Vidal-Romani J.R.,Instituto Universitario Of Geologia |
Gonzalez-Lopez L.,Instituto Universitario Of Geologia |
Vaqueiro M.,Instituto Universitario Of Geologia |
Sanjurjo-Sanchez J.,Instituto Universitario Of Geologia
Environmental Earth Sciences | Year: 2015
Runoff flows not only on magmatic rocks massifs surface but also through their internal discontinuities, which define the secondary permeability of the rock. The effects, especially erosive, of the water movement on surface are well known although it is not the same with the effects of water infiltration through the rock. Especially, when it does so at low speed (trickles or seepage) granular disaggregation of the rock is produced at small scale, associated with a specific type of sediment (speleothems) of clast-supported open fabric which is able to store very small volumes of interstitial water, becoming a specific subterraneous microenvironment where some organisms develop their biological cycle totally or partially. Some products derived from the metabolic activity of these organisms incorporated to the infiltration water increase their ability to attack (weathering and dissolution) the rock. This process ends during the dry season when the troglobiont organisms die and the water-transported load, either dragged or in solution (mainly silicon), is sedimented forming the speleothems. The study of these deposits using several techniques, mineralogical, sedimentological, and biological (including metagenomics), indicates an influence of microorganisms on the formation of these deposits; therefore, it is correct to consider them as biospeleothems. © 2014, Springer-Verlag Berlin Heidelberg.