DOCSLIB.ORG

Geophysical Constraints on the Surface Distribution of Authigenic Carbonates Across the Hydrate Ridge Region, Cascadia Margin

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geophysical Constraints on the Surface Distribution of Authigenic Carbonates Across the Hydrate Ridge Region, Cascadia Margin Available online at www.sciencedirect.com R Marine Geology 202 (2003) 79^120 www.elsevier.com/locate/margeo Geophysical constraints on the surface distribution of authigenic carbonates across the Hydrate Ridge region, Cascadia margin Joel E. Johnson a;Ã, Chris Gold¢nger a, Erwin Suess b a Oregon State University, College of Oceanic and Atmospheric Sciences, 104 Ocean Admin. Bldg., Corvallis, OR 97331, USA b GEOMAR Research Center for Marine Geosciences, 24148 Kiel, Germany Received 28 June 2002; received in revised form 30 June 2003; accepted 18 August 2003 Abstract On active tectonic margins methane-rich pore fluids are expelled during the sediment compaction and dewatering that accompany accretionary wedge development. Once these fluids reach the shallow subsurface they become oxidized and precipitate cold seep authigenic carbonates. Faults or high-porosity stratigraphic horizons can serve as conduits for fluid flow, which can be derived from deep within the wedge and/or, if at seafloor depths greater than V300 m, from the shallow source of methane and water contained in subsurface and surface gas hydrates. The distribution of fluid expulsion sites can be mapped regionally using sidescan sonar systems, which record the locations of surface and slightly buried authigenic carbonates due to their impedence contrast with the surrounding hemipelagic sediment. Hydrate Ridge lies within the gas hydrate stability field offshore central Oregon and during the last 15 years several studies have documented gas hydrate and cold seep carbonate occurrence in the region. In 1999, we collected deep-towed SeaMARC 30 sidescan sonar imagery across the Hydrate Ridge region to determine the spatial distribution of cold seep carbonates and their relationship to subsurface structure and the underlying gas hydrate system. High backscatter on the imagery is divided into three categories, (I) circular to blotchy with apparent surface roughness, (II) circular to blotchy with no apparent surface roughness, and (III) streaky to continuous with variable surface roughness. We interpret the distribution of high backscatter, as well as the locations of mud volcanoes and pockmarks, to indicate variations in the intensity and activity of fluid flow across the Hydrate Ridge region. Seafloor observations and sampling verify the acoustic signals across the survey area and aid in this interpretation. Subsurface structural mapping and swath bathymetry suggest the fluid venting is focused at the crests of anticlinal structures like Hydrate Ridge and the uplifts along the Daisy Bank fault zone. Geochemical parameters link authigenic carbonates on Hydrate Ridge to the underlying gas hydrate system and suggest that some of the carbonates have formed in equilibrium with fluids derived directly from the destabilization of gas hydrate. This suggests carbonates are formed not only from the methane in ascending fluids from depth, but also from the shallow source of methane released during the dissociation of gas hydrate. The decreased occurrence of high-backscatter patches and the dramatic reduction in pockmark fields, imaged on the eastern part of the survey, suggest gas hydrate near its upper stability limit may be easily destabilized and thus, responsible for these seafloor features. High backscatter along the left-lateral Daisy Bank fault suggests a long history of deep-seated fluid venting, probably unrelated to destabilized gas hydrate in the subsurface. * Corresponding author. Fax: +1-541-737-2064. E-mail address: [email protected] (J.E. Johnson). 