Max Coleman

NASA, Вашингтон, West Virginia, United States

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Publications (78)177.19 Total impact

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    ABSTRACT: Low chloride concentration in water samples is a limitation for chlorine stable isotope measurements using a gas source isotope ratio mass spectrometer (IRMS). Here we describe an optimized method of chloride (Cl−) pre-concentration for dilute waters using a strong anion-exchange resin (Amberlite AG 1-X4). In order to validate our method and its reliability for δ37Cl measurements we made high precision δ37Cl measurements by dual inlet (DI) IRMS, also applicable to δ37Cl measurements by continuous flow IRMS.
    No preview · Article · Sep 2015 · Chemical Geology
  • John Ludden · Francis Albarède · Max Coleman
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    ABSTRACT: As geochemists and mineralogists, we are well aware of the impact of our science. We can often reel off examples of how our discoveries have influenced industry and improved humankind's knowledge about how the Earth works, as well as how natural and anthropogenic processes have led to its present state. Moreover, because of a century of analytical developments and conceptual breakthroughs, geochemists are now versatile and can now work across the entire spectrum of the Earth sciences. However, we are not so good at promoting the social and economic impacts of geochemistry.
    No preview · Article · Aug 2015 · Elements
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    ABSTRACT: Hydrothermal vents harbor ecosystems mostly decoupled from organic carbon synthesized with the energy of sunlight (photosynthetic carbon source) but fueled instead by oxidation of reduced compounds to generate a chemosynthetic carbon source. Our study aimed to disentangle photosynthetic and chemosynthetic organic carbon sources for the shrimp species Rimicaris hybisae, a primary consumer presumed to obtain its organic carbon mainly from ectosymbiotic chemoautotrophic bacteria living on its gill cover membrane. To provide ectosymbionts with ideal conditions for chemosynthesis, these shrimp live in dense clusters around vent chimneys; they are, however, also found sparsely distributed adjacent to diffuse vent flows, where they might depend on alternative food sources. Densely and sparsely distributed shrimp were sampled and dissected into abdominal tissue and gill cover membrane, covered with ectosymbiotic bacteria, at two hydrothermal vent fields in the Mid-Cayman rise that differ in vent chemistry. Fatty acids (FA) were extracted from shrimp tissues and their carbon isotopic compositions assessed. The FA data indicate that adult R. hybisae predominantly rely on bacteria for their organic carbon needs. Their FA composition is dominated by common bacterial FA of the n7 family (~41%). Bacterial FA of the n4 FA family are also abundant and found to constitute good biomarkers for gill ectosymbionts. Sparsely distributed shrimp contain fractions of n4 FA in gill cover membranes ~4% lower than densely packed ones (~18%) and much higher fractions of photosynthetic FA in abdominal tissues, ~4% more (compared with 1.6%), suggesting replacement of ectosymbionts along with exoskeletons (molt), while they take up alternative diets of partly photosynthetic organic carbon. Abdominal tissues also contain photosynthetic FA from a second source taken up presumably during an early dispersal phase and still present to c. 3% in adult shrimp. The contribution of photosynthetic carbon to the FA pool of adult R. hybisae is, however, overall small (max. 8%). Significant differences in carbon isotopic values of chemosynthetically derived FA between vent fields suggest that different dominant C fixation pathways are being used.
    No preview · Article · Jun 2015 · Deep Sea Research Part I Oceanographic Research Papers
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    ABSTRACT: In this study, we have used stable isotopes of megafauna, microbial mats and particulate organic matter to examine the effect of depth and vent fluid composition on the carbon sources at two proximal, chemically distinct hydrothermal vent fields along the Mid-Cayman Rise. The basalt hosted Piccard vent field (4980 m) is twice as deep as the ultramafic hosted Von Damm vent field (2300 m) and has very different faunal assemblages. Of particular note is the presence of seep-associated fauna, Escarpia and Lamellibrachia tubeworms, at the Von Damm vent field.
