Image analysis from TEM and AFM micrograph, Table S1, S2, S3, Figure S1, Figure S2

We report on metal enrichment along a natural pH gradient owing to increased CO2 degassing at cold, shal- low seeps of Vulcano Island in the Mediterranean Sea, off Sicily. We assessed composition of unfiltered and filtered seawater (b100 nm) along acidic zones ranging between ambient and pH 5, and showed that most seep derived elements are present as nanoclusters which then aggregate into larger colloids while mixing with ambient seawater along a pH gradient. Size and elemental composition of such naturally occurring nanoparticles assessed by modern characterisation methods were in good agreement with the results from conventional analytical methods. We provide analytical evidence for the presence in the water column of a large fraction of seep derived ele- ments (e.g. approximately 50% of iron, over 80% of Mn, 100% of Cr, S and Zn) in the form of nano sized par- ticles (e.g. b100 nm) even at typical open ocean pHs. We launch in situ sampling protocols and sample preparation procedures for multi-method suitable to obtain accurate measurements on nanoparticles from environmental samples. Based on our results a first insight to the formation of natural nanoparticles at cold CO2 seeps is presented and the persistence of such nano-clusters in the surrounding seawater is stipulated.

Carbon and Nitrogen concentrations and isotopic composition of ODP Site 170-1040 and Leg 205 sites

We determined the C and N concentrations and isotopic compositions of sediments in the prism sampled during Ocean Drilling Program Legs 170 and 205 offshore Costa Rica, with the goals of evaluating sediment sources and extents of diagenesis and identifying any effects of infiltrating fluids on the sedimentary C and N. The sediments from Leg 170 Site 1040 contain 0.85-1.96 wt% total organic carbon (TOC) with Vienna Peedee belemnite (VPDB) d13CVPDB from -26.3 per mil to -22.5 per mil, and 832-2221 ppm total nitrogen (TN) with d15Nair from +3.5 per mil to +6.6 per mil. Sediment TN concentrations and d15N values show dramatic downhole increases within the uppermost 130 m of the section and more gradual downhole decreases from 130 meters below seafloor (mbsf) to the base of the décollement at ~370 mbsf. Concentrations and isotopic compositions of TOC are relatively uniform within the entire section, showing some minor perturbation within the décollement zone. In the uppermost 100 m, upsection increases in TN concentrations at constant TOC concentrations produce significant increases in atomic TOC/TN ratios from ~8 to ~18. Carbonate (calcite) contents in the wedge sediments are generally low (<4 wt%), but the d13C and Vienna standard mean ocean water (VSMOW) d18OVSMOW values vary significantly from -26.1 per mil to +4.1 per mil and from +30.0 per mil to +35.3 per mil, respectively. Concentrations and isotopic compositions of TOC and TN for sediments from Leg 205 Sites 1254 and 1255 overlap well with C-N data for sediments from the same depth intervals obtained during Leg 170 at Site 1040.

Radiochemistry at DSDP Leg 54 and 70 Holes

Use of the hydraulic piston corer during DSDP Leg 70 in the Galapagos mounds area allowed recovery of an undisturbed sedimentary sequence down to the basement. It thus became possible to establish the chronology of different events. Several holes on and off the mounds were studied, using uranium series disequilibrium methods of age determination and oxygen isotope stratigraphy. The following sequence was thereby established: 1) From 600,000 to 300,000 years ago there was normal pelagic sedimentation, with an injection of uranium-rich solution, probably of hydrothermal origin, between 400,000 and 300,000 years ago. 2) From 300,000 to 90,000 years ago, nontronitic clay formed, replacing a pre-existing sediment. 3) From 60,000 to 20,000 years ago, manganese oxide deposits formed, probably also replacing pre-existing sediments. 4) About 19,000 years ago there occurred a uranium injection from seawater, attributed to the end of the hydrothermal circulation. In some holes, especially Hole 424, Leg 54, younger manganese oxides have been found, indicating that some mounds may be presently active.

