scholarly journals IODP Expedition 331: Strong and Expansive Subseafloor Hydrothermal Activities in the Okinawa Trough

2012 ◽  
Vol 13 ◽  
pp. 19-27 ◽  
Author(s):  
K. Takai ◽  
M. J. Mottl ◽  
S. H. H. Nielsen ◽  
Keyword(s):  
Okinawa Trough ◽  
Anaerobic Oxidation Of Methane ◽  
Microbial Oxidation ◽  
Ocean Drilling Program ◽  
The North ◽  
Oxidation Of Methane ◽  
Integrated Ocean Drilling Program ◽  
The Okinawa Trough ◽  
Alteration Minerals ◽  
Physical And Chemical

Integrated Ocean Drilling Program (IODP) Expedition 331 drilled into the Iheya North hydrothermal system in the middle Okinawa Trough in order to investigate active subseafloor microbial ecosystems and their physical and chemical settings. We drilled five sites during Expedition 331 using special guide bases at three holes for reentry, casing, and capping, including installation of a steel mesh platform with valve controls for postcruise sampling of fluids. At Site C0016, drilling at the base of the North Big Chimney (NBC) mound yielded low recovery, but core included the first Kuroko-type black ore ever recovered from the modern subseafloor. The other four sites yielded interbedded hemipelagic and strongly pumiceous volcaniclastic sediment, along with volcanogenic breccias that are variably hydrothermally altered and mineralized. At most sites, analyses of interstitial water and headspace gas yielded complex patterns with depth and lateral distance of only a few meters. Documented processes included formation of brines and vapor-rich fluids by phase separation and segregation, uptake of Mg and Na by alteration minerals in exchange for Ca, leaching of K at high temperature and uptake at low temperature, anhydrite precipitation, potential microbial oxidation of organic matter and anaerobic oxidation of methane utilizing sulfate, and methanogenesis. Shipboard analyses have found evidence for microbial activity in sediments within the upper 10–30 m below seafloor (mbsf) where temperatures were relatively low, but little evidence in the deeper hydrothermally altered zones and hydrothermal fluid regime. <br><br> doi:<a href="http://dx.doi.org/10.2204/iodp.sd.13.03.2011" target="_blank">10.2204/iodp.sd.13.03.2011</a>

scholarly journals Microbial Community Stratification Controlled by the Subseafloor Fluid Flow and Geothermal Gradient at the Iheya North Hydrothermal Field in the Mid-Okinawa Trough (Integrated Ocean Drilling Program Expedition 331)

2014 ◽  
Vol 80 (19) ◽  
pp. 6126-6135 ◽  
Author(s):  
Katsunori Yanagawa ◽  
Anja Breuker ◽  
Axel Schippers ◽  
Manabu Nishizawa ◽  
Akira Ijiri ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Microbial Communities ◽  
Okinawa Trough ◽  
Geothermal Gradient ◽  
Hydrothermal Field ◽  
Rrna Gene ◽  
Ocean Drilling Program ◽  
Content Type ◽  
Ocean Drilling ◽  
Integrated Ocean Drilling Program

ABSTRACTThe impacts of lithologic structure and geothermal gradient on subseafloor microbial communities were investigated at a marginal site of the Iheya North hydrothermal field in the Mid-Okinawa Trough. Subsurface marine sediments composed of hemipelagic muds and volcaniclastic deposits were recovered through a depth of 151 m below the seafloor at site C0017 during Integrated Ocean Drilling Program Expedition 331. Microbial communities inferred from 16S rRNA gene clone sequencing in low-temperature hemipelagic sediments were mainly composed of members of theChloroflexiand deep-sea archaeal group. In contrast, 16S rRNA gene sequences of marine group IThaumarchaeotadominated the microbial phylotype communities in the coarse-grained pumiceous gravels interbedded between the hemipelagic sediments. Based on the physical properties of sediments such as temperature and permeability, the porewater chemistry, and the microbial phylotype compositions, the shift in the physical properties of the sediments is suggested to induce a potential subseafloor recharging flow of oxygenated seawater in the permeable zone, leading to the generation of variable chemical environments and microbial communities in the subseafloor habitats. In addition, the deepest section of sediments under high-temperature conditions (∼90°C) harbored the sequences of an uncultivated archaeal lineage of hot water crenarchaeotic group IV that may be associated with the high-temperature hydrothermal fluid flow. These results indicate that the subseafloor microbial community compositions and functions at the marginal site of the hydrothermal field are highly affected by the complex fluid flow structure, such as recharging seawater and underlying hydrothermal fluids, coupled with the lithologic transition of sediments.

