DOCSLIB.ORG

Biomediation of Submarine Sediment Gravity Flow Dynamics Melissa J

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Biomediation of Submarine Sediment Gravity Flow Dynamics Melissa J https://doi.org/10.1130/G46837.1 Manuscript received 3 August 2019 Revised manuscript received 3 October 2019 Manuscript accepted 4 October 2019 © 2019 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 19 November 2019 Biomediation of submarine sediment gravity flow dynamics Melissa J. Craig1, Jaco H. Baas2, Kathryn J. Amos1, Lorna J. Strachan3, Andrew J. Manning4, David M. Paterson5, Julie A. Hope6, Scott D. Nodder7 and Megan L. Baker2 1 Australian School of Petroleum, The University of Adelaide, Adelaide, South Australia 5000, Australia 2 School of Ocean Sciences, Bangor University, Menai Bridge LL59 5AB, UK 3 School of Environment, University of Auckland, Auckland 1142, New Zealand 4 HR Wallingford, Howbery Park, Wallingford OX10 8BA, UK 5 Scottish Oceans Institute, School of Biology, University of St. Andrews, St. Andrews KY16 8LB, UK 6 Institute of Marine Science, University of Auckland, Auckland 1142, New Zealand 7 National Institute of Water & Atmospheric Research, Wellington 6021, New Zealand ABSTRACT (Tolhurst et al., 2002). Small concentrations of Sediment gravity flows are the primary process by which sediment and organic carbon are EPS (CEPS < 0.063% by weight, wt%), represent- transported from the continental margin to the deep ocean. Up to 40% of the total marine ing baseline levels in estuarine sediment, can in- organic carbon pool is represented by cohesive extracellular polymeric substances (EPS) crease the development time of bed forms expo- produced by microorganisms. The effect of these polymers on sediment gravity flows has not nentially (Malarkey et al., 2015). EPS research been investigated, despite the economic and societal importance of these flows. We present to date has focused on coastal environments. the first EPS concentrations measured in deep-sea sediment, combined with novel labora- The presence of EPS in deep-sea sediment and tory data that offer insights into the modulation of the dynamics of clay-laden, physically their impact on SGFs is not known. cohesive sediment gravity flows by biological cohesion. We show that EPS can profoundly EPS represent up to 40% of the marine or- affect the character, evolution, and runout of sediment gravity flows and are as prevalent in ganic carbon pool (Falkowski et al., 1998). The deep oceans as in shallow seas. Transitional and laminar plug flows are more susceptible to burial of organic carbon (Corg) in marine sedi- EPS-induced changes in flow properties than turbulent flows. At relatively low concentra- ment represents the second largest sink of atmo- tions, EPS markedly decrease the head velocity and runout distance of transitional flows. spheric CO2 (Galy et al., 2007). However, global This biological cohesion is greater, per unit weight, than the physical cohesion of cohesive carbon budget studies typically estimate Corg flux clay and may exert a stronger control on flow behavior. These results significantly improve by measuring the particulate organic matter set- our understanding of the effects of an unrealized biological component of sediment gravity tling through the water column and accumulat- flows. The implications are wide ranging and may influence predictive models of sediment ing in marine sediment (Martin et al., 1987; gravity flows and advance our understanding about the ways in which these flows transport Muller-Karger et al., 2005; Decho and Gutier- and bury organic carbon globally. rez, 2017). SGFs are not currently considered to be a significant orgC transport and burial process INTRODUCTION of clay-rich SGFs show that at sufficiently high in Corg flux models on continental margins. This Clay, inherently associated with organic concentrations of clay, flocs bind to form a net- is surprising, since fine-grained sediment flows matter, is the most abundant sediment type on work that behaves as a gel, increasing viscos- have been found to transport the majority of Corg