- View All
For Reporting Year
The research in this portion of the second Deep Energy project addressed (i.) the role of water-rock reactions, with a specific focus on serpentinization, in the production of reduced gases including hydrogen and methane; (ii.) The rates of reaction in low and high temperature systems; in mafic and ultramafic terrains; and in rocks of varying degrees of age and alteration (young marine versus Phanerozoic and Precambrian continental systems); (iii.) The development of models of reduced gas flux on a global scale. Field programs will nurture experimental programs and, by identifying unique sample suites ranging from abiotic to biotic end-members and mixtures, will feed into the developments in isotopologue research. This effort also has natural strong ties to the Deep Life’s studies of Rock Hosted Microbial Communities project. Furthermore there will be a shared interest in characterizing diversity of deep microbial communities in Precambrian cratons using deep DNA sequencing technology in connection with the DCO Census of Deep Life.
Deep Energy funded landmark Nature papers (Holland, Sherwood Lollar1 and Ballentine 2013; Sherwood Lollar, Onstott and Ballentine, 2014) redefined the deep continental crust carbon-fluid landscape; demonstrating the existence of deep carbon-fluid regimes preserved up to planetary (Ga) timescales and identifying the Precambrian continental crust as a source of hydrogen that doubles the global budget from serpentinization and radiolysis. The most recent work during 2013-2015 provided a first examination of global H2 production via water-rock reaction (serpentinization and radiolysis) from the > 70% of the continental lithosphere that is Precambrian in age. Key to the discovery is the map of global occurrences of H2 (see below) and CH4-rich deep saline groundwaters.
This first work on the role of Precambrian continental lithosphere as an energy source for both abiogenic and biogenic methane production doubled estimated global H2 production from serpentinization and radiolysis compared to previous estimates, identified this extra production to be in the under-explored continental crust, and provided a new foundation model for the Earth’s Carbon Budget. Global models such as this are key inputs for the Decadal Goals of the DCO for the Next Five Years. A major objective of the previous Deep Energy projects were to develop new techniques for defining the temporal and physical framework of deep carbon bearing fluid systems and derive a foundational estimate of the hydrogen production feedstock that drives both the Abiogenic Carbon cycle (via hydrogen driven reactions such as Fischer-Tropsch synthesis), and the Biological Deep Carbon cycle (as hydrogen sustains microbial communities that produce methane and higher hydrocarbons and in turn may be sustained by methanotrophy). Activities included both field work at mine sites across the Canadian Shield (in concert with Industrial Partners in the Mining Industry) and substantial efforts from the Stable Isotope Laboratory at Toronto to support the clumped methane isotopologue work at MIT and UCLA through provisions of isotopically characterized standard materials, key field samples and cross-calibration and ground-truthing of analytical developments reflected in two papers with the Ono Lab at MIT. Samples sent to UCLA are currently under analysis.
Continuing this work, within the reporting period the Lollar-Ballentine team have extended our investigations to investigate the age and character of free fracture fluids through their noble gas content from more and deeper locations within the Kidd creek system (This first involved Dr Jon Fellowes who was succeeded by Dr Oliver Warr when Ballentine moved to Oxford). These include investigation of samples from the same flow analyzed by Holland at 7850 ft depth, and new samples from 9500 ft in the system which have become available with new mining operations. Additionally, samples have been collected from two mines in Sudbury: Nickel Rim (5675 feet) and Fraser Mine (4700 feet), also over an 11 month period. Results from these samples show fluids in the deep sections of the Kidd Creek mine to have indicators of yet greater age. Results from the Sudbury complex show some similar characteristics, showing the ubiquity of ancient deep fluids systems in the crust, but with important differences that reflect different age (younger) and geological setting (no 129Xe anomaly) compared to the Kidd Creek system. These samples, based on the preliminary results from the reporting period, are the focus of the next stage of recently funded investigation.
