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Topographic history of the Australian region since the Cretaceous

Summary: Comparison of Models

From 140 Ma Dip 50 From 140 Ma Dip 30 From 140 Ma strong lower mantle From 50 Ma From 50 Ma NE focus
temp(pdf) temp(pdf) temp(pdf) temp(pdf)
surf(pdf) surf(pdf) surf(pdf) surf(pdf)

TOMOGRAPHY

  • Tomography 300-410 (pdf)
  • Tomography 410-510 (pdf)
  • Tomography 300-660 (pdf)
  • Tomography 660-1500 (pdf)

    • Present day locations of subduction zones

  • fossil slabs (pdf)

    • Hot Antarctica Models since 50 Ma

    Model Viscosity Phase change Temperature Movies Topography
    Weak asthenosphere
    M9 100,0.1,5,50 clap410=4
    clap660=-2    		 R(pdf) S(pdf)
    M9new 100,0.1,5,50 clap410=4
    clap660=-2    		 R(pdf) S(pdf)

    Hot Antarctica cross section compared with other models (pdf)

    GRL PAPER & FIGURES

  • paper(doc)
  • Figure1
  • Figure2
  • Figure3
  • Figure4
  • Figure5

    • Geodynamic Models since 50 Ma

    This table contains all the models run from 50 Ma.

    Model Viscosity Phase change Temperature Movies Surface Movies XY North XY QLD & MAR Tilt
    weak lower mantle
    M1 100,1,5,10 clap410=4
    clap660=-2    		 R(pdf) S(pdf) pdf pdf pdf
    M2 100,1,5,10 clap410=4
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M3 100,1,5,10 clap410=2
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M4 100,1,5,10 clap410=2.9
    clap660=-3    		 R(pdf) pdf pdf pdf pdf
    Strong lower mantle
    M5 100,1,5,50 clap410=4
    clap660=-2    		 R(pdf) pdf pdf pdf pdf
    M6 100,1,5,50 clap410=4
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M7 100,1,5,50 clap410=2
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M8 100,1,5,50 clap410=2.9
    clap660=-3    		 R(pdf) pdf pdf pdf pdf
    Weak asthenosphere
    M9 100,0.1,5,50 clap410=4
    clap660=-2    		 R(pdf) pdf pdf pdf pdf
    M10 100,0.1,5,50 clap410=4
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M11 100,0.1,5,50 clap410=2
    clap660=-4    		 R(pdf) pdf pdf pdf pdf
    M12 100,0.1,5,50 clap410=2.9
    clap660=-3    		 R(pdf) pdf pdf pdf pdf

