Geomorphic and Geochemical Evidence for the Source of Sand in the Algodones Dunes, Colorado Desert, Southeastern California

Abstract

The Algodones dunes of southeastern California comprise one of the largest active dune fields in the United States. The source of sand of the Algodones dunes is controversial, and the source of stabilized aeolian sand in the adjacent East Mesa area has not been investigated at all. We used mineralogical compositions and trace element concentrations to ascertain the most likely source of sand for these active and stabilized dunes. Results indicate that alluvium derived from the San Bernardino Mountains, which enters the Salton trough to the northwest of the dune fields, and alluvium derived from the Chocolate Mountains, which is deposited immediately to the northeast of the dunes, do not appear to be significant sources of sediment for the Algodones and East Mesa dunes. Both active aeolian sand from the Algodones dunes and stabilized aeolian sand on East Mesa are probably derived from sediments of ancient Lake Cahuilla, which formerly occupied part of the Salton Trough and left sandy shoreline sediments to the west and northwest of where the dune fields are now found. Lake Cahuilla sediments, in turn, were apparently derived from the Colorado River, when the river shifted its course and emptied into the Salton Trough, rather than the Gulf of California.