    No preview · Article · Jun 2015 · Deep Sea Research Part I Oceanographic Research Papers
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    ABSTRACT: A new tool was developed for large volume sampling to facilitate marine microbiology and biogeochemical studies. It was developed for remotely operated vehicle and hydrocast deployments, and allows for rapid collection of multiple sample types from the water column and dynamic, variable environments such as rising hydrothermal plumes. It was used successfully during a cruise to the hydrothermal vent systems of the Mid-Cayman Rise. The Suspended Particulate Rosette V2 large volume multi-sampling system allows for the collection of 14 sample sets per deployment. Each sample set can include filtered material, whole (unfiltered) water, and filtrate. Suspended particulate can be collected on filters up to 142 mm in diameter and pore sizes down to 0.2 μm. Filtration is typically at flowrates of 2 L min−1. For particulate material, filtered volume is constrained only by sampling time and filter capacity, with all sample volumes recorded by digital flowmeter. The suspended particulate filter holders can be filled with preservative and sealed immediately after sample collection. Up to 2 L of whole water, filtrate, or a combination of the two, can be collected as part of each sample set. The system is constructed of plastics with titanium fasteners and nickel alloy spring loaded seals. There are no ferrous alloys in the sampling system. Individual sample lines are prefilled with filtered, deionized water prior to deployment and remain sealed unless a sample is actively being collected. This system is intended to facilitate studies concerning the relationship between marine microbiology and ocean biogeochemistry.
    Full-text · Article · Sep 2014 · Deep Sea Research Part I Oceanographic Research Papers
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    ABSTRACT: Sulfite is an important sulfoxy intermediate in oxidative and reductive sulfur cycling in the marine and terrestrial environment. Different aqueous sulfite species exist, such as dissolved sulfur dioxide (SO2), bisulfite (HSO3‑), pyrosulfite (S2O52‑) and sulfite sensu stricto (SO32‑), whereas their relative abundance in solution depends on the concentration and the pH. Conversion of one species into another is rapid and involves in many cases incorporation of oxygen from, or release of oxygen to, water (e.g. SO2 + H2O ↔ HSO3‑ + H+), resulting in rapid oxygen isotope exchange between sulfite species and water. Consequently, the oxygen isotope composition of sulfite is strongly influenced by the oxygen isotope composition of water. Since sulfate does not exchange oxygen isotopes with water under most earth surface conditions, it can preserve the sulfite oxygen isotope signature that it inherits via oxidative and reductive sulfur cycling. Therefore, interpretation of δO values strongly hinges on the oxygen isotope equilibrium fractionation between sulfite and water which is poorly constrained. This is in large part due to technical difficulties in extraction of sulfite from solution for oxygen isotope analysis.
    No preview · Article · Nov 2013 · Geochimica et Cosmochimica Acta
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    Full-text · Dataset · Oct 2013
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    Full-text · Dataset · Oct 2013
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    A.C. Allwood · I W Burch · J M Rouchy · M Coleman
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    ABSTRACT: Abstract The ∼5.3-6.0 million-year-old evaporitic gypsum deposits of Cyprus and Crete contain a variety of stromatolites that formed during the Messinian salinity crisis. We recognize four stromatolite morphotypes, including domical, conical, columnar, and flat-laminated structures. Observations of morphological and textural variations among the different morphotypes reveal significant diversity and complexity in the nature of interactions between microorganisms, gypsum deposition, and gypsum crystal growth. Nonbiological processes (detrital gypsum deposition, in situ crust precipitation, syntaxial crystal growth, subsurface crystal growth, and recrystallization) interacted with inferred microbial processes (including localized growth of biofilms, trapping and binding of grains in mats, nucleation of gypsum on cells) to produce distinct morphological-textural assemblages. Evidence for biological origins is clear in some stromatolite morphotypes and can come from the presence of microfossils, the spatial distribution of organic matter, and stromatolite morphology. In one stromatolite morphotype, the presence of the stromatolite, or the biota associated with it, may have determined the morphology of gypsum crystals. In some stromatolite morphotypes, definitive evidence of a microbial influence is not as clear. There are broad similarities between the Messinian gypsum stromatolites and carbonate stromatolites elsewhere in the geologic record, such as the formation of precipitated and granular layers; the development of domed, columnar, and conical morphotypes; the potential for microbes to influence mineral precipitation; and the recrystallization of deposits during burial. However, in detail the array of microbial-sedimentary-diagenetic process interactions is quite distinct in gypsiferous systems due to differences in the way gypsum typically forms and evolves in the paleoenvironment compared to carbonate. Unique aspects of the taphonomy of gypsum compared to carbonate chemical sediments, generally speaking, include the following: the potential for growth of individual crystals to determine the shape of a stromatolite (and possibly vice versa), a more diverse set of outcomes relating to preservation versus destruction of textures through crystal growth and recrystallization, and a greater likelihood of preserving microfossils through encapsulation in large crystals. These insights gained from the study of terrestrial gypsum sedimentary rocks provide valuable guidance for the search for clues to past life in sulfate chemical sediments on Mars. Key Words: Stromatolites-Gypsum-Evaporites-Mars-Biosignature. Astrobiology 13, 870-886.
