March 27, 2020
Calluqueo Glacier in Landsat images from 1986 and 2020. Yellow arrow is the 2020 terminus location, red arrow the 1986 terminus location, purple dots indicate the snowline. Point A-D indicate bedrock areas that have expanded with glacier thinning.
Calluqueo Glacier is the largest glacier of the Monte San Lorenzo range on the Chile-Argentina border. This Chilean glaciers flows west from the border and in 1986 terminated in Lago “Calluqueo”. From 1985 to 2005/2008 Monte San Lorenzo glaciers lost 18.6% of their area (Falaschi et al 2013). In this region glaciers thinned by ~0.5 m/year from 2000-2012 with most of the thinning on Calluqueo Glacier occurring below 1300 m (Falaschi et al 2017). The glacial history of the region has been documented with excellent visual depictions including moraines and trimlines encircling Lago Calluqueo by Davies et al (2020), see below example. Here we examine the changes in Calluqueo Glacier from 1986-2020 using Landsat images.
In 1986 Calluqueo Glacier terminated in Lago Calluqueo at an elevation of 450 m, with a 750 m wide calving front in the 1.7 km 2 glacial lake. Lago Calluqueo is impounded by a stabilized moraine complex, see map below. The snowline was at 1400 m with Point A, B and C locations of limited bedrock exposure in 1986. By 2000 the glacier had retreated to the western shore of the lake that had expanded to 3.0 km2. The snowline in 2000 was at 1700 m. In 2019 the glacier has receded from the lake shore far enough so it no longer has any direct interaction or avalanche potential into the lake. The snowline in 2019 is at 1750-1800 m. By 2020 the glacier has retreated 1500 m since 1986 to an elevation of 700 m, in the vicinity of bedrock knob Point D that emerged from beneath the ice. The bedrock ribs at Point A, B and C have all expanded by more than 100% since 1986 as the glacier thins. The snowline in 2020 is at 1750-1800 m.
Calluqueo Glacier will continue to retreat given the ongoing thinning and recent persistently high snowline +1700 m elevations. The glacial history and landforms generated in this region are illustrated by Davies (2018). Retreat here follows that of the Sierra de Sangra region, Argentina and glaciers of the Northern Patagonia Icefield, such as Fiero Glacier and Acodado Glacier.
Calluqueo Glacier in Landsat images from 2000 and 2019. Yellow arrow is the 2020 terminus location, red arrow the 1986 terminus location, purple dots indicate the snowline.
In the map above from Davies et al (2020) GIS app. 1) Cosmogenic Be10 based dates, 2) Sandur, 3) Glacial Trimline, 4) Glacial Moraine, 5) Lichenometry based dates, 6) Empty Cirque. Martin et al (2019) identify 3 and 4 as being of Holocene age formation.
2) Sandur, 3) Glacial Trimline, 4) Glacial Moraine. Point A-D same as in top image.