The Carboniferous of the Netherlands and surrounding areas; a basin analysis Hendrik Kombrink GEOLOGICA ULTRAIECTINA Mededelingen van de Faculteit Geowetenschappen departement Aardwetenschappen Universiteit Utrecht No. 294 Members of the dissertation committee: Prof. Dr. P.L. de Boer Faculty of Geosciences, Utrecht University, the Netherlands Dr. J.D. Collinson John Collinson Consulting, Staffordshire, United Kingdom Prof. Dr. A. Schäfer Steinmann Institute – Geology, University of Bonn, Germany Prof. Dr. D.A. Spears Department of Analytical Sciences, University of Sheffield, United Kingdom Prof. Dr. P.A. Ziegler Institute of Geology and Paleontology, University of Basel, Switzerland The research for this thesis was carried out at TNO – Geological Survey of the Netherlands and Utrecht University, Faculty of Geosciences. www.tno.nl www.geo.uu.nl ISBN/EAN: 978-90-5744-160-8 Graphic design: GeoMedia (7320), Faculty of Geosciences, Utrecht University Cover illustration: “Kaart van Noordwest-Europa in den Boven Carboontijd.” Figure 1 from Van Waterschoot van der Gracht (1918), Eindverslag der Rijksopsporing van Delfstoffen 1903-1916. Martinus Nijhoff (’s-Gravenhage), 644 pp. The Carboniferous of the Netherlands and surrounding areas; a basin analysis (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. J.C. Stoof, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 19 december 2008 des middags te 14.30 uur door Hendrik Kombrink geboren op 19 december 1979 te Terneuzen, Nederland Promotoren: Prof. dr. Th.E. Wong Prof. dr. C.J. van der Zwan Contents 1 Introduction 11 1.1 General introduction 11 1.2 History of research on the Carboniferous in the Netherlands 13 1.3 Aims and summary of this thesis 15 1.4 Stratigraphy and timescales 18 2 Tectonics and sedimentation in the Northwest European Carboniferous Basin 21 2.1 Introduction 21 2.1.1 Plate-tectonic setting 24 2.2 Dinantian 26 2.2.1 Subsidence mechanisms 26 2.2.2 Basin fill 26 2.3 Namurian 32 2.3.1 Subsidence mechanisms 32 2.3.2 Transition carbonate platform and basinal shales 33 2.3.3 Basin fill 34 2.4 Westphalian 37 2.4.1 Subsidence mechanisms 37 2.4.2 Basin fill 38 2.4.2.1 Westphalian A 38 2.4.2.2 Westphalian B 40 2.4.2.3 Westphalian C 40 2.4.2.4 Westphalian D 42 2.5 Stephanian 42 2.5.1 Subsidence mechanisms 42 2.5.2 Basin Fill 45 3 Seismic interpretation of Early Carboniferous (Dinantian) carbonate platforms in 47 the Netherlands; implications for the palaeogeographical and structural development of the Northwest European Carboniferous Basin 3.1 Introduction 48 3.2 Geological setting 51 3.2.1 Block-and-basin model 53 3.2.2 Carbonate platforms UK 53 3.2.3 Carbonate platforms Belgium 55 3.2.4 Carbonate platforms in western Germany 55 3.2.5 Carbonate platforms in the Netherlands and the Southern North Sea 55 3.2.6 Role of Dinantian highs during Late Westphalian inversion in the UK 56 3.2.7 Time-equivalent carbonate platforms outside the NWECB 56 3.3 Results 57 5 3.3.1 Carbonate platforms 57 3.3.2 Internal structure of the platforms 59 3.3.3 Structure of the Namurian and Westphalian overburden 59 3.4 Discussion 61 3.4.1 Dinantian carbonate platforms 61 3.4.2 Dinantian basins 64 3.4.3 Inversion 64 3.5 Conclusions 65 4 Late Carboniferous foreland basin formation and Early Carboniferous stretching 67 in Northwestern Europe – Inferences from quantitative subsidence analyses in the Netherlands 4.1 Introduction 68 4.2 Basin evolution and fill 70 4.3 Data 73 4.4 Subsidence curves 74 4.5 2D forward flexural subsidence modelling 76 4.5.1 Constraints on kinematics of the Rheno-Hercynian belt and 76 the geometry of the adjacent Variscan foreland basin 4.5.2 Model scenarios 77 4.5.3 Model setup and parameters 78 4.5.4 Model results 79 4.5.5 Discussion of model results 81 4.6 Tectonic subsidence modelling applying lithospheric stretching 82 4.6.1 Numerical Model 82 4.6.2 Rifting history models 82 4.6.2.1 Model 1 – Dinantian rifting (syn-rift) with uniform lithospheric extension, 83 followed by Namurian-Westphalian B thermal sag (post-rift). 4.6.2.2 Model 2 – Dinantian and Namurian rifting (syn-rift), followed 85 by Westphalian A/B thermal sag (post-rift). 