Changes

[[File:1.png|200px|thumbnail|Figure 1. General map of the Neuquén Basin showing the location of main sites. Based on Spalletti & Veiga (2007).]]

[[File:1.png|200px|thumbnail|Figure 1. General map of the Neuquén Basin showing the location of main sites. Based on Spalletti & Veiga (2007).]]

The Nequén Basin  has a broadly triangular shape and is located between 32° and 40°S latitude on the eastern side of the Andes in Argentina and central Chile (Fig 1). It covers an area of over 120000 km2 and comprises a continuous record of up to 4000 meters of stratigraphy (Veiga et al. 2005). This triangular basin is limited on its western margin by the Andean magmatic arc and on its southern and NE margins by  the cratonic areas of the North Patagonian Massif and the Sierra Pintada System, respectively (Fig 1).  This Late Triassic- Early Cenozoic succession includes continental and marine siliciclastics, carbonates and evaporites that accumulated under a variety of basin styles (Veiga et al. 2005).  

The Nequén Basin  has a broadly triangular shape and is located between 32° and 40°S latitude on the eastern side of the Andes in Argentina and central Chile (Fig 1). It covers an area of over 120000 km2 and comprises a continuous record of up to 4000 meters of stratigraphy.<ref name=Veiga_et_al>Veiga, G. D., L. A. Saplletti, J. A. Howell, & E. Schwarz, 2005. The Neuquén Basin, Argentina: A Case Study in Sequence Stratigraphy and Basin Dynamics: Geological Society, London, Special Publications 252. </ref> This triangular basin is limited on its western margin by the Andean magmatic arc and on its southern and NE margins by  the cratonic areas of the North Patagonian Massif and the Sierra Pintada System, respectively (Fig 1).  This Late Triassic- Early Cenozoic succession includes continental and marine siliciclastics, carbonates and evaporites that accumulated under a variety of basin styles.<ref name=Veiga_et_al />

[[File:2.png|200px|thumbnail|left|Figure 2. Jurassic and Lower Cretaceous lithostratigraphy of the Neuquén Basin. Based on Spalletti & Veiga (2007).]]

[[File:2.png|200px|thumbnail|left|Figure 2. Jurassic and Lower Cretaceous lithostratigraphy of the Neuquén Basin. Based on Spalletti & Veiga (2007).]]

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). (<ref>Manceda, R., & D. Figueroa, 1995, [http://archives.datapages.com/data/specpubs/memoir62/18manced/0369.htm Inversion of the Mesozoic Neuquén rift in the Malargue fold and thrust belt, Mendoza, Argentina], in: A. J. Tankard, S. R. Suarez, & H. J. Welsink (eds), Petroleum Basins of South America, [http://store.aapg.org/detail.aspx?id=476 AAPG Memoir 62], pp. 369-382.</ref>; 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 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).<ref>Manceda, R., & D. Figueroa, 1995, [http://archives.datapages.com/data/specpubs/memoir62/18manced/0369.htm Inversion of the Mesozoic Neuquén rift in the Malargue fold and thrust belt, Mendoza, Argentina], in: A. J. Tankard, S. R. Suarez, & H. J. Welsink (eds), Petroleum Basins of South America, [http://store.aapg.org/detail.aspx?id=476 AAPG Memoir 62], pp. 369-382.</ref>;<ref name=Vergani> Vergani, G. D., A. J. Tankard, H. J. Belotti, & H. J. Welsink, 1995, [http://archives.datapages.com/data/specpubs/memoir62/19vergan/0383.htm Tectonic evolution and paleogeography of the Neuquén Basin, Argentina], in: A. J. Tankard, R. Suárez Soruco & H. J. Welsink (eds), Petroleum Basins of South America, [http://store.aapg.org/detail.aspx?id=476 AAPG Memoir 62], pp. 383-402. </ref><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<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><ref>Ramos, V.A., 1999, Evolución Tectónica de la Argentina, in: R. Caminos (ed.) Geología Argentina. Instituto de Geología y Recursos Minerales, Anales, 29, 715-759. </ref> 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><ref>Ramos, V.A., 1999, Evolución Tectónica de la Argentina, in: R. Caminos (ed.) Geología Argentina. Instituto de Geología y Recursos Minerales, Anales, 29, 715-759. </ref> and uplift of the foreland thrust belt (Fig. 2).<ref name=Veiga_et_al />

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 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>  

== Facial variations in Vaca Muerta Formation in the margin of the Neuquén basin ==

== Facial variations in Vaca Muerta Formation in the margin of the Neuquén basin ==

The basal transegresive sequence in this sector of the basin retains the characteristics of sourcerock constant across large areas (Veiga and Orchuela 1989).

The basal transegresive sequence in this sector of the basin retains the characteristics of sourcerock constant across large areas.<ref>Veiga, R. D., & I. A. Orchuela, 1989, Identificación de niveles generadores de hidrocarburos a partir de técnicas de perfilaje en la formación Vaca Muerta. I Congreso Nacional de Exploración de Hidrocarburos, p. 1061-1093. Mar del Plata, Argentina.</ref>

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.

* Veiga, R. D. e I. A. Orchuela, 1989, Identificación de niveles generadores de hidrocarburos a partir de técnicas de perfilaje en la formación Vaca Muerta. I Congreso Nacional de Exploración de Hidrocarburos, p. 1061-1093. Mar del Plata, Argentina.

*

* Villar, H. J., C. Barcat, S. Talukdar y W. Dow, 1993, Facies generadoras de hidrocarburos, correlación petróleoroca madre y sistema petrolero en el área sudoriental del Engolfamiento Neuquino. XII Congreso Geológico Argentino y II Congreso de Exploración y Desarrollo de Hidrocarburos, Actas I, p. 382-394. Mendoza, Argentina.

* Villar, H. J., C. Barcat, S. Talukdar y W. Dow, 1993, Facies generadoras de hidrocarburos, correlación petróleoroca madre y sistema petrolero en el área sudoriental del Engolfamiento Neuquino. XII Congreso Geológico Argentino y II Congreso de Exploración y Desarrollo de Hidrocarburos, Actas I, p. 382-394. Mendoza, Argentina.

* Villar, H. J., L. Legarreta, C. E. Cruz, G. A. Laffitte y G. Vergani, 2005, Los cinco sistemas petroleros coexistentes en el sector sudeste de la Cuenca Neuquina: Definición geoquímica y comparación a lo largo de una transecta de 150km. VI Congreso de Exploración y Desarrollo de Hidrocarburos, Actas en CD. Mar del Plata, Argentina.

* Villar, H. J., L. Legarreta, C. E. Cruz, G. A. Laffitte y G. Vergani, 2005, Los cinco sistemas petroleros coexistentes en el sector sudeste de la Cuenca Neuquina: Definición geoquímica y comparación a lo largo de una transecta de 150km. VI Congreso de Exploración y Desarrollo de Hidrocarburos, Actas en CD. Mar del Plata, Argentina.

* Weaver, C., 1931, Paleontology of the Jurassic and Cretaceous of West Central Argentina. Memoir University of Washington 1, 469 p., Seattle.

* Weaver, C., 1931, Paleontology of the Jurassic and Cretaceous of West Central Argentina. Memoir University of Washington 1, 469 p., Seattle.