A biomarker record of temperature and phytoplankton community structure in the Okinawa Trough since the last glacial maximum

2017 ◽  
Vol 88 (1) ◽  
pp. 89-97 ◽  
Author(s):  
Jiaping Ruan ◽  
Yunping Xu ◽  
Su Ding ◽  
Yinghui Wang ◽  
Xinyu Zhang
Keyword(s):  
Phytoplankton Community ◽  
Okinawa Trough ◽  
Kuroshio Current ◽  
Community Change ◽  
Community Structures ◽  
Ocean Drilling Program ◽  
The Holocene ◽  
The Okinawa Trough ◽  
The Kuroshio ◽  
The Last Glacial

AbstractA variety of biomarkers were examined from Ocean Drilling Program Core 1202B to reconstruct temperature and phytoplankton community structures in the southern Okinawa Trough since 20 ka. Two molecular temperature proxies ( $${\rm U}_{{37}}^{{{\rm K}\prime}} $$ and TEX86) show 5°C to ~6°C warming during the glacial-interglacial transition. Prior to the Holocene, the $${\rm U}_{{37}}^{{{\rm K}\prime}} $$ -derived temperature was generally 1°C to 4°C higher than TEX86-derived temperature. This difference, however, was reduced to <1°C in the Holocene. Correspondingly, the phytoplankton biomarkers (e.g., C37:2 alkenone, brassicasterol, C30 1,15 diol, and dinosterol) indicate a shift of planktonic community structures, with coccolithophorids becoming more abundant in the Holocene at the expense of diatoms/dinoflagellates. This shift is related to the variability of nutrients, temperature, and salinity in the Okinawa Trough, likely controlled by the sea level and the intensity of the Kuroshio Current. The phytoplankton community change may have had profound implications for atmospheric CO2 fluctuations during glacial-interglacial cycles since diatoms and dinoflagellates have a higher efficiency of the biological pump than coccolithophorids.

scholarly journals Microbial Alkalinity Production and Silicate Alteration in Methane Charged Marine Sediments: Implications for Porewater Chemistry and Diagenetic Carbonate Formation

2022 ◽  
Vol 9 ◽  
Author(s):  
Patrick Meister ◽  
Gerhard Herda ◽  
Elena Petrishcheva ◽  
Susanne Gier ◽  
Gerald R. Dickens ◽  
...  
Keyword(s):  
Transport Model ◽  
Total Alkalinity ◽  
Anaerobic Oxidation Of Methane ◽  
Deep Biosphere ◽  
Ocean Drilling Program ◽  
Oxidation Of Methane ◽  
Carbonate Formation ◽  
Reaction Transport ◽  
The Stability ◽  
Fundamental Insight

A numerical reaction-transport model was developed to simulate the effects of microbial activity and mineral reactions on the composition of porewater in a 230-m-thick Pleistocene interval drilled in the Peru-Chile Trench (Ocean Drilling Program, Site 1230). This site has porewater profiles similar to those along many continental margins, where intense methanogenesis occurs and alkalinity surpasses 100 mmol/L. Simulations show that microbial sulphate reduction, anaerobic oxidation of methane, and ammonium release from organic matter degradation only account for parts of total alkalinity, and excess CO2 produced during methanogenesis leads to acidification of porewater. Additional alkalinity is produced by slow alteration of primary aluminosilicate minerals to kaolinite and SiO2. Overall, alkalinity production in the methanogenic zone is sufficient to prevent dissolution of carbonate minerals; indeed, it contributes to the formation of cemented carbonate layers at a supersaturation front near the sulphate-methane transition zone. Within the methanogenic zone, carbonate formation is largely inhibited by cation diffusion but occurs rapidly if cations are transported into the zone via fluid conduits, such as faults. The simulation presented here provides fundamental insight into the diagenetic effects of the deep biosphere and may also be applicable for the long-term prediction of the stability and safety of deep CO2 storage reservoirs.

