High-resolution paleomagnetic secular variation and relative paleointensity records from south-western Argentina

C. S. G. GOGORZA; GRUPO DE PALEOMAGNETISMO

Buzios

Simposio; I Magnet Brazil: State of the art and future challenges; 2011

ON-MCT/IAG-USP/INPE

High-resolution paleomagnetic secular variation and relative paleointensity records from south-western ArgentinaClaudia S.G. GogorzaGroup of Paleomagnetism (IFAS, UNCPBA)The PASADO Science Team Most of the high-resolution paleomagnetic studies were carried out on sediments from the Northern Hemisphere and only a few curves were obtained from the Southern Hemisphere. During the last decade we therefore have made an effort to reconstruct the behaviour of the Holocene geomagnetic field by studying sediment records from a group of lakes from south-western Argentina. In this review the results of paleosecular variation and paleointensity records from lakes El Trébol, Escondido y Moreno and laguna Potrok Aike are reported, in an attempt to improve our knowledge about the behaviour of the geomagnetic field in this region.Measurements of directions (declination D and inclination I) and intensity of natural remanent magnetization (NRM), magnetic susceptibility at low and high frequency (specific, X and volumetric, k), anhysteretic remanent magnetization (ARM), isothermal remanent magnetization (IRM) and saturation of the isothermal remanent magnetization (SIRM) were carried out.Rock magnetic studies suggest that the main carriers of magnetization are ferrimagnetic minerals, predominantly pseudo single domain magnetite.The cores were correlated very well based on magnetic parameters, such as X and NRM intensity, as well as with lithological features.The obtained records meet the strictest criteria for relative paleointensity records: the most commonly applied mineral magnetic criteria, paleomagnetic stability, agreement between results of different paleomagnetic normalisation and agreement with records obtained from other geographical areas. Comparing the paleointensity curves with records obtained from other geographical areas has allowed us to reach reliable conclusions about centennial to millennial-scale features.