Carol Lutken - Academia.edu (original) (raw)

Papers by Carol Lutken

The northern Gulf of Mexico is dominated by salt tectonics, resulting fracturing and numerous sea... more The northern Gulf of Mexico is dominated by salt tectonics, resulting fracturing and numerous seafloor seeps and vents. Woolsey Mound, site of the Gulf of Mexico Hydrates Research Consortium's seafloor observatory, has been investigated extensively via surveys, direct sampling and seafloor instrument systems. This study presents an innovative approach to seismic data interpretation, integrating three different resolution datasets and maximizing seismic coverage of the complex natural hydrocarbon plumbing system at Woolsey Mound.

3D industry seismic data reveal the presence of a salt body at in the shallow subsurface that has generated an extended network of faults, some extending from the salt body to the seafloor (master faults). Higher resolution seismic data show acoustic wipe-out zones along the master faults with expulsion features – seafloor pockmarks and craters – located immediately above them and associated, in the subsurface, with high-amplitude, negative anomalies at constant depth of 0.2 s TWTT b.s.f., interpreted as free gas. Since pockmarks and craters provide pathways for hydrocarbons to escape from depth into the water column, related sub-surface seismic anomalies may indicate free gas at the base of the gas hydrates stability zone (GHSZ). Fluid flow and gas hydrates formation are segmented laterally along faults. Gas hydrates formation and dissociation vary temporally in the vicinity of active faults, and can temporarily seal them as conduits for thermogenic fluids. Periodic migrations of gases and other fluids may perturb the GHSZ in terms of temperature and pressure, producing the observed lack of classical BSRs.

Offshore Technology Conference, 2005

Geological Society, London, Memoirs, 1990

... Current deflection may have played a role in the formation of the Atlantic psychro-sphere in ... more ... Current deflection may have played a role in the formation of the Atlantic psychro-sphere in the late Eocene (although see Matthews & Poore 1980 for a glacial model). However, Benson's model does not apply to the Early Carboniferous. ...

Discussion of results of preliminary studies at the sea-floor observatory site in the Northern Gu... more Discussion of results of preliminary studies at the sea-floor observatory site in the Northern Gulf of Mexico.

During the past five years, several sets of very high resolution seismic data from the Mississipp... more During the past five years, several sets of very high resolution seismic data from the Mississippi Canyon region of the northern Gulf of Mexico have been acquired and processed by the Center for Marine Resources and Environmental Technology (CMRET). These data have been recovered in support of an effort to site a permanent remote multi-sensor sea floor observatory for the

A presentation at the Oceans 98 Conference in Nice described a then newly initiated program to in... more A presentation at the Oceans 98 Conference in Nice described a then newly initiated program to install a net of acoustic vertical line arrays (VLAs) on the continental slope of the northern Gulf of Mexico. Since then, the project has evolved into the development of a multi-sensor sea floor observatory that incorporates geochemical as well as geophysical systems. Some of

Woolsey Mound, a carbonate/hydrate complex of cold seeps, vents, and seafloor pockmarks in Missis... more Woolsey Mound, a carbonate/hydrate complex of cold seeps, vents, and seafloor pockmarks in Mississippi Canyon Block 118, is the site of the Gulf of Mexico Hydrates Research Consortium's (GOMHRC) multi-sensor, multi-disciplinary, permanent seafloor observatory. In preparation for installing the observatory, the site has been studied through geophysical, biological, geological, and geochemical surveys. By integrating high-resolution, swath bathymetry, acoustic imagery, seafloor video, and shallow geological samples in a morpho-bio-geological model, we have identified a complex mound structure consisting of three main crater complexes: southeast, northwest, and southwest. Each crater complex is associated with a distinct fault. The crater complexes exhibit differences in morphology, bathymetric relief, exposed hydrates, fluid venting, sediment accumulation rates, sediment diagenesis, and biological community patterns. Spatial distribution of these attributes suggests that the complexes represent three different fluid flux regimes: the southeast complex seems to be an extinct or quiescent vent; the northwest complex exhibits young, vigorous activity; and the southwest complex is a mature, fully open vent. Geochemical evidence from pore-water gradients corroborates this model suggesting that upward fluid flux waxes and wanes over time and that microbial activity is sensitive to such change. Sulfate and methane concentrations show that microbial activity is patchy in distribution and is typically higher within the northwest and southwest complexes, but is diminished significantly over the southeast complex. Biological community composition corroborates the presence of distinct conditions at the three crater complexes. The fact that three different fluid flux regimes coexist within a single mound complex confirms the dynamic nature of the plumbing system that discharges gases into bottom water. Furthermore, the spatial distribution of bio-geological processes appears to be a valid indicator of multiple fluid flux regimes that coexist at the mound.

PALAIOS, 1990

... INTRODUCTION "The whole of it came not at once-Twas murder by degrees" Emily Dickin... more ... INTRODUCTION "The whole of it came not at once-Twas murder by degrees" Emily Dickinson The suggestion that mass extinction events are periodic (Raup and Sepkoski, 1984, 1986) has prompted a search for a general cause of such extinctions. ...

Offshore Technology Conference, 2006

The Leading Edge, 2015

Geophysical investigations of the first 100 m below the seafloor in deep-marine environments are ... more Geophysical investigations of the first 100 m below the seafloor in deep-marine environments are done to assess drilling hazards, to plan routes for pipelines and cables, and to study benthic organism communities. The tool of choice for these investigations is subbottom profiling, which uses acoustic signals in the range of 1 to 25 kHz to image near-bottom stratigraphy. An existing engineering-scale, direct-current resistivity (DCR) system for use in deep-marine, near-bottom environments has been adapted. It is potentially useful in settings in which the presence of free gas, gas hydrates, coarse sediment, cemented carbonate, or highly deformed sediment limits the effectiveness of the subbottom-profiling method. The adapted DCR system was used to survey Woolsey Mound, Mississippi Canyon Block 118 (MC118), Gulf of Mexico, to characterize the shallow gashydrate system. Three conventional modes of DCR data acquisition -continuous-resistivity profiling (CRP), static array, and time lapse with a fixed array -were evaluated on the deep seafloor. High-resistivity anomalies likely associated with high concentration of hydrate deposits were imaged with all three modes of acquisition.