It should be noted that due to the age of the systems, these samples have all accumulated radiogenic noble gas excess beyond that of any other terrestrial fluid. However, the absolute abundances of the non-radiogenic noble gases are very low. Ensuring all isotopes of each noble gas over this dynamic range were able to be determined has been analytically demanding on an unprecedented scale. Further complications were caused by the mid-project relocation to Oxford. This has required moving the GVI Helix mass spectrometer (the instrument used by Holland to obtain his results) from Manchester, as well as configuring two brand new mass spectrometers, the Helix SFT and Argus, for accurate noble gas determination. Oliver Warr, the DCO funded postdoc has now installed, calibrated and implemented in the reporting period a system that will serve as the basis for all future analyses of deep crustal carbon systems.
Dr Jon Fellows in this reporting period also chaired and organized the first DCO early career scientist conference in Costa Rica https://deepcarbon.net/feature/meeting-report-early-career-scientist-workshop#.VZpQ4E1FCUk
Terrestrial systems-geochemical data mining
Noble gases are unique tracers of terrestrial volatiles used to study sources of natural gases, waters and oils, as well as processes governed formation, evolution and behavior of natural water reservoirs and hydrocarbon (HC) deposits. During more than 50 years, since the first fundamental contribution by R.E. Zartman, G.J. Wasserburg and J.H.Reynold (1961), abundances of noble gas isotopes were measured in thousands of terrestrial fluids and discussed in 100th scientific contributions, thus improving our knowledge about origin and evolution of volatile components of our planet.
Two major objectives were envisaged within the frame of the noble gas sub-project: (i) to compile an experimental data, first of all results of measurements of He isotope composition in terrestrial fluids; (ii) to review scientific contributions discussing noble gas isotopes as tracers of terrestrial HC materials and related ground waters. In the course of DCO project 4560 new samples have been compiled and added into the pre-existing noble gas data base (NG DB), which at present amounts to 7262 samples. This is far the largest NG data source now available to the world scientific community. The NG DB includes data from published papers, dissertations, technical reports, electronic sources and those reported via private communications. In most cases the NG DG presents coordinates of the samples, which allows visualization of the data (i.e., their presentation as maps)) and thus their comparison with other geochemical and / or geophysical characteristics of given region or a large territory, such as a continent.
During 2014 careful review, checking out and improvement of the NG DB took place as well redaction of used geochemical and geological terminology; all concentrations were represented as dimensionless values, comments to the NG DB were prepared and in March 2015 the NG DB was ready to be opened for geochemical community (see <http://deepcarbon.net/dco_datasets>).
The second aim of the project envisaged Review of available scientific literature, related to using noble gases as traces of HC materials. At present the manuscript is completed: this is a large paper including Text (37000 words), 1 Table, 31 Figures, Glossary and 150 references. The Review presents not merely the known published issues, but also new ideas and interpretations. It also includes Russian contributions, poorly known to international geochemical community. The Review should be submitted later in this summer (2015). For example, it is shown, that the “average” (statistically representative) HC fields, situated at different tectonic settings (i.e., ancient plates with 300 to 800 Myr old basement; young plated with less than 300 Myr old basement; and presently mobile belts, island arcs and other tectonically active regions) contain much more radiogenic noble gas species compared with those produced in situ by radioactive decay within HC bearing rocks during their sedimentation ages. Hence, HC fields may be considered as samplers of noble gases from rather large volumes of ground waters (degassed in the course of HC field production), and quantitative estimates of the volume ratio of HC source rocks over HC field rocks are possible. These ratios are generally vary from 10th to 100th. Moreover, NG abundances in HC fields also allow the time interval between ground water recharge and degassing to be constrained. These time intervals are very long and quite similar to the sedimentation ages of HC field rocks at different tectonic settings, thus highlighting the ancient apparent ages of ground waters participating in HC field formation. Correspondingly, these relationships indicate young ages of the HC materials compared with ages of the sediments in which HCs had been transferred and which contain them at present.
Songliao Basin Drilling
Gas from the deep earth, including biotic and abiotic hydrocarbons and other inorganic gases, is of much significance both in the exploration of deep energy and our understanding of the deep world. On the basis of traditional viewpoint, the exorbitantly temperature in the deep earth may resulting in the over-maturity of organic matter which then lose the ability to generate oil and gas. However recent researches have proved that this concept is actually outdated. Researchers have attested that organic matters can remain stable even under the high temperature conditions in the deep, and a lot of deep reservoirs have been found worldwide. Confirmed by the experimental results, it has been shown that pressure can effectively inhibit the maturation of organic matters in source rock. In addition to the degradation of organic matters, hydrocarbons can also be generated by inorganic matters such as carbon dioxide through Fischer - Tropsch reaction.
