Marine Sediments: Mass Physical Properties

1. Marine Sediments: Mass Physical Properties Outline: I. Introduction to Mass Physical Properties II. Fabric and Mass Physical Properties III. Depositional and Post-Depositional Processes Mass Physical Properties

2. Introduction to Mass Physical Properties ●Review geotechnical terminology: - bulk density: - water content by dry weight: - void ratio: - porosity:- grain specific gravity: - liquid limit: - plastic limit:- plasticity index: - liquidity index:- shear strength:- cohesion: - sensitivity: ●Why might these variables be important? Mass Physical Properties

3. Introduction to Mass Physical Properties ●Techniques for measuring geotechnical properties include: - X-Ray diffraction (XRD): Sample exposed to x- rays of fixed wavelength; reflected radiation is measured; reflection angle used to calculate inter-atomic spacing (D value, Ang.). Mass Physical Properties

4. Introduction to Mass Physical Properties SEM – Rock Salt ●Techniques for measuring geotechnical properties include: - Scanning electron microscopy (SEM): Electron beam focused on sample, results in emission of electrons and radiation, which is detected and used to produce an image. Mass Physical Properties

5. Introduction to Mass Physical Properties TEM – Cosmic dust ●Techniques for measuring geotechnical properties include: - Transmission electron microscopy (TEM): Electron beam is transmitted through sample, image formed is magnified and directed onto a fluorescent screen, CCD camera or film. Mass Physical Properties

6. X-Radiography Whole-core logging Tri-axial deformation Introduction to Mass Physical Properties ●Techniques for measuring geotechnical properties include: - Tests for fabric, consolidation, permeability and porosity Mass Physical Properties

7. Introduction to Mass Physical Properties ●How was sediment created, deposited, structured or changed post deposition? ●Ultimate sediment state (geotechnical properties / variability) depends on… - geological and oceanographic processes - source materials and environmental setting ●Interactions of these produce primary and post-depositional properties. ● Primary textures and geotechnical properties are determined by… - particle size - mineralogy - particle size distribution - microstructure (fabric and physico-chemistry) Mass Physical Properties

8. Introduction to Mass Physical Properties ●Once on seafloor, post-depositional processes begin; and can be grouped into three categories (Bennett and Nelsen, 1983)… - biogeochemical - physical/chemical - mechanical ●1970s-80s: Study of sediment physical properties was in pioneer stage; reports = limited data over large areas. ● Minimal interpretations; DSDP and ODP routinely collect physical data; now a HUGE global body of data exists. ● Data synthesis and interpretations lag way behind data collection. Mass Physical Properties

9. Introduction to Mass Physical Properties ●Mass properties of sediment depend upon: 1. Texture 2.Composition 3.Mode of deposition 4. Depositional history 5. Depositional processes (bioturbation, currents, waves) 6. Post-depositional processes (compaction, de-watering, fluid circulation, chemical reactions) 7.Environmental changes (facies, sedimentation rates) Mass Physical Properties

10. Introduction to Mass Physical Properties Conceptual Model for Surficial Sediment of Continental Margin / Ocean Basin (Tucholke, 1987) ● Properties will parallel environments. ●Slope properties will vary because facies are variable there. ● Rise properties are ~ uniform (bottom current reworking). ● Rise can have variable properties where dissected by valleys or where down slope processes have deposited material. Mass Physical Properties

11. Introduction to Mass Physical Properties Geotechnical properties of surface sediments in a mega-corridor: U.S. Atlantic slope, rise, and deep sea basin (Bennett et al., 1980) Deep water sampling… Mass Physical Properties

12. Introduction to Mass Physical Properties (Bennett et al., 1980) Slope sampling… Rise sampling… Mass Physical Properties

13. Introduction to Mass Physical Properties (Bennett et al., 1980) ● What sediments do we find in these environments? - Fluvial-marine deposits: On shelf, slope and rise; sands through silty clays, generally fine seaward. -Calcareous oozes: Prevalent in mega-corridor; consist of > 30% carbonate (mostly skeletal material). - Red clays: Prevalent in mega-corridor; = clay minerals and carbonate debris (variable textures and mineralogy). Mass Physical Properties

