxic conditions can preserve on the long term the geochemical signature of Ce 3 + or Ce 4 + upon reserve that no early diagenetic transformation altered it.
23.
This torrential-stream deposit, close to enlaced rivers, laid to the deposition of sandy-clayey materials, with a variable iron content, coming from a diagenetic possibilities of evolutions.
24.
Cementation is the diagenetic process by which coarse clastic sediments become lithified or consolidated into hard, compact rocks, usually through the deposition or precipitation of minerals in the spaces between the individual grains of sediment.
25.
Since it is difficult to account for such a distribution of elements by post-mortem diagenetic processes, it would appear that the elements ( and thus the sediment ) were incorporated into the organism whilst it was alive.
26.
The regional persistence of tonsteins and relict phenocrysts indicate that they formed as the result of the diagenetic alteration of volcanic ash falls in an acidic ( low pH ) and low-salinity environment, consistent with a freshwater swamp.
27.
In older sequences diagenetic alteration combined with greater uncertainties in estimating absolute ages due to lack of overlap between other geochronometers ( for example U-Th ) leads to greater uncertainties in the exact shape of the Sr isotope seawater curve.
28.
Cataclastic flow usually occurs at diagenetic to low-grade metamorphic conditions, however this depends on the mineralogy of the material and the extent of pore fluid pressure, as high fluid pressure will promote cataclastic flow in any metamorphic environment.
29.
Most oil shale deposits were formed during Middle Cambrian, Early and Middle Ordovician, Late Devonian, Late Jurassic, and Paleogene times through burial by sedimentary loading on top of the algal swamp deposits, resulting in conversion of the organic matter to kerogen by diagenetic processes.
30.
The mineral composition of manganese-bearing minerals is dependent on how the nodules are formed; sedimentary nodules, which have a lower Mn 2 + content than diagenetic, are dominated by Fe-vernadite, Mn-feroxyhyte, and asbolane-buserite while diagenetic nodules are dominated by buserite I, birnessite, todorokite, and asbolane-buserite.
