Cabana (ancient lake)

Lake Cabana is an ancient lake in the Altiplano.

The lake reached a water level of 3,900 metres (12,800 ft) over the central and northern Altiplano,[1] 90 metres (300 ft) above the current lake levels of Lake Titicaca.[2] The Capalla-Ulloma sill, which separates the Altiplano into a northern and southern basin,[3] did not exist at that time and it did not split up the Cabana lake body. It left deposits reaching thicknesses of 50 metres (160 ft) of thickness;[4] they have been found on the western and eastern sides of the basin.[2] Erosion platforms and terraces covered with gravels[5] and other wave cut structures are remnants of Lake Cabana.[6]

In 1984, this lake was named by a group of researchers[7] around A. Lavenu.[8] Other ancient lakes on the Altiplano are Lake Mataro, Lake Ballivian, Lake Minchin and Lake Tauca.[9] An erosion surface at 3,900 metres (12,800 ft) elevation and associated clays were formerly attributed with Ballivián[10][11] but today shorelines at that elevation are instead associated with Cabana.[1]

The lake existed about 1 million years ago. It was preceded by Lake Mataro and succeeded by Lake Escara and Lake Ballivian, the latter in the north and the former in the south.[1] The Kaluyo glaciation preceded the formation of Lake Cabana,[4] earlier it was believed that the 3,900 metres (12,800 ft) high formations predated any glaciation.[12] A phase of tectonic extension in the Titicaca basin may have favoured the formation of this lake.[13] The existence of this lake may have facilitated the diversification of Heleobia snails, but increased speciation only occurred during the subsequent Ballivian episode.[14]