RESEARCH
Origin of the Atacama Desert Nitrate Deposits
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We have ongoing research in the Atacama Desert in northern Chile, the worlds driest place. We are interested in the biogeochemical origin of the nitrate deposits, soil evolution, and its relation to climatological factors. Initial findings (Atacama GCA) proved that nitrate in the driest regions is from long term deposition of nitrate gases and particles produced by photochemistry. In wetter regions and local moisture niches, nitrification by bacteria becomes an important source of soil nitrate. This dependence on moisture is reflected in the oxygen isotopes which we can then use in paleosol nitrate to determine the moisture availability during ancient soil formation. This is a new proxy for assessing past aridity and continental uplift (Geology Neogene, Science Editor Choice).

Making camp after a day of searching for out crops and sampling soils. At higher elevations outside of Calama, more abundant moisture allows scrub to grow that is used as a food source by Guanacos , an Andean camel.

Abandoned nitrate works, old shelters and ore plants that processed the nitrate “Caliche” mined by blasting and picks shovel. Several modern nitrate plants still exist but have modernized using heavy machinery to collect the caliche, which is processed and shipped to Antofagasta or Tocapillo for export as fertilizer



Paleosol at “El Hotel” covered by a 9 million year old ash providing a minimum age of this ancient soil.



Ancient river cut exposing geologic sequences including ancient soils. Isotopic, chemical and petrographic data gives us clues as to what the climate conditions were like during their formation.