4.6.3 Discussion of model results 85 4.7 Subsidence mechanisms in the CNWECB 85 4.8 Conclusions 87 5 The alluvial architecture of the Coevorden Field (Upper Carboniferous), 89 the Netherlands 5.1 Introduction 89 5.2 Geological setting 90 5.2.1 The Tubbergen Formation in the northeastern part of the Netherlands 90 5.2.2 Sediments of Westphalian C and D age in northwestern Germany 91 5.2.3 Tectonic setting 92 5.2.4 Palaeoclimate and sea level 93 5.3 Data and methods 93 5.4 Core description and interpretation 93 5.4.1 Description of the core 93 5.4.1.1 Sandstone body G (3066-3071 m) 93 6 5.4.1.2 Sandstone body H (3043-3057 m) 95 5.4.1.3 Sandstone body J1 (3036-3041 m) 95 5.4.1.4 Sandstone body J2 (3005-3031 m) 95 5.4.1.5 Sandstone body K (2978-2997 m) 96 5.4.1.6 Fine-grained sediments 96 5.4.2 Interpretation of the core 97 5.5 Interpretation of lithology in well-logs 97 5.5.1 Sandstone bodies in well-logs 99 5.5.2 Fine-grained deposits and coals in well-logs 99 5.6 Correlation 99 5.6.1 Width of sand bodies 100 5.6.2 Palaeogeographic maps 100 5.7 Concluding discussion 101 6 Namurian black shale deposition in Northern England: marine or lacustrine? 103 6.1 Introduction 103 6.2 Geological setting 107 6.3 Materials 109 6.4 Methods 110 6.4.1 Analytical techniques 110 6.4.2 Thin sections 110 6.4.3 Grain size 110 6.4.4 The use of C/S ratios and trace elemental concentrations 111 6.5 Results 112 6.5.1 Thin sections 112 6.5.2 Organic carbon and sulfur contents 112 6.5.3 Trace elements 115 6.6 Discussion 116 6.6.1 Thin sections 116 6.6.2 Sedimentation rate 117 6.6.3 Inferences on palaeosalinity 118 6.6.4 Limitations to a model of continuous marine sedimentation 119 6.7 Conclusions 120 7 Geochemistry of marine and lacustrine bands in the Upper Carboniferous of the 121 Netherlands 7.1 Introduction 121 7.2 Geological setting 125 7.3 Materials 126 7.4 Methods 127 7.5 Results 131 7.5.1 Organic matter 131 7.5.2 Pyrite 131 7.5.3 Trace elements 133 7.6 Discussion 133 7.7 Conclusions 136 7 8 Synthesis 139 References 143 Appendix A: C/S, major and trace element data described in chapter 6 167 Appendix B: C/S, major and trace elements data described in chapter 7 171 Epiloog 175 Curriculum Vitae 179 Samenvatting 181 8 – Schön ist eigentlich alles, was man mit Liebe betrachtet – Christian Morgenstern, Stufen 9 10 CHAPTER 1 Introduction 1.1 General introduction Carboniferous sediments of the Netherlands and surrounding areas accumulated in an east- west striking basin in a period of 60 million years (359 – 299 Myr). This basin is known as the Northwest European Carboniferous Basin (NWECB). The present-day contour of the NWECB (white dashed line in figure 1.1) is not a genetic basin but the remnant of a much larger shelf complex (Fig. 1.1) of which the distal parts have been shortened, partly eroded and incorporated in the Rheno-hercynian fold and thrust belt (Fig. 2.2). Active foldbelts Fennoscandian 0 1000 High Km Landmass Basin Moscow Platform Oceanic crust Greenland High Ukrainian High C B E East Silesian W Massif N RHB Variscan orogen CAB Avalon High Intra-AlpineTerrane St. Anthony Basin Aquitane Cantabria Basin Austro-Alpine Terrane South Alpine - Dinarid Terrane Oceanic crust Oceanic crust Figure 1.1 Palaeotectonic map of Northwest Europe during the Early Carboniferous. The dashed white line indicates the present-day contours of the Northwest European Carboniferous Basin. RHB: Rhenohercynian Basin, CAB: Central Armorican Basin. Redrawn after Ziegler (1989). Introduction 11 Trough/Basin WSW Chapters 2 & 3 Chapter 5 ENE Chapter 4 Chapter 6 Visean carbonates Chapter 7 Carbonate platform Westphalian D 1 km Westphalian C Pre-Carboniferous Basement Westphalian B Westphalian A Namurian Dinantian mixed sil./carb. High (NL), Block (UK) Tournaisian carbonates 10 km Dinantian carbonates Figure 1.2 Schematic cross-section of the Carboniferous in the Netherlands. The stratigraphic distribution of the chapters in this thesis is indicated. In general, the Early Carboniferous is characterised by carbonate deposition on shelves and isolated platforms while in intervening basins calciturbidites and mudstones were deposited (Ziegler, 1990; Geluk et al., 2007; Figs 1.2 & 3.1). The Namurian is characterised by increasing siliciclastic influx from the rising Variscan Mountains in the south and the Fennoscandian Shield in the north (Ricken et al., 2000; Collinson, 2005). In this way, Namurian sediments progressively in filled and blanketed the submarine relief that had existed during the Early Carboniferous (Fig. 1.2). Due to an ongoing regressive trend, Namurian basinal shales and turbidites were gradually replaced by delta-plain conditions at the end of the Namurian. This marks the onset of the Westphalian. Most of the economically interesting coal seams formed during the Westphalian A and B in a lower delta plain environment (Drozdzewski, 2005; Van Buggenum & den Hartog Jager, 2007).