Submicromorphology of pedogenic carbonate accumulations as a proxy of modern and paleoenvironmental conditions

Resumen

It is likely that the
morphology of pedogenic carbonate accumulations (CAs) relates to
soil formation conditions and processes. The technique of electron
microscopy is especially efficient and applicable to the description
of CAs morphology. This method allows estimating the structure and
organization of CAs visually and their composition with the X-ray
energy dispersive spectrometer for both buried paleosols and surface
soils. The relations between submicromorphological features of CAs
and conditions of their formation in soil were established: (i) in
contrasting climates (alternation of dry and wet seasons), colloform
(cryptocrystalline) films are formed; (ii) in dry periods CAs with
perfect crystals and sharp borders are formed; (iii) in more humid
periods the CAs crystals become irregular with broken faces and
holes on surfaces; (iv) needle-shaped calcite crystals are formed in
fast-changing water regimes from saturated solutions; (v) perfect
crystals grow in quiet conditions from solutions of normal
concentration. Submicromorphological studies of the CAs in
pedochronosequences can account for trends in changes undergone by
soils/paleosols and permit estimation of the general trend of soil
evolution.