INSTITUTO ARGENTINO DE NIVOLOGIA, GLACIOLOGIA Y CIENCIAS AMBIENTALES
Unidad Ejecutora - UE
congresos y reuniones científicas
Characteristics of two Rock Glaciers in the Arid Argentinean Andes Based on Initial Surface Investigations
LUKAS ARENSON; SILVIO PASTORE; DARIO TROMBOTTO; SASCHA BÖLLING; MAURICIO QUIROZ; XAVIER OCHOA
Congreso; 6th Canadian Permafrost Conference 2010, Calgary, AB.; 2010
In the arid Andes of Argentina and Chile, permafrost conditions frequently exist at high altitudes. These permafrost conditions range from dry rock to ice-rich soils. The ground ice in these latter permafrost zones is often the only source of multi-year ice due to the common absence of substantial surface snow and ice areas, such as glaciers or perennial snow patches. However, the climatic and geomorphological conditions in the high, arid Andes are favourable for the formation and preservation of rock glaciers, and several talus and valley shaped rock glaciers can be found, at all sorts of different stages. Information on the characteristics of high Andes rock glaciers is of great importance to potential mine developers and regulators. In particular, the role of the ground ice present in the rock glaciers within the hydrological cycle and in the general regional hydrology need to be understood in more detail. To better understand rock glacier behaviour Xstrata Copper San Juan initiated a periglacial environment investigation program, in which two rock glaciers are analysed in detail. The rock glaciers are located within the El Pachón valley, of the San Juan Province, Argentina, which is part of the study area of a proposed open pit copper mine development. We present the findings from the initial investigations that included surface geophysical investigations, shallow boreholes and ground temperature measurements, as well as test pit excavations. The investigations confirmed that the rock glaciers studied are active, ice-rich and are located at the lower permafrost elevation limit of the area. These initial results further helped in setting up an additional investigation program that is currently being carried out, which will include deep boreholes, thermistors, deformation monitoring and additional surface geophysics to determine the role and significance of these rock glaciers in the hydrological setting of the El Pachón valley.