14. Introduction to Mass Physical Properties (Bennett et al., 1980): Sediment type distribution Mass Physical Properties

15. Introduction to Mass Physical Properties (Bennett et al., 1980) ●Rise deposits = high water contents, porosities and shear strength; low wet weight and variability. ●Slope deposits = similar properties as rise, more variable. ●N. Atlantic deposits = most variable (differences in types/textures). ●Calcareous oozes = highest values compared to red clays and fluvial deposits. Slope and rise textures Mass Physical Properties

16. Introduction to Mass Physical Properties (Bennett et al., 1980) ● See Bennett et al. (1985) (map other physical properties on slope and upper rise). ● Properties described fitTucholke’s conceptual model…recall: - Properties parallel environments. - Slope properties are variable because facies are variable. - Rise properties are ~ uniform (bottom current reworking). - Rise properties vary where dissected by valleys or where down slope processes have deposited material. Mass Physical Properties

17. Fabric and Mass Physical Properties ●Physico-chemistry controls geotechnical properties, including load responses. ● Fabric (Bennett et al., 1981) - Particles = single plate-like units. - Domains = ~ stacks of face-to- face clay plates with some stepped face-to-face associations. - Chains = Series of particles in face- to-face or edge-to-face contact; bonds hold particles together (sediment strength). Mass Physical Properties

18. Fabric and Mass Physical Properties Silica flocs - SEM Smectite - TEM ●Fabric (Bennett et al., 1981) - Flocs = Units of particles arranged edge-to-face resulting in large intra-voids (space w/in flocs). - Voids = Spaces between particles or flocs. Mass Physical Properties

19. Fabric and Mass Physical Properties Remolding (Bennett et al., 1981 (MS Delta and East Pacific Sediments)) ● “Remolded” = disturbed. ●Smectiteand Illite clay: - Undisturbed clay: randomly oriented domains with contacts and high void ratio. - Disturbed clay: particle swirl pattern with local areas of oriented particles; fewer contacts, more isolated particles. - Remolded shear strength <<< natural shear strength, why? Mass Physical Properties

20. Fabric and Mass Physical Properties Remolding (Bennett et al., 1981) ● Pacific red clay: - Clay-size = smectite + trace illite, clinoptilolite and quartz. - Silt-size = clinoptilolite, smectiteand quartz. - Complex fabric of flocsand chains of plate-like particles. - Upon remolding, flocsand linking chains break down into randomly oriented domains. Mass Physical Properties

21. Fabric and Mass Physical Properties 100x Remolding (Bennett et al., 1981) ● Pacific red clay: Mass Physical Properties

22. Fabric and Mass Physical Properties Compaction (Bennett et al., 1981) ●Smectiteand illite clays (MS pro-delta): Mass Physical Properties

23. Fabric and Mass Physical Properties Compaction (Bennett et al., 1981) ●Smectiteand illite clays (MS pro-delta): - High-void-ratio: randomly oriented domains and short linking chains. -Low-intermediate-void-ratio: more particle-to-particle packing; still mostly randomly oriented domains with few chains. -Very low-void-ratio: highly oriented domains and thin, long voids. Mass Physical Properties

24. Fabric and Mass Physical Properties Zeolitic red clay Compaction (Bennett et al., 1981) ●Zeolitic red clay – Hawaiian Arch: Mass Physical Properties

25. Zeolitic red clay Fabric and Mass Physical Properties Compaction (Bennett et al., 1981) ●Zeolitic red clay – Hawaiian Arch: - Consolidated sample from 143m examined. - Very high void ratio, lots of intra- void space amid flocs; voids formed by flocs connected by chains. - Different clays behave differently under compaction; note that kaolinite has >> particle orientation than smectite under identical vertical stress (fig. 5, Bennett et al., 1989). Mass Physical Properties

26. Depositional and Post-Depositional Processes ●Depositional and post-depositional processes affect sediment fabric and geotechnical properties. ● Bennett and Nelsen (1983) discuss these relationships as they apply to the shelf edge environment. ●Bioturbation: - can change fabric, grain size, sorting, porosity, water content, compressibility, shear strength, acoustical properties and bottom stability (Murray et al., 2002). Heavily bioturbated ash beds, upper Miocene – Pliocene age Purisima Fm., central CA, USA Mass Physical Properties