0025-3227 / 03 / $ ^ see front matter ß 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0025-3227(03)00268-8 MARGO 3397 29-10-03 80 J.E. Johnson et al. / Marine Geology 202 (2003) 79^120 ß 2003 Elsevier B.V. All rights reserved. Keywords: SeaMARC 30; sidescan sonar; gas hydrate; £uid £ow; accretionary wedge 1. Introduction ROVs, tv-camera tows, and coring and dredging devices. Pore £uid expulsion is a common process in The ¢rst documentation of authigenic carbon- accretionary wedges on active continental margins ates and chemosynthetic biological communities and is coincident with the dehydration and com- associated with pore £uid expulsion on an active paction of the sediment column during accretion- continental margin occurred at the ¢rst accretion- ary wedge development. Fluid expulsion can (1) ary ridge west of Hydrate Ridge, o¡shore central be episodic along high-porosity stratigraphic ho- Oregon (Fig. 1), in the mid-1980s (Suess et al., rizons and/or faults exposed at the sea£oor (e.g. 1985; Kulm et al., 1986; Ritger et al., 1987). Since Kulm et al., 1986; Lewis and Cochrane, 1990; then, other sites along the Paci¢c rim have also Moore and Vrolijk, 1992; Sample, 1996; Sample been discovered (e.g. Henry et al., 1989; Le Pi- and Reid, 1998), (2) occur during mud volcanism chon et al., 1992; Ohta and Laubier, 1987). The (e.g. Brown, 1990; Kopf, 2002), and/or (3) occur occurrence of authigenic carbonates on Hydrate during di¡use, intergranular £uid £ow (e.g. Ridge was documented during ODP (Ocean Drill- Moore and Vrolijk, 1992 and references therein). ing Program) Leg 146 drilling in 1992(see West- An abundant component in the £uids escaping brook et al., 1993), inferred from reprocessed from organic-rich accretionary wedges is dissolved GLORIA sidescan sonar imagery by Carson et thermogenic and biogenic methane. When sub- al. (1994), and further constrained by submersible jected to the lower temperature, lower pressure, observations and sea£oor sampling (e.g. Torres et and oxidizing bacteria-rich environment near the al., 1999; Bohrmann et al., 2000; Greinert et al., sea£oor surface, these methane-rich £uids can 2001). Gas hydrates are also well developed at precipitate cold seep carbonates of aragonite, cal- Hydrate Ridge and were ¢rst inferred on seismic cite, and/or dolomite compositions (Ritger et al., re£ection pro¢les collected as the site survey for 1987; Greinert et al., 2001). In addition, some of ODP sites 891 and 892( MacKay et al., 1992). The this methane is temporarily incorporated as free widespread distribution of the BSR (bottom sim- gas into the gas hydrate fabric near the sea£oor ulating re£ector), marking the base of gas hydrate prior to expulsion (Suess et al., 2001), if at high stability (Hyndman and Spence, 1992), or the top enough gas concentrations and appropriate pres- of a free gas zone trapped beneath the hydrate sure (water depths at least 300 m) and temper- (MacKay et al., 1994), suggests the ridge is ature (bottom water temperatures approaching capped by gas hydrate (Tre¤hu et al., 1999). The 0‡C) conditions (Kvenvolden, 1993). ¢rst recovery of gas hydrate on Hydrate Ridge Both surface and deep-towed sidescan sonar occurred during ODP Leg 146 at site 892( Hov- surveys o¡er a unique method for regional map- land et al., 1995) when the crest of the northern ping of sea£oor £uid venting sites because the summit was drilled through a hydrologically ac- acoustic impedence contrast (densityUsound tive fault (Fig. 1). Since then, several researchers velocity) between the authigenic carbonates pre- have returned to collect samples of the gas hy- cipitated at these sites and the surrounding drate and authigenic carbonates and to conduct hemipelagic sediments is detectable. Sidescan so- other geophysical surveys to characterize the be- nar surveys are valuable because they provide a havior of the hydrate system in this active tectonic regional-scale survey of sea£oor £uid venting oc- setting (e.g. Torres et al., 1999; Bohrmann et al., currences and distributions, and they also help 2000; Suess et al., 1999, 2001; Tre¤hu