    Preview · Article · Sep 2013 · Astrobiology
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    ABSTRACT: The oxygen isotope composition of sulfate serves as an archive of oxidative sulfur cycling. Studies on the aerobic oxidation of reduced sulfur compounds showed discrepancies in the relative incorporation of oxygen from dissolved molecular oxygen (O2) and water (H2O) into newly formed sulfate, which likely result from slight differences in the production and consumption rate of sulfoxy intermediates that exchange oxygen isotopes with water. Sulfite is often considered the final sulfoxy intermediate in the oxidation of reduced sulfur compounds to sulfate and its residence time strongly affects the oxygen isotope signature of produced sulfate. However, data on the oxygen isotope signature of sulfate derived from sulfite oxidation are scarce.
    No preview · Article · Sep 2013 · Chemical Geology
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    ABSTRACT: [1] Deep-sea ultramafic-hosted vent systems have the potential to provide large amounts of metabolic energy to both autotrophic and heterotrophic microorganisms in their dispersing hydrothermal plumes. Such vent-systems release large quantities of hydrogen and methane to the water column, both of which can be exploited by autotrophic microorganisms. Carbon cycling in these hydrothermal plumes may, therefore, have an important influence on open-ocean biogeochemistry. In this study, we investigated an ultramafic-hosted system on the Mid-Cayman Rise, emitting metal-poor and hydrogen sulfide-, methane-, and hydrogen-rich hydrothermal fluids. Total organic carbon concentrations in the plume ranged between 42.1 and 51.1 μM (background = 43.2 ± 0.7 μM (n = 5)) and near-field plume samples with elevated methane concentrations imply the presence of chemoautotrophic primary production and in particular methanotrophy. In parts of the plume characterized by persistent potential temperature anomalies but lacking elevated methane concentrations, we found elevated organic carbon concentrations of up to 51.1 μM, most likely resulting from the presence of heterotrophic communities, their extracellular products and vent larvae. Elevated carbon concentrations up to 47.4 μM were detected even in far-field plume samples. Within the Von Damm hydrothermal plume, we have used our data to hypothesize a microbial food web in which chemoautotrophy supports a heterotrophic community of microorganisms. Such an active microbial food web would provide a source of labile organic carbon to the deep ocean that should be considered in any future studies evaluating sources and sinks of carbon from hydrothermal venting to the deep ocean.
    No preview · Article · Jan 2013 · Geochemistry Geophysics Geosystems
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    ABSTRACT: Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world's ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise collected using a combination of CTD-rosette operations and dives of the Hybrid Remotely Operated Vehicle (HROV) Nereus in 2009 followed by shore based work-up of samples for geochemical and microbiological analyses. Our data indicate that the Mid-Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.
