Testing lake-level reconstructions based on rock magnetic proxies for the sediment record of Laguna Cháltel (Patagonia, Argentina)

IRURZUN, MARÍA A.; PALERMO, PEDRO; GOGORZA, CLAUDIA S. G.; SINITO, ANA M.; ALDANA, MILAGROSA; COSTANZO-ÁLVAREZ, VINCENZO; OHLENDORF, CHRISTIAN; ZOLITSCHKA, BERND

QUATERNARY RESEARCH

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2020 vol. 95 p. 113 - 128

0033-5894

 This study was carried out on sediment cores collected with a gravity corer from Laguna Cháltel, an almost circular crater lake located in Patagonia, Argentina (49.9°S, 71°W). The main magnetic carrier was Ti-magnetite in the pseudo?single domain range. A model using magnetic grain size and concentration, previously applied to Laguna Potrok Aike to infer lake-level changes, was used for Laguna Cháltel. The main requirement to apply the model is uniform magnetic mineralogy, whichis the case for Laguna Cháltel. After magnetic data were compared with previously studied lake levels, it was found thatthe magnetic proxies that best follow hydrologic changes are ARM/SIRM (anhysteretic remanent magnetisation/saturationof isothermal remanent magnetisation) and ARM. The concentration proxy (ARM measured with a 100 mT alternatingfield and 0.05 mT direct field) was also used as wind indicator. High wind strength was found at around 3650 cal yr BP,and low wind strength for the last century. ARM/SIRM and ARM were used to infer the strength of fluvial runoff intothe lake for a core collected close to the shore and near a tributary. The results show that the magnetic model is promisingfor inferring lake-level variations, particularly in Patagonian lakes.