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Estudio Paleobotánico Paleoecológico Y Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… ESTUDIO PALEOBOTÁNICO, PALEOECOLÓGICO Y PALEOAMBIENTAL EN LA LOCALIDAD DE LAGUNA FLECHA NEGRA, MACIZO DEL DESEADO, JURÁSICO SUPERIOR, PROVINCIA DE SANTA CRUZ, ARGENTINA. Licenciada Ana Julia Sagasti Tesis para optar al título de Doctor en Ciencias Naturales Director: Dr. Juan Leandro García Massini Director: Dr. Diego Guido Facultad de Ciencias Naturales y Museo Universidad Nacional de La Plata 1 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… FACULTAD DE CIENCIAS NATURALES Y MUSEO ESTUDIO PALEOBOTÁNICO, PALEOECOLÓGICO Y PALEOAMBIENTAL EN LA LOCALIDAD DE LAGUNA FLECHA NEGRA, MACIZO DEL DESEADO, JURÁSICO SUPERIOR, PROVINCIA DE SANTA CRUZ, ARGENTINA. TESIS DOCTORAL Lic. Ana Julia Sagasti Dr. Juan. L. García Massini Dr. Diego M. Guido Director Director La Plata – Argentina 2017 2 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… “…No se veía un árbol, y apenas algún cuadrúpedo o ave; únicamente el guanaco aparecía en la cima de algún cerro, velando como fiel centinela por su rebaño. Todo era silencio y desolación. Sin embargo, al pasar por regiones tan yermas y solitarias, sin ningún objeto brillante que llame la atención, se apodera del ánimo un sentimiento mal definido, pero de íntimo gozo espiritual. El espectador se pregunta por cuántas edades ha permanecido así aquella soledad, y por cuántas más perdurará en este estado.” Charles Darwin. Diario del viaje de un Naturalista. “Adueñarnos del mundo de las ideas, para que las nuestras, sean las ideas del mundo.” Antonio Gramsci. 3 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… DEDICATORIA A mi compañero, Gastón. Al final del viaje, estamos tú y yo, intactos. 4 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… AGRADECIMIENTOS Quiero expresar mi agradecimiento a todos aquellos que contribuyeron al desarrollo de esta Tesis. A Alba Zamuner, que guió mis primeros pasos en la Paleobotánica. A mis directores, Juan García Massini, Diego Guido, Eduardo Morel y Alan Channing, que aportaron discusiones y perspectiva a mi formación. A la Universidad Nacional de La Plata, por la educación Pública, Gratuita y de Calidad. A las autoridades de la Facultad de Ciencias Naturales y Museo, y CONICET, que me permitieron realizar este Doctorado. A Héctor Barbero y Guadalupe Godoy, que me enseñaron que el pensamiento crítico no es sólo teoría, sino práctica cotidiana. A la Dra. Josefina Bodnar, colega y amiga, que me enseñó a enseñar Paleobotánica. Al Dr. Ignacio Escapa y el equipo de Paleobotánica del Museo Paleontológico Egidio Feruglio, Andrés Elgorriaga, Ana Andruchov Colombo, Cristina Nunes y Luis Miguel Sander, que me abrieron sus puertas y contribuyeron al desarrollo de mis estudios. A mis colegas de la División Paleobotánica, Eliana P. Coturel, Daniel Ganuza, Patricio Knigth y Adolfo Zúñiga, que me acompañaron en este camino. A mis Padres, Viviana y Carlos, que me enseñaron a ser independiente, sin dejar jamás de acompañarme. A mis amigos y amigas, por el apoyo incondicional. A Gregoria Cochero, Santiago Hernandez del Pino y Celeste Scattolini, por las discusiones sobre metodología y la terapia de grupo. A Caroline Gommendy, Sebastián Zurita, Ezequiel Bechi, Anabela Vague, Walter Defrik, Raúl Carriga, Julia Martino, Nahuel Martinez e Isabel Oeyen, gracias por los vinos y las risas, materia prima de la vida adulta. 5 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… ÍNDICE I. Resumen ........................................................................................................................ 9 I. Abstract. ...................................................................................................................... 12 II. Introducción ............................................................................................................... 15 Relevancia del problema. ........................................................................................... 15 Objetivos ..................................................................................................................... 18 Objetivo general: .................................................................................................... 18 Objetivos específicos: ............................................................................................. 18 Hipótesis. .................................................................................................................... 19 Hipótesis principal .................................................................................................. 19 Hipótesis auxiliares ................................................................................................ 19 III. Antecedentes geológicos ..................................................................................... 20 Provincia Geológica Macizo del Deseado. ................................................................. 20 Historia geológica del Grupo Bahía Laura. ................................................................ 22 Formación La Matilde ................................................................................................ 28 Formación Chon Aike. ............................................................................................... 29 IV. Antecedentes paleobotánicos. .................................................................................. 31 Reseña del estudio de las megafloras jurásicas en la Argentina ................................. 31 Floras estudiadas en ambientes con influencia geotérmica del Macizo del Deseado. 50 Estudios previos de la Flora Fósil de la Formación Chon Aike. ................................ 51 V. Materiales y métodos ................................................................................................. 53 Área estudiada. ........................................................................................................... 53 Tareas efectuadas en el campo. .................................................................................. 54 Tareas en laboratorio y gabinete ................................................................................. 56 Preparación e ilustración del material .................................................................... 56 Análisis y determinación del material .................................................................... 57 Terminología utilizada. ........................................................................................... 58 Interacciones multitróficas en leños degradados. ................................................... 63 Estudios tafonómicos y paleoecológicos ................................................................ 63 Reconstrucción ecológica de las paleocomunidades. ............................................. 63 VI. Marco geológico ....................................................................................................... 65 Sistema geotérmico del Jurásico de Santa Cruz. ........................................................ 65 Geología de la localidad Laguna Flecha Negra .......................................................... 66 Sucesión volcaniclástica de base a techo (Figura 6.2). ............................................... 67 6 Ana Julia Sagasti – Estudio paleobotánico, paleoecológico y paleoambiental… Análisis de facies de la localidad Laguna Flecha Negra (Tabla 6.1). ........................ 72 Discusión. ................................................................................................................... 74 Conclusiones ............................................................................................................... 76 VII. Sistemática paleobotánica ....................................................................................... 78 Introducción. ............................................................................................................... 78 Clase Polypodiopsida Cronquist, Takhtajan y Zimmerman 1966 .............................. 80 Orden Gleicheniales Link 1833 .............................................................................. 80 Orden Cyatheales Frank in Leunis 1877 ................................................................ 81 Incertae sedis. ......................................................................................................... 82 Clase Cycadeoideopsida (=Bennettitopsida) Scott, 1923 ........................................... 85 Orden Cycadeoideales sensu Stewart y Rothwell, 1993 ........................................ 85 Clase Coniferopsida Gifford y Foster 1989 ................................................................ 93 Orden CONIFERALES sensu Stewart y Rothwell 1993 ....................................... 93 Incertae sedis ............................................................................................................ 128 Anexo xilotafoflora................................................................................................... 135 Conclusiones. ............................................................................................................ 145 VIII. Interacciones multitróficas en leños degradados. ................................................ 149 Introducción .............................................................................................................. 149 Resultados ................................................................................................................
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