DOCSLIB.ORG

Tertiary Uplift and Its Implications for the Tectonic Evolution Of

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Tertiary Uplift and Its Implications for the Tectonic Evolution Of -Ì.ótg THE UNIVERSITY OF ADELAIDE Department of Geology and Geophysics South Australia Tertiary uptift and its Implications for the Tectonic Evolution of Sedimentary Basins, Offshore South-'West tlnited Kingdom. Robert John Menpes B.Sc. Hons (Adelaide 1992) Submitted in fulfilment of the requirement for the degree of Doctor of Philosophy September 1997 Contents Abstract vtr Acknowledgments .ix 1. Introduction I 1.1 Project Rationale.... I t.z The Celtic Sea/South-Western Approaches.. I 1.3 The Scope of this Thesis 2 2 . Geological History of the Celtic Sea/South-Western Approaches 5 2.1 Introdu ction 5 2.2 Structural Framework of the Celtic Sea/South-Western Approaches 6 2.2.1 Caledonian and Variscan structural trends.......... 2.2.2 Cornubian batholith 2.2.3 Mesozoic structural elements..... 2.3 Permo-Triassic Basin Formation 2.3.1 Permo-Triassic post-orogenic col1apse........................ 2.3.2 Mid- to Late Triassic rifting......... 2.4 Early-Middle Jurassic Thermal Subsidence.. 2.5 Late Jurassic-Early Cretaceous Rifting and the "Cimmerian" Unconformity 2.6 Late Cretaceous/Tertiary Thermal Subsidence.. 2.1 Tertiary Invelsion..... 2.1 .l Palaeocene exhumation 2.1.2 Eocene-Oligocene subsidence.......... 2.1.3 Oligo-Miocene exhumation.............. 2.8 Internal and External Basin Geometries............ 3. Quantifying Exhumation using Compaction Methodology.. 29 3.1 Introduction 29 3.2 Porosity in Sedimentary Rocks..... 29 3.2.1 Primary and secondary porosity. 29 3.2.2 Intergranular and intragranular porosity... 29 3.2.3 Absolute and effective porosity....... 30 Menpes Table of Contents 3.3 Compaction of Sedimentary Rocks...... .30 3.3. 1 Processes of porosity loss dependent on burial-depth............. .30 3 .3.2 Processes of porosity loss independent of burial-depth... ..... .31 3.3.3 E,xamples of compaction trends.... .31 3.4 Geophysical Logs and Porosity Determination................ .32 3.4.1 Porosity logs........... .32 3.4.2 Selection of porosity log for compaction analysis .34 3.4.3 Determining porosity from the sonic 1og..... .35 3.5 Basic Principles of the Compaction Methodology........... .35 3 .5 . I In troduction .35 3.5.2 Previous studies involving compaction-based quantification of exhumation... .36 3.5.3 The advantages of using multiple stratigraphic units in compaction analyses. .36 3.6 Quantifying Exhumation and Maximum Burial-Depth .37 3.6.1 Quantifying exhumation. .37 3.6.2 Exhumation, apparent exhumation, and maximum burial-depth............... .37 3.6.3 Uplift, erosion, and exhumation............. .39 3.1 Selection of Stlatigraphic Units for Analysis. .40 3.8 Interval Transit Time/Depth Plots and Normal Compaction Relations..... .42 3.8.1 Linear versus exponential normal compaction relations .42 3 .8.2 Normal compaction relations and reference wells .. ... .. .. .42 4. Tertiary Exhumation in the celtic Sea/south-western Approaches 49 4.1 In troduction 49 4.2 Comparison of Apparent Exhumation Results from the Eight Stratigraphic Units Analysed 49 4.2.1 Statistical testing of apparent exhumation results......... 49 4.2.2 Discussion of statistical results...... 54 4.3 Apparent Exhumation in the Celtic Sea/South-Western Approaches . .. .. .. s6 4.4 Exhumation at the Time of Denudation in the celtic sea/South-western Approaches........, 67 4.4.1 Timing of exhumation in the Celtic Sea/South-'Western Approaches.... 67 4.4.2 Magnitude of exhumation in the celtic Sea/south-western Approaches 67 4.5 Maximum B urial-Depth in the Celtic Sea/South-Western Approaches ................. 