Plate dynamics, mantle structure and tectonic evolution of the Caribbean region Steven van Benthem UTRECHT STUDIES IN EARTH SCIENCES NO 044 Members of the Assessment Committee: Prof. Dr. G. Bertotti Department of Geosciences and Engineering, Delft University of Technology Delft, the Netherlands Prof. Dr. S.A.P.L. Cloetingh Department of Earth Sciences, Universiteit Utrecht Utrecht, the Netherlands Dr. L. Kennan Shell Global Solutions International Rijswijk, the Netherlands Prof. Dr. R.L.M. Vissers Department of Earth Sciences, Universiteit Utrecht Utrecht, the Netherlands Prof. Dr. W. Spakman Department of Earth Sciences, Universiteit Utrecht Utrecht, the Netherlands The research of this thesis was carried out at: Tectonophysics group Department of Earth Sciences Faculty of Geosciences Utrecht University Budapestlaan 4 3584CD Utrecht The Netherlands ISBN: 978-90-6266-340-8 Printed in the Netherlands by Wöhrmann Print Service, Zutphen Copyright © 2013 Steven van Benthem Niets uit deze uitgave mag worden vermenigvuldigd en/of openbaar gemaakt door middel van druk, fotokopie of op welke andere wijze dan ook zonder voorafgaande schriftelijke toestemming van de auteur. All rights reserved. No part of this publication may be reproduced in any form, by print or photo print, microfilm or any other means, without written permission of the author. Cover illustration: Seismicity and topography of the Caribbean region. Plate dynamics, mantle structure and tectonic evolution of the Caribbean region De plaatdynamica, mantelstructuur en de tektonische evolutie van het Caribisch gebied (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. G.J. van der Zwaan, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op maandag 28 oktober 2013 des ochtends te 10.30 uur door Steven Arnout Cornelus van Benthem geboren op 23 augustus 1979 te Zwolle, Nederland Promotor: Prof. Dr. M.J.R. Wortel Co-promotor: Dr. R.M.A. Govers The research described in this thesis was financially supported by the Netherlands Organisation for Scientific Research / Earth and Life-Sciences (NWO / ALW). Para Alba Contents Chapter 1 Introduction .............................................................................................................. 9 1.1 Short overview of the tectonic history of the Caribbean plate ........................................................ 9 1.2 Studies on the structure of the mantle under the Caribbean. .......................................................... 9 1.3 Models for slab structure under the northeastern Caribbean ........................................................ 11 1.4 Aim of this thesis .................................................................................................................................. 13 1.5 Thesis outline ........................................................................................................................................ 14 Chapter 2 The Caribbean plate; pulled, pushed or dragged? ................................................ 16 2.1 Introduction .......................................................................................................................................... 16 2.1.1 The Caribbean plate ...................................................................................................................... 18 2.2 Forces on the Caribbean plate: ........................................................................................................... 20 2.2.1 Driving forces ................................................................................................................................. 20 2.2.2 Coupling stresses to the sub-lithospheric mantle ..................................................................... 21 2.2.3 Resistive forces ............................................................................................................................... 22 2.2.4 Torque balance ............................................................................................................................... 23 2.3 Torque balance results ......................................................................................................................... 23 2.4 Stress, rotation and fault slip ............................................................................................................... 24 2.4.1 Model setup .................................................................................................................................... 25 2.4.2 Grouping models ........................................................................................................................... 26 2.5 Results .................................................................................................................................................... 26 2.6 Conclusions ........................................................................................................................................... 35 Acknowledgements..................................................................................................................................... 36 Appendix ...................................................................................................................................................... 37 Chapter 3 Tectonic evolution and mantle structure of the Caribbean ................................... 38 3.1 Introduction .......................................................................................................................................... 38 3.2 Mantle structure under the Caribbean region ................................................................................. 44 3.2.1 The tomographic model and resolution ..................................................................................... 44 3.2.2 Connecting tectonic evolution with mantle structure .............................................................. 45 3.2.3 An overview of imaged slabs ....................................................................................................... 45 3.3 Comparing tectonic reconstructions with imaged mantle structure ............................................. 47 3.3.1 Overall constraints on tectonic reconstructions ....................................................................... 47 3.3.2 Lesser Antilles subduction............................................................................................................ 47 3.3.3 Muertos subduction ....................................................................................................................... 53 3.3.4 South Caribbean subduction ........................................................................................................ 53 3.3.5 Nicaragua Rise subduction ........................................................................................................... 54 3.3.6 Farallon subduction and the Great Arc of the Caribbean ....................................................... 54 3.3.7 Cocos plate subduction and the Panama slab window ............................................................ 58 3.4 Scoring tectonic reconstructions ........................................................................................................ 60 3.5 Conclusions ........................................................................................................................................... 61 3.6 Appendix ............................................................................................................................................. 613 Chapter 4 What drives microplate motion and deformation in the northeastern Caribbean plate boundary region? ............................................................................................................ 65 4.1 Introduction .......................................................................................................................................... 65 4.2 Mechanisms for plate boundary deformation in the northeastern Caribbean ............................ 67 4.2.1 Bahamas collision .......................................................................................................................... 67 4.2.2 Slab Edge Push .............................................................................................................................. 70 4.2.3 Two mechanisms acting in concert ............................................................................................. 71 4.3 Model setup .......................................................................................................................................... 72 4.3.1 Domain and material properties .................................................................................................. 72 4.3.2 Boundary conditions for the Present-day models ..................................................................... 72 4.3.3 Boundary conditions for models for 30-2.5 Ma ........................................................................ 75 4.3.4 Regional faults/shear zones in the Caribbean plate ................................................................. 75 4.3.5 Calculation of uplift rate ............................................................................................................... 80 4.4 Benchmarking and analysis of present-day models ........................................................................