Imperial College London

ProfessorMarkSephton

Faculty of EngineeringDepartment of Earth Science & Engineering

Head of the Department of Earth Science and Engineering
 
 
 
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Contact

 

+44 (0)20 7594 6542m.a.sephton Website

 
 
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Assistant

 

Ms Daphne Salazar +44 (0)20 7594 7401

 
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Location

 

G30 (via G28)Royal School of MinesSouth Kensington Campus

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Summary

 

Publications

Publication Type
Year
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200 results found

Gordon PR, Sephton MA, 2018, A Method for Choosing the Best Samples for Mars Sample Return, ASTROBIOLOGY, Vol: 18, Pages: 556-570, ISSN: 1531-1074

JOURNAL ARTICLE

Lewis JMT, Najorka J, Watson JS, Sephton MAet al., 2018, The Search for Hesperian Organic Matter on Mars: Pyrolysis Studies of Sediments Rich in Sulfur and Iron, ASTROBIOLOGY, Vol: 18, Pages: 454-464, ISSN: 1531-1074

JOURNAL ARTICLE

Mohialdeen IMJ, Mustafa KA, Salih DA, Sephton MA, Saeed DAet al., 2018, Biomarker analysis of the upper Jurassic Naokelekan and Barsarin formations in the Miran Well-2, Miran oil field, Kurdistan region, Iraq, ARABIAN JOURNAL OF GEOSCIENCES, Vol: 11, ISSN: 1866-7511

JOURNAL ARTICLE

Montgomery W, Watson JS, Lewis JMT, Zeng H, Sephton MAet al., 2018, Role of Minerals in Hydrogen Sulfide Generation during Steam-Assisted Recovery of Heavy Oil, ENERGY & FUELS, Vol: 32, Pages: 4651-4654, ISSN: 0887-0624

JOURNAL ARTICLE

Moreno-Paz M, Gomez-Cifuentes A, Ruiz-Bermejo M, Hofstetter O, Maquieira A, Manchado JM, Morais S, Sephton MA, Niessner R, Knopp D, Parro Vet al., 2018, Detecting Nonvolatile Life- and Nonlife-Derived Organics in a Carbonaceous Chondrite Analogue with a New Multiplex Immunoassay and Its Relevance for Planetary Exploration, ASTROBIOLOGY, Vol: 18, Pages: 1041-1056, ISSN: 1531-1074

JOURNAL ARTICLE

Royle SH, Oberlin E, Watson JS, Montgomery W, Kounaves SP, Sephton MAet al., 2018, Perchlorate-Driven Combustion of Organic Matter During Pyrolysis-Gas Chromatography-Mass Spectrometry: Implications for Organic Matter Detection on Earth and Mars, Journal of Geophysical Research: Planets, Vol: 123, Pages: 1901-1909, ISSN: 2169-9097

©2018. The Authors. The search for life on Mars targets the detection of organic matter from extant or extinct organisms. Current protocols use thermal extraction procedures to transfer organic matter to mass spectrometer detectors. Oxidizing minerals on Mars, such as perchlorate, interfere with organic detection by thermal extraction. Thermal decomposition of perchlorate releases oxygen, which promotes combustion of organic carbon. We have assessed the minimum mass ratio of organic carbon to perchlorate required to detect organic matter by thermal extraction and mass spectrometry. Locations on Mars with organic carbon to perchlorate ratios above 4.7–9.6 should be targeted. Because habitability is enhanced by the presence of liquid water and because perchlorate is a water-soluble salt, locations on Mars with evidence of past or recent liquid water are high priority targets.

