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An overview of smectite clays

An overview of smectite clays

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Smectites Smectites Presentation Transcript

  • Smectites Heather Jordan GEOSC 440 03/17/2005
  • What are smectites?
    • Single octahedral sheet between 2 tetrahedral sheets
      • 2:1 Phyllosilicates:
        • Smectite
        • Vermiculite
        • Illite
  • What are smectites?
    • Layer charge from substitutions:
      • Octahedral: Mg 2+ , Fe 2+ , Mn 2+ or Al 3+
      • Tetrahedral: Al 3+ or Fe 3+ for Si 4+
    • Interlayer expands (up to 30% by volume); “swelling clays”
      • Separation depends on interlayer cations present & ionic strength of solution
  • What are smectites?
    • Platelet Dimensions
      • 200-500 nm in diameter
      • 0.93 nm thick
    • General Formula:
      • A 0.3 D 2-3 [T 4 O 10 ]Z 2 •nH 2 O
    • 2:1  1:1
      • Ratio of tetrahedral: octahedral sheets
      • Weathering
  • Smectite Group Members
    • Allettite: Ca 0.2 Mg 6 (Si,Al) 8 O 20 (OH) 4 • 4H 2 O
    • Beldellite: (Na,Ca 0.5 ) 0.3 Al 2 (Si,Al) 4 O 10 (OH) 2 •nH 2 O
    • Hectorite: Na 0.3 (Mg,Li) 3 Si 4 O 10 (F,OH) 2
    • Montmorillonite: (Na,Ca) 0.33 (Al,Mg) 2 Si 4 O 10 (OH) 2 •nH 2 O
    • Nontronite: Na 0.3 Fe 2 (Si,Al) 4 O 10 (OH) 2 •nH 2 O
    • Saponite: Ca 0.25 (Mg,Fe) 3 (Si,Al) 4 O 10 (OH) 2 •nH 2 O
    • Sauconite: Na 0.3 Zn 3 (Si,Al) 4 O 10 (OH) 2 •4H 2 O
    • Stevensite: (Ca,Na) x Mg 3 Si 4 O 10 (OH) 2
    • Swinefordite: Li(Al,Li,Mg) 4 (Si,Al) 8 O 20 ,(OH,F)4 •xH 2 O
    • Volkonskoite: Ca 0.3 (Cr,Mg,Fe) 2 (Si,Al) 4 O 10 (OH) 2 •4H 2 O
    • Yakhontovite: (Ca,Na) 0.5 (Cu,Fe,Mg) 2 Si 4 O 10 (OH) 2 •3H 2 O
    • Zincsilite:
    • Zn 3 Si 4 O 10 (OH) 2 •4H 2 O
  • Thixotrophy
    • Ability to form stiff gels at low concentrations that change viscosity as shear application changes
      • No Shear: Double layers repelled & + surface attracted to - edge  “house of cards” configuration
      • Shear: Aligns clay particles & ↓ viscosity
  • Smectite-Illite (S-I) Transition
    • Temperature, Pressure & Time
    • Abiotic Reaction:
      • 300-450 o C
      • 100 MPa
      • 4-5 Months
    • Biological Reaction:
      • Metal-Reducing Bacteria
      • Room Temperature
      • 1 atm
      • 2 weeks
    http://www.sciencemag.org/cgi/reprint/303/5659/830.pdf
  • Structural Comparison: Smectite to Illite
  • On the mechanical role of smectite in subduction zones Peter Vrolijk Department of Geological Sciences, University of Michigan
  • What is a decollement?
    • “ A shallow dipping to subhorizontal fault or shear zone”
    • French: “Ungluing”
    • The detachment of the upper cover from its substratum
    • Also known as:
      • - Detachment fault
      • - Decollement Fault
      • - Sole Fault
    (Image modified from Demian’s lecture sketch)
  • Objective of the Study
    • Find out if subduction zone decollements occur in smectite-rich horizons
    • Review previous research :
      • Rock Deformation
      • Physical Properties of Sediments
      • Smectite-Illite (S-I) Transition
    • How these effect seismicity in subduction zones
  • Why is this research relevant?