Songliao Basin, as China’s largest oil-producing region, has a long history of petroleum exploitation. It has a clear two-layer structure and was formed by rifting and down-warping. According to the seismic data, a thin layer of low-velocity zone exists at the bottom of the basin, showing extremely high geothermal flux, and can be inferred as a fluid-phase magma chamber. An effort led by Prof. Chengshan Wang is focused on the deep drilling activity in the basin.
Analysis of the chemical constituents and isotopes of the gas sample collected from the SK-Ⅱdrilling process has been done to show the origin of the gas. Through the analysis, it’s obvious that the carbon isotope ratios of gas within some regions of Songliao Basin significantly distribute in reverse order, while the hydrogen isotope ratios show positive sequence distribution. The combination of carbon, hydrogen and helium isotope is a powerful evidence to prove that these gases are certainly abiogenic rather than organic origin. And at the same time, it reveals the fact that mantle fluid has affected the element composition of hydrocarbon in the source rock of Songliao Basin. The role of the magma chamber at the bottom of the basin has also been figured out by studying the carbon dioxide found in the nature gas well which has the character of magma origin.
The SK-Ⅱ drilling project conducted in the Songliao Basin has successfully revealed the existence of large-scale, economic abiogenic gas resources, and will undoubtedly benefit the society and economy. SK-Ⅱand its correlative project will become a model example to the exploration of abiogenic gas reservoirs all over the world.
Continental Serpentinization Systems
This effort led by Giuseppe Etiope of INGV involved an assessment of abiotic methane production temperature in continental serpentinization systems based on CH4 isotopologue geothermometry and geologic data.
In July-August 2013 the specifications of gas sampling and storage for isotopologue analyses were defined in agreement with Caltech and MIT laboratories. Technical meetings were organized between Caltech lab (Eiler) and GasConsult Int. (Schoell). In the period September-November 2013, three sets of gas and water samples were collected from seeps and springs in continental serpentinization sites in:
- Greece (Othrys ophiolite), field work by INGV (Etiope).
- Portugal (Cabeco de Vide intrusive complex), field work by INGV (Etiope).
- Turkey (Chimaera seep in Tekirova ophiolite), field work by Istanbul University (Hosgormez).
Samples were sent to the project partners of Caltech (J. Eiler lab; Greek, Portuguese and Turkish samples) and MIT (S. Ono lab; Turkish samples) for stable C and H isotopic and CH4 isotopologue analyses.
The second year was focused on a new sampling of gas in Italy (Genova hyperalkaline spings) and to the follow-up of the analyses performed by Caltech and MIT and interpretation of the results. The new samples from Italy were sent to Caltech in June 2014. Unfortunately no isotopologue data, regarding the samples from Greece, Portugal and Italy have been received from Caltech so far, despite repeated requests. Only a generic information about the estimated temperature of formation of methane of the Chimaera seep was received. E-mail correspondence with Caltech was then focused on the isotopologue data of Chimaera gas. Their results suggest a quite high temperature of formation of CH4 (>200 °C) which is in contrast with the geologic setting of Chimaera and with the results obtained by MIT, i.e. around 130°C. Caltech and MIT analysed exactly the same gas, collected from the same seep, the same day. There was no follow up on the possible explanations of this difference in the results, and on how Caltech wants to address this fact.
During a meeting at the AGU conference in San Francisco (December 2014) INGV and MIT decided to perform additional analyses and elaborate the existing data considering that Chimaera gas is not totally abiotic (up to 20% of gas may be thermogenic as suggested in Etiope et al 2011; EPSL). Accordingly, in February 2015 a new set of gas samples from Chimaera was collected and planned to be sent to MIT. Unfortunately MIT informed that the laboratory was not operative due to technical problems caused by the low winter temperatures in Boston. Dr. Ono communicated that the analyses could not be done until autumn 2015. It was decided, then, to contact Ed Young at UCLA; he accepted to analyze the Chimaera gas with his new Panorama system. The samples are now in his laboratory, waiting for analyses.
