The Iceland Palaeomagnetism Database (ICEPMAG v1.0) Justin A. D. Tonti-Filippini FacultyFaculty of of Earth Earth Sciences Sciences UniversityUniversity of of Iceland Iceland 20182018 THE ICELAND PALAEOMAGNETISM DATABASE (ICEPMAG V1.0) Justin A. D. Tonti-Filippini 60 ECTS thesis submitted in partial fulfilment of a Magister Scientiarum degree in Geophysics Supervisor Maxwell Christopher Brown Faculty Coordinator Páll Einarsson Faculty of Earth Sciences School of Engineering and Natural Sciences University of Iceland Reykjavík, October 2018 The Iceland Palaeomagnetism Database (ICEPMAG v1.0) 60 ECTS thesis submitted in partial fulfilment of a M.Sc. degree in Geophysics Copyright © 2018 Justin A. D. Tonti-Filippini All rights reserved Faculty of Earth Sciences School of Engineering and Natural Sciences University of Iceland Sturlugata 7 101, Reykjavík, Reykjavík Iceland Telephone: 525 4000 Bibliographic information: Justin A. D. Tonti-Filippini, 2018, The Iceland Palaeomagnetism Database (ICEPMAG v1.0), M.Sc. thesis, Faculty of Earth Sciences, University of Iceland. Printing: Háskólaprent, Fálkagata 2, 107 Reykjavík Reykjavík, Iceland, October 2018 For Mary and Nicholas Abstract Iceland’s lavas preserve a unique record of Earth’s magnetic field for the past sixteen million years, and were used by early pioneers of palaeomagnetism to test several concepts which became crucial to modern geoscience. Iceland represents one of very few high latitude (>60◦) locations where long sequences of lavas suitable for palaeo- magnetic research are accessible. Since the early 1950s, research in Iceland has produced a large collection of palaeomagnetic data which has not previously been collected into a comprehensive database. ICEPMAG (http://icepmag.org/) com- piles palaeomagnetic data published in journal articles, academic theses and other databases from over 9,200 sampling sites in Iceland - one of the world’s largest col- lections of palaeomagnetic data from a single location. ICEPMAG was constructed utilising the principles and structure of GEOMAGIA50, and maintains the vocab- ulary of MagIC to allow easy transfer to the global palaeomagnetic database. The ICEPMAG database can be searched through a publicly available website which provides a range of customisable constraints, including rock and sample/specimen types, age constraints, dating methods, palaeointensity methods, geographic con- straints (by region, location and between specified coordinates), authors and years of publication, as well as statistical constraints such as directional polarity, α95 and precision parameter κ. Query results are presented in a results table, with options to produce interactive maps of site locations, VGP plots and downloadable spread- sheets. All the entries in ICEPMAG contain palaeointensity or palaeodirectional data: 8649 contain direction only, 218 intensity only, and 337 both direction and intensity. ICEPMAG will contribute an additional 50 studies and 6,570 sites to the global MagIC database. v Contents List of Figures ix List of Tables xi Abbreviations xiii Acknowledgements xv 1. Introduction1 2. Background5 2.1. Overview of palaeomagnetism . .5 2.1.1. Early history (pre 18th century) . .5 2.1.2. The birth of palaeomagnetism (18th to 20th century) . .6 2.2. Palaeomagnetism in Iceland . .8 2.2.1. Early developments (1920s to 1960s) . .8 2.2.2. Palaeodirectional work (1964 to 2018) . 12 2.2.3. Palaeointensity studies . 16 2.3. Existing palaeomagnetic databases . 17 2.3.1. Magnetic Information Consortium (MagIC) . 18 2.3.2. GEOMAGIA50 Paleomagnetic Database . 18 2.3.3. IAGA Global Paleomagnetic Database (GPMDB) . 18 2.3.4. Absolute Palaeointensity (PINT) Database . 19 2.3.5. PALEOMAGIA (Paleomagnetic Information Archive) . 19 3. Methodology and framework 21 3.1. Construction of the database . 21 3.1.1. Building the source library . 21 3.1.2. Designing the database structure . 23 3.1.3. Adding data to ICEPMAG . 24 3.1.4. Programming the server and website . 26 3.2. Practical experience . 28 4. Data types and experimental methods 29 4.1. Study/contribution details . 29 4.2. Geographic information . 29 vii Contents 4.3. Geological information . 31 4.4. Dating methods . 32 4.5. Sampling information . 33 4.6. Laboratory measurements . 34 4.7. Magnetisation and susceptibility . 35 4.8. Direction calculations . 36 4.9. VGP calculations . 39 4.10. Palaeointensity methods . 40 4.10.1. ‘Thellier’ type methods . 41 4.10.2. ‘Shaw’ methods . 42 4.10.3. Microwave methods . 42 4.10.4. Other methods . 42 4.11. Dipole moments (VDM and VADM) . 43 5. Online implementation and functionality 45 5.1. ICEPMAG website . 45 5.1.1. Home page . 46 5.1.2. Study page . 46 5.1.3. Query form . 46 5.1.4. Results page . 51 5.1.5. Location map . 54 5.1.6. VGP plot . 