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FANGOLITAS BITUMINOSAS ASOCIADAS A FLUJOS FLUIDOS DE FANGO, FORMACIÓN VACA MUERTA (TITHONIANO -VALANGINIANO), CUENCA NEUQUINA, ARGENTINA

  • November 2018
  • Conference: XVI RAS
  • At: General Roca, Río Negro, Argentina
Authors:
Germán Otharán at Universidad Nacional del Sur
Germán Otharán
Carlos Zavala at Universidad Nacional del Sur
Carlos Zavala
Mariano Arcuri at Universidad Nacional del Sur
Mariano Arcuri
Mariano Di Meglio at Universidad Nacional del Sur
Mariano Di Meglio
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Abstract

Se presenta un estudio sedimentológico de afloramiento y subsuelo de la Formación Vaca Muerta en áreas centrales de la Cuenca Neuquina. El estudio de afloramiento estuvo enfocado al análisis puntual de cortes macroscópicos pulidos de concreciones carbonáticas, las cuales preservan un registro excepcional de los rasgos sedimentarios primarios presentes en depósitos fangolíticos. El estudio de subsuelo permitió desarrollar un análisis sedimentológico continuo de diferentes testigos corona de la Formación Vaca Muerta. Los resultados obtenidos sugieren que existe una gran variedad de depósitos de grano fino (<62,5) acumulados a partir de flujos fluidos de fango de distinta naturaleza. Su origen parece estar relacionado a dos procesos principales: flujos hiperpícnicos fangosos de larga duración (origen extracuencal) y flujos de fango intracuencales asociados a procesos de resedimentación. Los flujos de fango intracuencales serían más frecuentes en sectores próximos al quiebre de la plataforma, generando depósitos con bajo contenido orgánico. Por otro lado, los flujos hiperpícnicos fangosos de origen extracuencal habrían actuado como excelentes medios de transferencia de sedimentos finos y materia orgánica desde áreas emergidas hasta zonas internas de la cuenca, atravesando relieves de muy baja pendiente. En su trayectoria cuenca adentro, habrían incorporado material intracuencal previamente depositado creando depósitos mixtos. La rápida transferencia de fango rico en materia orgánica (tipo II y III) hacia sectores internos de la cuenca habría permitido alcanzar un soterramiento rápido y eficiente, evitando su exposición en el fondo marino. Este proceso habría favorecido la preservación de fangos bituminosos en sectores internos de la Cuenca Neuquina.
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XVI
RAS
26 al 30 de noviembre de 2018
General Roca - Río Negro
LIBRO DE RESÚMENES
XVI REUNIÓN ARGENTINA DE SEDIMENTOLOGÍA 2018
LIBRO DE RESÚMENES
ORGANIZAN
AUSPICIAN
Libro de Resúmenes de la XVI Reunión Argentina de Sedimentología:
Sedimentología Sin Frontera. 26 al 30 de noviembre de 2018. General Roca,
Río Negro, Argentina.
Edición: Alejandro David Báez y Ricardo Gómez
Diseño Visual: Julio Bariani y Manuela Zalazar
XVI REUNIÓN ARGENTINA DE SEDIMENTOLOGÍA 2018
LIBRO DE RESÚMENES
COMITÉ ORGANIZADOR
Presidente
Juan José Ponce (CONICET-UNRN)
Vice-Presidente
Aldo Omar Montagna (YPF-UNRN)
Secretaria
Nerina Canale (CONICET-UNRN)
Tesorera
Débora Mical Campetella (CONICET-UNRN)
Vocales
Noelia Beatriz Carmona (CONICET-UNRN)
Alberto Tomás Caselli (CONICET-UNRN)
Emiliano Santiago (YPF)
Silvio Casadío (CONICET-UNRN)
Fabián Gutiérrez (YPF)
Josefina Pons (CONICET-UNRN)
Martín Cevallos (CGC-UNSJ)
Nayibe Otalora Ardila (YPF)
Julieta Omarini (CONICET-UNRN)
Manuela Zalazar (CONICET/YTEC-UNRN)
Alejandro David Báez (CONICET-UNRN)
Ricardo Gómez (AGENCIA-UNRN)
Maximiliano Nicolás Rodríguez (CONICET-UNRN)
XVI REUNIÓN ARGENTINA DE SEDIMENTOLOGÍA 2018
LIBRO DE RESÚMENES
COMITÉ CIENTÍFICO
Cecilia Eugenia del Papa (CONICET-CICTERRA)
Eduardo Luis Piovano (CONICET-CICTERRA)
Gastón Matías Iovine Palafox (YPF)
Matías Miguel Salvarredy Aranguren (YPF-UNPSJB)
Marcelo Krause (CONICET-MEF)
Eduardo Sergio Bellosi (CONICET-MACNBR)
Pablo Bouza (CONICET-CENPAT).
