Sucesión de eventos deformacionales en base a la correlación de mesoestructuras, Punta Tota, Basamento paleoproterozoico de Tandilia, Argentina.

SERGIO DELPINO,; JORGE DRISTAS,; LUIS DIMIERI

Revista de la Asociación Geológica Argentina, Serie D, Publicación especial

Asociación Geológica Argentina

Lugar: Buenos Aires; Año: 2001 vol. 5 p. 143 - 150

0328-2767

The succession of deformational events is evaluated on the basis of the correlations between mcsostructurcs observed in the Punta Tota locality, situated NE of Balcarce City, Tandilia, Argentina. The rclaiionships between structures indícate the development of at least two deformational phases, represented by the foliations Sr S, and their associated structures: 1) The deformational phase F, (S,), predates the formation of migmatites. The preexisting bcdding So and the S, foliation subparallel to it, strongly controlled the emplacement of leucosomes in the form of thin sheets and coarse pegmatitic veins; 2) The deformational phase F, (S J localized in bands, affected intensively the lower sector of the Punta Tota locality and has the characteristics of the shear zones; 3) A strong "lit par lit" injection and evidences of normal displacement, seem to indícate that rotated S! planes towards a suitable position for extensión (S|r) within the shear zone originated by F2, would havc acted as propitious zones for the emplacement of mobilisates. This would indícate the contemporaneousness of the migmatization with the second deformational phase F,, developed about 1800 Ma.; 4) The conjunction of structures and their spatial oricntations, suggest that this last evcnt would have been the result of shear stresses subparallel to the strike of the preexisting planes So-Srproducingasinistral rotation of structures. A probable model for the correlation of observed structures is statcd.