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Tesis Doctoral Tafonomía En Ambientes Lacustres Tesis Doctoral Tafonomía en ambientes lacustres : estudio paleobiológico, sedimentológico y tafonómico de las secuencias lacustres triásicas de la Cuenca de Ischigualasto-Villa Unión (formaciones Chañares, Ischichuca y Los Rastros) Mancuso, Adriana Cecilia 2004 Tesis presentada para obtener el grado de Doctor de la Universidad de Buenos Aires en Ciencias Geológicas de la Universidad de Buenos Aires Este documento forma parte de la colección de tesis doctorales y de maestría de la Biblioteca Central Dr. Luis Federico Leloir, disponible en digital.bl.fcen.uba.ar. Su utilización debe ser acompañada por la cita bibliográfica con reconocimiento de la fuente. This document is part of the Master's and Doctoral Theses Collection of the Central Library Dr. Luis Federico Leloir, available in digital.bl.fcen.uba.ar. It should be used accompanied by the corresponding citation acknowledging the source. Cita tipo APA: Mancuso, Adriana Cecilia. (2004). Tafonomía en ambientes lacustres : estudio paleobiológico, sedimentológico y tafonómico de las secuencias lacustres triásicas de la Cuenca de Ischigualasto-Villa Unión (formaciones Chañares, Ischichuca y Los Rastros). Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. hCitttap t:ip//oh Cdhli.chaagon:dle.net/20.500.12110/tesis_n3798_Mancuso Mancuso, Adriana Cecilia. "Tafonomía en ambientes lacustres : estudio paleobiológico, sedimentológico y tafonómico de las secuencias lacustres triásicas de la Cuenca de Ischigualasto-Villa Unión (formaciones Chañares, Ischichuca y Los Rastros)". Tesis de Doctor. Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. 2004. http://hdl.handle.net/20.500.12110/tesis_n3798_Mancuso Dirección: Biblioteca Central Dr. Luis F. Leloir, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. Contacto: [email protected] Intendente Güiraldes 2160 - C1428EGA - Tel. (++54 +11) 4789-9293 UNIVERSIDAD DE BUENOS AIRES FACULTAD DE CIENCIAS EXACI‘AS Y NATURALES DEPARTAMENTO DE CIENCIAS GEOLÓGICAS TESIS DOCI'ORAL Tafonomía en ambientes lacustres: estudio paleobiológico, sedimentológico y tafonómico de las secuencias lacustres triásicas de la Cuencade ' Ischigualasto-Villa Unión (formaciones Chañares, Ischichuca y Los Rastros). ' Adriana cecilia Mancuso Director: Dr. Ricardo M.Palm. 'Ï ":7 (W. rx, ¡J Í k ' “v Dra. Claudia A. Marsicano Área Paleontología, Departamento de Ciencias Geológicas Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires 2004 UNIVERSIDAD DE BUENOS AIRES FACULTAD DE CIENCIAS EXACTASY NATURALES DEPARTAMENTO DE CIENCIAS GEOLÓGICAS Ph.D. Thesis Taphonomyin lacustrine environment: paleobiologic, sedimentologic and taphonomic study of the Triassic lacustrine sequences of the Ischigualasto- VillaUnión Basin (Chañares, Ischichuca and Los Rastros formations). Adriana CeciliaMancuso Director: Dr. Ricardo M. Palma Dra. Claudia A.Marsicano Área Paleontología, Departamento de Ciencias Geológicas Facultad de Ciencias Exactas y Naturales Universidad de Buenos Aires 2004 Mancuso, 2004 Tafonomía en ambientes lacustres ÍNDICE Resumen Abstract Agradecimientos Introducción 1 Marco Geológico 4 Contenido paleontológico La Tafonomía 14 Desarrollos y Aportes Marco Teórico Metodología 21 Atributos tafonómicos Materiales estudiados Sedimentología 33 Formación Chañares Formación LosRastros Tafonomía 77 Formación Chañares Formación LosRastros Discusión 136 Plantas Invertebrados Vertebrados Formación LosRastros Formación Chañares Modelos Tafonómicos 172 Evolución paleoambiental Referencias 183 Mancuso, 2004 Tafonomía en ambientes lacustres Apéndice I Apéndice II Apéndice III Apéndice IV RESUMEN Se ha realizado un estudio sedimentológico y tafonómico sobre las secuencias fluvio-lacustres (formaciones Chañares y Los Rastros) de la Cuenca Ischigualasto-Villa Unión. Se han reconocido tres tafofacies que caracterizan la historia tafonómica de los restos exhumados de los niveles de la Formación Chañares. Así, se postuló un modelo tafonómico con dos escenarios posibles para la preservación de los restos fósiles. Un escenario refleja la muerte natural dentro del ecosistema de Chañares, y el otro un evento de mortandad en masa desencadenado por el contexto volcánico. Por su parte, se reconocieron once tafofacies para las plantas, cuatro para los invertebrados y cuatro para los vertebrados de la Formación Los Rastros. Sobre esa base se desarrolló un modelo tafonómico que caracteriza al ambiente lacustre-deltaico de Los Rastros. Así, las facies de lago distal presentan principalmente elementos autóctonos (conchostráceos) en buen estado de preservación general y con mayor abundancia que los elementos considerados alóctonos (plantas, insectos, conchostráceos) al cuerpo de agua. Por otro lado, las facies deltaicas son portadoras