Changes

It is one of the producing basins of more important hydrocarbons of the country (La Cuenca Neuquina: una perspectiva integrada).

It is one of the producing basins of more important hydrocarbons of the country (La Cuenca Neuquina: una perspectiva integrada).

Bodenbender  in 1892, informally described for the frist time the outcrops of the highly bituminous shales with oil shows in the nucleus of ammonites (Leanza, 2011) and Weaver (1931) formally adopted the name VacaMuerta Formation for the most important source rock of the Neuquén Basin.

Bodenbender  in 1892,<ref>Bodenbender, G., 1892, Sobre el terreno Jurásico y Cretácico de los Andes Argentinos, entre el Río Diamante y el Río Limay.Academia Nacional de Ciencias, 13: 5-44. Córdoba.</ref> informally described for the frist time the outcrops of the highly bituminous shales with oil shows in the nucleus of ammonites (Leanza, 2011) and Weaver (1931) formally adopted the name VacaMuerta Formation for the most important source rock of the Neuquén Basin.

Within the stratigraphic column, overlieswith sharp contact the continental deposits of the Tordillo and QuebradadelSapo formations denoting the Tithonian transgression. Nevertheless, in some areas it can overlay in angular discordance on different pre-Tithonian units (Leanza and Hugo, 1977; Leanza, 2009).

Within the stratigraphic column, overlieswith sharp contact the continental deposits of the Tordillo and QuebradadelSapo formations denoting the Tithonian transgression. Nevertheless, in some areas it can overlay in angular discordance on different pre-Tithonian units (Leanza and Hugo, 1977; Leanza, 2009).

This formation comprises a set of sedimentitas mainly marine they be distant to sides and in less measurement sediment continetal deposited between the late low titoniano and valanginiano early. This age is verified based on  biozone amonoideos , calciesferas and calpionélidos (Kietzman et. to. 2014b).

This formation comprises a set of sedimentitas mainly marine they be distant to sides and in less measurement sediment continetal deposited between the late low titoniano and valanginiano early. This age is verified based on  biozone amonoideos , calciesferas and calpionélidos.<ref>Kietzmann, D. A., R. M. Palma, A. C. Riccardi,  J. M. Chivelet, & J. López-Gómez, 2014, Sedimentology and sequence stratigraphy of a Tithonian–Valanginian carbonate ramp (Vaca Muerta Formation): A misunderstood exceptional source rock in the Southern Mendoza area of the Neuquén Basin, Argentina: Sedimentary Geology 302, p. 64-86.</ref>

This formation belongs to the Group Low and this Mendoza over the Formation Tordillo (deposits of fluvial, wind fan and lacustrine).

This formation belongs to the Group Low and this Mendoza over the Formation Tordillo (deposits of fluvial, wind fan and lacustrine).

The evolution and development of the Nequén Basin c an be considered in three stages.  

The evolution and development of the Nequén Basin c an be considered in three stages.  

* Stage 1. Late Triassic-Early Jurassic: prior to the onset of subduction on its western margin, this part of Gondwana was characterized by large transcurrent fault systems. This led to extensional tectonics whitin the basin and the evolution of a series of narrow, isolated depocentres (Fig. 2) (Manceda & Figueroa 1995; Vergani et al. 1995; Franzese & Spalletti 2001).  

* Stage 1. Late Triassic-Early Jurassic: prior to the onset of subduction on its western margin, this part of Gondwana was characterized by large transcurrent fault systems. This led to extensional tectonics whitin the basin and the evolution of a series of narrow, isolated depocentres (Fig. 2). (Manceda & Figueroa 1995; Vergani et al. 1995; <ref>Franzese, J. R., & L. A. Spalletti, 2001, Late Triassic –early Jurassic continental extension in southwestern Gondwana: tectonic segmentation and pre-break up rifting: Journal of South American Earth Sciences, vol. 4, pp. 257-270.</ref>

* Stage 2. Early Jurassic-Early Cretaceous: development of a steeply dipping, active subduction zone and the associated evolution of a magmatic arc along the western margin of Gondwana led to back-arc subsidence within the Neuquén Basin. This post-rift  stage of basin development locally accounts for more tan 4000 meters of the basin fill (Fig. 2) (Vergani et al. 1995).  

* Stage 2. Early Jurassic-Early Cretaceous: development of a steeply dipping, active subduction zone and the associated evolution of a magmatic arc along the western margin of Gondwana led to back-arc subsidence within the Neuquén Basin. This post-rift  stage of basin development locally accounts for more tan 4000 meters of the basin fill (Fig. 2) (Vergani et al. 1995).  

* Stage 3. Late Cretaceous-Cenozoic: transition to a shallowly dipping subduction zone resulting in compression and flexural subsidence, asocciated with 45-57 km of cristal shortening (Introcaso et al. 1992; Ramos 1999b) and uplift of the foreland thrust belt (Fig. 2) (Veiga et al. 2005).  

* Stage 3. Late Cretaceous-Cenozoic: transition to a shallowly dipping subduction zone resulting in compression and flexural subsidence, asocciated with 45-57 km of cristal shortening (<ref>Introcaso, A., M. C. Pacino, & H. Fraga, 1992. Gravity, isostasy and Andean crustal shortening between latitudes 30° and 35°S: Tectonophysics, 205, pp. 31-48.</ref>; Ramos 1999b) and uplift of the foreland thrust belt (Fig. 2) (Veiga et al. 2005).  