    • The characteristics of sediments at subduction zones could tell us where decollements form
    • By understanding what happens at decollements we learn more about the S-I transition
    • Aspects of the S-I transition process at decollements tells us something about seismicity
  • Previous Research: Subduction Zones
    • Sediment-Rich:
      • Long decollements
      • Smectite-rich sediments
    • Decollements:
      • Formation is associated with prism structure
      • ↑ Fluid pressure  ↓ friction  ↓ tapering
      • ↑ ploughing up of prism  ↓stress & zones of ↑ porosity
    (Image modified from Demian’s lecture sketch)
  • Previous Research: Subduction Zones
    • Pelagic Sediments: subducted
    • Terrigenous Deposits: accrete at prism base
    • Changes in mechanical properties result in peeling of terrigenous from pelagic
    • Decollement is just beneath area of partition at base of smectite-rich zone
    (Image modified from Demian’s lecture sketch)
  • Methods: Data Collection
    • Sediments from an active decollement have only been collected once
    • Seismic reflection data  mineralogical composition of sediments
    • Decollement geometry from drill cores
    (Image taken from Demian’s Lecture Presentation)
  •  
  •  
  •  
  •  
  • Results
    • Not enough data
      • Smectites & decollement formation
      • More drilling needed
    • 2 Regions with the most data:
      • Decollements occur in smectite-rich zones
    (Image taken from Demian’s Lecture Presentation)
  • Implications: For Decollement Generation
    • Mineralogical Reasons why smectite is weakest sediment in subduction zones
      • Recall smectite structure
      • Water = weakness (H-bonds)
      • Relative Deformation Stresses
      • Water tightly adsorbed to smectite
        • Remains during deformation (↑ porosity)
  • What dictates smectite distribution in ocean sediments?
    • Transformation from volcanic ash
      • Abundant ash
      • Sufficient time & pressure
      • Between pelagic & hemipelagic sediments (due to dilution & age)
    • Detrital clay influx
  • Sediment Minerology Evolution: S-I Transition
    • Metamorphic transitions on subducting plate
    • 80% complete 100-110 o C
    • ↑ Rate of subduction; ↓ S-I transition rate
    • Subduction Observations:
      • Japan Trench (fast)
      • Barbados (slow)
  • Implications: For Subduction Zones
    • S-I: Sediment Strengthening
    • How it relates to seismicity
  • Does this lead to development of the seismic front?
    • During S-I, ↓ smectite (as it is converted to illite)
    • Decollement strengthened
    • Friction ↑
    • Deformation & strain on overriding plate
    • Seismicity results
  • Conclusions
    • Decollements form in smectite-rich sediments
    • More drilling needed at prisms
    • Columb Wedge Theory: coefficient of basal sliding friction may need modification
    • Seismicity related to strengthening (due to S-I)
  • Comments & Criticisms: Where to Begin?
    • Overgeneralization from too small a sample size
    • Too little is known about the lithology to draw conclusions about the relationship of smectite to decollement formation
    • Keeping physical models in mind (structure, hydration, the effect of shear, S-I, etc.), Is the model logical?
      • Shear reduces viscosity (house of cards to plates)
      • S-I (squeezes out water; no more H-bonds to break)
      • Leads to strengthening  Seismicity
    • Would I have published this? NO!!!
  • ??QuESTIONS??
  • For more thoroughly exhilarating reading on smectites:
    • Alba, M.D, et al. (2001) Hydrothermal reactivity of Lu-saturated smectites: Part I. A long-range order study. American Minerologist . 86: 115-123.
    • Alba, M.D., et al. (2001) Hydrothermal reactivity of Lu-saturated smectites: Part II. A short-range order study. American Minerologist . 86: 124-131
    • Blum, A.E., Eberl. D.D. & Rutherford, D.W. Quatitative Determination of Smectite Surface Areas by the sorption of polyvinylpyrrolidone. Ninth Annual V.M. Goldschmidt Conference . 7567.pdf
    • Cervini-Silva, J., et al. (2001) Transformation of Chlorinated Aliphatic Compounds by Ferruginous Smectite. Environmental Science and Technology. 35: 805-809.