70 4.6 Comparison of Results with Related Published Studies 13 4.7 Implications of Exhumation Results for Models of Basin Evolution 13 5 Determining Apparent Exhumation from Chalk Outcrop Samples, Cleveland Basin/East Midlands Shelf.......... 71 5.1 Introduction. 77 Menpes lt Table of Contents 5.2 Previous Studies of Apparent Exhumation of the Cleveland BasinÆast Midlands Shelf.. 1l 5.3 Post-Variscan Geological History of the Cleveland BasinÆast Midlands Shelf ................ 79 5.4 Methodology for Quantifying Apparent Exhumation. 80 5.4.1 Selection of normal compaction relation....... 80 5.4.2 Calculation of mean porosities from well data........... 83 5.4.3 Determination of porosity of Chalk samples 83 5.5 Apparent Exhumation in the Cleveland BasinÆast Midlands Shelf.......... 85 5.6 Conclusions 91 6 Determining the Tectonic Subsidence/Uplift History of the Celtic Sea/South-Western 4pproaches................. 93 6.1 Introduction 6.2 Selection and Depth Conversion of SWAT Seismic Profiles....... 6.3 Basic Principles of Sediment Decompaction . .. ... .. .. 6.4 Decompaction of Exhumed Sequences 6.4.1 Exhumation with no later subsidence.............. 6.4.2 Exhumation of greater or equal magnitude to later subsidence 6.4.3 Exhumation of lesser magnitude than later subsidence... 6.4.4 Exhumation and sediment densities. 6.5 Porosity/Depth Relations for Sediment Decompaction............. 6.5.1 Interval transit-time/porosity relationships 6.5.2 Porosity/depth plots and relationships for decompaction 6.6 Backstripping and Decompaction of the Celtic Sea/South-Western Approaches Profile 6.7 Calculation of Tectonic Subsidence.. 6.1.1 Sedirnentloading 6.'1.2 Palaeobathymetry......... 6.7.3 Eustatic sea-level change 6.8 Calculation of Tectonic Uplift .....,... 6.9 Tectonic Subsidence/Uplift History of the Celtic Sea/South-Western Approaches.......... 7 . Tectonic Models of Basin Evolution ...1 15 1.1 Introduction 115 '7.2 Modelling the Subsidence/Uplift History of Sedimentary Basins in One, Two, and Three Dimensions ....1 15 7.3 Pure Shear Models of Lithospheric Deformation............ .....1 16 7.3.1 McKenzie's (1978) pure shear model.......... .....1 l6 7 .3.2 Two-layer pure shear heterogeneous extension ....1 l8 Menpes Iil Table of Contents 7.3.3 Incorporating multiple rifting events into two-layer, heterogeneous extension...................... 7.4 odling's (1992) Method for Modelling Multiple Lithospheric Deformarion Events 7 '4.1 Superimposing two lithospheric deformation events using Odling's (1992) method.... 7.5 Discussion of the Assumptions and Constraints used in Odling's (1992) Method in this Thesis 7 .5.1 Airy versus flexural isostasy 7.5.2 Pure shear versus simple shear ......... 7 .5.3 Instantaneous versus time-dependent extension.................. 7.5.4 Depth of decoupling between upper and lower lithospheric deformation..............,..... 8 Modelling the Tectonic Evolution of the Cettic Sea/ South-Western 4pproaches................. 121 8.1 Introduction 127 8.2 Results of the Two-layer Heterogeneous Model of Lithospheric Deformation ............. 127 8.2.1 An initial analysis of the tectonic evolution of the Celtic Sea./South-Western Approaches: balanced B factors..... 127 8.2.2 A revised analysis of the tectonic evolution of the Celtic Sea,/South-Western Approaches: required B factors..... 130 8.3 Discussion of the Results of the Two-layer Heterogeneous Modelling of Lithospheric Deformation 133 8.3. I Subcrustal deformation distributed from adjacent areas........... 135 8.3.2 Thermal anomalies.... 136 8.4 Comparison of Modelling Results with Other Studies in the Celtic Sea,/South-Western Approaches 131 8.5 Igneous Underplating as a Cause of Tertiary Exhumation 138 9 . Summary and Conclusions 141 9.1 Introduction ..t41 9.2 Tertiary Exhumation, Celtic Sea/South-Vy'estern Approaches ......... ..141 9.3 Tectonic Modelling, Celtic Sea/South-'Western Approaches.. ..143 9.4 Compaction Analysis, Cleveland Basin/East Midlands Shelf.... ..t44 9.5 Unresolved Issues and Recommendations for Future Research........ ..t44 Appendix I r41 Appendix II 153 Appendix III 155 Menpes lv Table of Contents References 157 Menpes Abstract Sonic velocities from the Danian Chalk, Upper two-layer, heterogeneous deformation model. Two- Cretaceous Chalk, Lower Cretaceous Greensand/Gault dimensional, multiple-event modelling of the tectonic Clay, Lower Cretaceous Vy'ealden, Upper Jurassic history has shown a distinct difference in the nature of mudstones, Triassic Mercia Mudstone (above and both crustal and subcrustal deformation between the below salt), and Triassic Sherwood Sandstone have internal basins closest to the Cornubian Platform (St. been used to quantify apparent exhumation (i.e. Mary's, Plymouth Bay, and South Celtic Sea basins), amount of missing section) in the Celtic Sea/South- and the external basins further away from the Western Approaches. The recognised structural Cornubian Platform (North Celtic Sea, Fastnet, inversion axes of the Brittany, South-West Channel, Brittany, and South-West Channel basins). The latter North Celtic Sea, Caernarvon, Cardigan Bay, and Kish basins are best modelled by localised crustal Bank basins are highs in apparent exhumation of up deformation, with minimal associated subcrustal to 2 kilometres. However apparent exhumation of deformation. In contrast, the St. Mary's, Plymouth approximately one kilometre also occurred in the Bay, and South Celtic Sea basins, as well as the uninverted St. Mary's and Plymouth Bay basins, and Cornubian Platform, are best modelled by significant on the margins of the Armorican and Cornubian subcrustal deformation, with little or no associated Platforms and the Pembroke Ridge. Hence Tertiary crustal deformation. The amount of crustal exhumation was regional, and not restricted to deformation in the external basins is not sufficient to inversion axes, and thus it must have had a thick- balance the excess subcrustal deformation in the skinned origin. internal basins and Cornubian
Load more

Recommended publications
  • 1 Age and Petrogenesis of the Lundy Granite: Palaeocene Intraplate
    ORE Open Research Exeter TITLE Age and petrogenesis of the Lundy granite: Paleocene intraplate peraluminous magmatism in the Bristol Channel, UK AUTHORS Charles, J-H; Whitehouse, MJ; Andersen, JC; et al. JOURNAL Journal of the Geological Society DEPOSITED IN ORE 04 October 2017 This version available at http://hdl.handle.net/10871/29676 COPYRIGHT AND REUSE Open Research Exeter makes this work available in accordance with publisher policies. A NOTE ON VERSIONS The version presented here may differ from the published version. If citing, you are advised to consult the published version for pagination, volume/issue and date of publication Age and petrogenesis of the Lundy granite: Palaeocene intraplate peraluminous magmatism in the Bristol Channel, UK 1 2 3 3 1 J-H. CHARLES , M.J. WHITEHOUSE , J.C.Ø. ANDERSEN , R.K. SHAIL & M.P. SEARLE 1 Department of Earth Sciences, Oxford University, South Parks Road, Oxford, OX13AN, UK 8 2 Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden 3 Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK. Abstract: The Lundy granite forms part of the Lundy Igneous Complex which is the southernmost substantive expression of the British Cenozoic Igneous Province (BCIP). Its Qz+Pl+Kfs+Bt±Grt±Tpz 16 mineralogy and peraluminous character contrast with other BCIP granites farther north but are similar to the granites of the adjacent Early Permian Cornubian Batholith. We present the results of mapping, petrographical and mineral chemical analysis, and the first U-Pb zircon ages for the granite (59.8 ± 19 0.4 – 58.4 ± 0.4 Ma) and cross- cutting basic dykes (57.2 ± 0.5 Ma) which confirm a Palaeocene age 20 for magmatism.