Earth (Hillier, 1995). Recent advances in our ity and suppressing shear-generated turbulence (de Haas et al., 2002). Here, we present the first understanding of the properties of clay have re- (Baas and Best, 2002; Baas et al., 2009). These measurements of EPS from deep-sea sediment defined our models of submarine sediment grav- flows, and their deposits, are radically different cores, and, through novel experiments, we test ity flows (SGFs) in both modern and ancient to fully turbulent flows and highlight the impor- if EPS-derived biological cohesion is capable of environments (Wright and Friedrichs, 2006; tance of understanding how cohesive material inhibiting turbulence and intensifying cohesive Barker et al., 2008; Sumner et al., 2009). SGFs affects SGFs. SGF behavior. This has fundamental implica- are volumetrically the most significant sediment Extracellular polymeric substances (EPS) tions for (1) understanding SGF behavior in the transport process in the ocean, they can pose de- are secreted by microorganisms in many envi- natural environment, (2) models of Corg flux on structive hazards to offshore infrastructure, and ronments, from rivers and estuaries to hypersa- continental margins and estimating Corg burial, as their deposits form major hydrocarbon reser- line systems and deep-sea hydrothermal vents well as (3) reconstruction of past environments voirs (Talling, 2014). Understanding and predic- (Decho and Gutierrez, 2017). The adhesion of from ancient deposits and predicting hydrocar- tion of SGF behavior therefore have scientific, this exopolymer to sediment grains forms a ma- bon reservoir properties. economic, and social importance. trix of EPS, sediment, and single-cell organisms Clay-rich SGFs are governed by the ability called a biofilm, which is considered to be the METHODS of clay minerals to aggregate, or flocculate (Mc- primary mechanism by which benthic micro- To explore the impact of biological cohe- Cave and Jones, 1988). Laboratory experiments organisms stabilize the sediment they inhabit sion on the dynamics of cohesive SGFs, series CITATION: Craig, M.J., et al., 2020, Biomediation of submarine sediment gravity flow dynamics: Geology, v. 48, p. 72–76, https://doi.org/10.1130/G46837.1 72 www.gsapubs.org | Volume 48 | Number 1 | GEOLOGY | Geological Society of America Downloaded from https://pubs.geoscienceworld.org/gsa/geology/article-pdf/48/1/72/4904671/72.pdf by University of St Andrews user on 21 January 2020 of experimental SGFs were generated with and tional flows experiencing turbulence suppression were also visually indistinguishable from turbu- without EPS. These flows were generated in a by physical cohesion (Table 1). Turbidity cur- lent clay-only flow F07. However, the Uh of F08 5-m-long, 0.2-m-wide, and 0.5-m-deep, smooth- rents traveled the length of the tank and gener- and F09 decreased more rapidly than for F07 bottomed lock-exchange tank (Fig. DR1 in the ated shear waves along their upper interface with between 4 m and 4.2 m along the tank, result- 1 GSA Data Repository ). The reservoir was filled the ambient fluid Table 2( ). The TTPFs featured a ing in lower Uh values at 4.6 m (Fig. 1). At the with a mixture of kaolinite clay (volumetric con- dense, laminar lower “plug” layer with coherent highest CEPS, F10 began to decelerate rapidly at centration Cclay = 5–23 vol%), EPS, and seawa- fluid entrainment structures (Baker et al., 2017; 2.5 m and halted at 3.9 m. ter. Xanthan gum was used as a proxy for natural Figs. DR4 and DR5) that transitioned upward TTPFs at Cclay = 22 vol% and Cclay = 23 EPS (cf. Tan et al., 2014). Xanthan gum shares into a dilute turbulent layer (Table 2). vol% exhibited distinct decreases in Uh and chemical similarities with a wide variety of EPS runout distance as EPS were added (Fig. 2; and is widely used as a substitute for EPS in FLOWS WITH EPS Fig. DR8). Normalized to the maximum head marine ecology, soil science, and sediment sta- Adding EPS to the turbidity currents with velocity, Uh,max, and runout distance of the clay- bility research (see the Data Repository). The Cclay < 15 