27. Depositional and Post-Depositional Processes (a) mole track (b) pocket gopher (c) dugong (d) tidal flat feeding pit (e) blue-spotted stingray (f) common earthworm (g) burrowing shrimp Mass Physical Properties

28. Depositional and Post-Depositional Processes DISCUSSION Murray, J.M.H., A. Meadows, P.S. Meadows, 2002. Biogeomorphologicalimplications of microscale interactions between sediment geotechnics and marine benthos: A review, Geomorphology 47: 15-30. Mass Physical Properties

29. Depositional and Post-Depositional Processes ●Bioturbation: - burrowers can create open sediment fabric via ingestion, defecation and pelletization = weaker sediment. - Rowden et al. (1998) studied N. Sea surface sediments: Mass Physical Properties

30. Depositional and Post-Depositional Processes ●Bioturbation: - Rowden et al. (1998) concluded that: ● Burrowing macro-benthos modify sediment fabric seasonally. Temporal variability ● Summer =  macro-benthos =  water contents and  acoustic shear wave velocities,  bulk density and  bed rigidity. ●Summer storms =  particulate and associated (metals) fluxes. Mass Physical Properties

31. Depositional and Post-Depositional Processes ●Bioturbation: Can “Go Both Ways” - “Tubers” can maketight fabrics (mucous, piling) = stronger sediment. - Somecritters make stuff that sediment strength, Wigglesworth- Cooksey et al. (2001) studied diatoms and bacteria… Mass Physical Properties

32. Depositional and Post-Depositional Processes ●Bioturbation: - Wigglesworth-Cooksey et al. (2001) concluded that: ● EPS - ECPM largely responsible for sediment stabilization and bio- film architecture. ● Possibly due to lytic activities on diatom exo-polymers, bacteria likely inhibit sediment stability. Mass Physical Properties

33. Depositional and Post-Depositional Processes ●Internal and surface waves: - Wave energy can transport sediment. - Visco-elastic response of fine-grained sediments and subsurface variation of pore pressure. - Expansion and contraction of nepheloid layer, surface sediment and ripple marks (90-150+ m) shown by Bennett and Nelson (1983). WHAT MAY A HURRICANE DO? - Can develop excess pore pressures (weaken sediments); changes in pore pressure at wave and tidal frequencies. - Does it affect fabric? Mass Physical Properties

34. Depositional and Post-Depositional Processes ●Currents: - Bottom / near bottom currents found throughout oceans; these change intensity and location over time. Do they affect fabric? Can they build unique fabrics? - Park et al. (2000) studied piston core samples from the E. Pacific: Mass Physical Properties

35. Depositional and Post-Depositional Processes ●Currents: - Park et al. (2000): ● Homogenous fine-grained sediments with low sedimentation rates (0.81 – 1.02 mm/kyr). Mass Physical Properties

36. Depositional and Post-Depositional Processes ●Currents: - Park et al. (2000): ● Radiolarian assemblage: - Quaternary + re-worked, dissolution- resistant Tertiary species (upper sections). - Tertiary species dominate lower sections. - OVERALL: Decreasing abundances and fossil quality with depth. - Why? Active re-working by bioturbation and re-deposition by bottom currents. Mass Physical Properties

37. Depositional and Post-Depositional Processes ●Currents: - Park et al. (2000): ● Magnetic lineation at color boundaries related to changes in depositional conditions. ● AMS = anisotropy of magnetic susceptibility data. Mass Physical Properties

38. Depositional and Post-Depositional Processes ●Currents: - Park et al. (2000): ● Variable AMS properties with depth reflect sedimentation mode. ● Orientations of susceptibility axes show most magnetic fabrics are produced in stable sedimentary environments. ● Sedimentation without current = no flow controlled re-alignment = primary fabric is magnetic foliation (susceptibility axes normal to surface). ● Sedimentation w/ current = flow controlled re-alignment. Mass Physical Properties