Carlos Alberto Zavala (GCS-UNS)
Ricardo Gómez Omil (WINTERSHALL)
Juan José Ponce (CONICET-UNRN)
Carlos Oscar Limarino (IGEBA)
Ezequiel González (YTEC)
Maisa Andrea Tunik (CONICET-UNRN)
Alberto Tomás Caselli (CONICET-UNRN)
Walter Baez (CONICET-INENCO)
Romina Daga (CONICET-CNEA)
Mario Schiuma (YPF S.A.)
Ernesto Schwarz (CONICET-CIG)
Silvia Marcomini (IGEBA)
Carlos Echevarria (PAMPAENERGÍA)
Gonzalo Diego Veiga (CONICET-CIG)
Alfonsina Tripaldi (CONICET-IGEBA)
Agustín Arguello Scotti (YPF. S.A.)
José Oscar Allard (UNPSJB)
Nicolás Foix (CONICET-UNPSJB)
Jorge Hechem (YPF)
Carlos Daniel Arregui (PAMPA ENERGIA-UNCOMA)
Diana Cuadrado (CONICET-IADO)
Miguel de Moraes Lima Silveira (Petrobras S.A.)
Ivan Lanusse (YPF)
Guillermina Sagasti (YPF)
Silvio Casadío (CONICET-UNRN)
María Angélica Diez (UNRN)
Leandro D’elía (CONICET-CIG)
175
XVI REUNIÓN ARGENTINA DE SEDIMENTOLOGÍA 2018
T-S11: SISTEMAS NO CONVENCIONALES
FANGOLITAS BITUMINOSAS ASOCIADAS A FLUJOS
FLUIDOS DE FANGO, FORMACIÓN VACA MUERTA
(TITHONIANO -VALANGINIANO), CUENCA NEUQUINA,
ARGENTINA
Germán Aníbal Otharán1,2,3, Carlos Alberto Zavala2,3, Mariano Arcuri2,3,
Mariano Di Meglio2,3, Agustín Zorzano2,3, Denis Marchal4 y Guillermina
Köhler4
1 CONICET
2 GCS Argentina SRL. Interna 1320, Bahía Blanca, 8000, Buenos Aires, Argentina
3 Departamento de Geología, Universidad Nacional del Sur. Av. Alem 1253, cuerpo B´ - 2º Piso, Bahía
Blanca, 8000, Argentina
4 Pampa Energía S.A. Maipú 1, CABA
gotharan@gcsargentina.com
Se presenta un estudio sedimentológico de afloramiento y subsuelo de la
Formación Vaca Muerta en áreas centrales de la Cuenca Neuquina. El estudio
de afloramiento estuvo enfocado al análisis puntual de cortes macroscópicos
pulidos de concreciones carbonáticas, las cuales preservan un registro
excepcional de los rasgos sedimentarios primarios presentes en depósitos
fangolíticos. El estudio de subsuelo permitió desarrollar un análisis
sedimentológico continuo de diferentes testigos corona de la Formación Vaca
Muerta. Los resultados obtenidos sugieren que existe una gran variedad de
depósitos de grano fino (<62,5) acumulados a partir de flujos fluidos de fango
de distinta naturaleza. Su origen parece estar relacionado a dos procesos
principales: flujos hiperpícnicos fangosos de larga duración (origen
extracuencal) y flujos de fango intracuencales asociados a procesos de
resedimentación. Los flujos de fango intracuencales serían más frecuentes en
sectores próximos al quiebre de la plataforma, generando depósitos con bajo
contenido orgánico. Por otro lado, los flujos hiperpícnicos fangosos de origen
extracuencal habrían actuado como excelentes medios de transferencia de
sedimentos finos y materia orgánica desde áreas emergidas hasta zonas
internas de la cuenca, atravesando relieves de muy baja pendiente. En su
trayectoria cuenca adentro, habrían incorporado material intracuencal
previamente depositado creando depósitos mixtos. La rápida transferencia de
fango rico en materia orgánica (tipo II y III) hacia sectores internos de la cuenca
habría permitido alcanzar un soterramiento rápido y eficiente, evitando su
exposición en el fondo marino. Este proceso habría favorecido la preservación
de fangos bituminosos en sectores internos de la Cuenca Neuquina.