vol% produced no visual changes in only flows, the combinedC clay = 22 vol% and range of CEPS used in the experiments (0–0.268 flow behavior and no measurable differences Cclay = 23 vol% data are strongly correlated with wt%), was informed by seabed sediment cores in the Uh profiles (Figs. DR6 and DR7). At CEPS (Figs. DR9 and DR10). In Cclay = 22 vol% obtained during RV Tangaroa cruise TAN1604, Cclay = 15 vol%, the EPS-laden flows Table 1( ) flows, CEPS ≤ 0.089 wt% still produced TTPFs from 127 to 1872 m depths in the Hauraki Gulf, North Island of New Zealand (Figs. DR2 and TABLE 1. BASIC EXPERIMENTAL DATA DR3; Table DR1). These EPS data are based on Kaolinite EPS weight Uh,max Flow –1 bulk carbohydrate content, collected using the Flow Cclay (vol%) (%) ROD (m) (m s ) classification standard assay method of DuBois et al. (1956). F01 5 0 – 0.377 Turbidity current F02 5 0.134 – 0.379 Turbidity current The maximum CEPS recorded in the TAN1604 F03 5 0.250 – 0.381 Turbidity current cores was 0.260 wt%, with an average value of F04 10 0 – 0.367 Turbidity current F05 10 0.132 – 0.353 Turbidity current 0.139 wt%. For comparison, background EPS F06 10 0.264 – 0.348 Turbidity current F07 15 0 – 0.430 Turbidity current content ranges from 0.01 to 0.1 wt% measured F08 15 0.066 – 0.417 Turbidity current in estuarine sediment and from 0.1 to 0.67 wt% F09 15 0.133 – 0.416 Turbidity current F10 15 0.265 3.91 0.420 Turbidity current measured in freshwater sediment (Gerbersdorf F11 22 0 4.69 0.552 TTPF et al., 2009; Malarkey et al., 2015). F12 22 0.067 3.63 0.455 TTPF F13 22 0.089 3.20 0.438 TTPF In the laboratory, we compared the head ve- F14 22 0.133 2.13 0.217 Plug flow locity, U , and runout distance of clay-only con- F15 22 0.265 0.92 0.194 Plug flow h F16 23 0 3.66 0.471 TTPF trol flows with equivalent flows containing EPS F17 23 0.052 2.94 0.439 TTPF F18 23 0.087 1.80 0.419 Plug flow to test if biological cohesion intensifies cohesive F19 23 0.130 1.32 0.211 Plug flow flow behavior.U h versus horizontal distance was F20 23 0.259 0.60 0.160 Slide measured using a high-definition video camera.
Load more

Recommended publications
  • Odd-Eirik Heimsund
    Numerical simulation of turbidity currents: a new perspective for small- and large- scale sedimentological experiments Snorre Heimsund Thesis for Candidatus Scientiarum degree in Sedimentology/Petroleum Geology Department of Earth Science University of Bergen 2007 i ABSTRACT Turbidity currents are a variety of subaqueous sediment-gravity flows, in which the suspension of sediment by water turbulence produces a water-sediment mixture that is denser than the ambient water and hence flows due to gravity along a topographic gradient. This type of sediment gravity flow is the most important mechanism for the dispersal and deposition of sand on deep-sea floors, as well as on the underwater slopes of many deltas and lakes. The hydrodynamics of turbidity currents are difficult to study in the natural environments, whereas laboratory experiments are limited to small-scale flows, time-consuming and not necessarily easier when it comes to the measuring of flow properties and establishing of the relationships between the turbulent flow structure and the transport and deposition of sediment. Mathematical models of turbidity current, integrated by computational fluid dynamics (CFD) and realized as numerical simulations, can be used to obviate these difficulties, and also to upscale laboratory datasets and to integrate the data from nature and experiments. The concept CFD refers to the numerical solution, by computational methods, of the governing equations describing fluid flow: the set of Navier-Stokes equations and the multi-phase fluid dynamics. CFD is widely used in the engineering branches of fluid mechanics, but is a relatively new numerical approach in the field of sedimentological research. In the present study, a three-dimensional model has been constructed by using the CFD software Flow-3D™ to simulate the flow of turbidity currents, including their internal hydraulic characteristics as well as sediment erosion and deposition.