et al., 2002; guide later sea£oor observation and sampling this study). e¡orts conducted with manned submersibles, On Hydrate Ridge and in other accretionary MARGO 3397 29-10-03 J.E. Johnson et al. / Marine Geology 202 (2003) 79^120 81 Fig. 1. Shaded relief bathymetry of the Hydrate Ridge region. Contour interval is 100 m and bathymetric grid is 100-m pixel res- olution. Inset shows Paci¢c Northwest bathymetry and topography (Haugerud, 1999) and the location of Hydrate Ridge region on the lower continental slope of the Cascadia accretionary prism. Hydrate Ridge is a NE^SW-trending thrust ridge with north- ern and southern summits; (NHR) Northern Hydrate Ridge; (SHR) Southern Hydrate Ridge. The ridge is located V10 km from the deformation front (DF) and bordered on the west and east by slope basins (HRB-W) Hydrate Ridge Basin-West and (HRB-E) Hydrate Ridge Basin-East. ODP (Ocean Drilling Program) site 891 on the crest of the ¢rst accretionary ridge (FAR) and site 892on NHR are shown. Daisy Bank (DB) is also shown. ridges within the hydrate stability zone, a close preted on sidescan sonar records and observed on association between gas hydrates and carbonates the sea£oor. may exist because £uids dewatered from the prism Our recent research e¡orts have been focused not only supply methane to the gas hydrate stabil- on identifying the structural controls on the dis- ity zone, but also transfer heat to shallower tribution of authigenic carbonates in the Hydrate depths, which can induce the destabilization of Ridge region and their relationship to the under- the gas hydrate (Suess et al., 2001). On both the lying gas hydrate system. In this paper, we present northern and southern summits of Hydrate Ridge, the results of our 1999 SeaMARC 30 (SM30) the authigenic carbonate and pore water carbon deep-towed sidescan sonar survey coupled with and oxygen isotopes support this association by sea£oor observations and samples and subsurface suggesting the carbonates are precipitated in part geologic mapping, based on seismic re£ection from methane derived from destabilized gas hy- data, to determine the distribution of authigenic drate (Bohrmann et al., 1998; Greinert et al., carbonates and their relationship to large-scale 2001).
Load more

Recommended publications
  • A Marine Electromagnetic Survey to Detect Gas Hydrate at Hydrate Ridge, Oregon
    Geophysical Journal International Geophys. J. Int. (2011) doi: 10.1111/j.1365-246X.2011.05105.x A marine electromagnetic survey to detect gas hydrate at Hydrate Ridge, Oregon K. A. Weitemeyer,1 S. Constable1 and A. M. Trehu´ 2 1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, CA 92093-0225, USA. E-mail: [email protected] 2College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331-5503,USA Accepted 2011 June 6. Received 2011 May 27; in original form 2010 April 8 SUMMARY Gas hydrates are a potential energy resource and hazard for drilling and infrastructure, yet estimates of global volume vary by over three orders of magnitude. Hydrates are electrically resistive compared to water saturated sediment and so electromagnetic methods provide an additional tool to seismic surveys and drilling for determining hydrate saturations. A marine electromagnetic survey was carried out at Hydrate Ridge, Oregon, USA, with the aim of test- ing the use of controlled source electromagnetic (CSEM) and magnetotelluric (MT) methods to map gas hydrate and free gas below the gas hydrate stability zone. A 2-D CSEM inversion supports the scenario deduced from previous seismic and drilling results, which indicate two mechanisms of hydrate emplacement: a transport-dominated and reaction-dominated regime. GJI Geomagnetism, rock magnetism and palaeomagnetism A prominent resistive region of 2.5–4 m at a depth of about 130 mbsf, near the seismic bottom simulating reflector (BSR), suggests that 27 to 46 per cent of the bulk volume is filled with hydrate, depending on whether Archie’s Law or the Hashin-Strikman bounds are used.