    No preview · Article · Dec 2010
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    ABSTRACT: We describe a continuous high-pressure flow reactor designed to simulate the unforced convective interaction of hydrothermal solutions and ocean waters with submarine crust on early Earth-conditions appropriate to those that may have led to the onset of life. The experimental operating conditions are appropriate for investigating kinetic hydrothermal processes in the early history of any sizable wet, rocky planet. Beyond the description of the fabrication, we report an initial experiment that tested the design and investigated the feasibility of sulfide and silica dissolution in alkaline solution from iron sulfide and basaltic rock, and their possible subsequent transport as HS(-) and H(2)SiO(2-)(4) in hot alkaline solutions. Delivery of hydrogen sulfide and dihydrogen silicate ions would have led to the precipitation of ferrous hydroxide, hydroxysilicates, and iron sulfides as integral mineral components of an off-ridge compartmentalized hydrothermal mound in the Hadean. Such a mound could, we contend, have acted as a natural chemical and electrochemical reactor and, ultimately, as the source of all biochemistry on our planet. In the event, we show that an average of ∼1 mM/kg of both sulfide and silica were released throughout, though over 10 mM/kg of HS(-) was recorded for ∼100 minutes in the early stages of the experiment. This alkaline effluent from the reactor was injected into a reservoir of a simulacrum of ferrous iron-bearing "Hadean Ocean" water in an experiment that demonstrated the capacity of such fluids to generate hydrothermal chimneys and a variety of contiguous inorganic microgeode precipitates bearing disseminations of discrete metal sulfides. Comparable natural composite structures may have acted as hatcheries for emergent life in the Hadean.
    Full-text · Article · Oct 2010 · Astrobiology
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    ABSTRACT: Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise. Our data indicate that the Mid- Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity. Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 14020-14025, doi:10.1073/pnas.1009205107. This research was funded through NASA (ASTEP) and WHOI (Ocean Ridge Initiative).
    Full-text · Article · Aug 2010 · Proceedings of the National Academy of Sciences
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    ABSTRACT: We present the first systematic characterization of the extent and distribution of hydrothermal activity along the previously unexplored Mid-Cayman Rise, Earth's deepest mid-ocean ridge as part of a NASA-funded ASTEP program.
    No preview · Article · Apr 2010
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    ABSTRACT: The Mid-Cayman Rise, an isolated deep mid-ocean ridge, hosts all 3 known submarine vent-types AND the deepest vents known, making it an ideal natural laboratory for continuing studies of astrobiology, evolutionary biology and the origins of life.
    No preview · Article · Apr 2010
  • K. Ziegler · M. L. Coleman · R. E. Mielke · E. D. Young
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    ABSTRACT: Microbial pyrite oxidation experiments in spiked water and the triple oxygen isotopes of resulting sulfate suggest that Delta17OSO4 signatures can trace microbial vs. inorganic sulfate formation, and, therefore, have the potential as biosignature.
    No preview · Article · Mar 2010
  • C. G. Hubbard · S. Black · M. L. Coleman
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    ABSTRACT: Oxygen isotopes have been used to gain insight into pyrite oxidation mechanisms for some 25 years. Two distinct approaches are currently being used to interpret field data. We show the discrepancies between these approaches and recent models of pyrite oxidation, identifying the areas of uncertainty that need to be addressed. The first approach uses fractionation factors derived from experimental work to express sulfate-oxygen in terms of the percentage of water-oxygen and atmospheric-oxygen. Recent models of pyrite oxidation suggest that only water-oxygen interacts with the S-moiety on the pyrite surface, regardless of whether Fe3+ or O2 is the oxidant. In this case, atmospheric-oxygen can only be incorporated into the final sulfate during the oxidation of dissolved sulfoxyanion intermediates. Published pathways of sulfoxyanion oxidation suggest a maximum of 34% atmospheric-oxygen in the final sulfate. In contrast, field studies using this first approach suggest that >50% atmospheric-oxygen can be incorporated. The second approach presents two end-member scenarios and is more consistent with recent pyrite oxidation models: (i) 100% water-oxygen from the direct release of sulfate from the pyrite surface, resulting in little or no fractionation; (ii) release of intermediate sulfoxyanions, oxidation to sulphite, sulphite-water oxygen isotopic exchange followed by oxidation to sulfate. This approach predicts a maximum of 25% atmospheric-oxygen in the final sulfate but laboratory studies have shown the incorporation of up to 45% atmospheric-oxygen. We present recommendations for the further experimental work needed to refine our understanding of oxygen isotopes in pyrite oxidation.