    Geodynamic Models since 140 Ma

    Model Viscosity Phase change Temperature Surface Composition XY plots
    99 100,1,5,50 clap410=4
    clap660=-2    		 T(pdf) S(pdf) X100(pdf) XY (pdf)
    107 100,1,5,50 clap410=4
    clap660=-4    		 T(pdf) S(pdf) C(pdf)
    C2(pdf)     		X100(pdf) XY (pdf)
    105 # 100,1,5,50 clap410=2
    clap660=-4    		 T(pdf) S(pdf) XY (pdf)
    111 100,1,5,50 clap410=2.9
    clap660=-3    		 R(pdf)
    Weak lower mantle
    102 100,1,5,10 clap410=4
    clap660=-2    		 R(pdf) S(pdf) X100(pdf) XY (pdf)
    108 100,1,5,10 clap410=4
    clap660=-4    		 T(pdf) S(pdf) X100(pdf) XY (pdf)
    112 100,1,5,10 clap410=2
    clap660=-4    		 T(pdf) S(pdf)
    106 * 100,1,5,10 clap410=2.9
    clap660=-3    		 T(pdf) S(pdf) XY (pdf)
    Weak asthenosphere Strong lower mantle
    129 100,0.1,5,50 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    128 100,0.1,5,50 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    130 100,0.1,5,50 clap410=2
    clap660=-4    		 T(pdf) S(pdf)
    Weak asthenosphere Strong lower mantle 660 km cut
    132 100,0.1,5,50 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    131 100,0.1,5,50 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    Weak asthenosphere
    103 100,0.1,5,10 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    113 100,0.1,5,10 clap410=4
    clap660=-4    		 T(pdf)
    Strong 660 phase change
    118 100,1,5,50 clap410=4
    clap660=-6    		 T(pdf) S(pdf)
    119 100,1,5,10 clap410=4
    clap660=-6    		 T(pdf) S(pdf)
    120 100,0.1,5,10 clap410=4
    clap660=-6    		 T(pdf) S(pdf)
    Plots with Dip 30
    115 100,1,5,50 clap410=4
    clap660=-4    		 T(pdf)
    116 100,1,5,50 clap410=2
    clap660=-4    		 T(pdf) S(pdf)
    117 100,1,5,10 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    Very strong Lower mantle
    121 100,1,5,100 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    122 100,1,5,100 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    123 100,1,5,100 clap410=2
    clap660=-4    		 T(pdf) S(pdf)
    No material between 660 and Lower mantle
    124 100,1,5,100 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    125 100,1,5,100 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    126 100,1,5,100 clap410=2
    clap660=-4    		 T(pdf) S(pdf)
    Weak asthenosphere strong lower mantle
    127 100,0.1,5,100 clap410=4
    clap660=-2    		 T(pdf) S(pdf)
    128 100,0.1,5,100 clap410=4
    clap660=-4    		 T(pdf) S(pdf)
    129 100,0.1,5,100 clap410=2
    clap660=-4    		 T(pdf) S(pdf)

    XY plots of convergence

  • Continued convergence on the eastern margin of Australia quantified (pdf) Total distance converged = 670 km
  • convergence at the Melanesian subduction zone quantified (pdf) Total distance converged = 1013 km

    • XY plots of convergence

  • Continued convergence on the eastern margin of Australia quantified (pdf) Total distance converged = 670 km
  • convergence at the Melanesian subduction zone quantified (pdf) Total distance converged = 1013 km

    • Modeling Parameters

    Modeling parameters document (pdf)
    Log of viscosity variation with temperature
    viscosity variation with temperature
    Old models
    Layer Viscosity '98 Value clap slope MPa/K '98 Value dens difference kg/m3 '98 Value
    0-100 e23 e23 0 0 0 0
    100-410 e21 e21 4 2 100 ~165
    410-660 e21 e21 -2 -4.2 340 263
    660 -CMB e23 e22 0 0 0 0

    Coupled Subduction Study with 50 degree slab dip and inital slab positioned near QLD

    We place the slab closer to the Australian coastling consistent with estimated stretching since the Late Cretaceous