scholarly journals Methane emission and consumption at a North Sea gas seep (Tommeliten area)

2005 ◽  
Vol 2 (4) ◽  
pp. 1197-1241 ◽  
Author(s):  
H. Niemann ◽  
M. Elvert ◽  
M. Hovland ◽  
B. Orcutt ◽  
A. Judd ◽  
...  
Keyword(s):  
North Sea ◽  
Oil And Gas ◽  
Salt Diapir ◽  
Anaerobic Oxidation Of Methane ◽  
Cold Seeps ◽  
The North ◽  
Oxidation Of Methane ◽  
Phylogenetic Cluster ◽  
Carbonate Formation ◽  
Gas Seepage

Abstract. The North Sea hosts large coal, oil and gas reservoirs of commercial value. Natural leakage pathways of subsurface gas to the hydrosphere have been recognized during geological surveys (Hovland and Judd, 1988). The Tommeliten seepage area is part of the Greater Ekofisk area, which is situated above the Tommeliten Delta salt diapir in the central North Sea. In this study, we report of an active seep site (56°29.90'N, 2°59.80'E) located in the Tommeliten area, Norwegian Block 1/9, at 75 m water depth. Here, cracks in a buried marl horizon allow methane to migrate into overlying clay-silt and sandy sediments. Hydroacoustic sediment echosounding showed several venting spots coinciding with the apex of marl domes where methane is released into the water column and potentially to the atmosphere during deep mixing situations. In the vicinity of the gas seeps, sea floor observations showed small mats of giant sulphide-oxidizing bacteria above patches of black sediments and carbonate crusts, which are exposed 10 to 50 cm above seafloor forming small reefs. These Methane-Derived Authigenic Carbonates (MDACs) contain 13C-depleted, archaeal lipids indicating previous gas seepage and AOM activity. High amounts of sn2-hydroxyarchaeol relative to archaeol and low abundances of biphytanes in the crusts give evidence that ANaerobic MEthane-oxidising archaea (ANME) of the phylogenetic cluster ANME-2 were the potential mediators of Anaerobic Oxidation of Methane (AOM) at the time of carbonate formation. Small pieces of MDACs were also found subsurface at about 1.7 m sediment depth, associated with the Sulphate-Methane Transition Zone (SMTZ). The SMTZ of Tommeliten is characterized by elevated AOM and Sulphate Reduction (SR) rates, increased concentrations of 13C-depleted tetraether derived biphytanes, and specific bacterial Fatty Acids (FA). Further biomarker and 16S rDNA based analyses give evidence that AOM at the Tommeliten SMTZ is mediated by archaea belonging to the ANME-1b group and Sulphate Reducing Bacteria (SRB) most likely belonging to the Seep-SRB1 cluster. The zone of active methane consumption was restricted to a distinct horizon of about 20 cm. Concentrations of 13C-depleted lipid biomarkers (e.g. 500 ng g-dw-1 biphythanes, 140 ng g-dw-1 fatty acid ai-C15:0), cell numbers (1.5x108 cells cm-3), AOM and SR rates (3 nmol cm-3 d-1 in the SMTZ are 2-3 orders of magnitude lower compared to AOM zones of highly active cold seeps such as Hydrate Ridge or the Gulf of Mexico.