39. Depositional and Post-Depositional Processes ●Currents: - Park et al. (2000): ● Variation of Antarctic Bottom Water (AABW) current = changes in fossil distributions, sediment color and AMS lineation / fabric. ● Fabrics indicate intensified bottom currents from late Miocene to Pliocene (~9 – 4 MYA). ● Novel approachcombines magnetism, color and micro-fossils to “see” effects of changing bottom water flow on fabric over time. Mass Physical Properties

40. Depositional and Post-Depositional Processes Niigata Earthquake in Japan on June 16, 1964 ●Seismic activity: Another that “Goes Both Ways” - Increase consolidation and change geotechnical properties due to repetitive, low intensity shaking.LIQUEFACTION Mass Physical Properties

41. Depositional and Post-Depositional Processes ●Seismic activity: Another that “Goes Both Ways” - Decreases consolidation and changes geotechnical properties due to high intensity shaking; submarine mass wasting? (turbidites) ●Facies change: - Infinite possibilities; for example, a fine sand deposited above a clay drives dewatering and compaction of clay. ●Fluctuating sedimentation rates: - Sedimentation rate figures prominently in consolidation. - Sedimentation rate translates directly into loading rate or overburden stress per unit area with time. Mass Physical Properties

42. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Effect of changing sedimentation rates seen by examining change in effective stress over time. Mass Physical Properties

43. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Effective stress (σ') is not directly measurable(theoretical), inferred from total stress and pore pressure: σ‘ = σ – u where σ = total stress and u = pore water pressure. - Effective stress = part of total stress carried by particles rather than interstitial water. - Cool fact: If negative (pore water pressure > total stress) sediment “boils” (quicksand). Mass Physical Properties

44. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Bryant et al., 1991: Microfabricandphysical property characteristics of a consolidated clay section: ODP site 697, Weddell Sea. Mass Physical Properties

45. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Bryant et al., 1991. Mass Physical Properties

46. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Bryant et al., 1991. ● Changing rates effect: Bulk density Total stress Effective stress ● What is / are the driving force(s)? Mass Physical Properties

47. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Bryant et al., 1991. ● Pleistocene loading rate = 2.75 x 102kPa/Ma. ● Loading rate decreased to 3.00 x 102kPa/Ma from latter early Pliocene to early Pleistocene. ● From 4.5 – 4.0 Ma, loading rate ~ 32.66 x 102kPa/Ma. Mass Physical Properties

48. Depositional and Post-Depositional Processes ●Fluctuating sedimentation rates: - Bryant et al., 1991. ● At glacial maxima… ● Non-polar regions = high sedimentation Why? ● Polar basins = low sedimentation Why? ● Effects of variable sedimentation on physical properties and small scale (though widespread) evidence of how large scale processes are recorded. Mass Physical Properties

49. Marine Sediments: Mass Physical Properties ●Readings for next set of material:hemipelagites and pelagites. **Bryant, W.R., R.H. Bennett, 1988. Origin, physical, and mineralogical nature of red clays: the Pacific Ocean basin as a model. Geo- Marine Letters, 8: 189-249. **DeMaster, D.J., 2002. The accumulation and cycling of biogenic silica in the Southern Ocean: revisiting the marine silica budget. Deep- Sea Research II, 49: 3,155-3,167.DISCUSSION **McCarthy, F.M.G., D.J. Findlay, M.L. Little, 2004. The micropaleontological character of anomalous calcareous sediments of late Pliocene through early Pleistocene age below the CCD in the northwestern North Pacific Ocean.Palaeo, 215: 1-15. Mass Physical Properties

50. Marine Sediments: Mass Physical Properties ●Readings for next set of material:hemipelagites and pelagites. **Rea, D.K., T.R. Janecek, 1982. Late Cenozoic changes in atmospheric circulation deduced from North Pacific eoliansediments. Marine Geology, 49: 149-167. Schultz, P.H., R.E. Lianza, 1992. Recent grazing impacts on the Earth recorded in the Rio Cuarto crater field, Argentina. Nature, 355(6357): 234-237. **Stow, D.A.V., D.J.W. Piper, 1984. Fine-Grained Sediments: Deep-water Processes and Facies. The Geological Society by Blackwell Scientific Publications, Boston, 659p. Mass Physical Properties