A MULTIDISCIPLINARY STUDY OF BIOMARKERS IN HYDROTHERMAL DEPOSITS: APPLICATIONS TO THE SEARCH FOR LIFE ON MARS A thesis submitted for the degree of Doctor of Philosophy By Louisa Jane Preston Imperial College London Department of Earth Science and Engineering November 2008 1 I, Louisa Jane Preston declare that the work presented in this thesis is my own. Signed………………………………………………..Date……………………………. 2 ABSTRACT Hydrothermal systems have been suggested as suitable environments for the appearance of life on the Early Earth and may provide habitats for microorganisms on Mars. The deposits created by these systems are preserved in the geological record. This research investigates the key mineralogical, textural and biological markers found in terrestrial hydrothermal deposits that can be used as analogues in the search for evidence of life on Mars. Samples of silica sinter from Iceland and New Zealand, the Rhynie Chert 396 Ma old deposit from Aberdeenshire and hydrothermally altered impactites from the Chicxulub impact crater have been analysed to understand the mineralogical properties unique to the different hydrothermal conditions and the evidence of extant or extinct microorganisms within them. Re-colonisation of basaltic substrates by hot spring-derived cultures was also carried out. This research was conducted using a multidisciplinary approach with the analytical techniques and instruments involved currently used for in-situ and orbital observations of planetary bodies. The principal techniques, Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography Mass Spectrometry (GCMS), were used due to their combined capabilities in the identification of a variety of rocks and minerals, and a wide range of organic compounds. This PhD research has shown that FTIR in particular is an exceptional analytical technique for use in astrobiological investigations. This research has characterised hydrothermal deposits of different ages and created by different processes on Earth to ascertain their potential for preserving organic compounds in similar deposits on Mars. Results indicate that siliceous hydrothermal deposits of recent and ancient formation yield biomolecular evidence for past and present microbial colonisation as do hydrothermally altered impact deposits and re-colonised basaltic substrates. The identification of mineralogical and biological information using FTIR reflectance spectroscopy has wide implications in the search for life on Mars and other planetary bodies. 3 ACKNOWLEDGEMENTS You never completely comprehend when you decide to do a PhD the scale of what you are undertaking and the amount of people you are going to need to help you through it. A research project of this size can never be done alone, nor should it be attempted. Imperial College London (and the RSM!), has been a support network and home throughout my MSci and now PhD, a total of seven years, which have been the best years of my life. I am, and will always be, grateful for the opportunities Imperial has given me, the friends I have made and will always consider it my home. Foremost I would like to thank my supervisors Richard Ghail and Matthew Genge, for taking a risk on an unusual project and for relishing the challenge. Rich I thank for taking me to New Zealand in my first year and for helping to collect the samples that shaped the next three years. I will always smile when I remember the fantastic trip we had. With Matt it is hard to know where to begin. He has been a long suffering boss; he would say he has been nagged, I would say kept on his toes. He has been a constant support for me, someone to spar with over project ideas and data interpretations, to plan exciting trips to Iceland with, and always saves the day! I thank him most for the extensive freedom he gave me to take the research where I felt it needed to go, for which I will always be grateful. I thank them both for their belief in me and their friendship. Staying with Imperial, I have to thank Mark Sephton and Zita Martins for their time and patience in helping me understand the GCMS and the sometimes confusing results it produced. I am eternally grateful to you both. I also want to thank Jo Morgan for her kind donation of the Chicxulub samples. There are many people at the Natural History Museum that I would like to thank: Firstly, a huge thank you to Gretchen Benedix, for getting me enrolled on the XRD training course and for revolutionising my project by training me on the FTIR, all whilst she was heavily pregnant with her gorgeous twins. I owe you a lot and will always be grateful for your advice and guidance. The EMMA team, an invaluable group in every PhD students work. Thank you to Alex Ball for my Photoshop tutelage, Lauren Howard for guiding me through the maze