A novel 1D thermo-hydro-biogeochemical hydrate model to assess the full benthic environmental impact of methane gas hydrate dissociation

2021 ◽  
Author(s):  
Maria De La Fuente ◽  
Sandra Arndt ◽  
Tim Minshul ◽  
Héctor Marín-Moreno
Keyword(s):  
Environmental Impact ◽  
Gas Hydrate ◽  
Transport Processes ◽  
Anaerobic Oxidation Of Methane ◽  
Anaerobic Oxidation ◽  
Microbial Oxidation ◽  
Saturation State ◽  
Hydrate Dissociation ◽  
Oxidation Of Methane ◽  
The Impact

&lt;p&gt;Large quantities of methane (CH&lt;sub&gt;4&lt;/sub&gt;) are stored in gas hydrates at shallow depths within marine sediments. These reservoirs are highly sensitive to ocean warming and if destabilized could lead to significant CH&lt;sub&gt;4&lt;/sub&gt; release and global environmental impacts. However, the existence of such a positive feedback loop has recently been questioned as efficient CH&lt;sub&gt;4 &lt;/sub&gt;sinks within the sediment-ocean continuum likely mitigate the impact of gas hydrate-derived CH&lt;sub&gt;4&lt;/sub&gt; emissions on global climate. In particular, benthic anaerobic oxidation of methane (AOM) represents an important CH&lt;sub&gt;4 &lt;/sub&gt;sink capable of completely consuming CH&lt;sub&gt;4&lt;/sub&gt; fluxes before they reach the seafloor. However, the efficiency of this benthic biofilter is controlled by a complex interplay of multiphase methane transport and microbial oxidation processes and is thus highly variable (0-100%). In addition, AOM potentially enhances benthic alkalinity fluxes with important, yet largely overlooked implications for ocean pH, saturation state and CO&lt;sub&gt;2&lt;/sub&gt; emissions. As a consequence, the full environmental impact of hydrate-derived CH&lt;sub&gt;4&lt;/sub&gt; release to the ocean-atmosphere system and its feedbacks on global biogeochemical cycles and climate still remain poorly quantified. To the best our knowledge, currently available modelling tools to assess the benthic CH&lt;sub&gt;4&lt;/sub&gt; sink and its environmental impact during hydrate dissociation do not account for the full complexity of the problem. Available codes generally do not explicitly resolve the dynamics of the microbial community and thus fail to represent transient changes in AOM biofilter efficiency and windows of opportunity for CH&lt;sub&gt;4&lt;/sub&gt; escape. They also highly simplify the representation of&amp;#160; multiphase CH&lt;sub&gt;4 &lt;/sub&gt;transport processes and gas hydrate dynamics and rarely assess the influence of hydrate-derived CH&lt;sub&gt;4&lt;/sub&gt; fluxes on benthic-pelagic alkalinity and dissolved inorganic carbon fluxes. To overcome these limitations, we have developed a novel 1D thermo-hydro-biogeochemical hydrate model that improve the quantitative understanding of the benthic CH&lt;sub&gt;4&lt;/sub&gt; sink and benthic carbon cycle-climate feedbacks in response to methane hydrate dissociation caused by temperature and sea-level perturbations. Our mathematical model builds on previous thermo-hydraulic hydrate simulators, expanding them to include the dominant microbial processes affecting CH&lt;sub&gt;4&lt;/sub&gt; fluxes in a consistent and coupled mathematical formulation. The micro-biogeochemical reaction network accounts for the main redox reactions (i.e., aerobic degradation, organoclastic sulphate reduction (OSR), methanogenesis and aerobic-anaerobic oxidation of methane (AeOM-AOM)), carbonate dissolution/precipitation and equilibrium reactions that drive biogeochemical dynamics in marine hydrate-bearing sediments . In particular, the AOM rate is expressed as a bioenergetic rate law that explicitly accounts for biomass dynamics. Finally, the model allows tracking the carbon isotope signatures of all dissolved and solid carbon species. In this talk we will present the model structure for the multiphase-multicomponent hydrate system, describe the specific constitutive and reaction equations used in the formulation, discuss the numerical strategy implemented and illustrate the potential capabilities of the model.&lt;/p&gt;