    [Show full text]
  • Seascape Character Assessment Report
    Seascape Character Assessment for the South West Inshore and Offshore marine plan areas MMO 1134: Seascape Character Assessment for the South West Inshore and Offshore marine plan areas September 2018 Report prepared by: Land Use Consultants (LUC) Project funded by: European Maritime Fisheries Fund (ENG1595) and the Department for Environment, Food and Rural Affairs Version Author Note 0.1 Sally First draft desk-based report completed May 2016 Marshall Maria Grant 1.0 Sally Updated draft final report following stakeholder Marshall/ consultation, August 2018 Kate Ahern 1.1 Chris MMO Comments Graham, David Hutchinson 2.0 Kate Ahern Final Report, September 2018 2.1 Chris Independent QA Sweeting © Marine Management Organisation 2018 You may use and re-use the information featured on this website (not including logos) free of charge in any format or medium, under the terms of the Open Government Licence. Visit www.nationalarchives.gov.uk/doc/open-government- licence/ to view the licence or write to: Information Policy Team The National Archives Kew London TW9 4DU Email: [email protected] Information about this publication and further copies are available from: Marine Management Organisation Lancaster House Hampshire Court Newcastle upon Tyne NE4 7YH Tel: 0300 123 1032 Email: [email protected] Website: www.gov.uk/mmo Disclaimer This report contributes to the Marine Management Organisation (MMO) evidence base which is a resource developed through a large range of research activity and methods carried out by both MMO and external experts. The opinions expressed in this report do not necessarily reflect the views of MMO nor are they intended to indicate how MMO will act on a given set of facts or signify any preference for one research activity or method over another.
    [Show full text]
  • Mapping of the Haig Fras Site of Community Importance (SCI)
    JNCC/Cefas Partnership Report Series Report No. 4 Mapping of the Haig Fras Site of Community Importance (SCI) Barrio Froján, C., Diesing, M. & Curtis, M. September 2015 © JNCC, Cefas 2015 ISSN 2051-6711 Mapping of the Haig Fras Site of Community Importance (SCI) Barrio Froján, C., Diesing, M. & Curtis, M. September 2015 © JNCC, Cefas, 2015 ISSN 2051-6711 Mapping of the Haig Fras Site of Community Importance (SCI) For further information please contact: Joint Nature Conservation Committee Monkstone House City Road Peterborough PE1 1JY www.jncc.defra.gov.uk This report should be cited as: Barrio Froján, C., Diesing, M. & Curtis, M. 2015. Mapping of the Haig Fras Site of Community Importance (SCI). JNCC/Cefas Partnership Report Series, No. 4. Mapping of the Haig Fras Site of Community Importance (SCI) Summary This report describes the results from multidisciplinary field surveys of the Haig Fras reef complex, presently designated as a Site of Community Importance (SCI) and a candidate Special Area of Conservation (cSAC). Since the designation of Haig Fras as an SCI, new evidence has come to light suggesting that the Annex I reef habitat, for which the site was selected, extends outside the existing site boundary, prompting the present investigation to map the full extent of reef habitat at Haig Fras. The Centre for Environment, Fisheries and Aquaculture Science (Cefas) and the Joint Nature Conservation Committee (JNCC) jointly surveyed the Haig Fras complex, collecting remotely sensed multibeam data and directly observed ground-truthing data. These datasets have been analysed to determine the full extent of the Annex I reef and produce an updated habitat map of the area.
