Lilley Marvin

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  • Preprint
    Stable isotopic evidence in support of active microbial methane cycling in low-temperature diffuse flow vents at 9°50’N East Pacific Rise
    ( 2008-01) Proskurowski, Giora ; Lilley, Marvin D. ; Olson, Eric J.
    A unique dataset from paired low- and high-temperature vents at 9°50’N East Pacific Rise provides insight into the microbiological activity in low-temperature diffuse fluids. The stable carbon isotopic composition of CH4 and CO2 in 9°50’N hydrothermal fluids indicates microbial methane production, perhaps coupled with microbial methane consumption. Diffuse fluids are depleted in 13C by ~10‰ in values of δ13C of CH4, and by ~0.55‰ in values of δ13C of CO2, relative to the values of the high-temperature source fluid (δ13C of CH4 = -20.1 ± 1.2‰, δ13C of CO2 = -4.08 ± 0.15‰). Mixing of seawater or thermogenic sources cannot account for the depletions in 13C of both CH4 and CO2 at diffuse vents relative to adjacent high-temperature vents. The substrate utilization and 13C fractionation associated with the microbiological processes of methanogenesis and methane oxidation can explain observed steady-state CH4 and CO2 concentrations and carbon isotopic compositions. A mass-isotope numerical box-model of these paired vent systems is consistent with the hypothesis that microbial methane cycling is active at diffuse vents at 9°50’N. The detectable 13C modification of fluid geochemistry by microbial metabolisms may provide a useful tool for detecting active methanogenesis.
  • Article
    Multi-stage evolution of the Lost City hydrothermal vent fluids
    (Elsevier, 2022-08-13) Aquino, Karmina A. ; Früh-Green, Gretchen L. ; Rickli, Jörg ; Bernasconi, Stefano M. ; Lang, Susan Q. ; Lilley, Marvin D. ; Butterfield, David A.
    Serpentinization-influenced hydrothermal systems, such as the Lost City Hydrothermal Field (LCHF), are considered as potential sites for the origin of life. Despite an abundance of reducing power in this system (H2 and CH4), microbial habitability may be limited by high pH, elevated temperatures, and/or low concentrations of bioavailable carbon. At the LCHF, the relative contribution of biotic and abiotic processes to the vent fluid composition, especially in the lower temperature vents, remain poorly constrained. We present fluid chemistry and isotope data that suggest that all LCHF fluids are derived from a single endmember produced in the hotter, deeper subsurface essentially in the absence of microbial activity. The strontium isotope composition (87Sr/86Sr) of this fluid records the influence of underlying mantle and/or gabbroic rocks, whereas sulfur isotope composition indicates closed-system thermochemical sulfate reduction. Conductive cooling and transport is accompanied by continued sulfate reduction, likely microbial, and mixing with unaltered seawater, which produce second-order vents characterized by higher δ34Ssulfide and lower δ34Ssulfate values. Third-order vent fluids are produced by varying degrees of subsurface mixing between the first- and second-order fluids and a seawater-dominated fluid. Additional biotic and abiotic processes along different flow paths are needed to explain the spatial variability among the vents. Relationships between sulfur geochemistry and hydrogen concentrations dominantly reflect variations in temperature and/or distance from the primary outflow path. Methane concentrations are constant across the field which point to an origin independent of flow path and venting temperature. At Lost City, not all vent fluids appear to have zero Mg concentrations. Thus, we propose an extrapolation to a Sr isotope-endmember composition as an alternative method to estimate endmember fluid compositions at least in similar systems where a two-component mixing with respect to Sr isotopes between seawater and endmember fluids can be established.