    [Show full text]
  • 2. Seismic Sequence Stratigraphy and Tectonic Evolution of Southern Hydrate Ridge1
    Tréhu, A.M., Bohrmann, G., Torres, M.E., and Colwell, F.S. (Eds.) Proceedings of the Ocean Drilling Program, Scientific Results Volume 204 2. SEISMIC SEQUENCE STRATIGRAPHY AND TECTONIC EVOLUTION OF SOUTHERN HYDRATE RIDGE1 Johanna Chevallier,2,3 Anne M. Tréhu,2 Nathan L. Bangs,4 Joel E. Johnson,2,5 and H. Jack Meyer6 ABSTRACT 1Chevallier, J., Tréhu, A.M., Bangs, N.L., Johnson, J.E., and Meyer, H.J., This paper presents a seismic sequence and structural analysis of a 2006. Seismic sequence stratigraphy and tectonic evolution of southern high-resolution three-dimensional seismic reflection survey that was Hydrate Ridge. In Tréhu, A.M., acquired in June 2000 in preparation for Ocean Drilling Program (ODP) Bohrmann, G., Torres, M.E., and Leg 204. The seismic data were correlated with coring and logging re- Colwell, F.S. (Eds.), Proc. ODP, Sci. sults from nine sites drilled in 2002 during Leg 204. The stratigraphic Results, 204: College Station, TX and structural evolution of this complex accretionary ridge through (Ocean Drilling Program), 1–29. doi:10.2973/odp.proc.sr.204.121.2006 time, as inferred from seismic-stratigraphic units and depositional se- 2COAS, Oregon State University, quences imaged by the seismic data, is presented as a series of inter- Ocean Administration Building 104, preted seismic cross sections and horizon time or isopach maps across Corvallis OR 97331, USA. southern Hydrate Ridge. Our reconstruction starts at ~1.2 Ma with a Correspondence author: shift of the frontal thrust from seaward to landward vergent and thrust- [email protected] 3Present address: Wintershall AG, ing of abyssal plain sediments over the older deformed and accreted Friedrich-Ebert-Strasse 160, D-34119 units that form the core of Hydrate Ridge.
    [Show full text]
  • Mantle-Derived Helium and Multiple Methane Sources in Gas Bubbles Of
    Geochemistry, Geophysics, Geosystems RESEARCH ARTICLE Mantle-Derived Helium and Multiple Methane 10.1029/2018GC007859 Sources in Gas Bubbles of Cold Seeps Along Key Points: the Cascadia Continental Margin • Mantle-derived helium detected in cold methane seeps at the Cascadia Tamara Baumberger1,2 , Robert W. Embley1,2, Susan G. Merle1,2 , Marvin D. Lilley3 , Margin can be used as tracer for deep 4 2 fracture systems Nicole A. Raineault , and John E. Lupton • Multiple methane sources as well as 1 2 fi mixing and oxidation processes are Cooperative Institute for Marine Resources Studies, Oregon State University, Newport, OR, USA, NOAA Paci c Marine present at the Cascadia Margin cold Environmental Laboratory, Newport, OR, USA, 3School of Oceanography, University of Washington, Seattle, WA, USA, seeps 4Ocean Exploration Trust, Narragansett, RI, USA • The Cascadia Margin seeps are unequivocally dominated by methane Abstract During E/V Nautilus NA072 expedition, multibeam sonar surveys located over 800 individual bubble streams rising from the Cascadia Margin between the Strait of Juan de Fuca and Cape Mendocino at depths between 104 and 2,073 m. Gas bubbles were collected directly at the seafloor using gastight Correspondence to: sampling bottles. These bubbles were consistently composed of over 99% methane with traces of carbon T. Baumberger, [email protected] dioxide, oxygen, nitrogen, noble gases, and more rarely higher hydrocarbons. A common previous view was that a biogenic source was responsible for seeps from within the gas hydrate stability zone (upper limit near 500-m isobath) and a thermogenic source was responsible for seeps from the upper slope and the shelf.