    [Show full text]
  • The Stimulation of a Hot-Dry-Rock Geothermal Reservoir in The
    Proceedings Eighth Workshop Geothermal Reservoir Engineering Stanford Univeraity. Stanford. CAlifornia. December 1982 SGP-TR-60 THE STIMULATION OF A HOT DRY ROCK GEOTHERMAL RESERVOIR IN THE CORNUBIAN GRANITE, ENGLAND A S BATCHELOR CAMBORNE SCHOOL OF MINES GEOTHERMAL ENERGY PROJECT PENRYN, CORNWALL, TRlO 9DU ENGLAND ABSTRACT INTRODUCTION A Hot Dry Rock geothermal reservoir has been Hot Dry Rock geothermal exploitation has a created at a depth of 2000 m in granite. The well established literature (eg, Smith (19751, stimulation was carried out using 40 000 m’ Smith (19781, Parsons (19191, Batchelor (10 million US gal) from a 350 m open hole (19781, Armstead (19791, Milora et a1 (19761, section that had been treated with a purpose- etc, and there is active research in a number designed explosive tool. On-line seismic of countries. However, only two, USA and mapping has shown that the reservoir has Great Britain, have substantial field developed in the direction of the maximum programnes and only the USA has reached principal stress despite the fact that the potential production temperatures. The work in joint directions are not orientated in that. the UK by the author has concentrated on direction. Photographic and television developing stimulation techniques to create inspection has been used to correlate acoustic HDR reservoirs in a jointed, highly stressed seisviewer and conventional wire logging granite body heated by natural radioactivity. results including observations of fracture Figure 1 shows a panoramic view of the site width at the wellbore during pressurisation. during pumping operations. Downward growth of the reservoir has been A massive hydraulic stimulation commenced on 4 observed despite the fact that the stimulation November this year in Cornwall, England, and fluid was fresh water.
    [Show full text]
  • South-West England
    CHPM2030 DELIVERABLE D6.2.1. REPORT ON PILOTS: EVALUATION OF THE CHPM POTENTIAL OF CORNWALL, SOUTH WEST ENGLAND Summary: This report investigates the potential for combined heat and metal production from south-west England, considering availability of legacy geoscience information, the geological environment, geothermal characteristics, potential for deep metal enrichment, and technical, environmental, social and regulatory factors that could influence the future development of this technology in the region. Authors: Paul A J Lusty, British Geological Survey, Principal Economic Geologist Richard B Haslam, British Geological Survey, Structural Geologist Richard A Shaw, British Geological Survey, Economic Geologist Eimear A Deady, British Geological Survey, Minerals Geoscientist Paul Williamson, British Geological Survey, Senior Geophysicist This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement nº 654100. CHPM2030 DELIVERABLE 1.1 TABLE OF CONTENTS Table of contents .................................................................................................................................. 2 LIST OF FIGURES ................................................................................................................................... 3 LIST OF TABLES ..................................................................................................................................... 8 1 Executive summary .....................................................................................................................
    [Show full text]
  • 1 Age and Petrogenesis of the Lundy Granite
    Age and petrogenesis of the Lundy granite: Palaeocene intraplate peraluminous magmatism in the Bristol Channel, UK 1 2 3 3 1 J-H. CHARLES , M.J. WHITEHOUSE , J.C.Ø. ANDERSEN , R.K. SHAIL & M.P. SEARLE 1 Department of Earth Sciences, Oxford University, South Parks Road, Oxford, OX13AN, UK 8 2 Swedish Museum of Natural History, Box 50007, SE-104 05 Stockholm, Sweden 3 Camborne School of Mines, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK. Abstract: The Lundy granite forms part of the Lundy Igneous Complex which is the southernmost substantive expression of the British Cenozoic Igneous Province (BCIP). Its Qz+Pl+Kfs+Bt±Grt±Tpz 16 mineralogy and peraluminous character contrast with other BCIP granites farther north but are similar to the granites of the adjacent Early Permian Cornubian Batholith. We present the results of mapping, petrographical and mineral chemical analysis, and the first U-Pb zircon ages for the granite (59.8 ± 19 0.4 – 58.4 ± 0.4 Ma) and cross- cutting basic dykes (57.2 ± 0.5 Ma) which confirm a Palaeocene age 20 for magmatism. Zircon inheritance is limited but two cores imply the presence of Lower Palaeozoic igneous rocks in the unexposed basement of SW England. The anomalous southerly location of the Lundy Igneous Complex is a consequence of mantle melting arising from the superposition of localised lithospheric extension, related to intraplate strike-slip tectonics, with the distal ancestral Icelandic plume. Granite generation primarily reflects crustal partial melting during the emplacement of mantle-derived melts.
    [Show full text]