The second year was also aimed at the sampling of high temperature gas for isotopologue analyses. Gas was collected at geothermal-volcanic systems of Nisyros (Greece), Pantelleria and Vulcano (Italy) by Jens Fiebig (Frankfurt University) and the samples have been sent to Caltech laboratory (John Eiler). Three fumarolic gas samples from Nisyros and Pantelleria were sent to John Eiler's lab for clumped isotope analysis on methane. For this purpose, Nisyros was sampled in June 2013 by Jens Fiebig. At the end of May 2015 John Eiler stated that these samples could not have been measured so far. He expects them to be analyzed by the end of this summer the latest. In addition, the INGV team elected to invest part of their DCO funds to set up a technique for hydrogen isotope analysis of nmol quantities of methane. The technique works fine now and has been applied to determine the hydrogen isotopic composition of methane discharging from the Plegrean Fields, Vesuvio and Ischia.
Finally, the rest of the DCO funds will be used to support hydrocarbon work on Icelandic fumaroles. It is the ultimate aim of this field campaign to determine the C- and H isotopic composition of the n-alkanes as well as the clumped isotopic composition of methane contained in these fumaroles. Icelandic volcanic gaseous emissions exhibit a large range of 3He/4He ratios, indicating that He derives both from the upper and lower mantle. Analyzing the C- and H-isotopic composition of the n-alkanes as well as the clumped isotopic composition of the methane might help to unravel whether the mantle contributes to overall methane generation underneath Iceland. This work will be part of a close collaboration between Jens Fiebig, Andri Stefansson (University of Reykjavik), Shuhei Ono (MIT) and David Hilton (Scripps). For logistic reasons the sampling cannot be performed by the end of the project; it will be held in August-September 2015.
Oceanic Lithosphere Systems
The group of Gretchen Früh-Green at the ETH Zurich focused their research on sources and sinks of carbon and processes of fluid-rock interaction in modern and ancient rocks of the oceanic lithosphere. This includes comparative field studies of geochemical and microbial processes during serpentinization and the precipitation of carbonate (±brucite) in two high alkaline, ultramafic environments: the active marine Lost City hydrothermal system (MAR, 30°N), and high alkaline, Ca-OH springs associated with present-day serpentinization and carbonate deposits in the Voltri Massif (Liguria, N. Italy). An additional goal was to combine radiocarbon with stable isotope studies to determine whether the source of carbon for high concentrations of organic acids (formate, acetate) in the Lost City fluids is mantle-derived or seawater bicarbonate. This involved considerable method development. Lipid biomarkers that are diagnostic of methanogens and sulfate reducers were isolated and their 14C content determined. Stable isotope and radiocarbon analyses of both formate and the limited biomarkers yielded F14C signatures that reflect a mixed carbon source dominated by mantle carbon and suggest that the dominant micro-organisms living in the Lost City chimneys consumes an abiotically formed organic molecule. Analyses of methane from alkaline springs in the Voltri Massif, Liguria yielded signatures that were radiocarbon free and which substantiates a mantle carbon origin of methane in present-day serpentinization systems.
In addition, investigations using Scanning Electron Microscopy (SEM) highlight the close association between microbial biofilms, calcium carbonate, and brucite. In some instances, brucite forms long ropes that may be attributed to microbially-influenced precipitation. In other instances, aragonite appears to precipitate first and then is covered by brucite. Dense biofilms are intimately linked with the growing minerals. These studies have involved collaborations with Susan Lang (ETH), Marvin Lilley (Univ. Washington), Matt Schrenk (DCO-Deep Life, E. Carolina Univ.), William Brazelton (now at Univ. Utah), Stefano Bernasconi (ETH) and Tomaso Bontognali (ETH), many of which are new to DCO. Results have been presented at Goldschmidt 2013, Fall AGU 2013, Fall 2014 and Goldschmidt 2014.
G. Früh-Green has also been strongly involved in the planning and technical developments to core and seal 10 sites across the Atlantis Massif during IODP Expedition 357, which will take place Oct.–Dec. 2015 (co-chief scientists Gretchen Früh-Green, ETH Zürich; Beth Orcutt, Bigelow Laboratory for Ocean Sciences; http://www.eso.ecord.org/expeditions/357/357.php). A major scientific goal for the expedition is to better understand the role of serpentinization of mantle rocks in driving hydrothermal systems, in sustaining microbial communities, and in the sequestration of carbon in ultramafic rocks.