Ultimate and failure strengths of normal muds and serpentinite muds of ODP Leg 125 samples

Serpentinite seamounts in the Mariana forearc have been explained as diapirs rising from the Benioff zone. This hypothesis predicts that the serpentinites should have low strengths as well as low densities relative to the surrounding rocks. Drilling during Leg 125 showed that the materials forming Conical Seamount in the Mariana forearc and Torishima Forearc Seamount in the Izu-Bonin forearc are water-charged serpentinite muds of density <2 g/cm**3. Wykeham-Farrance torsion-vane tests showed that they are plastic solids with a rheology that bears many similarities to the idealized Cam clay soil model and is well described by critical-state soil mechanics. The serpentinite muds have ultimate strengths of 1.3 to 273.7 kPa and yield strengths of approximately 1.0 to 50 kPa. These muds thus are orders of magnitude weaker than salt and are, in fact, comparable in density and strength to common deep-sea clay muds. Such weak and low-density materials easily become diapiric. Serpentinite muds from the summit of Conical Seamount are weaker and more ductile than those on its flanks or on Torishima Forearc Seamount. Moreover, the summit muds do not contain the pronounced pure- and simple-shear fabrics that characterize those on the seamount flanks. The seamounts are morphologically similar to shield volcanoes, and anastomosing serpentinite debris flows descending from their summits are similar in map view to pahoehoe flows. These morphologic features, together with the physical properties of the muds and their similarities to other oceanic muds and the geochemistry of the entrained waters, suggest that many forearc serpentinite seamounts are gigantic (10-20 km wide, 1.5-2.0 km high) mud volcanoes that formed by the eruption of highly liquid serpentinite muds. Torishima Forearc Seamount, which is blanketed by more ìnormalî pelagic/volcaniclastic sediment, has probably been inactive since the Miocene. Conical Seamount, which seems to consist entirely of serpentinite mud and is venting fresh water of unusual chemistry from its summit, is presently active. Muds from the flanks of Conical Seamount are stronger and more brittle than those from the summit site, and muds from Torishima Forearc Seamount are stronger yet; this suggests that the serpentinite debris flows are compacted and dewatered as they mature. The shear fabrics probably result from downslope creep and flow, but may also be inherited.

Characterization of diagenetic fluids at ODP Site 103-639

Site 639, drilled during Leg 103 of the Ocean Drilling Program, penetrated an Upper Jurassic to Lower Cretaceous carbonate platform on a tilted fault block along the Galicia margin off the northwest Iberian Peninsula. The carbonate platform is composed primarily of a sequence of dolomite overlying limestone. Samples were analyzed for mineral chemistry, stable isotope geochemistry, fluid inclusion microthermometry, and volatile contents and by dolomite pyrolysis mass spectrometry for trace sulfate minerals. The dolomite recovered from the Galicia margin at Site 639 formed during shallow burial from sulfate-bearing, hypersaline brines at slightly elevated temperatures. The light oxygen isotopic signatures of the dolomite are interpreted as the result of the evaporative loop and slightly elevated temperatures during dolomite formation or from reequilibration at higher temperatures during deeper burial. The hypersalinity is interpreted to be associated with a nearby, shallow restricted basin that formed during rifting of the Iberian margin from Newfoundland. The dolomitization of the platform is therefore a by-product of the rifting.

Deep drilling of glaciers: Russian projects in the Arctic (1975-1995)

The data collection "Deep Drilling of Glaciers: Soviet-Russian projects in Arctic, 1975-1995" was collected by the following basic considerations: - compilation of deep (>100 m) drilling projects on Arctic glaciers, using data of (a) publications; (b) archives of IGRAN; (c) personal communication of project participants; - documentation of parameters, references. Accuracy of data and techniques applied to determine different parameters are not evaluated. The accuracy of some geochemical parameters (up to 1984 and heavy metalls) is uncertain. Most reconstructions of ice core age and of annual layer thickness are discussed; - digitizing of published diagrams (in case, when original numerical data were lost) and subsequent data conversion to equal range series and adjustment to the common units. Therefore, the equal-range series were calculated from original data or converted from digitized chart values as indicated in the metadata. For the methodological purpose, the equal-range series obtained from original and reconstructed data were compared repeatedly; the systematic difference was less then 5-7%. Special attention should be given to the fact, that the data for individual ice core parameters varies, because some parameters were originally measured or registered. Parameters were converted in equal-range series using 2 m steps; - two or more parameter values were determined, then the mean-weighted (i.e. accounting the sample length) value is assigned to the entire interval; - one parameter value was determined, measured or registered independently from the parameter values in depth intervals which over- and underlie it, then the value is assigned to the entire interval; - one parameter value was determined, measured or registered for two adjoining depth intervals, then the specific value is assigned to the depth interval, which represents >75% of sample length ; if each of adjoining depth intervals represents <75% of sample length, then the correspondent parameter value is assigned to both intervals of depth. This collection of ice core data (version 2000) was made available through the EU funded QUEEN project by S.M. Arkhipov, Moscow.

