INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
Indicators of present global warming through changes in active layer-thickness, estimation of thermal difussivity anf geomorphological observations in the Morenas Coloradas rock glacier, Central Andes of Mendoza, Dry Andes, Argentina
DARIO TROMBOTTO; ENRIQUE BORZOTTA
Cold Regions Science and Technology
Elsevier (La versión on line es de septiembre del 2008)
Lugar: Amsterdam, The Netherlands; Año: 2008 vol. 55 p. 321 - 321
This contribution analyses 2 sites with temperature profiles in the active layer of the composed rock glacier Morenas Coloradas, Cordón del Plata, Mendoza, Argentina, using monitory data collected between 1989 and 2006 in order to observe and to illustrate the impact of global change in the cryolithozone of the Dry Andes at these latitudes (32-33° S). A remarkable change in the active layer and suprapermafrost of this rock glacier of the Cordón del Plata is registered at the monitoring sites. The observed changes imply direct consequences for the cryogenic environment and the Andean creeping permafrost. The nose of the Morenas Coloradas rock glacier for example (Balcón I, 3560 m a.s.l.), already expresses inactivity; the permafrost table is found at great depth. On the other hand data collected at Balcón I and II allow to estimate the theoretical thermal diffusivity alpha at the active layer of Morenas Coloradas. Alpha may be decisive for the study of cryogenic dynamics at other altitudes and latitudes in the region where data are still scarce. Low alpha values (< 0.2 × 10-6 m2/s) correlate with occurrence of freezing and ice at low altitudes. While the glaciers are turning into small insignificant bodies in the high mountains, the periglacial level with creeping permafrost and linked with rock glaciers is expanding altitudinally, passing a transitional rooting area which is indirectly feeding the rock glaciers with their covered or dead ice. The ice of glacigenic origin contributes to the genesis of this type of permafrost. As the permafrost table is found at greater depths, the rock glaciers need to be monitored in order to define a balance between the upper periglacial level (in terms of altitude) with mountain continuous - quasi continuous permafrost and the lower periglacial level to where the lowest fronts of creeping permafrost are reaching. The variations of the cryogenic structure of the rock glaciers of the Cordón del Plata caused by warming processes, will have direct consequences for the volume of frozen sediments and therefore for the hydrology of the entire region, a fact that has to be taken into account for future socio-economic programs of the respective provincial governments.