A highly diverse silicic end member of a bimodal magma suite formed in an active continental back arc, Okinawa Trough

2021 ◽  
Author(s):  
Arran Murch ◽  
Kenichiro Tani ◽  
Takashi Sano ◽  
Shigekazu Yoneda
Keyword(s):  
Magma Mixing ◽  
Okinawa Trough ◽  
Fractional Crystallisation ◽  
Chemical Diversity ◽  
Crustal Assimilation ◽  
Arc Volcanism ◽  
The North ◽  
The Okinawa Trough ◽  
Formation Conditions ◽  
Back Arc

&lt;p&gt;The Okinawa Trough (OT) is an incipient continental back-arc basin that extends from Kyushu in the north to Taiwan in the south. The Okinawa Trough can be split in to three segments, the Northern (NOT), Middle (MOT), and Southern (SOT) with active back-arc volcanism restricted to volcanic centres located in en-echelon grabens the MOT and SOT. Previous studies have shown magmatism in the OT is bimodal (basaltic to rhyolitic), with at least two types of silicic melts inferred to form through pure fractional crystallisation from basalt and by fractional crystallisation along with minor crustal assimilation (Shinjo and Kato, 2000).&lt;/p&gt;&lt;p&gt;Here we present petrological descriptions, along with major, trace element and Sr&amp;#8211;Nd isotopic data for 75 silicic end member samples recovered as both lava and pumice, collected during the R/V Sonne HYDROMIN1 and 2 cruises in 1988 and 1990, respectively. Samples were dredged from various seafloor knolls and ridges located in the Io and Iheya grabens and from Izena Hole in the MOT, and from a single volcanic ridge in the Yaeyama graben and a single isolated knoll in the SOT.&lt;/p&gt;&lt;p&gt;Results show a chemically highly diverse silicic end member magmas, with at least four identifiable groups based on differences in the degree of enrichment of incompatible elements (LREE, K, Rb, Ba, etc.). Each group contains at least one dense lava sample suggesting the chemical diversity is a primary feature of magmatism in the Okinawa Trough rather than a result of the floating in of pumiceous material from various locations.&lt;/p&gt;&lt;p&gt;Using petrological descriptions and the chemistry of samples along with MELTS modelling we plan to calculate magma formation conditions and identify any evidence of magma mixing or crustal assimilation. In doing so we hope to provide a model to explain the diversity of silicic magma chemistry in the MOT and SOT.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Shinjo, R., and Kato, Y. (2000). Geochemical constraints on the origin of bimodal magmatism at the Okinawa Trough, an incipient back-arc basin. Lithos 54, 117&amp;#8211;137. doi:10.1016/S0024-4937(00)00034-7.&lt;/p&gt;

scholarly journals Stratified Communities of Active Archaea in Deep Marine Subsurface Sediments

2006 ◽  
Vol 72 (7) ◽  
pp. 4596-4603 ◽  
Author(s):  
Ketil B. Sørensen ◽  
Andreas Teske
Keyword(s):  
16S Rrna ◽  
Sediment Surface ◽  
Anaerobic Oxidation Of Methane ◽  
Rt Pcr ◽  
Ocean Drilling Program ◽  
Clone Libraries ◽  
Oxidation Of Methane ◽  
Geochemical Properties ◽  
Wide Range ◽  
Subsurface Sediments

