Fábrica magnética en el perfil del Río Pilcomayo aflorante en el extremo Sur de las Sierras Subandinas Bolivianas

LEANDRO C. GALLO; RENATA N. TOMEZZOLI; ALEJANDRA DALENZ FARJAT; ROBERTO M. HERNÁNDEZ; ARZADÚN, GUADALUPE; LUCIA C. CONTARDO; JUAN M. CALVAGNO

Montevideo

Simposio; Third Biennial Meeting of Latinmag; 2013

Universidad de la República

We present here preliminar results of the anisotropy of magnetic susceptibility (ASM) measurement. The sequence was sampling on the Pilcomayo River located in the Tarija province at the southern border of the bolivian subandean ranges, Lat.: 21 ° S, Long.: 63 ° W. Here outcrop San Telmo, Cangapi and Vitiacua Formations, whose ages range from Carboniferous to Permo - Triassic with doubts. Directional AMS data arises from the general observation that there is an expression of oblate fabric. Each site has good internal consistency and distinctive features dependent of the liythology. Overall ASM Kmin axis tends to be located in the NW quadrant with approximate 55° of inclination and has a direct correlation to the pole of the bedding planes while the Kint and Kmax axes are located in a girland of NNE-SSW which tends to be parallel to the general direction of the sequence. Kmax axes approach to be horizontal and from the South. The degree of anisotropy only in some specimens reachs up to 12%. The average susceptibility of the entire population is 4.7X10-4. The relationships found between the axes of the ellipsoids of anisotropy and bedding planes show a bimodal magnetic fabric that reflect a tectonic participation on a primary depositional fabric that conserve the conditions of sedimentation.