ADVERTIMENT. Lʼaccés als continguts dʼaquesta tesi queda condicionat a lʼacceptació de les condicions dʼús establertes per la següent llicència Creative Commons: http://cat.creativecommons.org/?page_id=184 ADVERTENCIA. El acceso a los contenidos de esta tesis queda condicionado a la aceptación de las condiciones de uso establecidas por la siguiente licencia Creative Commons: http://es.creativecommons.org/blog/licencias/ WARNING. The access to the contents of this doctoral thesis it is limited to the acceptance of the use conditions set by the following Creative Commons license: https://creativecommons.org/licenses/?lang=en Department de Geologia Evolution of fluvial drainage during mountain building in the Eastern Cordillera of the Colombian Andes Ph. D. Thesis 2016 Lucía Struth Izquierdo 1 2 DRAINAGE REORGANIZATION DURING MOUNTAIN BUILDING IN THE EASTERN CORDILLERA OF THE COLOMBIAN ANDES by LUCÍA STRUTH IZQUIERDO A Thesis Submitted in Fulfillment of the Requirements for the Degree of DOCTOR IN GEOLOGY by the UNIVERSITAT AUTÒNOMA DE BARCELONA PhD thesis supervised by Dr. Antonio Teixell Cácharo Departament de Geologia Universitat Autònoma de Barcelona June 2016 3 4 A mi familia. “Talk about a dream, try to make it real” Bruce Springsteen 5 6 Table of contents Abstract ..................................................................................................................................................... 9 Resumen .................................................................................................................................................. 10 Chapter 1: Introduction ......................................................................................................................... 11 1.1. Geologic framework ......................................................................................................................... 11 1.1.1. General evolution of the Eastern Cordillera and the northern Andes ................................... 11 1.1.2. Structure of the Eastern Cordillera ........................................................................................ 15 1.1.3. Stratigraphy ............................................................................................................................ 16 1.2. Fluvial and climatic setting of the Eastern Cordillera ....................................................................... 18 1.2.1. Fluvial drainage configuration ................................................................................................ 18 1.2.2. Climate .................................................................................................................................... 21 1.3. Starting hypotheses and objectives of the thesis ............................................................................. 23 2. Chapter 2: Drainage reorganization during mountain building in the river System of the Eastern Cordillera of the Colombian Andes ........................................................ 25 2.1. Introduction ...................................................................................................................................... 27 2.2. Digital topographic analysis .............................................................................................................. 28 2.2.1. Methods ................................................................................................................................. 29 2.2.2. Analysis and results ................................................................................................................ 30 2.2.3. River capture and evidence for drainage divide migration .................................................... 37 2.3. Causes and implications of drainage reorganization ........................................................................ 38 2.3.1. Mechanism causing drainage reorganization ........................................................................ 38 2.3.2. Implications for sediment supply into the adjacent basins.................................................... 40 2.4. Conclusions ....................................................................................................................................... 40 3. Chapter 3: Plateau reduction by drainage divide migration in the Eastern Cordillera of Colombia defined by morphometry and 10Be terrestrial cosmogenic nuclides........................................................................................................................ 43 3.1. Introduction ...................................................................................................................................... 45 3.2. Methods ............................................................................................................................................ 45 3.2.1. Analysis of the digital drainage network ................................................................................ 45 3.2.2. Cosmogenic nuclides analysis ................................................................................................ 47 3.3. Results ............................................................................................................................................... 51 3.3.1. Digital drainage analysis ......................................................................................................... 51 3.3.2. Landscape evolution rates ...................................................................................................... 55 3.4. Discussion ......................................................................................................................................... 58 7 3.4.1. Drainage network dynamics ................................................................................................... 58 3.4.2. Calibration of geomorphic parameters .................................................................................. 59 3.4.3. Local climatic, lithologic and tectonic effects......................................................................... 61 3.5. Conclusions ....................................................................................................................................... 65 4. Chapter 4: The Colombian Eastern Cordillera Plateau: a recent fluvial captured area .................................................................................................................................. 67 4.1. Introduction ...................................................................................................................................... 69 4.2. Methodology .................................................................................................................................... 69 4.2.1. Cosmogenic analysis ............................................................................................................... 71 4.3. Results ............................................................................................................................................... 72 4.3.1. Knickpoint distribution from longitudinal profiles ................................................................. 72 4.3.2. χ-plots ..................................................................................................................................... 74 4.3.3. χ-map ...................................................................................................................................... 78 4.3.4. Cosmogenic profile ................................................................................................................. 79 4.4. Discussion ......................................................................................................................................... 79 4.4.1. Northern plateau capture: Suárez and Chicamocha basins ................................................... 80 4.4.2. Southern plateau capture: Bogotá basin................................................................................ 82 4.4.3. A model of drainage network evolution ................................................................................ 85 4.5. Conclusions ....................................................................................................................................... 88 5. Conclusions ..................................................................................................................................... 91 5.1. River dynamics from topographic analysis and terrestrial cosmogenic nuclides ............................. 91 5.2. A new model of drainage network evolution ................................................................................... 92 References ............................................................................................................................................... 95 Appendix ............................................................................................................................................... 107 Supplementary Data – Chapter 2 and 3 ................................................................................................. 109 Supplementary Data – Chapter 4 ........................................................................................................... 112 Acknowledgments ................................................................................................................................. 113 8 Abstract The Eastern Cordillera of Colombia is