ABSTRACT Archaeal 16S rRNA was extracted from samples of deep marine subsurface sediments from Peru Margin site 1227, Ocean Drilling Program leg 201. The amounts of archaeal 16S rRNA in each extract were quantified by serial dilution and reverse transcription (RT)-PCR. The results indicated a 1,000-fold variation in rRNA content with depth in the sediment, with the highest concentrations found near the sediment surface and in the sulfate-methane transition zone (SMTZ). The phylogenetic composition of the active archaeal population revealed by cloning and sequencing of RT-PCR products changed with depth. Several phylotypes affiliated with marine benthic group B (MBGB) dominated clone libraries from the upper part of the SMTZ and were detected only in this layer. Members of the miscellaneous crenarchaeotal group (MCG) dominated clone libraries from the other layers. These results demonstrate that archaeal communities change in activity and community composition over short distances in geochemically distinct zones of deep subseafloor sediments and that these changes are traceable in the rRNA pool. It was shown for the first time that members of both the MCG and MBGB Archaea are more active in the SMTZ than in layers above and below. This indicates that they benefit either directly or indirectly from the anaerobic oxidation of methane. They also appear to be ecophysiologically flexible, as they have been retrieved from a wide range of marine sediments of various geochemical properties.

scholarly journals IODP Expedition 336: initiation of long-term coupled microbiological, geochemical, and hydrological experimentation within the seafloor at North Pond, western flank of the Mid-Atlantic Ridge

2014 ◽  
Vol 17 ◽  
pp. 13-18 ◽  
Author(s):  
K. Edwards ◽  
W. Bach ◽  
A. Klaus ◽  
Keyword(s):  
Ocean Drilling Program ◽  
Microbial Life ◽  
Microbial Inoculation ◽  
The North ◽  
Core Recovery ◽  
Integrated Ocean Drilling Program ◽  
Western Flank ◽  
Mid Atlantic Ridge ◽  
First Time

Abstract. Integrated Ocean Drilling Program (IODP) Expedition 336 addressed questions concerning subseafloor microbial life and its relation to seawater circulation and basalt–seawater reactions in the basaltic ocean crust. Sediment and basement samples were recovered at three drill sites located in the North Pond area, an 8 × 15 km large sediment pond on the 8 Ma western flank of the Mid-Atlantic Ridge around 22°45' N and 46°05' W in roughly 4450 m water depth. The average core recovery rate in basement was approx. 31%. The subseafloor depth of the basement holes ranges from 90 to 332 m; sediment thickness is between 36 and 90 m. Two of the holes (U1382A, and U1383C) were equipped with advanced Circulation Obviation Retrofit Kit (CORK) observatories, employing – for the first time – fiberglass casing. Another CORK string was deployed in Deep Sea Drilling Project (DSDP) Hole 395A, but the wellhead broke off upon final installment. Nonetheless, the North Pond observatory is fully operational and post-cruise observatory research is already underway. Combined geochemical and microbiological studies of the drill core samples and experimental CORK materials will help understand (1) the extent and activity of microbial life in basalt and its relation to basalt alteration by circulating seawater, and (2) the mechanism of microbial inoculation of an isolated sediment pond.

scholarly journals A revised and improved age model for the middle Miocene part of IODP Site U1318 (Porcupine Basin, offshore southwestern Ireland)

2017 ◽  
Vol 155 (5) ◽  
pp. 1105-1116
Author(s):  
WILLEMIJN QUAIJTAAL ◽  
STEVEN TESSEUR ◽  
TIMME H. DONDERS ◽  
PHILIPPE CLAEYS ◽  
STEPHEN LOUWYE
Keyword(s):  
North Atlantic ◽  
Middle Miocene ◽  
Ocean Drilling Program ◽  
Carbon And Oxygen Isotopes ◽  
Ocean Drilling ◽  
The North ◽  
Integrated Ocean Drilling Program ◽  
Isotope Record ◽  
Porcupine Basin ◽  
Age Model

AbstractIntegrated Ocean Drilling Program Leg 307 Site U1318 is one of the few relatively complete middle Miocene drillcores from the North Atlantic (Porcupine Basin, offshore southwestern Ireland). Using benthic foraminiferal stable carbon and oxygen isotopes, the existing age model for Site U1318 was improved. The stable isotope record displays globally recognized isotope events, used to revise the existing magnetostratigraphy-based age model. Two intervals contained misidentified magnetochrons which were corrected. The sampled interval now has a refined age of 12.75–16.60 Ma with a temporal resolution of c. 29 ka.

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