    [Show full text]
  • Seafloor Gravity Currents: Flow Dynamics in Overspilling And
    Seafloor gravity currents: flow dynamics in overspilling and sinuous channels Robert William Kelly The University of Leeds School of Computing EPSRC Centre for Doctoral Training in Fluid Dynamics Submitted in accordance with the requirements for the degree of Doctor of Philosophy. October 2018 This copy has been supplied on the understanding that it is copyright material and that no quotation from the thesis may be published without proper acknowledgement. The candidate confirms that the work submitted is his/her/their own, except where work which has formed part of jointly authored publications has been included. The contribution of the candidate and the other authors to this work has been explicitly indicated below. The candidate confirms that appropriate credit has been given within the thesis where reference has been made to the work of others. A version of Chapter 5 has been accepted for publication in Journal of Geophysical Research: Oceans: “The structure and entrainment characteristics of partially-confined gravity currents”. Robert Kelly, Robert Dorrell, Alan Burns and William McCaffrey. Journal of Geophysical Research: Oceans. Under review. In this manuscript the work is the candidate’s own, with the other authors having acted in a supervisory role, providing feedback and suggestions. i “In every outthrust headland, in every curving beach, in every grain of sand there is the story of the earth.” – Rachel Carson ii Acknowledgements It feels a bit bizarre to finally be writing this, as it means my time as a PhD student must be drawing to a close. Firstly, I would like to thank my team of supervisors, Bill McCaffrey, Robert Dorrell and Alan Burns, who gave me their utmost support throughout this project.
    [Show full text]
  • Origin and Evolution Processes of Hybrid Event Beds in the Lower Cretaceous of the Lingshan Island, Eastern China
    Australian Journal of Earth Sciences An International Geoscience Journal of the Geological Society of Australia ISSN: 0812-0099 (Print) 1440-0952 (Online) Journal homepage: http://www.tandfonline.com/loi/taje20 Origin and evolution processes of hybrid event beds in the Lower Cretaceous of the Lingshan Island, Eastern China T. Yang, Y. Cao, H. Friis, K. Liu & Y. Wang To cite this article: T. Yang, Y. Cao, H. Friis, K. Liu & Y. Wang (2018) Origin and evolution processes of hybrid event beds in the Lower Cretaceous of the Lingshan Island, Eastern China, Australian Journal of Earth Sciences, 65:4, 517-534, DOI: 10.1080/08120099.2018.1433236 To link to this article: https://doi.org/10.1080/08120099.2018.1433236 Published online: 16 May 2018. Submit your article to this journal Article views: 9 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=taje20 AUSTRALIAN JOURNAL OF EARTH SCIENCES, 2018 VOL. 65, NO. 4, 517–534 https://doi.org/10.1080/08120099.2018.1433236 Origin and evolution processes of hybrid event beds in the Lower Cretaceous of the Lingshan Island, Eastern China T. Yang a,b,c, Y. Cao a, H. Friisc, K. Liu a and Y. Wanga aSchool of Geosciences, China University of Petroleum, Qingdao, 266580, PR China; bShandong Provincial Key Laboratory of Depositional Mineralization & Sedimentary Minerals, Shandong University of Science and Technology, Qingdao 266580, Shandong, PR China; cDepartment of Geoscience, Aarhus University, Høegh-Guldbergs Gade 2, DK-8000 Aarhus C, Denmark ABSTRACT ARTICLE HISTORY On the basis of detailed sedimentological investigation, three types of hybrid event beds (HEBs) Received 13 September 2017 together with debrites and turbidites were distinguished in the Lower Cretaceous sedimentary Accepted 15 January 2018 – sequence on the Lingshan Island in the Yellow Sea, China.
