The objective of this paper is to analyze the subsidence mechanisms between Late Triassic and Late Jurassic for the central sector, in order to understand the tectonic evolution of the basin during that period. In addition, the Andean magmatic arc tectonics would have generated regional slopes, modifying the geometry of the basin during its evolution (Spalletti et al., 2008). Although the stratigraphy of the post-rift stage is consistent with documented eustatic cycles from a regional point of view, local tectonic factors (Vergani et al., 1995 Vergani, 2005) would have exercised a strong control over the stratigraphic evolution modifying sediment generation and dispersion patterns in the central - western area (Schwarz et al., 2006 Veiga et al., 2011). The stages in which the Neuquén Basin evolution has been divided imply different conditions of subsidence but the published papers about tectonic subsidence in this basin are scarce (Manceda and Figueroa, 1995 Sigismondi, 2012 Horton and Fuentes, 2016). This allows supposing that more complex tectonic processes than just the thermal subsidence could have operated during that stage. Many of these surfaces were considered as the product of eustatic variations (Legarreta and Gulisano, 1989) however, during this stage various tectonic events have been recognized, which led to consider tectonics as a transcendental control factor over the stratigraphic evolution (Zavala, 1993 Vergani et al., 1995 Fernández Seveso et al., 1996 Limeres, 1996 Burgess et al., 2000 Comínguez and Franzese, 2005 Ramos and Kay, 2006 Mescua et al., 2008 Barredo et al., 2008 Barredo and Stinco, 2010 Spalletti, 2013).
#FLEX2D GEODYNAMICS SERIES#
The post-rift stratigraphic record is characterized by a series of discontinuities and unconformities (Howell et al., 2005).
Its development begins in the Late Triassic and extends to the Cenozoic, being classically divided into three different stages: syn-rift stage (Late Triassic to Early Jurassic), post-rift stage (Early Jurassic to Early Cretaceous) and foreland stage (Late Cretaceous to Cenozoic) (Legarreta and Uliana, 1996). From the available data, a shift from thermal to dynamic subsidence from the Middle Callovian onwards seems to be the most plausible explanation for the subsidence evolution observed in the study area.Įven though the Neuquén Basin has been studied extensively for more than a century, both from the scientific and industry point of view (Howell et al., 2005), its tectonostratigraphic evolution is not yet fully understood.
Therefore, the post-rift stage of the Neuquén Basin for the study area would have had a more complex tectonic evolution than that determined exclusively by the thermal subsidence, and that superposition of mechanisms must be considered. Results obtained in this paper show that there is a change in the geometry of the tectonic subsidence curves, which depart considerably from the expected behavior for a basin dominated by thermal subsidence. The post-rift stage, comprised between Early Jurassic and Early Cretaceous, was classically assumed as dominated by thermal subsidence. The origin of the basin was linked to a lithospheric mechanical extension episode in the Late Triassic - Early Jurassic that, once completed, gave rise to a post-rift stage. The methodology consisted of the integration of outcrop and subsurface data, in order to obtain tectonic subsidence curves for the analyzed period in the study area. This paper presents a detailed study of the tectonic subsidence evolution during the Late Triassic - Late Jurassic period in the central area of the Neuquén Basin.
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