Kinematic analysis of a transtensional falut system: the atuel depocenter of the Neuquen basin, southern Central Andes, Argentina

BECHIS, FLORENCIA; GIAMBIAGI LAURA,; GARCIA, VICTOR; LANES, SILVIA; CRISTALLINI, ERNESTO; TUNIK, MAISA ANDREA

JOURNAL OF STRUCTURAL GEOLOGY

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2010 vol. 32 p. 886 - 899

0191-8141

The Atuel depocenter of the Neuquén basin originated as an Upper Triassic to Lower Jurassic rift system, later inverted during the Andean contractional deformation. In order to study the extensional architecture and the kinematic evolution of this depocenter, we collected a large amount of field and subsurface data, consisting of slip data from outcrop-scale normal faults, thickness and facies distribution within the synrift deposits, and structural data from angular and progressive unconformities. The Atuel depocenter has a NNW trend, showing a bimodal distribution of NNW and WNW major faults (first and second order faults). On the other hand, from kinematic indicators measured on outcrop-scale faults (third and fourth order faults), we found a mean NE internal extension direction, which is oblique to the general trend of the sub-basin. Taking these particular characteristics into account, we interpreted the Atuel depocenter as an oblique rift system. We evaluated two mechanisms in order to explain thedevelopment of this transtensional system: 1) reactivation of upper-crustal NNW-oriented Paleozoic shear zones, and 2) oblique stretching of a previous NNW-oriented lithospheric weakness zone.