    Model Close up Dynamic topography Notes
    101 100,0.1,1,50 clap410=4
    clap660=-2    		 reg(pdf)
    100 100,0.1,5,50 clap410=4
    clap660=-2    		 reg(pdf)
    Coupled 100 Close up M100
    TILT
    BASIN XY
    DYN TOPO
    tracers     		Same as 99 except decreased asth (50,0.1,5,50),
    Coupled 99 Close up M99
    TILT
    BASIN XY
    DYN TOPO
    tracers     		Same as 93 except lith decreased (50,1,5,50), lith_age depth is now 0.008 instead of 0.01, cleaned up age grids ie material is removed from the subuction zone to the wedge area.
    Coupled 98 Close up M98 tracer file
    TILT
    BASIN XY
    DYN TOPO
    tracers     		Same as 95 but decreased viscosity of lith to try to make model run(50,1,5,10). Same problem with tracers. The exiting is certainly a loss of tracers issue with the lower mantle set to 10.
    Coupled 97 Close up M97 TILT
    BASIN XY
    DYN TOPO
    tracers     		Same viscosity (100,1,5,10) mantle wedge viscosity 0.1. Wedge more spread out in the upper mantle.
    Coupled 96 Close up M96 tracer file
    TILT
    BASIN XY
    DYN TOPO
    tracers     		Same viscosity (100,1,5,10) decresed the mantle wedge viscosity to 0.01 from 0.1 reduce by factor of 100 instead of 10. Code ran slow and also exited. Same problem I think comes in tracer file. Loss of too many tracers.The slab gets dragged towards the east too far in this model.
    Coupled 95 Close up M95
    tracer file
    BASIN XY
    DYN TOPO
    tracers     		Reduced lower mantle viscosity. Visc layers:100,1,5,10 also reduced the depth to which the age grids are assimilated into the model from 0.01 (~60km) to lith_age_depth = 0.008 (~50 km). Hoping to remove some of material that gets inserted in NZ region. Exited. Appears to be an issue in the tracer file. Slab stays in the correct position in the upper mantle.
    Coupled 94 Close up M94 TILT39Ma
    BASIN XY
    DYN TOPO
    tracers     		Reduced Visc layers: 100,0.5,5,50. Contiguous slab to lower mantle. Slab extends to 2000 m depth. Slab for the AAD does not land in the right position the best so far is M93!
    93 100,1,5,50 clap410=4
    clap660=-2    		 regional map (flash)
    Coupled 93 Close up M93 TILT71Ma
    TILT37Ma
    BASIN XY
    DYN TOPO
    tracers     		Visc layers: 100,1,5,50. Contiguous slab to lower mantle. Slab extends to 2000 m depth. Fixed tracers.
    Southern maps
    northern maps
    Coupled 92 Close up M92 TILT
    BASIN XY
    DYN TOPO
    tracers     		Notes: Decrese the visc layers: 100,1,5,50. Changed the 660 density diff to (236 from 340). Added a different velocity to the surface (11 cm/yr). Model exits again at step 2681 ~41 Ma From the tracer file I can see that there is a problem with the continental tracers being advected into the mantle.
    Coupled 91 Close up M91 DYN TOPO Decrese the visc layers: 100,1,5,50. Model exits at step 2600 ~43Ma
    Coupled 90 Close up M90 TILT
    BASIN XY
    DYN TOPO    		 Even better looking subduction with less material dragged into the wedge from the slab and overriding plate.
    Coupled 89 Close up M89 surface Cause the slab to be pushed into the mantle more gets better subduction. However model exits at 2700 with no error. A lot of slab material gets dragged into the wedge area above the slab. Could be good for dynamic topography.
    Coupled 88 Close up M88 surface Notes: some overriding plate material dragged into mantle by barc vel. However the slab lies flat along the 660. Nice!
    Coupled 87 Close up surface notes: barc vel not great enough
    Coupled 80 Coupled 80 Surface Solver not converging
    Coupled 81 Coupled 81 Surface Increased the visc max 1000
    Coupled 82 Coupled 82 Surface Make the initial slab less diffuse
    Coupled 83 Coupled 83 Surface Decrease the tolerance from 6e-06 to 1e-06

    Science model

    Science model maps
    Science model close up
    Science model dynamic topography

    Geodynamic model compared to tomography

    Compare this tomographic slice rotated to equator coordinates
    To this geodynamic slice from Model 42 at 0 Ma
    This is a comparison of multiple tomography models through the same cross section: Several Tomography Models

    Here is a series of map sections (pdf)