mayormente de elementos considerados alóctonos (plantas, conchostráceos, peces, anfibio) al cuerpo del lago, con estados de preservación variados según las propiedades hidrológicas de los I‘CSÏOS. ABSTRACT A sedimentologic and taphonomic study has been performed in the fluvio­ lacustrine sequences (Chañares and Los Rastros formations) of the Ischigualasto­ Villa Unión Basin. Three taphofacies has been recognized that characterize the taphonomic history of the exhumed material of Chañares Formation. Thus, a taphonomic model has been proposed with two pathways for the preservation of the fossils. One pathway includes the natural mortality within the Chañares ecosystem, and the other, a mass mortality event triggered by the volcanic context. In addition, twelve plant taphofacies, four invertebrate taphofacies and four vertebrate taphofacies have been recognized for Los Rastros Formation. On this base, a taphonomic model that characterizes the lacustrine-deltaic environment of Los Rastros has been developed. Thus, the distal lake facies present mainly autochthonous elements (conchostracans) in the well preservation and more abundance that the alochthonous elements (plant, insect, conchostracans) to water body. On the other hand, the deltaic facies are mainly bearer of allochthonous elements (plant, conchostracans, fish, amphibian) to lake body with varied preservation according to the hydrological characteristic of the material. Mancuso, 2004 Tafonomía en ambientes lacustres AGRADECIMIENTOS En primer lugar quiero agradecer a aquellas personas que me acompañaron en el trabajo, tanto de campo como de laboratorio, y que pusieron el hombro, sus conocimientos y mucha paciencia para ayudarme en la difícil tarea de formarme como profesional. Entre esas personas se encuentran mi directora la Dra. Claudia Marsicano, mi gran amigo el Dr. Alberto Caselli, mi gran amiga la Lic. Silvia Barredo, mis amigas y compañeras del laboratorio Lic.Julia Desojo, Lic. Susana Breglia, Lic. Laura Nicoli, Lic. Nadia Domnanovich y Paula Muzzoppapa, la jefa del lab. Dra. Ana Maria Báez, la gente de paleo: Dra. Cecilia Laprida, Dra. Beatriz Aguirre Urreta, Dr. Darío Lazo, Lic. Marcela Cichowolski, Lic. Debora Rodríguez, Lic. Cecilia Rodríguez Amenábar y Dr. Guillermo Ottone; al Dr. Ricardo Palma, Dr. Oscar Limarino, Lic. Patricia Cicholi, Lic.Ana Tedezco, Dra. Silvia Lanés, Dr. Pablo Pazos y el resto de la gente de sedi, al Dr. Oscar Gallego, Dra. Adriana López Albarello, Lic. Andrea Arccuci, Dr. Diego Pol. En segundo lugar quiero agradecer a todos los que de alguna forma participaron y dieron luz al camino que transité en mi formación, tanto en este trabajo como en el resto de mi carrera. Es imposible nombrar a tantas personas ya que se encuentran aquí incluidas desde los profesionales, los buenos, por aportar eficientemente sus conocimientos y los malos, por mostrarme lo que no quiero ser, hasta mis compañeros y amigos. En el aspecto humano quiero agradecer muy especialmente a mi esposo Tomás por haberme apoyado y ayudado en los tra mos mas difíciles de este trabajo. Asimismo quiero recordar y agradecer a mi familia, por las veces que me Mancuso, 2004 Tafonomía en ambientes lacustres facilitaron las cosas y las veces que me las complicaron ya que de esa forma me prepararon para enfrentarme a este mundo. En forma particular quiero agradecer a mi tía por ser una persona muy especial la cual me da siempre mucha fuerza desde su oración y su aliento. En forma muy especial quiero agradecer a los amigos, a los que conocí en el ambiente de la facultad y me alentaron a nunca bajar la guardia y seguir siempre adelante, en forma especial a Diego Pol, Julián Faivovich, Ana Dogliotti, Silvina de Valais, Valeria Berler, Valeria Hey, Valeria Pérez Loinaze, Maria Jose Cerviño, Lara Lopardo, Ignacio Demarco, Lorena Benseñor, Andrea Dugour, Vero Zaldívar, Vale Ruiz Moreno, Sebastián Lotito, Sebastián Laría, Amancay Martínez, Vero Boggie, Federico Bottesi, Hernan Greco, Paula Tondi, Javier Martínez y a todos los que me estoy olvidando en este momento. También quiero agradecer a los amigos que hice en otros ámbitos y me acompañaron en forma especial en este camino. En el aspecto académico quiero agradecer muy especialmente a mis directores Dra. Claudia Marsicano y Dr. Ricardo Palma por el tiempo, paciencia y dedicación brindada para mi formación profesional. Por último es indispensable aclarar que este trabajo fue parcialmente financiado por PIP CONICET 0535 (Lic. Andrea Arcucci), UBACyT (Dra. Ana María Báez),The Jurassic Foundation (Lic.Adriana Mancuso), PIP CONICET 02228 (Dr. Guillermo Ottone). Mancuso, 2004 Tafonomía en ambientes lacustres INTRODUCCIÓN Los ambientes lacustres brindan importante información paleoclimática dado que son sistemas particularmente
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