Spina, V., Ringenbach, J.C., Ballard, J., Vergés, J., 2022. Exploration in a thick to thin-skinned transition: Faja Plegada triangle zone. Neuquén, Argentina, in: In: Andean Structural Styles, Gonzalo Zamora and Andrés Mora (Ed.), Elsevier. pp. 441–457. doi:10.1016/B978-0-323-85175-6.00035-3
Abstract
Pure kinematic models are classically used to validate and balance geological cross sections in fold-and-thrust belts, impacting the interpretation of the structural style, the kinematics, and finally their exploration potential. During the 1960s and 1970s, surface geological data were largely used to interpret the structural style of the “Faja Plegada,” along the outer sector of Chos Malal Triangle Zone (Argentina), with the aim to steer the hydrocarbon exploration. Some of the original proposed concepts are still considered valid nowadays. The discoveries of El Portón and Filo Morado fields encouraged the acquisition of seismic data in the area, to better image these structures, both for field development and further Hydrocarbon exploration.
The use of a thin-skinned structural model, with multiple detachments (Choiyoi Group, Vaca Muerta and Huitrín Formations), and a “Rocky Mountain structural style” have been used since the sixties to describe the anticline geometries and propose subthrust structures, enhancing hydrocarbon prospectivity in Chos Malal. Nevertheless, a thick-skinned structural model is considered more appropriate, even though the style of the area is still debated, and several alternative models have been illustrated in the scientific literature.
Despite the effort put into seismic acquisition, design, and processing, the subthrust images are still unclear and alternative interpretations can be proposed with a strong impact on the exploration potential.
This paper illustrates the impact that the improvement of the seismic reprocessing had in better understanding the kinematics and structural style of the area, and the consequent evolution of the exploration concepts, in terms of geometry and structural uncertainties. In addition, we discuss the role played by multiple detachments in controlling the localization and growth of the anticlines and also in the migration of the deformation from thick to thin-skinned along the outer front of the Chos Malal thrust belt.