INVESTIGADORES
ALVAREZ maria fernanda
capítulos de libros
Título:
Extracción de biominerales silíceos en distintos sedimentos utilizando dos técnicas básicas
Autor/es:
ALVAREZ, M.F., BORRELLI, N. Y M. OSTERRIETH
Libro:
Matices interdisciplinarios en estudios fitolíticos y de otros microfósiles. British Archaeological Reports (BAR), (M. A. Korstanje y M. del P. Babot, editoras)
Editorial:
British Archaeological Reports (BAR), Oxford.
Referencias:
Año: 2008; p. 31 - 38
Resumen:
The aim of this study is to make a methodological adjustment to the basic techniques used for silica biolith extraction in soils, paleosols and loess. Samples from Argentina, representating 5 distinct environments of the east-southeast of the province of Buenos Aires, were analized: hydromorphic paleosol, paleobasin, loessic paleosol, A-horizon of typical Argiudoll, and loess. Two techniques were applied in the treatment of samples: Technique I: granulometric separation (fractions < 38 µm and 38-62 µm) followed by heavy liquid separation with sodium polytungstate (d =2.3 g/cm3), and Technique II: centrifugation of the whole sample for different periods of time (3, 7 and 20 minutes), followed by heavy liquid separation with sodium polytungstate (d =2.3 g/cm3). With both techniques, the results show a predominance of phytoliths and much lower proportions of diatoms, chrysophytes and zooliths. However, we suggest the use of Technique II for silica biolith extraction for all types of  samples such as ours, because of the greater diversity of  phytolith morphotypes obtained as compared with Technique I, and because of Technique  II’s production of cleaner microscope slides with fewer clay particles, allowing for easier microfossil counting. Regarding the time of  centrifugation, there were no differences in the number of  biominerals and morphotypes of phytoliths when differing times were used with Technique II. Therefore, since a longer time for the centrifugation of samples is unnecessary, a centrifugation time of only 3 minutes is recommended.