    New Subduction Study

    We know that the slab must initially dip 20 to 30 degrees so the slab material is positioned beneath the AAD in the present. However this effects the subduction parameters (backarc velocity, viscosity).These have never been perfect even for greater slab dips (see below). Here we are altering the parameters to see if we can get better looking subduction for 30 degree dips.
    Model no. Layered Viscosity Activation Energy Dip Slab temp Transition zone
    Subduction west backarc velocity (3.5cm/yr barc vel over a broad region in the back-arc) 100,1,10,100 11,11,11,11 50 Cold temp not connected
    Subduction west backarc velocity (7cm/yr) 100,1,10,100 11,11,11,11 50 Cold temp not connected
    Subduction west colder 100,1,10,100 11,11,11,11 50 Cold temp not connected
    Subduction west 100,1,10,100 11,11,11,11 50 Normal temp connected
    S4 100,0.1,5,100 11,11,11,11 20 20% colder no connection
    S3 100,0.1,5,100 11,11,11,11 30 20% colder no connection
    S6 100,0.1,5,100 11,11,11,11 30 Normal temp connected
    S8 100,0.1,5,100 11,11,11,11 30 Normal temp no connection
    S9 100,1,10,100 11,11,11,11 30 20 % colder no connection
    S9 Without mantle domains 100,1,10,100 11,11,11,11 30 20 % colder no connection
    S10 100,1,10,100 11,11,11,11 30 normal temp no connection
    S11 100,1,10,100 11,11,11,11 30 normal temp no connection
    S12 100,1,10,100 11,11,11,11 30 20% colder no connection
    S13 100,0.1,5,100 11,11,11,11 30 20% colder no connection
    S14 100,0.1,5,100 11,11,11,11 30 Normal Temp no connection

    New Plots

  • Model with 4 tracer flavors
    		•  Regional maps Close up + viscosity contours
  • Model with viscous wedge
    		•  Regional maps Close up + viscosity contours
  • Same model without viscous wedge
    		•  M66 regional maps Close up
  • Rerun Science model with new boundary conditions
    		•  Regional Maps Close up
  • Rerun Science model with no age bc
    		•  Regional Maps Close up
  • Tracers distribution
    		•  20 degree slab dip with all tracers 30 degree slab dip with all tracers

    Detailed study of Model 54

    Model no. EW or NS line along nx/ny Tomo rot equator Tomo true
    M54 EW nx166 Eq:nx166
    M54 EW nx130 Eq:nx130 Pole:nx130
    M54 EW nx100 Eq:nx100 Pole:nx100
    M54 EW nx50 Eq:nx50 Pole:nx50
    M54 NS ny120 Eq:ny120 Pole:ny120

    Small scale convection from M54

    EW cross sect nx:166 NS cross sect ny:50 NS cross sect ny:51 NS cross sect ny:52

    Variation of slab dip, Viscosity and Activation energy

    Key to colored boxes
    Large backarc velocities
    44cm/yr:140-120 Ma 11cm/yr:120-99 Ma     		Small backarc velocities
    22cm/yr:140-120 Ma 11cm/yr:120-99 Ma     		No backarc velocities