Surface in situ measurements of atmospheric CO, CH4, and CO2 combined with selected meteorological measurements at the University of Wollongong, Australia

Wollongong, Australia is an urban site at the intersection of anthropogenic, biomass burning, biogenic and marine sources of atmospheric trace gases. The location offers a valuable opportunity to study drivers of atmospheric composition in the Southern Hemisphere. Here, a record of surface carbon monoxide (CO), methane (CH4) and carbon dioxide (CO2) was measured with an in situ Fourier transform infrared trace gas analyser between April 2011 and August 2014. Clean air was found to arrive at Wollongong in approximately 10% of air masses. Biomass burning influence was evident in the average annual cycle of clean air CO during austral spring. A significant negative short-term trend was found in clean air CO (-1.5 nmol/mol/a), driven by a reduction in northern Australian biomass burning. Significant short-term positive trends in clean air CH4 (5.4 nmol/mol/a) and CO2 (1.9 ?mol/mol/a) were consistent with the long-term global average trends. Polluted Wollongong air was investigated using wind-direction/wind-speed clustering, which revealed major influence from local urban and industrial sources from the south. High values of CH4, with anthropogenic DCH4/DCO2 enhancement ratio signatures, originated from the northwest, in the direction of local coal mining. A pollution climatology was developed for the region using back trajectory analysis and DO3/DCO enhancement ratios. Ozone production environments in austral spring and summer were associated with anticyclonic meteorology on the east coast of Australia, while ozone depletion environments in autumn and winter were associated with continental transport, or fast moving trajectories from southern latitudes. This implies the need to consider meteorological conditions when developing policies for controlling air quality.

Methane concentration profiles and isotopic composition of sediment cores from the Black Sea

We present high resolution profiles for the methane concentration and the carbon isotope composition of methane from surface sediments and from the sediment-water transition in the Black Sea. At shallow water sites methane migrates from the sediment into the water column, and the magnitude of this upward migrating flux depends on the depth of the sulfate-methane transition (SMT) in the sediment. The isotope data reveal that the sediments at shallow water sites are a source for methane depleted in 13C relative to the isotope composition of methane in the water column. At deep water sites the methane concentration first decreases with depth in the sediment to reach lowest values at the Unit I to Unit II transition. Below this transition the concentration increases again. Numerical modeling of methane concentration and isotope data shows that high methane oxidation rates occur in the surface sediment layer, indicating that the removal of methane in the surface sediments is not related to the anaerobic oxidation of methane coupled to sulfate reduction that occurs a few meters deep in the sediment, at the SMT. Instead, near-surface methane consumption in the euxinic Black Sea sediments appears to be related to lithological stratification. Furthermore, a map of the diffusive methane fluxes in the Black Sea surface sediments indicates that approximately half of the Black Sea seafloor acts as a sink for methane and thus limits the flux of methane to the atmosphere.

Calcium carbonate, biogenic opal, and organic carbon content and d15N ratios of sediments from the Bering Sea

Millennial-scale paleoceanographic changes in the Bering Sea during the last 71 kyrs were reconstructed using geochemical and isotope proxies (biogenic opal, CaCO3, and total organic carbon (TOC), nitrogen and carbon isotopes of sedimentary organic matters) and microfossil (radiolaria and foraminifera) data from two cores (PC23A and PC24A) which were collected from the northern continental slope area at intermediate water depths. Biogenic opal and TOC contents were generally high with high sedimentation rates during the last deglaciation. Laminated sediment depositions during the Early-Holocene (EH) and Bølling-Allerød (BA) were closely related with the increased primary productivity recorded by high biogenic opal and TOC contents and high d15N values. Enhanced surface-water productivity was attributed to increased nutrient supply from strengthened Bering Slope Current (BSC) and from increased amount of glacial melt-water, resulting in high C/N ratios and low d13C values, and high proportion of Rhizoplegma boreale during the last deglaciation. In contrast, low surface-water productivity during the last glacial period was due to depleted nutrient supply caused by strong stratification and to restricted phytoplankton bloom by extensive sea ice distribution under cold climates. Extensive formation of sea ice produces more oxygen-rich intermediate-water, leading to oxic bottom-water conditions due to active ventilation, which favored good preservation of oxic benthic foraminifera species. Remarkable CaCO3 peaks coeval with high biogenic opal and TOC contents in both cores during MIS 3 to MIS 4 are most likely correlated with Dansgaard-Oeschger (D-O) events. High d15N and d13Corg values during D-O interstadials support increased surface-water productivity resulting from nutrients supplied mainly by intensified BSC. During the EH, BA and D-O interstadials, dominant benthic foraminifera species indicate dysoxic bottom-water conditions as a result of increased surface-water productivity and weak ventilation of intermediate-water with mitigated sea ice development caused by strengthening of the Alaskan Stream. It is of note that the bottom-water conditions and formation of intermediate-water in the Bering Sea during the last glacial period are related to the variation of dissolved oxygen concentration of the bottom-water in the northeastern Pacific and to strong ventilation of intermediate-water in the northwestern Pacific. Thus, the millennial-scale paleoceanographic events in the Bering Sea during the D-O interstadials are closely associated with the intermediate-water ventilation, ultimately leading to weakening of North Pacific Intermediate Water.