    • Ghosh, A & McSween Jr., H.Y. Normative Minerology and Possible Origin of Mars Pathfinder Soils. Online.
    • Guangyao, H.L., et al. (2003) Sorption and Desorption of Pesticides by Clay Minerals and Humic Acid- Clay Complexes. Soil Science Society Americal Journal. 67: 122-131.
    • Johnston, C.T. et al. Spectroscopic Study of Nitroaromatic—Smectite Sorption Mechanisms. Environmental Science & Technology . American Chemical Society.
    • Kasama, T., et al. (2001) Experimental mixtures of smectite and rectorite: Re-investigation of “fundamental particles” and “interparticle diffraction”. American Minerologist. 86: 105-114.
    • Parry, W.T., Jasumback, M. & Wilson, P.M. (2002) Clay Minerology of Phyllic and Intermediate Agrillic Alteration at Bingham, Utah. Economic Geology . 97: 221-239.
    • Stixrude, L & Peacor, D.R. (2002) First-principles study of illite-smectite and implications for clay-mineral systems. Nature. 420: 165-168.
    • Trentstesaux, A., et al. (2003) Data Report: Pleistocene Paleoclimatic Cyclivity of Southern China: Clay Mineral Evidence Recorded in the South China Sea (ODP Site 1146). Proceedings of the Ocean Drilling Program, Scientific Results. 184: 1-10.
    • Vrolijk, P. & van der Pluijm, B.A. (1999) Clay Gouge. Journal of Structural Geology . 21: 1039-1048.
  • For more thoroughly exhilarating reading on smectites:
    • http://www.smm.org/general_info/bhop/Smectiteandbentoniteclay.html
    • http://www.mindat.org/min-11119.html
    • http://www.renneckerltd.com/rltd_aboutsmectite.htm
    • http://www.rtvanderbilt.com/veegum.pdf
    • http://www.claytone.net/clay/cchem.html
    • http://www7430.nrlssc.navy.mil/biogeochemistry/smectiteillite.htm
    • http://chemical.kowa.com/coop_chemical.html
    • http://www.cnr.berkeley.edu/~rsutton/cmsabstract.html
    • http://www.rtvanderbilt.com/veegumdd_a.htm
    • http://www.oilvel.com/Dutta_quotes2.html
    • http://www.workpage.com/e/58/177e.htm
    • http://www.renneckerltd.com/Products/rltd_magnabrite01.htm
    • http://www-odp.tamu.edu/publications/184_SR/VOLUME/CHAPTERS/210.PDF
    • http://cips.berkeley.edu/research/cervini-silva_transformation.pdf
    • http://www.cnr.berkeley.edu/~rsutton/modelclay.html
    • http://www.cnr.berkeley.edu/~rsutton/clays.html
    • http://www.glossary.oilfield.slb.com/Display.cfm?Term=smectite+clay
    • http://www.permont.com/11/1112/tsld002.htm
    • http://www.geo.wvu.edu/%7Ekite/Geol321Lect04Weathering2002/
    • http://members.segweb.org/PDF97-2/221_Prry.pdf
    • http://www.quanterra.org/Patissier.htm
    • http://www-odp.tamu.edu/publications/178_SR/chap_08/chap_08.htm
    • http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=343765
    • http://www.claytone.net/pain/pain.html
    • http://www.eytonsearth.org/claychemistry.html
    • http://www.seismo.berkeley.edu/~jill/silweath.html
    • http://www.gly.uga.edu/schroeder/geol3010/smectite.gif
    • http://www.petrotech-assoc.com/prod01.htm
    • http://www.glossary.oilfield.slb.com/DisplayImage.cfm?ID=183
    • http://energy.usgs.gov/factsheets/Petroleum/SEM.html
    • http://homepages.uc.edu:8000/~maynarjb/603/GeochemWater/ClayImages.htm
    • http://www.kimb.or.kr/im_data/picture/mineral/img/montmorillonite.jpg