    [Show full text]
  • Characterizing the Response of the Cascadia Margin Gas Hydrate Reservoir to Bottom Water Warming Along the Upper Continental Slope
    Characterizing the Response of the Cascadia Margin Gas Hydrate Reservoir to Bottom Water Warming Along the Upper Continental Slope Final Scientific/Technical Report October 1, 2013 – March 31, 2017 Principle Authors: Evan A. Solomon H. Paul Johnson Marie S. Salmi Theresa L. Whorley Report Issued: November 2017 DOE Award No.: DE-FE0013998 Submitted by: Evan A. Solomon University of Washington School of Oceanography Box 355351 Seattle, WA 98195-5351 e-mail: [email protected] Phone number: (206) 221-6745 Prepared for: United States Department of Energy National Energy Technology Laboratory Disclaimer “This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.” 2 TABLE OF CONTENTS Executive Summary 4 Publications Related to This Project 7 Introduction
    [Show full text]
  • Chronic Shallow Seawater Circulation Driven by Subsurface Gas Dynamics, at the Southern Hydrate Ridge Seep System, Cascadia Lauren Kowalski1
    Chronic shallow seawater circulation driven by subsurface gas dynamics, at the Southern Hydrate Ridge seep system, Cascadia Lauren Kowalski1 Advisor: Evan Solomon1 1University of Washington, School of Oceanography, Box 357940, Seattle, Washington, 98195- 7940 (401) 578-6794 [email protected] May 31, 2016 1. ABSTRACT Cold seeps, like Southern Hydrate Ridge (SHR) on the Cascadia margin, are ubiquitous features along continental margins where fluids discharge from the seafloor into the water column. Previous short-term fluid flow studies at SHR and other seep systems have observed upward flow of altered fluids concentrated in regions of bacterial mats and downward flow of seawater-like fluids in regions of vesicomyid clams. To investigate longer-term variability in magnitude and direction of fluid flow at SHR, three continuous-measurement flowmeter/chemical samplers (Mosquitos) were deployed in bacterial mats to measure fluid flow rates and solute fluxes. This two-year continuous record of fluid flow shows that the flow rate at SHR is temporally and spatially variable, however there is an annual trend of ~24-67 cm/yr of downward fluid flow in regions of bacterial mats. This net downward transport of seawater circulation is more constant than previously recognized and the results indicate that shallow seawater circulation is the key in reconciling the discrepancy between bottom up and top down measurements of fluid flow at seep sites. Mechanisms driving this shallow seawater circulation are explored in addition to the connection between fluid flow and the ecology of associated benthic communities. 2. INTRODUCTION Continental margin cold seeps are important regions for the exchange of fluids, solutes, gases, and isotope ratios between the lithosphere and the hydrosphere.
    [Show full text]
  • Sedimentology and Geochemistry of Gas Hydrate-Rich Sediments from the Oregon Margin (Ocean Drilling Program Leg 204)
    Sedimentology and Geochemistry of Gas Hydrate-rich Sediments from the Oregon Margin (Ocean Drilling Program Leg 204) Sedimentologia i Geoquímica de Sediments rics en Hidrats de Gas del Marge d’Oregon (Ocean Drilling Program Leg 204) Elena Piñero Melgar Doctoral Thesis Barcelona, May 2009 Cover: Photograph of a sample of massive gas hydrate recovered from 2.69 meters below seafloor near the summit of Hydrate Ridge during Leg 204 (Sample 204- 1250D-1H-CC, 12–14 cm). The photograph is by ODP Photographer John Beck. Portada: Fotografia d’una mostra d’hidrat de gas massiu recuperada a 2.69 metres sota el fons marí a prop del cim de southern Hydrate Ridge durant el Leg 204 (Mostra 204-1250D-1H-CC, 12–14 cm). La fotografia es del fotògraf d’ODP John Beck. Memòria de Tesi Doctoral presentada per Elena Piñero Melgar per a optar al títol de Doctora per la Universitat de Barcelona Tesi realitzada en la Unitat de Tecnologia Marina (UTM), Centre Mediterrani d’Investigacions Marines i Ambientals (CMIMA) del Consell Superior d’Investigacions Científiques (CSIC), Barcelona La doctoranda: Elena Piñero Melgar Les directores de la tesi: Dra. Eulàlia Gràcia i Mont Dra. Francisca Martínez-Ruiz Unitat de Tecnologia Marina (CSIC) Insituto Andaluz de Ciencias de la Tierra (CSIC / UGR) El tutor de la tesi: Dr. Mariano Marzo Carpio Departament d’Estratigrafia, Paleontologia i Geociències Marines Universitat de Barcelona Departament d’Estratigrafia, Paleontologia i Geociències Marines Universitat de Barcelona Programa de Doctorat en Ciències de la Terra Bienni 2003-2005 Sedimentology and Geochemistry of Gas Hydrate-rich sediments from the Oregon Margin (Ocean Drilling Program Leg 204) Sedimentologia i Geoquímica de Sediments rics en Hidrats de Gas del Marge d’Oregon (Ocean Drilling Program Leg 204) Elena Piñero Melgar Maig de 2009 Agraïments Aquesta tesi va començar com un cartell penjat a una paret.