  • Dataset
    Samples collected and their associated temperatures on an expedition to the Lost City hydrothermal field on R/V Atlantis cruise AT42-01 in September 2018
    (Biological and Chemical Oceanography Data Management Office (BCO-DMO). Contact:, 2020-03-30) Lang, Susan Q. ; Brazelton, William ; Fruh-Green, Gretchen ; Kelley, Deborah ; Lilley, Marvin
    Summary of samples collected by the Hydrothermal Organic Geochemistry (HOG) sampler on AT-4201 with ROV Jason, on dives J2_1107 through J2_1111, during R/V Atlantic cruise AT42-01, September 9 - October 1, 2018. For a complete list of measurements, refer to the full dataset description in the supplemental file 'Dataset_description.pdf'. The most current version of this dataset is available at:
  • Article
    Eruptive modes and hiatus of volcanism at West Mata seamount, NE Lau basin : 1996–2012
    (John Wiley & Sons, 2014-10-31) Embley, Robert W. ; Merle, Susan G. ; Baker, Edward T. ; Rubin, Kenneth H. ; Lupton, John E. ; Resing, Joseph A. ; Dziak, Robert P. ; Lilley, Marvin D. ; Chadwick, William W. ; Shank, Timothy M. ; Greene, Ronald ; Walker, Sharon L. ; Haxel, Joseph H. ; Olson, Eric J. ; Baumberger, Tamara
    We present multiple lines of evidence for years to decade-long changes in the location and character of volcanic activity at West Mata seamount in the NE Lau basin over a 16 year period, and a hiatus in summit eruptions from early 2011 to at least September 2012. Boninite lava and pyroclasts were observed erupting from its summit in 2009, and hydroacoustic data from a succession of hydrophones moored nearby show near-continuous eruptive activity from January 2009 to early 2011. Successive differencing of seven multibeam bathymetric surveys of the volcano made in the 1996–2012 period reveals a pattern of extended constructional volcanism on the summit and northwest flank punctuated by eruptions along the volcano's WSW rift zone (WSWRZ). Away from the summit, the volumetrically largest eruption during the observational period occurred between May 2010 and November 2011 at ∼2920 m depth near the base of the WSWRZ. The (nearly) equally long ENE rift zone did not experience any volcanic activity during the 1996–2012 period. The cessation of summit volcanism recorded on the moored hydrophone was accompanied or followed by the formation of a small summit crater and a landslide on the eastern flank. Water column sensors, analysis of gas samples in the overlying hydrothermal plume and dives with a remotely operated vehicle in September 2012 confirmed that the summit eruption had ceased. Based on the historical eruption rates calculated using the bathymetric differencing technique, the volcano could be as young as several thousand years.
  • Article
    A preliminary 1-D model investigation of tidal variations of temperature and chlorinity at the Grotto mound, Endeavour Segment, Juan de Fuca Ridge
    (John Wiley & Sons, 2017-01-18) Xu, Guangyu ; Larson, Benjamin I. ; Bemis, Karen G. ; Lilley, Marvin D.
    Tidal oscillations of venting temperature and chlorinity have been observed in the long-term time series data recorded by the Benthic and Resistivity Sensors (BARS) at the Grotto mound on the Juan de Fuca Ridge. In this study, we use a one-dimensional two-layer poroelastic model to conduct a preliminary investigation of three hypothetical scenarios in which seafloor tidal loading can modulate the venting temperature and chlorinity at Grotto through the mechanisms of subsurface tidal mixing and/or subsurface tidal pumping. For the first scenario, our results demonstrate that it is unlikely for subsurface tidal mixing to cause coupled tidal oscillations in venting temperature and chlorinity of the observed amplitudes. For the second scenario, the model results suggest that it is plausible that the tidal oscillations in venting temperature and chlorinity are decoupled with the former caused by subsurface tidal pumping and the latter caused by subsurface tidal mixing, although the mixing depth is not well constrained. For the third scenario, our results suggest that it is plausible for subsurface tidal pumping to cause coupled tidal oscillations in venting temperature and chlorinity. In this case, the observed tidal phase lag between venting temperature and chlorinity is close to the poroelastic model prediction if brine storage occurs throughout the upflow zone under the premise that layers 2A and 2B have similar crustal permeabilities. However, the predicted phase lag is poorly constrained if brine storage is limited to layer 2B as would be expected when its crustal permeability is much smaller than that of layer 2A.
  • Article
    Hydrothermal exploration of the southern Chile Rise: sediment‐hosted venting at the Chile Triple Junction
    (American Geophysical Union, 2022-03-04) German, Christopher R. ; Baumberger, Tamara ; Lilley, Marvin D. ; Lupton, John E. ; Noble, Abigail E. ; Saito, Mak A. ; Thurber, Andrew R. ; Blackman, Donna K.
    We report results from a hydrothermal plume survey along the southernmost Chile Rise from the Guamblin Fracture Zone to the Chile Triple Junction (CTJ) encompassing two segments (93 km cumulative length) of intermediate spreading-rate mid-ocean ridge axis. Our approach used in situ water column sensing (CTD, optical clarity, redox disequilibrium) coupled with sampling for shipboard and shore based geochemical analyses (δ3He, CH4, total dissolvable iron (TDFe) and manganese, (TDMn)) to explore for evidence of seafloor hydrothermal venting. Across the entire survey, the only location at which evidence for submarine venting was detected was at the southernmost limit to the survey. There, the source of a dispersing hydrothermal plume was located at 46°16.5’S, 75°47.9’W, coincident with the CTJ itself. The plume exhibits anomalies in both δ3He and dissolved CH4 but no enrichments in TDFe or TDMn beyond what can be attributed to resuspension of sediments covering the seafloor where the ridge intersects the Chile margin. These results are indicative of sediment-hosted venting at the CTJ.