The Neuquén Basin is characterized by a prograde depositional system, leading to formations of various origins: Loma Montosa Formation, coastal facies; Quintuco Formation, carbonate platform facies; Vaca Muerta Formation, slope facies and high TOC (Galeazzi et al. 2014).  

The Neuquén Basin is characterized by a prograde depositional system, leading to formations of various origins: Loma Montosa Formation, coastal facies; Quintuco Formation, carbonate platform facies; Vaca Muerta Formation, slope facies and high TOC.<ref name=Galeazzi>Galeazzi, S., F. Pose, & A. Gangui, 2014, Estratigrafía Secuencial del intervalo Quintuco- Vaca Muerta en el Engolfamiento Neuquino, Cuenca Neuquina, Argentina: IX Congreso de Exploracion y Desarrollo de Hidrocarburos, Rompiendo Paraigmas, IAPG.</ref>

The prograde sequence proceeds transitional way from the Quintuco Formation to the Vaca Muerta Formation. This latter Formation is known as “classic” shale gas/oil play and is constituted of marl and shale, with less than 3500 metres depths, overpressure conditions, thicknesses with high organic content and the adecuate thermal madurity to generate hydrocarbons (Galeazzi et al. 2014).  

The prograde sequence proceeds transitional way from the Quintuco Formation to the Vaca Muerta Formation. This latter Formation is known as “classic” shale gas/oil play and is constituted of marl and shale, with less than 3500 metres depths, overpressure conditions, thicknesses with high organic content and the adecuate thermal madurity to generate hydrocarbons.<ref name=Galeazzi />  

== Stratigraphy of Vaca Muerta Formation in El Trapial area ==

== Stratigraphy of Vaca Muerta Formation in El Trapial area ==

The Lowstand System Tract (LST) is not present, the Transgressive System Tract (TST) is very small and corresponds to the regional flood event. The section is dominated by high sea deposits prograding (Highstand System Tracts) where three subsequenceares individualized: A, B and C.

The Lowstand System Tract (LST) is not present, the Transgressive System Tract (TST) is very small and corresponds to the regional flood event. The section is dominated by high sea deposits prograding (Highstand System Tracts) where three subsequenceares individualized: A, B and C.

[[File:4.png|200px|thumbnail|left|Figure 4 Cuts estratigráfico leveled to the ceiling of the Group Low Mendoza, where there are observed the interpreted sequences and its facial changes inside the complex progradante (Borbolla et al. 2014)]]

[[File:4.png|200px|thumbnail|left|Figure 4 Cuts estratigráfico leveled to the ceiling of the Group Low Mendoza, where there are observed the interpreted sequences and its facial changes inside the complex progradante.<ref>Borbolla M. C., C. Cruz, J. Villar, N. Annizzotto, P. Benites, D. Cattaneo, 2014, Formación Vaca Muerta: variación lateral de facies y su implicancia en los cambios de espesor hacia el borde de cuenca. Perspectivas exploratorias en shale oil e la plataforma de Catriel,  Cuenca Neuquina,Argentina. Simposio de Recursos No Convencionales: ampliando el horizonte energético, pp. 321-329</ref>]]

=== Basal transgressive section ===

=== Basal transgressive section ===

== References ==

== References ==

* Legarreta, L., H. J. Villar, G. A. Laffitte, C. E. Cruz y G. Vergani, 2005, Cuenca Neuquina. VI Congreso de Exploración y Desarrollo de Hidrocarburos, en Chebli, G. A., J. S. Cortiñas, L. A. Spalletti, L. Legarreta y E. L. Vallejo (eds.), Frontera Exploratoria de la Argentina, p. 233-250. Mar del Plata, Argentina.

* Legarreta, L., H. J. Villar, G. A. Laffitte, C. E. Cruz y G. Vergani, 2005, Cuenca Neuquina. VI Congreso de Exploración y Desarrollo de Hidrocarburos, en Chebli, G. A., J. S. Cortiñas, L. A. Spalletti, L. Legarreta y E. L. Vallejo (eds.), Frontera Exploratoria de la Argentina, p. 233-250. Mar del Plata, Argentina.

* Legarreta, L., H. J. Villar, C. E. Cruz, G. A. Laffitte y R. Varadé, 2008, Revisión integrada de los sistemas generadores, estilos de migración-entrampamiento y volumetría de hidrocarburos en los distritos productivos de la Cuenca Neuquina, Argentina. VII Congreso de Exploración y Desarrollo de Hidrocarburos, en Cruz, C. E., J. F. Rodriguez, J. J.Hechem y H. J. Villar (eds.), Sistemas Petroleros de las Cuencas Andinas, p. 79-108, Mar del Plata,  Argentina.

* Legarreta, L., H. J. Villar, C. E. Cruz, G. A. Laffitte y R. Varadé, 2008, Revisión integrada de los sistemas generadores, estilos de migración-entrampamiento y volumetría de hidrocarburos en los distritos productivos de la Cuenca Neuquina, Argentina. VII Congreso de Exploración y Desarrollo de Hidrocarburos, en Cruz, C. E., J. F. Rodriguez, J. J.Hechem y H. J. Villar (eds.), Sistemas Petroleros de las Cuencas Andinas, p. 79-108, Mar del Plata,  Argentina.