    [Show full text]
  • Deformation, Fluid Venting, and Slope Failure at an Active Margin Gas Hydrate Province, Hydrate Ridge Cascadia Accretionary Wedge
    AN ABSTRACT OF THE DISSERTATION OF Joel E. Johnson for the degree of Doctor of Philosophy in Oceanography presented on July 19, 2004. Title: Deformation, Fluid Venting, and Slope Failure at an Active Margin Gas Hydrate Province, Hydrate Ridge Cascadia Accretionary Wedge Abstract Approved: Signatureredacted for privacy. Chris Goldfinger During the last 15 years, numerous geophysical surveys and geological sampling and coring expeditions have helped to characterize the tectonic setting, subsurface stratigraphy, and gas hydrate occurrence and abundance within the region of the accretionary wedge surrounding Hydrate Ridge. Because of these investigations, Hydrate Ridge has developed as an international site of active margin gas hydrate research. The manuscripts presented in this dissertation are focused on the geologic setting hosting the gas hydrate system on Hydrate Ridge. These papers examine how active margin tectonic processes influence both the spatial and temporal behavior of the gas hydrate system at Hydrate Ridge and likely across the margin. From a high resolution sidescan sonar survey (Chapter II) collected across the region, the distribution of high backscatter, as well as the locations of mud volcanoes and pockmarks indicates variations in the intensity and activity of fluid flow across the Hydrate Ridge region. Coupled with subsurface structural mapping, the origins for many of these features as well the locations of abundant gas hydrates can be linked to folds within the subsurface. Continued structural mapping, coupled with age constraints of the subsurface stratigraphy from ODP drilling, resulted in a model for the construction of the accretionary wedge within the Hydrate Ridge region (Chapter III). This model suggests the wedge advanced in three phases of growth since the late Pliocene and was significantly influenced by the deposition of the Astoria fan on the abyssal plain and left lateral strike slip faulting.
    [Show full text]
  • Sedimentology and Geochemistry of Gas Hydrate-Rich Sediments from the Oregon Margin (Ocean Drilling Program Leg 204)
    Sedimentology and Geochemistry of Gas Hydrate-rich Sediments from the Oregon Margin (Ocean Drilling Program Leg 204) Sedimentologia i Geoquímica de Sediments rics en Hidrats de Gas del Marge d’Oregon (Ocean Drilling Program Leg 204) Elena Piñero Melgar Doctoral Thesis Barcelona, May 2009 Cover: Photograph of a sample of massive gas hydrate recovered from 2.69 meters below seafloor near the summit of Hydrate Ridge during Leg 204 (Sample 204- 1250D-1H-CC, 12–14 cm). The photograph is by ODP Photographer John Beck. Portada: Fotografia d’una mostra d’hidrat de gas massiu recuperada a 2.69 metres sota el fons marí a prop del cim de southern Hydrate Ridge durant el Leg 204 (Mostra 204-1250D-1H-CC, 12–14 cm). La fotografia es del fotògraf d’ODP John Beck. Memòria de Tesi Doctoral presentada per Elena Piñero Melgar per a optar al títol de Doctora per la Universitat de Barcelona Tesi realitzada en la Unitat de Tecnologia Marina (UTM), Centre Mediterrani d’Investigacions Marines i Ambientals (CMIMA) del Consell Superior d’Investigacions Científiques (CSIC), Barcelona La doctoranda: Elena Piñero Melgar Les directores de la tesi: Dra. Eulàlia Gràcia i Mont Dra. Francisca Martínez-Ruiz Unitat de Tecnologia Marina (CSIC) Insituto Andaluz de Ciencias de la Tierra (CSIC / UGR) El tutor de la tesi: Dr. Mariano Marzo Carpio Departament d’Estratigrafia, Paleontologia i Geociències Marines Universitat de Barcelona Departament d’Estratigrafia, Paleontologia i Geociències Marines Universitat de Barcelona Programa de Doctorat en Ciències de la Terra Bienni 2003-2005 Sedimentology and Geochemistry of Gas Hydrate-rich sediments from the Oregon Margin (Ocean Drilling Program Leg 204) Sedimentologia i Geoquímica de Sediments rics en Hidrats de Gas del Marge d’Oregon (Ocean Drilling Program Leg 204) Elena Piñero Melgar Maig de 2009 Agraïments Aquesta tesi va començar com un cartell penjat a una paret.
    [Show full text]