... El hecho de que esta facies exhiba una diferencia composicional tan marcada entre láminas de fangolitas gruesas detríticas y fangolitas arenosas intraclásticas parece estar asociado a un fenómeno de competencia hidráulica entre las partículas. Se interpreta que el origen de las variaciones rítmicas en el tamaño del grano común a la facies FsL podría estar asociado a flujos de larga duración sujetos a ligeras fluctuaciones en su velocidad y concentración sedimentaria (Otharán y Zavala, 2018;Otharán et al., 2018b). ...
Análisis de facies en depósitos de grano fino asociados a flujos de fango. Formación Vaca Muerta (Tithoniano-Valanginiano), Cuenca Neuquina central, Argentina
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Facies analysis and stratigraphy across the Jurassic-Cretaceous boundary in a new basinal Tithonian–Berriasian section of the Vaca Muerta Formation, Las Tapaderas, Southern Mendoza Andes, Argentina
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Mineralogy and geochemistry of deeply-buried marine sediments of the Vaca Muerta-Quintuco system in the Neuquén Basin (Chacay Melehue section), Argentina: Paleoclimatic and paleoenvironmental implications for the global Tithonian-Valanginian reconstructions
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Hyperpycnal (over density) flows and deposits
Article
Full-text available
  • Dec 2020
A hyperpycnal flow forms when a relatively dense land-derived gravity flow enters into a marine or lacustrine water reservoir. As a consequence of its excess of density, the incoming flow plunges in coastal areas, generating a highly dynamic and often long-lived dense underflow. Depending on the characteristics of the parent flow (flow duration and flow rheology) and basin salinity, the resulting deposits (hyperpycnites) can be very variable. According to flow duration, land-derived gravity flows can be classified into short-lived or long-lived flows. Short-lived gravity flows last for minutes or hours, and are mostly related to small mountainous river discharges, alluvial fans, collapse of natural dams, landslides, volcanic eruptions, jökulhlaups, etc. Long-lived gravity flows last for days, weeks or even months, and are mostly associated with medium- to large-size river discharges. Concerning the rheology of the incoming flow, hyperpycnal flows can be initiated by non-Newtonian (cohesive debris flows), Newtonian supercritical (lahars, hyperconcentrated flows, and concentrated flows) or Newtonian subcritical flows (pebbly, sandy or muddy sediment-laden turbulent flows). Once plunged, non-Newtonian and Newtonian supercritical flows require steep slopes to accelerate, allow the incorporation of ambient water and develop flow transformations in order to evolve into a turbidity current and travel further basinward. Their resulting deposits are difficult to differentiate from those related to intrabasinal turbidites. On the contrary, long-lived Newtonian subcritical flows are capable of transferring huge volumes of sediment, freshwater and organic matter far from the coast even along gentle or flat slopes. In marine settings, the buoyant effect of interstitial freshwater in pebbly and sandy hyperpycnal flows can result in lofting due to flow density reversal. Since the excess of density in muddy hyperpycnal flows is provided by silt-clay sediments in turbulent suspension, lofting is not possible even in marine/saline basins. Muddy hyperpycnal flows can also erode the basin bottom during their travel basinward, allowing the incorporation and transfer of intrabasinal sediments and organic matter. Long-lived hyperpycnal flow deposits exhibit typical characteristics that allow a clear differentiation respect to those related to intrabasinal turbidites. Main features include (1) composite beds with gradual and recurrent changes in sediment grain-size and sedimentary structures, (2) mixture of extrabasinal and intrabasinal components, (3) internal and discontinuous erosional surfaces, and (4) lofting rhythmites in marine/saline basins.
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