JOURNAL ARTICLE

Schulze-Makuch D, Wagner D, Kounaves SP, Mangelsdorf K, Devine KG, de Vera J-P, Schmitt-Kopplin P, Grossart H-P, Parro V, Kaupenjohann M, Galy A, Schneider B, Airo A, Froesler J, Davila AF, Arens FL, Caceres L, Cornejo FS, Carrizo D, Dartnell L, DiRuggiero J, Flury M, Ganzert L, Gessner MO, Grathwohl P, Guan L, Heinz J, Hess M, Keppler F, Maus D, McKay CP, Meckenstock RU, Montgomery W, Oberlin EA, Probst AJ, Saenz JS, Sattler T, Schirmack J, Sephton MA, Schloter M, Uhl J, Valenzuela B, Vestergaard G, Woermer L, Zamorano Pet al., 2018, Transitory microbial habitat in the hyperarid Atacama Desert, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 115, Pages: 2670-2675, ISSN: 0027-8424

JOURNAL ARTICLE

Sephton MA, 2018, Selecting Mars samples to return to Earth, ASTRONOMY & GEOPHYSICS, Vol: 59, Pages: 36-38, ISSN: 1366-8781

JOURNAL ARTICLE

Sephton MA, 2018, Back is the future: Returning samples from Mars for analysis on Earth, First Break, Vol: 36, Pages: 73-75, ISSN: 0263-5046

Seeking evidence of life in the solar system will be partly the search for organic signatures in rock matrices. The search for organic matter is common to petroleum exploration on Earth and life search missions to Mars. Despite some commonality between investigations into life records on Earth and Mars, there are also significant differences. Favourable organic concentrations in petroleum source rocks are much higher than those needed for life-search targets on Mars. Choosing samples for collection on Mars for return to Earth requires more care at earlier stages than needed for collection of samples on Earth. During and after collection, samples of Mars must be protected from organic contamination that could confuse their potentially weak and poorly understood signals. While operations on Mars provide effectively unlimited sample but with limited instrumentation, analysis on Earth involve constrained amounts of returned samples but access to the world’s best analytical capabilities. Returning samples from Mars also presents the potential for historical firsts including new technologies and important preparations for the eventual human exploration of the red planet.

JOURNAL ARTICLE

Sephton MA, Waite JH, Brockwell TG, 2018, How to Detect Life on Icy Moons, Astrobiology, Vol: 18, ISSN: 1531-1074

The icy moons of the outer solar system present the possibility of subsurface water, habitable conditions and potential abodes for life. Access to evidence that reveals the presence of life on the icy moons can be facilitated by plumes that eject material from the subsurface out into space. One instrument capable of performing life-search investigations at the icy moons is the MAss SPectrometer for Planetary EXploration/Europa (MASPEX), which constitutes a high-resolution, high sensitivity multibounce time-of-flight mass spectrometer capable of measuring trace amounts (ppb) of organic compounds. MASPEX has been selected for the NASA Europa Clipper mission and will sample any plumes and the surface-sputtered atmosphere to assess any evidence for habitability and life. MASPEX is capable of similar investigations targeted at other icy moons. Data may be forthcoming from direct sampling but also impact dissociation because of the high speed of some analytes. Impact dissociation is analogous to the dissociation provided by modern analytical pyrolysis methods. Radiolytic dissociation on the Europan surface before or during the sputtering process can also induce fragmentation similar to pyrolysis. In this study, we have compiled pyrolysis-mass spectrometry data from a variety of biological and non-biological materials to demonstrate the ability of MASPEX to recognise habitability and detect life in any plumes and atmospheres of icy moons.

JOURNAL ARTICLE

Sephton MA, Waite JH, Brockwell TG, 2018, Searching for life with mass spectrometry, Astronomy & Geophysics, Vol: 59, Pages: 3.23-3.24, ISSN: 1366-8781

JOURNAL ARTICLE

Tan J, Lewis JMT, Sephton MA, 2018, The Fate of Lipid Biosignatures in a Mars-Analogue Sulfur Stream, SCIENTIFIC REPORTS, Vol: 8, ISSN: 2045-2322

JOURNAL ARTICLE

Abrams MA, Gong C, Garnier C, Sephton MAet al., 2017, A new thermal extraction protocol to evaluate liquid rich unconventional oil in place and in-situ fluid chemistry, Marine and Petroleum Geology, Vol: 88, Pages: 659-675, ISSN: 0264-8172

JOURNAL ARTICLE

Georgieva MN, Little CTS, Watson JS, Sephton MA, Ball AD, Glover AGet al., 2017, Identification of fossil worm tubes from Phanerozoic hydrothermal vents and cold seeps, Journal of Systematic Palaeontology, Pages: 1-43, ISSN: 1477-2019

© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. One of the main limitations to understanding the evolutionary history of hydrothermal vent and cold seep communities is the identification of tube fossils from ancient deposits. Tube-dwelling annelids are some of the most conspicuous inhabitants of modern vent and seep ecosystems, and ancient vent and seep tubular fossils are usually considered to have been made by annelids. However, the taxonomic affinities of many tube fossils from vents and seeps are contentious, or have remained largely undetermined due to difficulties in identification. In this study, we make a detailed chemical (Fourier-transform infrared spectroscopy and pyrolysis gas-chromatography mass-spectrometry) and morphological assessment of modern annelid tubes from six families, and fossil tubes (seven tube types from the Cenozoic, 12 Mesozoic and four Palaeozoic) from hydrothermal vent and cold seep environments. Characters identified from these investigations were used to explore for the first time the systematics of ancient vent and seep tubes within a cladistic framework. Results reveal details of the compositions and ultrastructures of modern tubes, and also suggest that two types of tubes from ancient vent localities were made by the annelid family Siboglinidae, which often dominates modern vents and seeps. Our results also highlight that several vent and seep tube fossils formerly thought to have been made by annelids cannot be assigned an annelid affiliation with any certainty. The findings overall improve the level of quality control with regard to interpretations of fossil tubes, and, most importantly, suggest that siboglinids likely occupied Mesozoic vents and seeps, greatly increasing the minimum age of the clade relative to earlier molecular estimates.

JOURNAL ARTICLE

Potiszil C, Montgomery W, Sephton MA, 2017, Effects of Pressure on Model Compounds of Meteorite Organic Matter, ACS EARTH AND SPACE CHEMISTRY, Vol: 1, Pages: 475-482, ISSN: 2472-3452

JOURNAL ARTICLE

Royle SH, Montgomery W, Kounaves SP, Sephton MAet al., 2017, Effect of Hydration State of Martian Perchlorate Salts on Their Decomposition Temperatures During Thermal Extraction, JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, Vol: 122, Pages: 2793-2802, ISSN: 2169-9097

JOURNAL ARTICLE

Sephton MA, 2017, Thermal extraction for organic-matter containing materials to answer questions both on Earth and in Space, First Break, Vol: 35, Pages: 113-117, ISSN: 1365-2397

The role of heat in the generation of petroleum has led to the study of organic matter-containing rocks by laboratory heating techniques. In particular, heat is used for the thermal extraction of organic matter in preparation for characterization by a range of detectors. Recently, thermal extraction has been used to answer certain planetary science questions such as the history of habitability for planets in the solar system and the search for evidence of life outside the Earth. The development of new thermal extraction protocols for challenging planetary science objectives provide methods that are readily translatable back to petroleum activities and include new shale screening and assessment techniques.

JOURNAL ARTICLE

Zafar R, Watson JS, Weiss DJ, Sephton MAet al., 2017, Organic compound-mineral interactions: Using flash pyrolysis to monitor the adsorption of fatty acids on calcite, JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS, Vol: 123, Pages: 184-193, ISSN: 0165-2370

JOURNAL ARTICLE

Gordon PR, Sephton MA, 2016, Rapid habitability assessment of Mars samples by pyrolysis-FTIR, Planetary and Space Science, Vol: 121, Pages: 60-75, ISSN: 1873-5088

Pyrolysis Fourier transform infrared spectroscopy (pyrolysis FTIR) is a potential sample selection method for Mars Sample Return missions. FTIR spectroscopy can be performed on solid and liquid samples but also on gases following preliminary thermal extraction, pyrolysis or gasification steps. The detection of hydrocarbon and non-hydrocarbon gases can reveal information on sample mineralogy and past habitability of the environment in which the sample was created. The absorption of IR radiation at specific wavenumbers by organic functional groups can indicate the presence and type of any organic matter present. Here we assess the utility of pyrolysis-FTIR to release water, carbon dioxide, sulphur dioxide and organic matter from Mars relevant materials to enable a rapid habitability assessment of target rocks for sample return. For our assessment a range of minerals were analysed by attenuated total reflectance FTIR. Subsequently, the mineral samples were subjected to single step pyrolysis and multi step pyrolysis and the products characterised by gas phase FTIR.Data from both single step and multi step pyrolysis-FTIR provide the ability to identify minerals that reflect habitable environments through their water and carbon dioxide responses. Multi step pyrolysis-FTIR can be used to gain more detailed information on the sources of the liberated water and carbon dioxide owing to the characteristic decomposition temperatures of different mineral phases. Habitation can be suggested when pyrolysis-FTIR indicates the presence of organic matter within the sample. Pyrolysis-FTIR, therefore, represents an effective method to assess whether Mars Sample Return target rocks represent habitable conditions and potential records of habitation and can play an important role in sample triage operations.

