New data on neotectonic contractional structures in Precordillera, south of Río de La Flecha: Structural setting from gravity and magnetic data. San Juan, Argentina

PERUCCA, L., RUIZ, F.

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2014 vol. 50 p. 1 - 11

0895-9811

The Central and Eastern Precordillera form oppositely verging thrust systems on the western and easternsides of the Matagusanos-Maradona-Acequión valley, establishing a thick-skinned triangle zone withsignificant changes in the axis position along strike. Between the del Agua and the de La Fecha rivers, theaxis of this triangular zone is located in the eastern portion of the depression. Changes in the position ofthe triangle zone axis along strike, whether to the east or to the west, took place during PlioceneePleistocene times. Geophysical and geodetic data indicate a subsurface structure striking NE, oblique tothe general direction of the foreland with dextral displacement. Accordingly, the change in the location ofthe triangular area could be attributed to stress transfer controlled by heterogeneities in the basement.By analytic signal analysis of magnetic anomalies, it is possible to assess the regional structural couplingbetween Pie de Palo and Eastern Precordillera. The oblique arrangement of basement blocks couldexplain transverse lineaments and the sigmoidal geometry of the Eastern Precordillera. Geophysical andgeological evidence shows that the depression is crossed by several EeW strike-slip faults. These faultspossibly controlled the position of the triangle zone axis until NeogeneePleistocene times by transferringdisplacements and provoking its jump along strike.Basement structures might have also played a primary role in the location of Quaternary faultstrending NeS. Finally, the eastewest cross-section geophysical model shows the triangular zone,responding to the different controls imposed by the pre-existing basement structures