Factors controlling alpine glaciations in the Sierra Baguales Mountain Range of southern Patagonia (50º S), inferred from the morphometric analysis of glacial cirques

Abstract

The Sierra Baguales Mountain Range, forming the eastern foothills of the Southern Patagonian Andes, has well-developed alpine-glaciated landforms which present an ideal opportunity to study climatic and non-climatic factors that control cirque development and morphology. One hundred and forty-three glacial cirques were studied with reference to 14 morphometric attributes which were analyzed using statistical analysis and GIS methodologies. The cirques were classified into two types using cluster analysis complimented with a composite map based on the attributes, the latter technique that is applied to glacial cirque analysis for the first time. Type 1 cirques are associated with glacial processes isolated from the Southern Patagonian Ice Field (SPIF), developed under locally cold and dry climatic conditions. Type 2 glacial cirques are associated with older, more extensive glacial processes controlled by regional-scale climate variables and the presence of the Pleistocene Ice Sheet. The results show that the development of most of the glacial cirques has been controlled mainly by their aspect, exposure to solar radiation, Southern Hemisphere Westerly winds, and cirque floor slope. Finally, we concluded that our analyses show the evolution of cirques in the Sierra Baguales Mountain Range was not uniform. Cirque glaciers that developed to the west, close to the Southern Patagonian Ice field, have been more dynamic, and therefore their cirques experienced more erosion than those located to the east.

The evolution of the Patagonian Ice Sheet from 35 ka to the Present Day (PATICE)

“…We do note that areas with cold-based glaciation would have left little geomorphic impact, and could be erroneously excluded from the reconstruction. Mesetas closer to the ice divide possess alpine glacial geomorphology (Araos et al, 2018;. The presence of abandoned cirques, truncated spurs, parabolic valleys and arêtes suggests that even if they are not glacierised today, these areas at least supported valley glaciation during past glacial cycles.…”

“…i. An upland glacier landsystem, with an assemblage of cirques, lateral and terminal moraines, some mountain glaciers and snow patches, flutes, and lakes within the overdeepened basins (e.g., Araos et al, 2018;Martin et al, 2019); ii. In the lowlands, a land-terminating glacial landsystem, with an assemblage of nested lateral-frontal moraine arcs, outwash plains, meltwater channels, sedimentary glacial lineations (including drumlins) and inset hummocky terrain (e.g.…”

“…The upland mountains of Patagonia beyond the present-day icefields bear evidence of an upland, Alpine-style of glaciation. This landsystem comprises amphitheatre-shaped cirques, some still occupied by glaciers García, 2012;Araos et al, 2018;Martin et al, 2019). Some cirques host remnant moraine-dammed lakes, eroded lateral moraines, closely-spaced frontal moraines and lineations interpreted as flutes (ibid.).…”

“…The broad valleys distributed along the eastern margin of North and Southern Patagonian Icefields, and east and west of the Andes in the Chilean Lake District, comprise over-deepened glacial troughs, often occupied by lakes, indicating the action of effluent ice sheet outlet lobes and smaller glaciers flowing away from the Andean divide (Araos et al, 2018). This large-scale sediment-landform assemblage typically comprises multiple moraine sets, for example those in the areas formerly occupied by the large eastern outlet glaciers .…”

Morphometry and spatial distribution of glacial cirques in the Western Fuegian Andes of Argentina, southernmost South America

“…Studies about glacial cirques are plentiful in the Northern Hemisphere, mainly in North America and Europe (see summaries in Evans, 1977 andSpagnolo, 2015). The Southern Hemisphere, on the other hand, has scarce previous works, and only a few isolated studies have focused on cirque distribution and/or their morphometric attributes: Clapperton (1971) in Islas Malvinas (Falkland Islands), Aniya and Welch (1981) in Antarctica, Brook et al (2006) in New Zealand, Ponce and Rabassa (2012) in Isla de los Estados (Staten Island), Argentina, and Araos et al (2018) in Southern Patagonia (50° S). In Tierra del Fuego, Coronato (1996) highlighted the incidence of climate and relief structure on the distribution of cirques and present cirque glaciers in a portion of the southwestern Argentine Fuegian Andes.…”