    [Show full text]
  • Turbidity Currents Comparing Theory and Observation in the Lab
    LABORATORY INSTRUCTIONS AND WORKSHEET Turbidity Currents Comparing Theory and Observation in the Lab By Joseph D. Ortiz and Adiël A. Klompmaker PURPOSE OF ACTIVITY DIMENSIONAL SCALING AS A MEANS The goal of this exercise is to enable students to explore some OF COMPARING FLUID FLOWS of the controls on fluid flow by having them simulate tur- We can employ dimensional scaling to compare the prop- bidity currents using lock-gate exchange tanks while vary- erties of various fluid flows. These provide a means of char- ing the bed slope and the turbidity. Observational data are acterizing the flow from a theoretical standpoint. When the compared with theoretical relationships known from the sci- assumptions underlying these simple theories are met, the entific literature. The exercise promotes collaborative/peer results match empirical observations. A current can pick up learning and critical thinking while using a physical model sediment off the bottom when the boundary shear stress (the and analyzing results. force acting on the particle in the direction of the current) exceeds the drag on the particle. How the particle is trans- WHAT THE ACTIVITY ENTAILS ported depends on its density, size, and the properties of the During two lab periods of two and half hours duration, stu- fluid flow. Larger particles are transported as bed load, roll- dents use a physical model to simulate turbidity currents flow- ing or scraping along the bottom. Smaller, less dense particles ing over differing bottom slopes. They are given a Plexiglas saltate (bounce along the bottom), and finer grains are trans- tank and gate, a wooden stand to change the bottom slope, a ported by suspension.
    [Show full text]
  • Physical and Biological Processes
    CHAPTER ONE Physical and biological processes (a) COPYRIGHTED MATERIAL (b) (a) Experimentally produced turbidity current. Courtesy Jeff Peakall. (b) Upper part of sediment slide deposits (Facies F2.1) draped by siltstone turbidites (Facies D2.2 and D2.3) in deep-marine volcaniclastics, Miocene Misaki Formation, Miura Peninsula, southeast Japan. Deep Marine Systems: Processes, Deposits, Environments, Tectonics and Sedimentation, First Edition. Kevin T. Pickering and Richard N. Hiscott. © 2016 Kevin T. Pickering and Richard N. Hiscott. Published 2016 by John Wiley & Sons, Ltd. Companion Website: www.wiley.com/go/pickering/marinesystems 4 Physical and biological processes 1.1 Introduction divided into four phases: (i) a phase of flow initiation; (ii) a period during the early history of the flow when characteristics of the trans- This chapter has two main functions. First, there is an introduction porting current change rather quickly to a quasi-stable equilibrium to the main processes responsible for the physical transport and state; (iii) a phase of long-distance transport to the base of the con- deposition of sediments derived from land areas and carried into tinentalslopeorbeyondand(iv)afinaldepositionalphase.Inmany the deep sea. Second, the origin of pelagic sediments (oozes, chalks, cases, the concentration of solid particles changes systematically along cherts) and organic-rich muds (e.g., black shales and sapropels with the flow path. Particle concentration is an important variable because >2% organic matter) is explained. For these sediments, transport mixtures of sediment and water can only become fully turbulent if the of material from an adjacent land mass is either not required, for concentration is low.
    [Show full text]
  • Hybrid Turbidite-Drift Channel Complexes: an Integrated Multiscale Model A
    https://doi.org/10.1130/G47179.1 Manuscript received 7 November 2019 Revised manuscript received 27 January 2020 Manuscript accepted 28 January 2020 © 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 18 March 2020 Hybrid turbidite-drift channel complexes: An integrated multiscale model A. Fuhrmann1, I.A. Kane1, M.A. Clare2, R.A. Ferguson1, E. Schomacker3, E. Bonamini4 and F.A. Contreras5 1 Department of Earth and Environmental Sciences, University of Manchester, Williamson Building, Oxford Road, Manchester M13 9PL, UK 2 National Oceanography Centre, European Way, Southampton SO14 3HZ, UK 3 Equinor, Martin Linges vei 33, 1364 Fornebu, Norway 4 Eni Upstream and Technical Services, Via Emilia 1, 20097 San Donato Milanese, Milan, Italy 5 Eni Rovuma Basin, no. 918, Rua dos Desportistas, Maputo, Mozambique ABSTRACT sedimentological model for bottom current– The interaction of deep-marine bottom currents with episodic, unsteady sediment gravity influenced submarine channel complexes. flows affects global sediment transport, forms climate archives, and controls the evolution of continental slopes. Despite their importance, contradictory hypotheses for reconstructing past GEOLOGICAL SETTING flow regimes have arisen from a paucity of studies and the lack of direct monitoring of such The Jurassic to Paleogene basins offshore of hybrid systems. Here, we address this controversy by analyzing deposits, high-resolution sea- East Africa formed during the breakup of Gond- floor data, and near-bed current measurements from two sites where eastward-flowing gravity wana (Salman and Abdula, 1995). Following flows interact(ed) with northward-flowing bottom currents. Extensive seismic and core data Pliensbachian to Aalenian northwest-southeast from offshore Tanzania reveal a 1650-m-thick asymmetric hybrid channel levee-drift system, rifting, ∼2000 km of continental drift took place deposited over a period of ∼20 m.y.