55 5.1.7. Data download . 56 6. Overview of ICEPMAG data 57 6.1. Geographic distributions . 57 6.2. Temporal distributions . 60 6.3. Palaeointensity results . 61 6.4. Other distributions . 63 7. Conclusion 67 7.1. Summary . 67 7.2. Path forward . 69 7.2.1. MagIC uploads . 69 7.2.2. Updates and error checking . 69 References 71 A. Appendix 83 viii List of Figures 1.1. A well-exposed sequence of lavas in Lundarháls, western Iceland. .2 1.2. Geological map of Iceland - bedrock classified by age, with regions and major towns and roads . .3 3.1. Overview for methodology for the construction of the ICEPMAG database 22 3.2. Workflow for population of master and relational tables from source library 25 3.3. SQL relational table for regions of Iceland with corresponding integer IDs 26 3.4. Workflow from compilation of the ICEPMAG database to output of website . 27 3.5. Example of PHP scripting to generate SQL statement for region/s se- lected on query page . 28 4.1. Regions of Iceland . 31 4.2. Example of palaeomagnetic sampling with a portable drill in Lundarháls, western Iceland, photo taken by J. Tonti-Filippini, 22nd June 2018. 33 4.3. Oriented palaeomagnetic sample drilled from an Icelandic lava, photo taken by J. Tonti-Filippini, 6th July 2018. 35 4.4. Orientation of a palaeomagnetic core in Lundarháls, western Iceland, photo taken by J. Tonti-Filippini, 20th June 2018. 37 5.1. Home page of the ICEPMAG website (screenshot) . 45 5.2. Example of study page containing details of the papers included in ICEP- MAG (searched authors for ‘Brown’) . 46 5.3. Query form - outputs (screenshot) . 47 5.4. Query form - include result options (screenshot) . 47 5.5. Query form - geographic constraints (screenshot) . 48 5.6. Query form - age constraints (screenshot) . 48 5.7. Query form - publication constraints (screenshot) . 49 5.8. Query form - rock, sample and specimen types (screenshot) . 49 5.9. Query form - palaeointensity and dating methods (screenshot) . 50 5.10. Query form - site statistics and polarity (screenshot) . 50 5.11. Results page - an example of query parameters (screenshot) . 51 5.12. Results page - an example of basic search query results (screenshot) . 52 5.13. Results page - an example of additional results columns from a detailed search (screenshot) . 52 5.14. Results page - an example table of references returned by a query (screen- shot) . 52 ix List of Figures 5.15. Results page - an example of the region and location tables returned by a query (screenshot) . 53 5.16. Results page - an example of palaeointensity and dating method tables (screenshot) . 53 5.17. Results page - an example of the additional relational tables returned from a detailed query (screenshot) . 54 5.18. Results page - an example of a location map produced from a query (screenshot) . 55 5.19. Results page - an example of a VGP plot produced from a query (all VGP calculations from the Westfjords region) . 56 5.20. Results page - an example of the link to a downloadable spreadsheet (screenshot) . 56 6.1. Map of ICEPMAG site locations (all results) . 58 6.2. Histogram of all ICEPMAG sites by latitude and longitude . 58 6.3. Histogram of sites by geographic region . 59 6.4. Histogram of sites by reference ID (see Table A.2) . 59 6.5. Histogram - sites by age (all results) . 60 6.6. Histogram - sites by age (Holocene only) . 61 6.7. Histogram - sites by palaeointensity method . 61 6.8. Geographic distribution of all palaeointensity results . 62 6.9. Histogram - all palaeointensity results by latitude and longitude . 63 6.10. Histogram - palaeointensity sites by age (all results) . 63 6.11. Histogram - number of studies by reference year (5 year intervals) . 64 6.12. Histogram - number of sites published by reference year . 64 6.13. Histogram - number of samples collected per site (all results <12) . 65 6.14. Histogram - sites by α95 value . 65 6.15. Histogram - sites by precision parameter κ (<4000) . 66 6.16. Histogram - sites by estimated bedding dip . 66 7.1. Error checking and update process for ICEPMAG . 70 x List of Tables 3.1. Relational table - Region IDs . 24 4.1. Master table - study details . 29 4.2. Master table - geographic information . 30 4.3. Master table - geological descriptions and data . 32 4.4. Master table - dating methods and data . 33 4.5. Master table - sampling information . 34 4.6. Master table - laboratory measurements . 34 4.7. Master table - magnetisation and susceptibility . 36 4.8. Master table - direction calculations . 38 4.9. Master table - VGP calculations . 40 4.10. Master table - palaeointensity . 43 4.11. Master table - dipole moments . 44 A.1. Master data fields/column names and relational tables . 84 A.2. Relational table - Reference IDs . 88 A.3. Relational table - Region IDs . 94 A.4. Relational table - location IDs . ..