    All Models

    Good Regional Maps Close Maps R topo Global Maps Gtopo step Layered Viscostity AE dip End
    41 Close 100,0.1,5,100 7,7,7,7 10 2Ma
    42 Close 100,0.1,5,100 7,7,7,7 20 0Ma
    ✓ 59 Close 200km 620km 320 100,1,10,100 7,7,7,7 20 0 Ma
    ✓ 56 Close 620km 100,0.1,5,100 11,11,11,11 20 5 Ma
    ✓ 65 Close 620km 100,1,10,100 11,11,11,11 20 0Ma
    67break Close 200km 620km 100,1,10,100 11,11,11,11 20 0Ma
    43 Close 200km 620km 100,0.1,5,100 7,7,7,7 30 0Ma
    ✓ 63 Close 200km 620km 100,1,10,100 7,7,7,7 30 0Ma
    64 Close 200km 620km 100,1,10,100 11,11,11,11 30 0Ma
    44 Close 100,0.1,5,100 7,7,7,7 40 0Ma
    50 Close 100,0.1,5,100 7,7,7,7 50 1Ma
    45 Close 100,0.1,5,100 7,7,7,7 10 0Ma
    46 Close 100,0.1,5,100 7,7,7,7 20 1Ma
    ✓ 61 Close 200km 620km 320 100,1,10,100 7,7,7,7 20 1Ma
    ✓ 57 Close 200km 100,0.1,5,100 11,11,11,11 20 7Ma
    ✓ 62 Close 200km 620km 320 100,1,10,100 11,11,11,11 20 0Ma
    47 Close 100,0.1,5,100 7,7,7,7 30 1Ma
    48 Close 100,0.1,5,100 7,7,7,7 40 0Ma
    49 Close 100,0.1,5,100 7,7,7,7 50 bad
    55 Close 100,0.1,5,100 7,7,7,7 10 0Ma
    54 Close 200km 100,0.1,5,100 7,7,7,7 20 0 Ma
    ✓ 60 Close 200kmA
    200kmB
    125km    		 620km 320 100,1,10,100 7,7,7,7 20 0Ma
    58 Close 100,0.1,5,100 11,11,11,11 20 6Ma
    ✓ 66 Close 200kmA 620km 320 100,1,10,100 11,11,11,11 20 0Ma
    53 Close 100,0.1,5,100 7,7,7,7 30 2Ma
    52 Close 100,0.1,5,100 7,7,7,7 40 1Ma
    51 Close 100,0.1,5,100 7,7,7,7 50 1Ma
    Comparison plots
    Model 42 and 46 (20,20) strong barc, weak barc
    M41 & 42 (10,20)
    M43 & 44 (30,40)
    M44 & 50 (40,50)
    AE: M42 & 56(20,20)    		 M45 & 46(10,20)
    M47 & 48(30,40)
    M48 & 49(40,50)
    AE:M46 & 57(20,20)    		 M55 & 54(10,20)
    M53 & 52(30,40)
    M52 & 51(40,50)
    AE: M54 & 58(20,20)

    Result 1:

    Subsidence and uplift of E margin of Australia 140 - 90 Ma

    Geologic observations, tectonic subsidence analysis suggest:
    1) Subsidence is greater in Surat than Eromanga. 140 -118
    2) Spike in subsidence in Surat ~118 Ma
    2) Spike in Eromanga ~100 Ma, where subsidence follows the passage of a slab beneath the basins.

    Result 2:

    Tilting of the Northern margin of Australia 40-0 Ma

    DiCaprio et al 2008 suggest: Northeastward-down tilt of Australia increases as the continent moves towards SE Asian subduction realm by up to 400 m.

    Tomography sections

    These plots were produced using scripts provided by Bernhard Steinberger.The model data was taken from the spice website: spice
    I downloaded the following directory: new .ab formatted models
    Model name Rotated coordinates to compare to geodynamic models Reference
    smean.31.m.ab smean rot original SMEAN (see Becker and Boschi 2002)
    smeanl.31.m.ab smean rot SMEAN with finer vertical sampling (more layers)
    sb4l16.31.m.ab sb4l16 rot Scripps http://mahi.ucsd.edu/Gabi/3dmodels.html
    saw24b16.31.m.ab saw24b16 rot Berkeley http://seismo.berkeley.edu/~barbara/global.html
    s20rts.31.m.ab s20rts rot Ritsema et al. http://oshi.geo.lsa.umich.edu/~jritsema/Research.html
    ngrand.31.m.ab ngrand rot Steve Grand and others (see Becker and Boschi 2002)
    pri-s05.31.m.ab pri-s05 rot Princeton (Montelli et al.) S model, Gcubed 2006
    pri-p05.31.m.ab pri-p05 rot Princeton (Montelli et al.) P model, Gcubed 2006
    tx2007.31.m.ab Simmons, N. A., A. M. Forte, and S. P. Grand (2007)
    s362d1.31.m.ab Harvard model, Gu and others (see Becker and Boschi 2002)

    22/1 Tuesday Conference Call

    29/1 Thursday Conference Call