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Vaca Muerta (in Spanish literally ''Dead Cow'') is a geologic formation of Jurassic and Cretaceous age, located at Neuquén Basin in Argentina. It is best known as the host rock for major deposits of tight oil (shale oil) and shale gas. The large oil discovery in the Vaca Muerta Formation was made in 2010 by the former Repsol-YPF, which announced the discovery in May 2011.〔 〕 The total proven reserves are around , and YPF's production alone is nearly .〔http://www.ypf.com/YPFHoy/YPFSalaPrensa/Paginas/Home.aspx, "YPF firmo un acuerdo con PETRONAS", 18.02.2014〕 In February 2012, Repsol YPF SA raised its estimate of oil reserves to .〔(【引用サイトリンク】title=Vacamuertashale.com )〕 The US EIA estimates total recoverable hydrocarbons from this Vaca Muerta Formation to be of oil and of natural gas, more than even the Neuquén Basin's hydrocarbon-rich Middle Jurassic Los Molles Formation holds. ==Geology== The Vaca Muerta Shale is a continuous tight oil and shale gas reservoir of late Jurassic (Tithonian) and early Cretaceous (Berriasian) age formation. The formation covers a total area of .〔 〕 The shale is at a depth of about where it has been found productive of oil and gas. Although called a shale, and with a total organic carbon content varying from 1 percent to 5 percent, the Vaca Muerta is predominately marl and consists of mature black shales, marls and lime mudstones.〔 〕〔 〕 Formed in a marine environment with little clay and brittle rock the deposit is (usually over ) thick extending throughout the basin.〔〔 Although in the name Vaca Muerta Formation was introduced to the geological literature in 1931 by an American geologist Charles E. Weaver, the highly bituminous shales in the Salado river valley in southern Mendoza were described in 1892 by Dr. Guillermo Bodenbender. German paleontologists Beherendsen and Steuer determined the Tithonian age of these shales.〔 〕 Where it surfaces, the Vaca Muerta Formation has been the site of paleontological finds: the crocodylomorph ''Cricosaurus'' and possibly ''Geosaurus'', the ichthyosaur ''Caypullisaurus'', and the pterosaurs ''Herbstosaurus'' and ''Wenupteryx''. The Vaca Muerta Formation represents most distal facies of the Lower Mendoza Mesosequence, a Tithonian–Valanginian broad shallowing-upward sedimentary cycle.〔Legarreta, L., Gulisano, C.A., 1989. Análisis estratigráfico secuencial de la Cuenca Neuquina (Triásico superior- Terciario inferior, Argentina). In: Chebli, G., Spalletti, L.A., (Eds.), Cuencas Sedimentarias Argentinas. Universidad Nacional de Tucumán, Serie Correlación Geológica 6, p. 221–243〕 In the southern part of the Neuquén Basin the Lower Mendoza Mesosequence includes the basinal deposits of the Vaca Muerta Formation (early to middle Tithonian), which to the south-southeast change to mixed carbonate-siliciclastic nearshore deposits of the Carrin Cura Formation (lower part of the middle Tithonian) and Picún Leufú Formation (middle Tithonian – lower Berriasian), and to continental deposits of the Bajada Colorada Formation of Tithonian – Berriasian age.〔Leanza, H.A., 1973. Estudio sobre los cambios faciales de los estratos limítrofes Jurásico-Cretácicos entre Loncopué y Picun Leufú, Provincia del Neuquén, República Argentina. Revista de la Asociación Geológica Argentina 28, 97–132.〕〔Spalletti, L.A., Franzese, J.R., Matheos, S.D. and Schwarz, E. (2000) Sequence stratigraphy of a tidally dominated carbonate-siliciclastic ramp; the Tithonian-Early Berriasian of the Southern Neuquén Basin, Argentina. Geological Society of London, Special Publication 157, pp. 433–446.