WAVELET ANALYSIS IN ROCK MAGNETIC PROPERTIES IN HOLOCENE AEOLIAN SEDIMENTS OF ARTURO DUNE, TIERRA DEL FUEGO, ARGENTINA

CAPPELLOTTO LUIGGINA; CORONATO ANDREA; ACHAGA ROMINA; GOGORZA CLAUDIA SUSANA GABRIELA; VELASCO HERRERA VÍCTOR MANUEL; ORGEIRA MARÍA JULIA; PONCE JUAN FEDERICO

Agadir

Encuentro; PAGES Agadir 2022; 2022

We performed a wavelet analysis in time series of magnetic properties obtained from a 19 m-thick profile of Arturo Dune, in the northern region of Isla Grande of Tierra del Fuego, Argentina (53° 43' 28'' S, 68° 18' 51'' W). The profile comprises a succession of aeolian units interdigitated with paleosoil levels.Considering the 14C dates from organic matter in the paleosoil levels presented by Coronato et al. (2021), an age model was created taking a continuous sedimentation rate to date the aeolian deposits. According to this model, the profile was developed along the Holocene, covering an age range from 832 to 12086 years BP.The results include different magnetic properties and ratios, such as coercive force (Hc), saturation magnetization (Ms), low-frequency (470 Hz) magnetic susceptibilities (kLF), anhysteretic remanent magnetization (ARM), among others, measured in aeolian sediment samples. These properties and ratios are widely used to study magnetic mineralogy, concentration, and magnetic grain size in sediment samples. Rock magnetic results indicate stable magnetic mineralogy in the aeolian deposits (magnetite or titanomagnetite, with low content of Ti), showing that the variations in the concentration and magnetic grain size parameters could be related to wind variations. The wavelet analysis has been relevant to distinguishing common and consistent periodicities in time series. Velasco Herrera et al. (2017) created a new algorithm to analyze spectral covariance for multiple-time series that can be applied to geophysical records. The statistical analysis of the magnetic parameters in the profile could indirectly indicate any prevailing periodicity of the wind variations over time recorded in the deposit. The results obtained through the wavelet and multiple cross wavelet analyses of the magnetic parameters suggested a periodicity of around 2800 years. By adding the South Atlantic Ocean paleotemperatures in the analysis, a periodicity of about 3000 years was obtained.The results that emerge from this wavelet analysis are similar to recurrent cycles that appear in other wavelet analyses of different records that identify fundamental solar modes (Soon et al. 2014). However, they are not conclusive about the sun-climate relationship on a series of millennial suborbital time scales, and more studies should be performed.