    [Show full text]
  • How Are Subaqueous Sediment Density Flows Triggered, What Is Their Internal Structure and How Does It Evolve?
    Earth-Science Reviews 125 (2013) 244–287 Contents lists available at ScienceDirect Earth-Science Reviews journal homepage: www.elsevier.com/locate/earscirev How are subaqueous sediment density flows triggered, what is their internal structure and how does it evolve? Direct observations from monitoring of active flows Peter. J. Talling a,⁎, Charles K. Paull b, David J.W. Piper c a National Oceanography Centre, European Way, Southampton SO14 3ZH, UK b Monterey Bay Aquarium Research Institute, 7700 Sandholt Road, Moss Landing, CA 95039-9644, USA c Geological Survey of Canada, Bedford Institute of Oceanography, Dartmouth, Nova Scotia B2Y 4A2, Canada article info abstract Article history: Subaqueous sediment density flows are one of the volumetrically most important processes for moving sediment Received 23 May 2011 across our planet, and form the largest sediment accumulations on Earth (submarine fans). They are also arguably Accepted 12 July 2013 the most sparely monitored major sediment transport processes on our planet. Significant advances have been Available online 21 July 2013 made in documenting their timing and triggers, especially within submarine canyons and delta-fronts, and fresh- water lakes and reservoirs, but the sediment concentration of flows that run out beyond the continental slope has Keywords: never been measured directly. This limited amount of monitoring data contrasts sharply with other major types Turbidity current fl fl Turbidite of sediment ow, such as river systems, and ensure that understanding submarine sediment density ows Flow velocity remains a major challenge for Earth science. The available monitoring data define a series of flow types whose Sediment concentration character and deposits differ significantly.
    [Show full text]
  • A 3D SEISMIC CASE STUDY from OFFSHORE ANGOLA Kehinde
    DEPOSITIONAL ARCHITECTURE AND PROCESSES OF SEDIMENT GRAVITY FLOWS: A 3D SEISMIC CASE STUDY FROM OFFSHORE ANGOLA Kehinde Olafiranye Department of Earth Science and Engineering Imperial College London Thesis submitted in accordance with the requirements for the degree of Master of Philosophy of Imperial College London October 2013 Declaration of originality I declare that this thesis is entirely my own work carried out in the Department of Earth Science and Engineering at Imperial College London under the supervision of Drs Christopher Jackson (Imperial College), David Hodgson (University of Leeds), and Gary Hampson (Imperial College). Full citation and adequate referencing have been made where any material could be construed as the work of others. No part of this work has been previously submitted to this or any other academic institution for a degree or diploma, or any other qualification. Kehinde Olafiranye Department of Earth Science and Engineering Imperial College London 2 Copyright Declaration ‘The copyright of this thesis rests with the author and is made available under a Creative Commons Attribution Non-Commercial No Derivatives licence. Researchers are free to copy, distribute or transmit the thesis on the condition that they attribute it, that they do not use it for commercial purposes and that they do not alter, transform or build upon it. For any reuse or redistribution, researchers must make clear to others the licence terms of this work’ 3 Abstract Deepwater environments are characterised by the deposits of mass flows (e.g. debrites, slumps, slides), sediment density flows (turbidites), and background hemipelagic and pelagic suspension fallout. ‘Mass transport’ is a general term used for the failure and downslope movement of sediment under the influence of gravity in both subaerial and subaqueous environments, the products of which are called Mass Transport Deposits (MTDs).
