Abstract:

Deep Seismic Study, in eastern and western foothills of Sierra de Aconquija, northwestern Sierras Pampeanas, Argentina, shows the deep structure of the range and the deep geometry of the Andean foreland basin. "Self-truncating" extended correlation algorithm was applied to compute cross-correlation between the sweep and the records of Vibroseis lines. Special procedures, such as finite difference migration, FX deconvolution, FMED processing and complex demodulation, were applied in order to improve the interpretation. On the eastern side of Sierra de Aconquija, the structure is characterized by reverse faulting with eastward vergence, with the Guasayán and El Rosario faults exhibiting the most deformation. To the south, the Guasayán fault produces the uplift of the Guasayán basement range over tertiary deposits, and can be identified in the seismic reflection record down to 40 km depth. On the western side of Sierra de Aconquija, the deep structure of Campo del Arenal is characterized by westward vergent structures controlled by the anisotropy of the Sierra de Aconquija basement. Further to the west, the deformation style changes to eastward vergence. As a whole, both fault systems depict a double wedge active thrusting. Conspicuous sub-horizontal acoustic-reflectors at about 18, 30, 40 and 50 km depth, are interpreted as present or past brittleductile transitions. © 2000 Society of Exploration Geophysicists.