JOURNAL ARTICLE

Gordon PR, Sephton MA, 2016, Organic Matter Detection on Mars by Pyrolysis-FTIR: An Analysis of Sensitivity and Mineral Matrix Effects, ASTROBIOLOGY, Vol: 16, Pages: 831-845, ISSN: 1531-1074

JOURNAL ARTICLE

Jardine PE, Fraser WT, Lomax BH, Sephton MA, Shanahan TM, Miller CS, Gosling WDet al., 2016, Pollen and spores as biological recorders of past ultraviolet irradiance, SCIENTIFIC REPORTS, Vol: 6, ISSN: 2045-2322

JOURNAL ARTICLE

Matthewman R, Crawford IA, Jones AP, Joy KH, Sephton MAet al., 2016, Organic Matter Responses to Radiation under Lunar Conditions, ASTROBIOLOGY, Vol: 16, Pages: 900-912, ISSN: 1531-1074

JOURNAL ARTICLE

Montgomery W, Bromiley GD, Sephton MA, 2016, The nature of organic records in impact excavated rocks on Mars, SCIENTIFIC REPORTS, Vol: 6, ISSN: 2045-2322

JOURNAL ARTICLE

Montgomery W, Potiszil C, Watson JS, Sephton MAet al., 2016, Sporopollenin, a Natural Copolymer, is Robust under High Hydrostatic Pressure, MACROMOLECULAR CHEMISTRY AND PHYSICS, Vol: 217, Pages: 2494-2500, ISSN: 1022-1352

JOURNAL ARTICLE

Montgomery W, Sephton MA, 2016, PRESSURE EFFECTS IN POLYCYCLIC AROMATIC NITROGENATED HETEROCYCLES (PANHs): DIAGNOSTIC QUALITIES AND COSMOBAROMETRY POTENTIAL, ASTROPHYSICAL JOURNAL, Vol: 819, ISSN: 0004-637X

JOURNAL ARTICLE

Najorka J, Lewis JMT, Spratt J, Sephton MAet al., 2016, Single-crystal X-ray diffraction study of synthetic sodium-hydronium jarosite, PHYSICS AND CHEMISTRY OF MINERALS, Vol: 43, Pages: 377-386, ISSN: 0342-1791

JOURNAL ARTICLE

Abubakar R, Muxworthy AR, Sephton MA, Southern P, Watson JS, Fraser AJ, Almeida TPet al., 2015, Formation of magnetic minerals at hydrocarbon-generation conditions, Marine and Petroleum Geology, Vol: 68, Pages: 509-519, ISSN: 0264-8172

JOURNAL ARTICLE

Lewis JMT, Watson JS, Najorka J, Duy L, Sephton MAet al., 2015, Sulfate Minerals: A Problem for the Detection of Organic Compounds on Mars?, ASTROBIOLOGY, Vol: 15, Pages: 247-258, ISSN: 1531-1074

JOURNAL ARTICLE

Luong D, Sephton MA, Watson JS, 2015, Subcritical water extraction of organic matter from sedimentary rocks, ANALYTICA CHIMICA ACTA, Vol: 879, Pages: 48-57, ISSN: 0003-2670

JOURNAL ARTICLE

Matthewman R, Court RW, Crawford IA, Jones AP, Joy KH, Sephton MAet al., 2015, The Moon as a Recorder of Organic Evolution in the Early Solar System: A Lunar Regolith Analog Study, Astrobiology, Vol: 15, Pages: 154-168, ISSN: 1531-1074

JOURNAL ARTICLE

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