    [Show full text]
  • Stacked Debris Flows Offshore Sakarya Canyon, Western Black Sea: Morphology, Seismic Characterization and Formation Processes
    Turkish Journal of Earth Sciences Turkish J Earth Sci (2021) 30: 247-267 http://journals.tubitak.gov.tr/earth/ © TÜBİTAK Research Article doi:10.3906/yer-2008-2 Stacked debris flows offshore Sakarya Canyon, western Black Sea: morphology, seismic characterization and formation processes Derman DONDURUR1 , Aslıhan NASIF1,2,* 1Institute of Marine Sciences and Technology, Dokuz Eylül University, İzmir, Turkey 2The Graduate School of Natural and Applied Sciences, Dokuz Eylül University, İzmir, Turkey Received: 03.08.2020 Accepted/Published Online: 02.12.2020 Final Version: 22.03.2021 Abstract: Analysis of ca. 1400 km of multichannel seismic data indicate that the distal part of the Sakarya Canyon within the continental rise is an unstable region with sediment erosion. Fourteen buried debris flows (DB1–DB14), in the stacked form within Plio–Quaternary sediments between 1400 and 1950 m water depth, were observed in the surveyed area. Their run-out distances range from 3.8 to 24.4 km. The largest debris flow DB10 affects ca. 225 km2 surficial area transporting ca. 15 km3 of sediment in S to N direction. The debris flows in the area are considered as gravity flows of unconsolidated sediments mobilized due to the excess pore pressures occurred in the unconsolidated shallow sediments arising from the high sedimentation rate. We also suggest that extensive seismic activity of North Anatolian Fault (NAF) located ca. 140 km south of the of the study area along with the possible local fault activity is also a significant triggering factor for the flows. The stacked form of the debrites indicates that the excess pore pressure conditions are formed periodically over the time in the continental rise, which makes the region a potentially unstable area for the installation of offshore engineering structures.
    [Show full text]
  • ABSTRACT: Ten Turbidite Myths; #90007 (2002)
    AAPG Search and Discovery Article #90007©2002 AAPG Annual Meeting, Houston, Texas, March 1-13, 2002 AAPG Annual Meeting March 10-13, 2002 Houston, Texas Ten Turbidite Myths Shanmugam, Ganapathy, Department of Geology, The University of Texas at Arlington, Arlington, TX Introduction The turbidite paradigm, which is based on the tenet that a vast majority of deep-water sediment is composed of turbidites (i.e., deposits of turbidity currents), has promoted many turbidite myths during the past 50 years. John E. Sanders (1926-1999), a pioneering process sedimentologist, first uncovered some of these turbidite myths. This paper provides a reality check by undoing ten of these turbidite myths. Myth No. 1: Turbidity currents are non-turbulent flows with multiple sediment- support mechanisms The principal myth revolves around disagreements concerning the hydrodynamic properties of turbidity currents. The generally accepted definition is that turbidity currents are a type of sediment-gravity flow with Newtonian rheology (Dott, 1963) and turbulent state (Sanders, 1965) in which the principal sediment-support mechanism is the upward component of fluid turbulence (Middleton and Hampton, 1973). However, following the approach of Kuenen (see comment in Sanders, 1965, p. 217-218), Kneller and Buckee (2000, p. 63) claim that turbidity currents can be non turbulent (i.e., laminar) in state. This is confusing because turbidity currents cannot exist without turbulence (Middleton, 1993). According to Middleton and Hampton (1973), turbidity currents are flows in which sediment is supported by fluid turbulence. However, Kneller and Buckee (2000, p. 63) misused the term “turbidity currents” for “transitional flows” with multiple sediment- support mechanisms.