of imaging techniques in the search for my ‘bugs’, John Spratt for always being on hand to fix every problem and Tony Wighton for his excellent sample preparation, his rude jokes and his ability to make crushing rocks great fun. A huge thank you and much respect goes to Anton Kearsley. He is an encyclopaedia of knowledge and is always happy to help with any problem. I am particularly thankful for his donation of the Rhynie Chert specimens that provided some of the most interesting data, and the most beautiful images, I have studied to date. A big thank you also goes to Sarah James, Gary Jones and Catherine Unsworth in the Chemistry Laboratory in the NHM for all the time they gave me and for their advice and wisdom. Finally, thank you to Mike Rumsey, Caroline Kirk, and Kieren Howard in Mineralogy for their expertise and tuition. 4 Leaving my host institutions I would like to thank D’Arcy Meyer Dombard (University of Illinois at Chicago, formerly Massachusetts Institute of Technology) for training me in some of the many aspects of microbiology and DNA extraction techniques, for making me feel part of the team at her laboratory in Boston and for answering questions from a ‘Geologist trying to be a Biologist’, no matter how stupid they were. It was an invaluable experience and I am lucky to have gained a valuable colleague and a friend. My acknowledgements would not be complete without a big thank you to all those ‘behind the scenes’ people of this three year endeavour. Firstly I would like to thank my pod mates, you know who you are! Thank you for the thrice daily coffee breaks, the 10 minute gossip sessions when brain freeze set in and for bringing laughter into what can be a lonely time. To Linda, what can I say … sushi and rosé, ranting and moaning, shopping, more shopping and RSM bar nights … thank you for being such a good friend and for always being there. We will take that trip to Disneyland soon! A huge thank you must be paid to Dan, a man whose Excel Spreadsheet talents should be acknowledged to the highest degree. Thank you for always trying to solve my problems, even when I didn’t want them solving, and for bringing a sense of perspective into my life, nothing is ever as bad as it seems. He has been a constant shoulder to lean on throughout my university life, my harshest critic and my biggest fan. I thank you from the bottom of my heart. I couldn’t have done this without you! Last but not least I want to thank my parents. They have encouraged me my entire life to reach for my dreams and to try and be the best I can, I hope I have made you proud. They have always been there to gently push me in the right direction (pointing out when I was 14 years old that I am not the next Picasso) which led me to discover a career and life that I am immensely proud of and couldn’t imagine being without. Thank you for your passion for my work, your support and understanding, the extra ‘funds’ you provided for well earned sunny breaks and for never doubting me. Thank You. 5 To my Dad With love, Zizz 6 7 CONTENTS Chapter 1 Introduction……………………………………………………………....19 1.1 Aim…………………………………………………………………………...19 1.2 Astrobiology………………………………………………………………….20 1.3 Mars…………………………………………………………………………..21 1.3.1 Life on Mars?............................................................................................21 1.3.2 The History of Water on Mars…………………………………………..23 1.3.3 Hydrothermal Activity on Earth and Mars……………………………...27 1.3.3.1 Evidence for Hydrothermal Processes on Mars - past and present...30 1.3.3.2 Martian Surface Materials………………………………………….32 1.4 Martian Analogue Field Areas……………………………………………….36 1.4.1 Waiotapu, New Zealand………………………………………………...37 1.4.2 Haukadalur Valley and Krýsuvík, Iceland……………………………...40 1.5 Extremophiles and Fossilisation……………………………………………...43 1.5.1 Extremophilic Microorganisms…………………………………………44 1.5.2 Fossilisation……………………………………………………………..46 1.6 Summary……………………………………………………………………...47 1.7 Objectives and Aims………………………………………………………….48 Chapter 2 Analytical Methods………………………………………………………50 2.1 Introduction…………………………………………………………………..50 2.2 Infrared Spectroscopy………………………………………………………...51 2.2.1 Theoretical Aspects of Vibrational Spectroscopy……………………….51 2.2.2 Fourier Transform Infrared Spectroscopy (FTIR)………………………54 2.2.2.1 Infrared Spectroscopy of Minerals…………………………………55 2.2.2.2 Infrared Spectroscopy of Organic Compounds…………………….56 2.2.3 Analytical Technique……………………………………………………58 2.3 Scanning Electron Microscopy (SEM)……………………………………….58 2.3.1 Backscattered Electrons (BSE)………………………………………….59 2.3.2 Secondary Electrons (SE)……………………………………………….59 2.3.3 Energy Dispersive Spectroscopy (EDS)………………………………...60 2.3.4 Analytical Technique Used……………………………………………...60 2.4 X-ray Diffraction (XRD)……………………………………………………..61 2.4.1