〕〔Leanza, H. A., Sattler, F., Martinez, R., Carbone, O., 2011. La Formación Vaca Muerta y Equivalentes (Jurásico Tardío – Cretácico Temprano) en la Cuenca. Neuquina. In: Leanza, H.A., Arregui, C., Carbone, O., Daniela, J.C., Vallés, J.M. (Eds.), Geología y Recursos Naturales de la Provincia del Neuquén, Neuquén, 113–129.〕 In the central part of the Neuquén Basin, also known as Neuquén embayment, the Lower Mendoza Mesosequence consists of basinal deposits of the Vaca Muerta Formation (early to upper Tithonian), which to the east change to shoreface deposits of the Quintuco Formation (upper Tithonian – lower Valanginian), and to sabkha deposits of the Loma Montosa Formation (lower Valanginian), forming a mixed carbonate-siliciclastic depositional system.〔Gulisano, C.A., Gutiérrez Pleimling, A.R., Digregorio, R.E., 1984. Análisis estratigráfico del intervalo Tithoniano-Valanginiano (Formaciones Vaca Muerta, Quintuco y Mulichinco) en el suroeste de la provincia de Neuquén. 9 Congreso Geológico Argentino, Actas 1, 221–235.〕〔Mitchum, R.M., Uliana, M.A., 1985. Seismic stratigraphy of carbonate depositional sequences, Upper Jurassic-Lower Cretaceous. Neuquén Basin, Argentina. In: Berg, R.B., Woolverton, D.G. (Eds.), Seismic Stratigraphy: An Integrated Approach to Hydrocarbon Exploration. AAPG Memoir 39, 255–274.〕 Westward the Vaca Muerta Formation includes slope facies (Huncal Member), and in the Chilean territory pass into shallow marine/volcanic deposits.〔(Leanza, H.A., Hugo, C.A., Repol, D., Salvarredy Aranguren, M., 2003. El Miembro Huncal (Berriasiano inferior): un episodio turbidítico en la Formación Vaca Muerta, Cuenca Neuquina, Argentina. Revista de la Asociación Geológica Argentina 58, 248–254 ).〕〔(Kietzmann, D.A., Vennari, V.V., 2013. Sedimentología y estratigrafía de la Formación Vaca Muerta (Tithoniano-Berriasiano) en el área del cerro Domuyo, norte de Neuquén, Argentina. Andean Geology 40, 41–65 ).〕〔(Spalletti, L. A., G. D. Veiga, E. Schwarz, and J. Franzese, 2008, Depósitos de flujos gravitacionales subácueos de sedimentos en el flanco activo de la Cuenca Neuquina durante el Cretácico Temprano: Revista de la Asociación Geológica Argentina, v. 63, 442–453. )〕 By contrast, in the southern Mendoza area the Lower Mendoza Mesosequence consists of aggradational and divergent sequences, with a maximum thickness of 500 m towards the center of the basin.〔 It includes basinal to middle carbonate ramp deposits of the Vaca Muerta Formation (early Tithonian – early Valanginian) and middle to inner ramp oyster-deposits of the Chachao Formation (early Valanginian), which form an homoclinal carbonate ramp system.〔(Kietzmann, D.A., Palma, R.M., Bressan, G.S., 2008. Facies y microfacies de la rampa tithoniana-berriasiana de la Cuenca Neuquina (Formación Vaca Muerta) en la sección del arroyo Loncoche – Malargüe, provincia de Mendoza. Revista de la Asociación Geológica Argentina 63, 696–713 ).〕〔Kietzmann, D.A., Martín-Chivelet, J., Palma, R.M., López-Gómez, J., Lescano, M., Concheyro, A., 2011a. Evidence of precessional and eccentricity orbital cycles in a Tithonian source rock: the mid-outer carbonate ramp of the Vaca Muerta Formation, Northern Neuquén Basin, Argentina. AAPG Bulletin 95, 1459–1474.〕〔Kietzmann, D.A., Palma, R.M., Riccardi, A.C., Martín-Chivelet, J., López-Gómez, J., 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, 64–86.〕 Westwad undated tidal to continental mixed deposits have been recognized and correlated with the Vaca Muerta and Chachao Formations, receiving the name of Lindero de Piedra Formation.〔Legarreta, L., Kozlowski, E., Boll, A., 1981. Esquema estratigráfico y distribución de facies del Grupo Mendoza en el ámbito surmendocino de la cuenca neuquina. 8º Congreso Geológico Argentino, Actas 3, 389–409.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Vaca Muerta」の詳細全文を読む スポンサード リンク
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