CIFICEN   24414
CENTRO DE INVESTIGACIONES EN FISICA E INGENIERIA DEL CENTRO DE LA PROVINCIA DE BUENOS AIRES
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Estudios de magnetismo ambiental y mineralógicos en sedimentos lacustres y fluviales de Antártica
Autor/es:
ANA M. BARRIOS; MARCOS A. E. CHAPARRO; ARACELI LAVAT; KARINA L. LECOMTE
Lugar:
Säo Pablo
Reunión:
Congreso; LATINMAG 2015 Quarta Reunião Bienal; 2015
Institución organizadora:
University of São Paulo
Resumen:
This study focuses on magnetic characteristics of river and lake sediments from James Ross Archipelago, located in the northeast of the Antarctic Peninsula. The analyzed magnetic parameters were particularly obtained from measurements of magnetic susceptibility, magnetic hysteresis, anhysteretic and isothermal remanent magnetization. Additionally, complementary studies of X-ray diffraction (XRD) and FTIR spectroscopy were performed so as to the mineralogical characterization of the sediments. The magnetic parameters analyzed in this study show changes in the magnetic mineralogy of sediments depending on their depth. In lake Buena (James Ross island), increased concentration of ferrimagnetic minerals (magnetite) is accompanied by the presence of very fine magnetic grains, and minerals such as hematite or greigite, identified by magnetic, XRD and FTIR studies. Previous studies discussed the possibility of physical and chemical processes (linked to erosion, evaporation, and Red-Ox reactions) and biological processes (linked to algal and bacterial respiration activity) in lakes from James Ross and Vega islands, which would generate high values of water?s pH (alkaline). Results show a dominant ferrimagnetic (magnetite) component in these sediments, and a magnetic contribution of at least one component that is due to the presence of: a) antiferromagnetic minerals (hematite/goethite), b) ferrimagnetic minerals (iron sulfides) and c) a bio-induced component (biogenic magnetite).