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This basin located in the sector western center of Argentina includes at present the provinces of Neuquén and Mendoza, extending towards the north in the mountain range of Saint John and to the east, in the extra-Andean region of Río Negro and west of The Pampa. This basin takes supreme relevancy as its extraordinary exhibitions and finished sequences estratigráficas of the Mesozoico which sedimentary record overcomes 6 meters of thickness. Its connection with the Pacific Ocean suffered successive closings along its history, characteristic that joins a succession of episodes of relative changes of the sea level. The result was a complex distribution of sedimentary deposits that include marine and continental successions.  

The Neuquén basin is located in west-central Argentina in the provinces of Neuquén and Mendoza, extending towards the north in the mountain range of Saint John and to the east, in the extra-Andean region of Río Negro and west of The Pampas. During the Mesozoic, the basin was a back-arc basin that was at times open to Pacific Ocean to the west. Opening and closing of this connection to the Pacific led to a complex distribution of sedimentary deposits that include marine and continental successions.  

It is one of the producing basins of more important hydrocarbons of the country.<ref>Aguirre-Urreta, B., and E. O. Cristallini, 2009, La Cuenca Neuquina: Una perspectiva integrada: Revista de la Asociación Geológica Argentina, v. 65, no. 2</ref>

It is one of the most important hydrocarbon-producing basins in Argentina.<ref>Aguirre-Urreta, B., and E. O. Cristallini, 2009, La Cuenca Neuquina: Una perspectiva integrada: Revista de la Asociación Geológica Argentina, v. 65, no. 2</ref>

In 1892, Bodenbender<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, v. 13, pp. 5-44.</ref> informally described for the first time the outcrops of the highly bituminous shales with oil shows in the nucleus of ammonites<ref name=Leanza_2011>Leanza, H. A., F. Sattler, R. Martinez, and O. Carbone, 2011, La Formación Vaca Muerta y Equivalentes (Jurásico Tardío – Cretácico Temprano) en la Cuenca. Neuquina, ''in''' H. A. Leanza, C. Arregui, O. Carbone, J. C. Daniela, and J. M. Vallés, eds., Geología y Recursos Naturales de la Provincia del Neuquén, Neuquén, p. 113–129.</ref> and Weaver<ref>Weaver, C., 1931, Paleontology of the Jurassic and Cretaceous of West Central Argentina: Memoir University of Washington 1, 469 p.</ref> formally adopted the name Vaca Muerta Formation for the most important source rock of the Neuquén Basin.

In 1892, Bodenbender<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, v. 13, pp. 5-44.</ref> informally described for the first time the outcrops of the highly bituminous shales with oil shows in the nucleii of ammonites<ref name=Leanza_2011>Leanza, H. A., F. Sattler, R. Martinez, and O. Carbone, 2011, La Formación Vaca Muerta y Equivalentes (Jurásico Tardío – Cretácico Temprano) en la Cuenca. Neuquina, ''in''' H. A. Leanza, C. Arregui, O. Carbone, J. C. Daniela, and J. M. Vallés, eds., Geología y Recursos Naturales de la Provincia del Neuquén, Neuquén, p. 113–129.</ref> and Weaver<ref>Weaver, C., 1931, Paleontology of the Jurassic and Cretaceous of West Central Argentina: Memoir University of Washington 1, 469 p.</ref> formally adopted the name Vaca Muerta Formation for the most important source rock of the Neuquén Basin.

Within the [[stratigraphic column]], overlies with 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.<ref name=Leanza_2011 /><ref>Leanza, H. A., H. G. Marchese, and J. C. Riggi, 1977, Estratigrafía del Grupo Mendoza con especial referencia a la Formación Vaca Muerta entre los Paralelos 35º y 40º l.s. Cuenca Neuquina-Mendocina: Revista de la Asociación Geológica Argentina, v. 32, p. 190–208.</ref>

The [[stratigraphic column]] shows that the Vaca Muerta overlies a sharp contact on the underlying continental deposits of the Tordillo and Quebradade/Sapo formations, but in some areas, the Vaca Muerta overlies an angular unconformity on different pre-Tithonian units.<ref name=Leanza_2011 /><ref>Leanza, H. A., H. G. Marchese, and J. C. Riggi, 1977, Estratigrafía del Grupo Mendoza con especial referencia a la Formación Vaca Muerta entre los Paralelos 35º y 40º l.s. Cuenca Neuquina-Mendocina: Revista de la Asociación Geológica Argentina, v. 32, p. 190–208.</ref>

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, and 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, v. 302, p. 64-86.</ref>

This formation is primarily composed of deep marine sediments that can be correlated laterally to slope and platform top carbonates and siliciclastics of the Quintuco Formation to the east and the Picun Lefeu Formation to the southwest. The age of the Vaca Muerta extends from Tithonian to Valanginian based on  ammonites, calcispheres, and calpionellid biozones.<ref>Kietzmann, D. A., R. M. Palma, A. C. Riccardi,  J. M. Chivelet, and 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, v. 302, p. 64-86.</ref>

The Vaca Muerta Formation is considered the to be an excellent source rock and in recent years gained greater importance as unconventional reservoir.

 

The Vaca Muerta Formation is considered the bedrock by excellence in the Neuquén basin, but in recent years gained greater importance as unconventional reservoir.

==Tectonic Frame==

==Tectonic Frame==

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File:1.png|{{figure number|1}}General map of the Neuquén Basin showing the location of main sites. Based on Spalletti & Veiga (2007).

File:1.png|{{figure number|1}}General map of the Neuquén Basin showing the location of main sites. Based on Spalletti & Veiga.<ref name=SpallettiVeiga2007>Spalletti, L. A., and G. D. Veiga, 2007, Variability of continental depositional systems during lowstand sedimentation: an example from the Kimmeridgian of the Neuquen Basin, Argentina: Latin American Journal of Sedimentology and Basin Analysis, v. 14, no. 2, p. 85-104</ref>

File:2.png|{{figure number|2}}Jurassic and Lower Cretaceous lithostratigraphy of the Neuquén Basin. Based on Spalletti & Veiga (2007).

File:2.png|{{figure number|2}}Jurassic and Lower Cretaceous lithostratigraphy of the Neuquén Basin. Based on Spalletti & Veiga.<ref name=SpallettiVeiga2007 />

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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 ([[:File:1.png|Figure 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 ([[:File:1.png|Figure 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 />  

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 ([[:File:1.png|Figure 1]]). It covers an area of over 120,000 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, and E. Schwarz, 2005, The Neuquén Basin, Argentina: A case study in sequence stratigraphy and basin dynamics: Geological Society (London) Special Publication 252</ref> This triangular basin is limited on its western margin by the Andean magmatic arc and on its southern and northeast margins by  the cratonic areas of the North Patagonian Massif and the Sierra Pintada System, respectively ([[:File:1.png|Figure 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 />  

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

The evolution and development of the Nequén Basin can 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 ([[:File:2.png|Figure 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 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 ([[:File:2.png|Figure 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 ([[:File:2.png|Figure 2]]).<ref name=Vergani />

* 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 ([[:File:2.png|Figure 2]]).<ref name=Vergani />

* 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 ([[:File:2.png|Figure 2]]).<ref name=Veiga_et_al />  

* 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 ([[:File:2.png|Figure 2]]).<ref name=Veiga_et_al />