Copyright by Valentina Marzia Rossi 2016 The Dissertation Committee for Valentina Marzia Rossi Certifies that this is the approved version of the following dissertation: Mixed-Energy Shallow-Marine Systems with Emphasis on Tidal Influence Committee: Ronald J. Steel, Supervisor Wonsuck Kim, Co-Supervisor Cornel Olariu William Fisher Sergio Longhitano Mixed-Energy Shallow-Marine Systems with Emphasis on Tidal Influence by Valentina Marzia Rossi, Laurea Magistrale Mixed-Energy Shallow-Marine Systems with Emphasis on Tidal Influence Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy The University of Texas at Austin December 2016 Dedication To my mom, my dad, my sister, and Julio. “The mountains are calling and I must go” – John Muir “In every walk with nature one receives far more than he seeks” – John Muir “… non vogliate negar l'esperïenza, di retro al sol, del mondo sanza gente. Considerate la vostra semenza: fatti non foste a viver come bruti, ma per seguir virtute e canoscenza” Dante Alighieri, Divina Commedia, Inferno canto XXVI, 116-120 Acknowledgements I would like to thank all the people that helped me throughout my PhD. My family and Julio for their constant support and help. Ron Steel, my co-advisor, for his help and great geological discussions. Wonsuck Kim, my co-supervisor, for his help and for his great support. Cornel Olariu, for great discussions and for helping me to improve all my research ideas. Sergio Longhitano (and Marta), for his help and support, and for the great time in the field. Donatella Mellere, for constant support and for motivating me. Domenico Chiarella, for his help in the field and not only. The PI’s of the Lajas Project, and in particular Bob Dalrymple, for his great help in the field and for great discussions. I would also like to thank Vicente and Graciela, that made me feel like at home in Argentina, and made my field experience there unforgettable. All my friends in Ron’s and Wonsuck’s research groups, Jinyu, Yang, Xiaojie, Logan, Austin, Allison, Anastasia, Brandee, Si, Shunli, YeJin, Max, WoongMo. Finally, I would like to thank the companies and institutions that have supported my research: Statoil, VNG Norge, Woodside and BHP Billiton, the RioMAR consortium, GSA, IAS and the Ronald K. DeFord Field Scholarship Fund. v Mixed-Energy Shallow-Marine Systems with Emphasis on Tidal Influence Valentina Marzia Rossi, PhD The University of Texas at Austin, 2016 Supervisors: Ronald J. Steel and Wonsuck Kim This research investigates mixed-energy shallow marine depositional systems (i.e., subject to the influence of river, wave and tidal currents), with particular emphasis on the role of tidal currents in controlling the final stratigraphic product. In modern coastal areas and in the rock record, many sedimentary systems bear the signature of changing and overlapping coastal processes. Understanding the evolution of the mixed tidal systems and their stratigraphic expression is fundamental both to the science of dynamic stratigraphy and for a proper exploitation of the stored natural resources. The research was carried out using four datasets: an outcrop dataset of measured sedimentological sections from the Jurassic Lajas Formation, Argentina; a dataset of previously published literature of process variability and sedimentary structures; a dataset of numerical simulations produced with Delft3D software; and an outcrop dataset of measured sedimentological sections from the Pleistocene Siderno Strait, Italy. The data here presented highlight the great degree of process variability in the rock record, and the importance of tidal currents in controlling deltaic morphology and stratigraphic architecture. The strata of the Lajas Formation show a clear process partitioning in different reaches of the deltaic system (proximal vs. distal and regressive vs. transgressive). In particular, tidal currents strongly reworked the delta front at times, vi creating sand-rich and amalgamated sandbodies. This project demonstrates that disentangling the signals of river, wave and tidal currents in the stratigraphy leads to a better interpretation of ancient mixed-energy systems. The study of the literature database shows that some sedimentary structures can be considered reliable indicators of a particular process (river, waves or tides), whereas other structures cannot be tied with confidence to any particular process. A process probability value is calculated for each sedimentary structure, and thus quantifies process variability and its uncertainty. This work encourages a new, more detailed and more quantified field methodology for facies sedimentology. The numerical modeling of tide-influenced deltas using Delft3D shows how different degrees of tidal influence in river-dominated deltas affect delta morphology and stratigraphy, when tidal currents are flowing perpendicularly to the shoreline. Increasing tidal influence induces deeper and more stable distributary channels that act as efficient conduits for sediment transport basinward. The delta-front geometry is also affected by tidal current reworking, evolving into a compound clinoform geometry. The research on the Siderno Strait, in contrast, highlights tidal influence on deltaic stratigraphic evolution when tidal currents flow parallel to the coastline. River-dominated deltas entering the tide-dominated strait tend to show a deflection of the delta-front sands in a direction parallel to the dominant tidal current. The delta-front sands became reworked by tidal currents into large dune fields within the strait. vii Table of Contents List of Tables ........................................................................................................ xii List of Figures ...................................................................................................... xiv Chapter 1: Introduction ...........................................................................................1 Problems and Significance ..............................................................................1 Objectives .......................................................................................................3 Overview of Chapters .....................................................................................4 Chapter 2: The role of tidal, wave and river currents in the evolution of mixed-energy deltas: Example from the Lajas Formation (Argentina) .......................................................................................................4 Chapter 3: Quantifying process regime in ancient shallow marine mixed- energy depositional systems: what are sedimentary structures really telling us? ......................................................................................5 Chapter 4: Impact of tidal currents on delta-channel deepening, stratigraphic architecture and sediment bypass beyond the shoreline .......................................................................................................5 Chapter 5: Tidal and Fluvial Processes Interplay in an Early Pleistocene, Delta-Fed, Strait Margin (Calabria, southern Italy) ......................6 References .......................................................................................................7 Chapter 2: The role of tidal, wave and river currents in the evolution of mixed-energy deltas: Example from the Lajas Formation (Argentina) ...............................11 Abstract .........................................................................................................11 introduction ...................................................................................................12 Geological setting .........................................................................................16 The Lajas Formation ............................................................................17 Methodology .................................................................................................18 Facies associations and depositional environments ......................................20 Facies Association 1 (Coastal Plain) ....................................................25 Facies Association 1.1 (Upper Coastal Plain) .............................25 Facies Association 1.2 (Lower Delta Plain) ...............................27 viii Facies Association 1.3 (Lower Delta-Plain Interdistributary Bays) ............................................................................................30 Facies Association 1.4 (Lower Delta Plain) ...............................31 Process summary ........................................................................34 Facies Association 2 (Delta Front and Subaqueous Platform) ............35 Facies Association 2.1 (Delta-Front Mouth Bars) ......................35 Facies Association 2.2 (Tidally Reworked Bars and Dunes) .....39 Facies Association 2.3 (Subaqueous Platform) ..........................45 Facies Association 2.4 (Shoreface) .............................................49 Process summary ........................................................................51 Facies Association 3 (Prodelta and Offshore) .....................................52 Facies Association 3.1 (Prodelta) ...............................................52 Facies Association 3.2 (Offshore/Offshore Transition) ..............52 Process summary ........................................................................54 Facies Association