Determinación de fases magnéticas en un lago cordillerano de Patagonia Norte, Argentina.

In this work, a detailed analysis of the magnetic composition of the upper meter of sediment from a core from Laguito del Morro, Northern Patagonia, Argentina, was carried out. Measurements of low-frequency magnetic susceptibility, anhysteric remanent magnetization, isothermal remanent magnetization curves (at room temperature), and determination of Curie temperatures were used. Remanence coercivity and different interparametric ratios were calculated. The values obtained for remanence coercivity allowed us to determine three magneto-zones with well-differentiated magnetic mineralogies. The ratio between the isothermal remanent magnetization at -100mT and the saturation magnetization only showed a behavior mirrored by the coercivity in zones I and II. The analysis of the curves at room temperature and the thermal experiments identified magnetite, titanomagnetite, and titanohematite, with magnetite being the main component. The identified zones range from 0 to 16 cm (present - 1890 CE)) for zone I, 16 to 66 cm (1890 - 1570 CE) for zone II and 66 to 100 cm (1260 - 1520 CE) for zone III. Particularly, zone II is framed within the so-called Little Ice Age, so it is expected that the mineralogical variations observed will have a strong climatic component as a cause of the change. [ABSTRACT FROM AUTHOR]