Major element oxides and 40Ar/39Ar plateau and isochron ages of ODP Hole 165-1001A

40Ar-39Ar incremental heating experiments and electron microprobe analyses were performed on basaltic rocks recovered from Site 1001 during Ocean Drilling Program Leg 165. The lower Nicaraguan Rise, on which Site 1001 lies, appears to be part of a larger Caribbean oceanic plateau that makes up the core of the Caribbean plate. Our results indicate an eruption age of 81 ± 1 Ma. A single flow-rim glass is tholeiitic and almost identical to the shipboard X-ray fluorescence analyses of the whole rock. The slightly porphyritic basalts have at least two populations of plagioclase, groundmass, and glomerocrystic plagioclase laths that appear to be in equilibrium with the surrounding melt and corroded tabular phenocrysts that have a higher An content (An84-86).

Table 1. Mean geochemical values for Baseline (pre-injection) and Monitor-1 (post-injection) samples, and the percent change between the two weighted means

The Weyburn Oil Field, Saskatchewan is the site of a large (5000 tonnes/day of CO2) CO2-EOR injection project By EnCana Corporation. Pre- and post-injection samples (Baseline and Monitor-1, respectively) of produced fluids from approximately 45 vertical wells were taken and chemically analyzed to determine changes in the fluid chemistry and isotope composition between August 2000 and March 2001. After 6 months of CO2 injection, geochemical parameters including pH, [HCO3], [Ca], [Mg], and ?13CO2(g) point to areas in which injected CO2 dissolution and reservoir carbonate mineral dissolution have occurred. Pre-injection fluid compositions suggest that the reservoir brine in the injection area may be capable of storing as much as 100 million tonnes of dissolved CO2. Modeling of water-rock reactions show that clay minerals and feldspar, although volumetrically insignificant, may be capable of acting as pH buffers, allowing injected CO2 to be stored as bicarbonate in the formation water or as newly precipitated carbonate minerals, given favorable reaction kinetics.

Geochemistry of subducted volcaniclastic sediments from Mariana arc magmas

The phase relations of natural volcaniclastic sediments from the west Pacific Ocean were investigated experimentally at conditions of 3-6 GPa and 800-900 °C with 10 wt.% added H2O (in addition to ~ 10 wt.% structurally-bound H2O) to induce hydrous melting. Volcaniclastic sediments are shown to produce a sub-solidus assemblage of garnet, clinopyroxene, biotite, quartz/coesite and the accessory phases rutile ± Fe-Ti oxide ± apatite ± monazite ± zircon. Hydrous melt appears at temperatures exceeding 800-850 °C, irrespective of pressure. The melt-producing reaction consumes clinopyroxene, biotite and quartz/coesite and produces orthopyroxene. These phase relations differ from those of pelagic clays and K-bearing mid ocean ridge basalts (e.g. altered oceanic crust) that contain phengite, rather than biotite, as a sub-solidus phase. Despite their relatively high melt productivity, the wet solidus for volcaniclastic sediments is found to be higher (825-850 °C) than other marine sediments (700-750 °C) at 3 GPa. This trend is reversed at high-pressure conditions (6 GPa) where the biotite melting reaction occurs at lower temperatures (800-850 °C) than the phengite melting reaction (900-1000 °C). Trace element data was obtained from the 3 GPa run products, showing that partial melts are depleted in heavy rare earth elements (REE) and high field strength elements (HFSE), due to the presence of residual garnet and rutile, and are enriched in large ion lithophile elements (LILE), except for Sr and Ba. This is in contrast to previous experimental studies on pelagic sediments at sub-arc depths, where Sr and Ba are among the most enriched trace elements in glasses. This behavior can be partly attributed to the presence of residual apatite, which also host some light REE in our supra-solidus residues. Our new experimental results account for a wide range of trace element and U-series geochemical features of the sedimentary component of the Mariana arc magmas, including imparting a substantial Nb anomaly to melts from an anomaly-free protolith.