    [Show full text]
  • Sediment Gravity Flows Triggered by Remotely-Generated Earthquake Waves
    PUBLICATIONS Journal of Geophysical Research: Solid Earth RESEARCH ARTICLE Sediment gravity flows triggered by remotely 10.1002/2016JB013689 generated earthquake waves Key Points: H. Paul Johnson1 , Joan S. Gomberg2,3 , Susan L. Hautala1, and Marie S. Salmi1 • Remotely generated seismic waves may destabilize accretionary margin 1School of Oceanography, University of Washington, Seattle, Washington, USA, 2U.S. Geological Survey, Seattle, sediment slopes 3 • Seafloor temperature and pressure Washington, USA, Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA measurements record sediment-laden gravity flows • Small slope failures leading to gravity Abstract Recent great earthquakes and tsunamis around the world have heightened awareness of the flows likely occur frequently along the inevitability of similar events occurring within the Cascadia Subduction Zone of the Pacific Northwest. Cascadia margin We analyzed seafloor temperature, pressure, and seismic signals, and video stills of sediment-enveloped instruments recorded during the 2011–2015 Cascadia Initiative experiment, and seafloor morphology. Supporting Information: Our results led us to suggest that thick accretionary prism sediments amplified and extended seismic • Supporting Information S1 wave durations from the 11 April 2012 Mw8.6 Indian Ocean earthquake, located more than 13,500 km Correspondence to: away. These waves triggered a sequence of small slope failures on the Cascadia margin that led to H. P. Johnson, sediment gravity flows culminating in turbidity currents. Previous studies have related the triggering of [email protected] sediment-laden gravity flows and turbidite deposition to local earthquakes, but this is the first study in which the originating seismic event is extremely distant (> 10,000 km). The possibility of remotely Citation: triggered slope failures that generate sediment-laden gravity flows should be considered in inferences of Johnson, H.
    [Show full text]
  • Hydrodynamic Fractionation of Minerals and Textures in Submarine Fans: Quantitative Analysis from Outcrop, Experimental, and Subsurface Studies
    HYDRODYNAMIC FRACTIONATION OF MINERALS AND TEXTURES IN SUBMARINE FANS: QUANTITATIVE ANALYSIS FROM OUTCROP, EXPERIMENTAL, AND SUBSURFACE STUDIES by Jane G. Stammer Copyright by Jane G. Stammer 2014 All Rights Reserved A thesis submitted to the Faculty and the Board of Trustees of the Colorado School of mines in partial fulfillment of the requirements for the degree of Doctor of Philosophy (Geology). Golden, Colorado Date _________________ Signed: _____________________ Jane G. Stammer Signed: _____________________ Dr. David R. Pyles Thesis Advisor Golden, Colorado Date _________________ Signed: _____________________ Dr. Paul Santi Professor and Head Department of Geology and Geological Engineering ii ABSTRACT Submarine fans are common on all of Earth’s siliciclastic margins and are among the largest hydrocarbon reservoirs around the globe. They contain compensationally-stacked channels and lobes that form a radially dispersive map pattern. Turbidity currents, a type of sediment gravity flow, are one of the main processes by which sediment is transported from the shelf to intra-slope- and basin-floor submarine fans. Turbidity currents hydrodynamically sort and deposit grains based on grain size, which is the primary control of settling velocity. Grain density and grain shape also contribute to particle settling velocity, yet only a few studies have focused on the effects of these variables on the behavior and deposits of turbidity currents. This dissertation analyzes how flow processes in turbidity currents relate to the spatial distribution of minerals and texture in turbidite lobes, and, in turn, how this affects reservoir quality. This dissertation uses three different methods of research: 1) physical experimentation of turbidity currents and their resulting deposits using the Deepwater Basin at Tulane University (Chapters 2 and 3); 2) outcrop analysis of a turbidite lobe from the Point Loma Formation, San Diego, California (Chapter 4); and 3) analysis of subsurface core data from Upper Miocene turbidites in Aspen Field, northern Gulf of Mexico (Chapter 5).
    [Show full text]