Experimental work at ETH has also been carried out in collaboration with Marvin Lilley (academic guest at ETH from Aug-Dec, 2013; May-June, 2014). Construction and testing of a custom-designed cryrogenic inlet system to concentrate gaseous phases and measure compound-specific isotopes by continuous-flow mass spectrometry has been completed. Measurements can now be made on fluids with a minimum concentration of 150nl CH4. ETH researchers are in the process of using this inlet system to measure C-O-H fluids from experimental capsules.
A new project (with leveraging from DCO) has been submitted to the Swiss National Science Foundations (SNSF) (planned start date: 1 Nov 2015) to combine microstructural studies of fluid and reaction pathways with in-situ probing to constrain microfracturing networks and heterogeneities of fluid-peridotite interactions drill cores from the Atlantis Massif (IODP Exp. 357) and from active serpentinization sites in Oman (ICDP drilling project with DCO funding). These data will be used to quantify mineralogical and chemical changes that control H2 production and the speciation, release or consumption of carbon during progressive serpentinization. Raman microspectroscopy, standard stable isotope analyses of bulk samples and in-situ ion microprobe analyses (SIMS and NanoSIMS) will be used to investigate the nature, composition and distribution of reduced carbon phases in rocks from the upper oceanic mantle, and to distinguish abiotic from biotic carbon in serpentinites. This project will also involve new collaborations within the DCO with Bénédicte Ménez (IPGP).
The IPGP team members led by Benedicte Menez focused on characterizing reactions and carbon transfers at the macro- and micro-environment scales in natural samples from the oceanic lithosphere.
They determined the identity of the absorbed or condensed organic matter (OM) accumulated in abyssal serpentinites and associated venting systems, and the amount of OM stored in the oceanic crust and its composition. The approach was based on micropetrographic investigation of OM in equilibrium with low-T phases. They used Raman microimaging, SEM and TEM whose results will be ultimately combined with synchrotron experiment to explore metal-OM coupling and distribution at micro to nano scale (D. Brunelli, M. Sforna). A strong collaboration was formally established with F. Jamme and M. Réfrégiers (synchrotron SOLEIL, France) with notably a co-funded 2-years postdoc that led to the development a multimodal approach involving single-or two-photon spectroscopy, deep UV microscopy and tofSIMS suited for oceanic serpentinites to shed light on the C and N speciation (C. Pisapia, B. Ménez) The organic carbon trapped in mantle-derived rocks likely represents a fraction not yet taken into count in the deep carbon cycle (papers in progress). Work focused on samples from present-day ridges (<1 Ma) and old mantle batches obducted in ophiolitic terrains (130-150 Ma) to reveal the presence and persistence of condensed organic matter in such systems. For the ridge sites sample suites were investigated from the Southwest Indian Ridge (Smoothseafloor region), the Mid Atlantic Ridge (4-6°N and Atlantis Massif) (papers in progress).
IPGP team members also performed studies of the carbonation reactions of serpentinites sampled along active detachment systems located at the South Western Indian Ridge (SWIR, 64°35'E ) investigated during the SMOOTHSEAFLOOR cruise (PI: D. Sauter and M. Cannat). In this framework M. Cannat and I. Martinez supervised a Master degree student from IPGP (V. Payré) to carefully study the carbonate-serpentine contacts in brecciated samples. Contacts between carbonate and serpentine are being studied on FIB thin sections. Moreover, to better constrain T and fluid composition, the first isotopologue measurements of ∆47 will be performed during the summer of 2015.
