INVESTIGADORES
ZARATE marcelo Aristides
artículos
Título:
geochemical characterization, correlation and optical dating of tephra in alluvial sequences of central western Argentina
Autor/es:
PHILLIP TOMS; MATHEW KING; MARCELO ZÁRATE; ROB KEMP; FRANKLIN FOIT
Revista:
QUATERNARY RESEARCH
Editorial:
ACADEMIC PRESS INC ELSEVIER SCIENCE
Referencias:
Lugar: Amsterdam; Año: 2004 vol. 62 p. 60 - 75
ISSN:
0033-5894
Resumen:
resumen
The synthesis of paleoclimatic archives provided by loess and alluvial sequences of central Argentina has been hindered by the lack of a
cohesive lithostratigraphic framework extending across the ChacoPampean plains and catchments of the Rios Desaguadero, Colorado, and
Negro. This condition originates in part from the dearth of absolute chronological controls. The occurrence of discrete tephra layers across
this region may provide an opportunity to address this deficiency if a tephrochronological framework can be established. The potential of
such a project is assessed within the context of a pilot study constrained within alluvial sequences of central western Argentina proximal to
potential source vents in the Southern Volcanic Zone. The intersite discrimination and correlation of tephra layers on a geochemical basis is
examined, with indirect chronological control for the eruption of each generated by optical dating. Alluvial sediments on either side of each
of five tephra units at a type site were dated using the optically stimulated luminescence of fine-silt-sized quartz, thus providing an age
control on each tephra (ca. 24,000, 30,000, 32,000, 39,000, and 48,000 yr). The geochemical composition of each tephra was derived. Using
these data, tephra layers at other sites in the study area were geochemically analyzed and, in instances of statistical concordance in major
oxide structure, correlated to the type site and therefore ascribed ages. This methodology identified a further sixth volcanic event between ca.
24,000 and 30,000 yr not registered by type-site tephras. The extension of this initial tephrochronological framework beyond the alluvial
sequences of central western Argentina is encouraged by the occurrence of geochemically distinct tephra verified and dated in this study.
D 2004 University of Washington. All rights reserved.2004 University of Washington. All rights reserved.