ABSTRACT Since 2006, we have been working on outfitting Gas Hydrate seafloor observatories with i... more ABSTRACT Since 2006, we have been working on outfitting Gas Hydrate seafloor observatories with instruments, called Pore-Fluid Arrays, to collect and measure in situ methane concentrations and other biogeochemical parameters over time. The central technology within the PFA's uses OsmoSampler instruments that use osmosis to pull fluids slowly through ports into 300 meter-long copper tubing coil. OsmoSamplers are robust, require no power, and give sample resolution on the order of days to weeks. They allow questions about the dynamics of a system, in our case, gas hydrate systems, to be asked. For example, at the Gulf of Mexico Gas Hydrate Research Consortium monitoring station, we asked "on what time scale do gas hydrates form or decompose?" A 4-month time-series from Mississippi Canyon 118 gave unexpected results showing methane dynamics from the deep-sea influenced by regional tectonic activity. In 2009, we extended this tectonic link to methane release by asking the specific question "is shallow gas released from the seafloor when regional tectonics is active, and, if so, what is the temporal variability of such release events?" To answer this, we deployed a PFA in an area of seafloor where extensive methane venting is known to occur, Northern Cascadia margin gas hydrate sites. This area has seafloor cracks with active bubble streams and thin bacterial mats suggesting shallow gas and possible pore-fluid saturation. One of these gas crack sites, informally named "bubbly gulch", was chosen to deploy a PFA for 9 months. The PFA was modified to be ROV-deployable and was made up of 4 OsmoSamplers that were each plumbed to a port along a 1-meter probe tip using small diameter tubing. Because of the high methane concentrations anticipated, in situ pressures were maintained within the coil by the addition of a high pressure valve. Water samples were collected from the overlying water, at the sediment-water interface, and 6 and 10 cm into the sediments. Bottom water temperatures were also measured over the time series to determine pumping rates of the samplers but also to look for any temporal variability. In May 2010, the samplers were retrieved on a NEPTUNE Canada cruise by ROPOS-ROV. The coils were subsequently sub-sampled by cutting every 4 meters of tubing. With a pumping rate of 0.5 mL/day, this allowed a temporal resolution of 5-6 days. This presentation will outline preliminary in situ methane, sulfate, and chloride concentrations and stable carbon isotopes of methane and dissolved inorganic carbon over time. It will discuss correlations, or lack thereof, to regional tectonic activity and highlight how dynamic the methane flux is, even at 1200 meters below sealevel.

... and Counter Boris Mizaikoff, School of Chemistry and Biochemistry, Georgia Institute of Techn... more ... and Counter Boris Mizaikoff, School of Chemistry and Biochemistry, Georgia Institute of Technology, Applied Sensors Laboratory, 770 State St, Atlanta, GA 30332 Task 5: Mid-Infrared Sensor Systems for Continuous Methane Monitoring in Seawater Angela Davis, AUGER ...

Nature Geoscience, 2012

The historic flood of 2011 provided a unique opportunity to examine how river flows carry sedimen... more The historic flood of 2011 provided a unique opportunity to examine how river flows carry sediment into marshes during a high water event and discover how differences in hydrodynamics between the Mississippi and Atchafalaya Rivers influenced wetland sedimentation.

Geology, 1989

... and Harland, 1981; Caputo and Crowell, 1985; Veevers and Powell, 1987), the link between pola... more ... and Harland, 1981; Caputo and Crowell, 1985; Veevers and Powell, 1987), the link between polar and ... Existing Paleozoic 180 curves cannot be interpreted as temperature curves (Visor et al ... pod genera from the following time intervals: early, middle, and late Tournaisian; early ...

Geological Society, London, Special Publications, 2009

Geochemistry, Geophysics, Geosystems, 2014

Geochemical profiles were coupled with seismic information to examine subsurface hydrocarbon sour... more Geochemical profiles were coupled with seismic information to examine subsurface hydrocarbon source, migration, and fate at a Gulf of Mexico carbonate-gas hydrate mound (Woolsey Mound). Three seafloor features were investigated in detail: 1) major faults resulting from a rising salt body, 2) an acoustic backscatter anomaly, and 3) a pockmark associated with a major fault. We analyzed sulfate, chloride, dissolved inorganic carbon, and hydrocarbon concentrations, and carbon isotopes in porewater extracted from 20 m piston cores to characterize gas source and calculate methane flux. Dissolved biogenic methane dominated the off-fault sites, while the contribution of thermogenic methane increased near a major fault where thermogenic gas hydrates were recovered. Within the pockmark, methane concentrations were low and isotopes indicated a biogenic source. Since pockmarks are typically formed from expulsive fluid flow, this suggests that either the pockmark is the legacy of a conduit that has become plugged or that the expulsed fluid is confined within the fault walls. At the acoustic anomaly, non-steady state sulfate profiles suggested temporal variability in methane flux. Estimates from >75 gravity cores collected across Woolsey Mound since 2002 were mapped to display the spatial variability in methane flux relative to the faults. Methane flux to the seafloor was generally low, but increased several fold near the faults suggesting that the faults may provide conduits for hydrocarbons to bypass the 'microbial biofilter' and cross the sediment water interface.