Geological observations at slow-spreading ridges are critical to understand water-rock interactions through the observation of both the alteration in sampled rocks, and the distribution and nature of hydrothermal activity. Oceanic detachment faults are of particular interest in that a) tectonic processes that expose deep seated rocks from the lower crust and upper mantle at the seafloor, b) hydrothermal activity appears to be pervasive at these sites, often in ultramafic host-rocks, and c) the exhumed materials systematically record a long history of fluid-rock interactions ranging from low to high temperatures. J. Escartin’s initial work focused on the Rainbow hydrothermal site (see Andreani et al., 2014) to obtain an overview of the geology of the area and understand its tectonic setting. This geological and tectonic synthesis set the ground for the 2015 Rainbow Workshop (June 2015), led by M. Andreani from the Lyon University, to coordinate efforts for a drilling proposal at this site, and drafting proposals for additional cruises (France, USA) to study further this site. During Year 1 J. Escartin (IPGP) also led a major oceanographic cruise (ODEMAR 2013) on the 13°20’N and 13°30’N detachments along the Mid-Atlantic Ridge during which they conducted extensive geological observations and sampling of the detachment fault surface using ROVs, complemented with high-resolution geophysical surveys with AUVs. The scientific exploitation of cruise data and samples is in progress, and a sizeable part of these are part of an on-going PhD Thesis by D. Bonnemains. who carried out systematic petrographic studies on thin sections, microstructural analyses with electron microscopy, and major and trace element analyses in addition to isotope geochemistry, largely funded by DCO. These results are being interpreted, integrated, and analyzed by D. Bonnemains, whose thesis is expected to be completed by Sep. 2016.
IPGP also published the results obtained on the hydrothermal field of Prony (New Caledonia; HYDROPRONY cruise PI: B. Pelletier IRD Nouméa) through 4 publications (Quéméneur et al. 2014; Monnin et al., 2014; Pisapia et al., 2015; Postec et al., 2015). These first four papers respectively describe the hydrothermal fluid chemistry, the microbial ecology and the geobiology along with the mineralogy. This system corresponds to an exciting example of hyperalkaline and H2/CH4-rich hydrothermal field sustained by serpentinization reactions. It is the closest known analog of the Lost City Hydrothermal Field close to the Mid-Atlantic Ridge, and observations at the micrometric scale has allowed C. Pisapia, B. Ménez and E. Gérard to propose a new model of Subsurface Lithotrophic Microbial Ecosystems that exist and persist independently from photosynthesis reaction (Pisapia et al., 2015). These efforts were the results of collaboration with an interdisciplinary research team affiliated with the Institute of Research for Development (IRD, Nouméa, New Caledonia), the Mediterranean Institute of Oceanography (MIO, Marseille, France), the CNRS-GET lab from Toulouse University (France), the Institut de Physique du Globe de Paris (IPGP) and the Institut de Minéralogie et de Physique des Milieux Condensés (IMPMC, Paris, France).
New measurements defined the fate of carbon and nutrients during shallow melting of the upper mantle along spreading ridges in relation to mantle source heterogeneities. Notably D. Brunelli conducted major and trace element analyses of relic primary minerals of a large collection of mantle peridotites. Sample collection is from eastern SWIR (SMOOTHSEAFLOOR), central SWIR (Andrew Bain) and western SWIR (Bouvet Triple Junction). Modelling for the melting, and melt extraction processes was carried out (paper in progress).
Ocean Hydrothermal Vents
Max Coleman from Caltech/NASA used DCO funds to participate in the Cayman hydrothermal vent cruise of 2013. From this effort he was able to track the food chain at two neighboring hydrothermal vent sites 20 km apart but at depths of 2300 m and nearly 5000 m. He was able to show that some essential fatty acid lipids, previously thought only to be produced by organisms in the photic zone were synthesized at depth by the chemosynthetic-based ecosystem in the vicinity of the event site. He further observed unexpected dietary habits of part of the extensive shrimp population, previously thought to be solely living off chemosynthetic bacteria but in fact are carnivorous, or even cannibalistic. The key finding for the carbon cycle is that oxidation of sulfide from the vent by chemo-synthetic bacteria produces a sink for dissolved CO2 and is converted into carbohydrate. This serves as the basis of the extensive ecosystem and provides biomass, some of which is buried within the sediment. The amount of trace carbon in the basalts was greater than expected, and comprised both acid soluble and acid insoluble fractions, the former believed to be carbonate resulting from interaction with ocean water. Further work on the speciation of the particular carbon forms is still needed.
1B. Sherwood Lollar also receives DCO funding from the Field Studies project led by Peter Kelemen