SEDIMENT DISTRIBUTION AND DEPOSITIONAL PROCESSES ON THE CARNEGIE RIDGE A Thesis by NELSON A. PAZMIÑO MANRIQUE Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2005 Major Subject: Oceanography SEDIMENT DISTRIBUTION AND DEPOSITIONAL PROCESSES ON THE CARNEGIE RIDGE A Thesis by NELSON A. PAZMIÑO MANRIQUE Submitted to Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved as to style and content by: _________________________ _______________________________ William R. Bryant William W. Sager (Chair of Committee) (Member) _________________________ _______________________________ Thomas W.C. Hilde Niall C. Slowey (Member) (Member) _________________________ Wilford Gardner (Head of Department) May 2005 Major Subject: Oceanography iii ABSTRACT Sediment Distribution and Depositional Processes on the Carnegie Ridge. (May 2005) Nelson A. Pazmiño Manrique, B.S., Escuela Superior Naval del Ecuador Chair of Advisory Committee: Dr. William R. Bryant Sediment sampling, bathymetric data, and seismic reflection profiling were used to classify sediment deposition patterns on the Carnegie Ridge. Core sampling was used to relate compositional characteristics between equivalent areas, and seismic profiling to establish vertical variations. Three study areas were selected based on core distribution along the ridge. Grids of the following parameters were obtained: slope, elevation, percentage of carbonate, SiO2, and organic carbon contents. The general CaCO3 content distribution is highest on the ridge except in the areas affected by terrigenous deposition from the mainland, and volcanic debris from Galapagos Volcanic Platform. The general SiO2 content distribution is highest south of the Equator, bordering the west ridge. The organic carbon content is high in the equatorial upwelling area and close to the mainland. The relationship between organic carbon and carbonate was determined through correlation analysis. Based on those analyses, and considering the mixture of sedimentary sources and tectonic processes, the carbonate sediment is more important to this area. Sediments on the Carnegie Ridge above the lysocline are affected by three different types of processes controlling the sediment deposition. The first is the location of the high productivity zone in which pelagic settling is the source of sediment. The second is the difference in sea water properties between the Panama and Peru Basins surrounding the ridge, which creates different depositional environments. These properties create horizontal and vertical variations within water masses. Intermediate depths are affected by northward Pacific Central Water and bottom waters by northward Pacific Deep Water. The deflection of the bottom water flow by the existence of the Carnegie Ridge as a natural barrier produces scouring effects on the south flank. The third process controlling deposition is underwater dissolution on the saddle and east ridge by organic carbon degradation, which is enhanced by bottom water flow. Significant differences in sedimentation types were found in areas with hilltops, contrasted slopes, and slope bases, primarily related to changing depths and water flows, and lateral transport along the steepest north scarp. iv DEDICATION To my family for their endless patience and support through all the days that I was absent, both at home and away working to get my degree and complete my goal. To God for his sight through my world. v ACKNOWLEDGEMENTS My sincere thanks to Dr. William Bryant for his vision, supervision and guidance during all processes of the thesis preparation. I am also deeply grateful to CPNV-EM Fernando Zurita for his confidence and the opportunity that he provided me to find new challenges in my career. I received most valuable support and advice from my committee members: Dr. William Bryant, Dr. Thomas Hilde, Dr. Niall Slowey and Dr. William Sager. Thanks for their guidance, suggestions, and corrections. To the department of Oceanography, and especially to the head of the Department, Dr. Wilford Gardner, who made it possible to complete my project in accordance with the department goals. Also, thanks to all Texas A&M staff, for their help in solving my research and administrative problems. My sincere thanks go to Dr. Thomas Hilde, who gave me many useful suggestions toward the advancement of my thesis. I am also grateful to the following: Dr. Lyle (Boise State Univ.), Dr.Volkmar (Leime Bundesamt für Seeschifffahrt und Hydrographie (BSH)), who provided me with the public domain information required by my thesis. Many of the datasets used in the study came from the collection of the National Geophysical Data Center (NGDC), DOD Data Center (Germany), Research Center for Marine Geosciences at Christhian Albrechts University (Germany), the Lamont-Doherty Earth Observatory, and the Scripps Institute of Oceanography: thanks to all of them for allowing access to public domain information. I also appreciated all the help and support of my friends and fellow students at Texas A&M University and Ecuadorian Oceanographic Institute (INOCAR), especially Lieutenant Cesar Arias of the Armada del Ecuador and Mrs. Essy Santana for their assistance during data collection. Also thanks to Leigh Holcombe and Jose Gavinha, my close friends. Special thanks to my wife Vanessa, my children Christian, Gabriel, Nicolás and Daniel, and my mother-in-law Ivone for understanding the importance of my project and being able to surpass so many problems without my presence. Finally, I would like to deeply thank my parents, Gulnara and Octavio, and my brothers Pablo and Ricardo, who have helped so much with my career and my family during all these years. vi TABLE OF CONTENTS Page ABSTRACT ................................................................................................................................iii DEDICATION ............................................................................................................................ iv ACKNOWLEDGEMENTS ......................................................................................................... v TABLE OF CONTENTS ............................................................................................................ vi LIST OF FIGURES...................................................................................................................viii LIST OF TABLES ...................................................................................................................... xi CHAPTER I INTRODUCTION..................................................................................................................1 Problem...............................................................................................................................2 Objectives ...........................................................................................................................2 Hypotheses..........................................................................................................................3 II GENERAL DESCRIPTION OF THE STUDY AREA..........................................................5 Geographic location............................................................................................................5 Oceanographic settings.......................................................................................................6 Geological settings: ..........................................................................................................10 Bathymetric summary.......................................................................................................14 III LITERATURE REVIEW....................................................................................................18 Sediment characterizations ...............................................................................................20 Sediment thickness ...........................................................................................................20 Seafloor composition........................................................................................................20 Deep currents.....................................................................................................................21 IV DATA AND METHODS....................................................................................................22 Data...................................................................................................................................22 Methods ............................................................................................................................22 Seafloor morphology description......................................................................................29 Core to core correlation ....................................................................................................31 Bottom currents ................................................................................................................32 V SEDIMENT CHARACTERIZATION.................................................................................34 Physiography of deposition environments........................................................................34 Sediment composition ......................................................................................................42 Sediment