    No preview · Article · Dec 2009
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    ABSTRACT: We report the first systematic exploration for and characterization of hydrothermal vents and vent ecosystems on the short (~110 km), deep (> 5000 m), ultra-slow-spreading (<20 mm yr-1) Mid-Cayman Rise in the Caribbean Sea. This work was carried out aboard the RV Cape Hatteras in October-November 2009 as part of the ChEss Project of the Census of Marine Life, funded through NASA’s ASTEP program and represents the first scientific field program funded to use WHOI’s new hybrid deep submergence vehicle, Nereus, first in AUV mode then in ROV mode. Prior to this work, evidence for hydrothermal venting had been found on every active spreading center investigated, including the comparably ultra-slow spreading ridges in the SW Indian Ocean and in the Arctic (Mohns, Knipovich & Gakkel Ridges). The organisms colonizing vents are renowned for their endemicity, their adaptations to the extreme chemical and physical conditions encountered and for differences in species level from one ocean basin to another. Consequently, the identification of any organisms colonizing vents of the Mid-Cayman Spreading Center offers a critical opportunity to build upon our understanding of the dispersion of vent species and the potential role of the rise of the Isthmus of Panama (dating from ~5 Ma) as a vicariant event leading to the evolutionary divergence of Atlantic and Pacific vent faunas. Further, the MCSC is so deep that any vents present may occur at depths greater than all previously known vent systems, extending the known limits to life on our planet in terms of pressure, temperature, and vent-fluid chemistry. Finally, hydrothermal circulation through ultramafic rocks can generate abiotic synthesis of organic matter: an analog for the prebiotic basis for the origin of life on early Earth and Mars. In future years of this 4-year study, therefore, we will also aim to assess the relative importance of abiotic organic synthesis versus recycling of bio-organic material and/or chemical energy as the primary energy source for any ecosystems discovered.
    No preview · Article · Nov 2009
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    ABSTRACT: A set of free-drift experiments was undertaken to synthesize carbonates of mixed cation content (Fe, Ca, Mg) from solution at 25 and 70 °C to better understand the relationship between the mineralogy and composition of these phases and the solutions from which they precipitate. Metastable solid solutions formed at 25 °C which are not predicted from the extrapolation of higher temperature equilibrium assemblages; instead, solids formed that were intermediary in chemical composition to known magnesite–siderite and dolomite solid solutions. A calcite–siderite solid solution precipitated at 25 °C, with the percentage of CaCO3 in the solid being proportional to the aqueous Ca/Fe ratio of the solution, while Mg was excluded from the crystal structure except at relatively high aqueous Mg/Ca and Mg/Fe ratios and a low Ca content. Alternatively, at 70 °C Mg was the predominant cation of the solid solutions. These results are compatible with the hypothesis that the relative dehydration energies of Fe, Ca and Mg play an important role in the formation of mixed cation carbonates in nature.
    Full-text · Article · Sep 2009 · Geochimica et Cosmochimica Acta

Publication Stats

1k Citations
177.19 Total Impact Points

Institutions

  • 2010-2015
    • NASA
      • Jet Propulsion Laboratory
      Вашингтон, West Virginia, United States
  • 2008-2015
    • California Institute of Technology
      • Jet Propulsion Laboratory
      Pasadena, California, United States
  • 1997-2013
    • University of Reading
      • School of Human and Environmental Sciences
      Reading, England, United Kingdom
  • 2006
    • Baylor University
      • Department of Geology
      Waco, Texas, United States
  • 2005
    • University of California, Berkeley
      • Department of Plant and Microbial Biology
      Berkeley, CA, United States
  • 2003
    • Institut de Physique du Globe de Paris
      Lutetia Parisorum, Île-de-France, France