The accumulations of carbonates may have very varied pedological origins. They can basically be divided into autochthonous and allochthonous.


AUTOCHTHONOUS. The carbonates come from the parent material, either because they were already present there, which is the most common case, or because, although they are not physically present in the rock, they have been newly formed in the soil as a result of the weathering of primary minerals, as may be the case of plagioclases, pyroxenes and amphiboles.


ALLOCHTHONOUS. The carbonates have no genetic relation to the original material. Their origin is due to some external contribution, either having been transported by water, by contamination of a regional water table or due to local run-off water, which are so important in mountainous areas. Finally, in some cases, especially in arid regions, carbonates in a particular soil may be of eolian origin.



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