Abnormal sediment_1 Distribution and Model Crash During Plate Subduction with LAB Thermal Adjustments

ASPECT
1

Hi everyone,

I’m encountering an unexpected issue with the sediment_1 component field in my ASPECT subduction models under Archean (Ar) and Phanerozoic (Ph) thermal regimes. When increasing the LAB temperature or reducing lithospheric thickness, half of the sediment develops a wedge-shaped morphology (see attached please), which destabilizes the crustal layer and ultimately causes the model to terminate with errors after significant slab tilting. Additionally, sporadic sediment_1 accumulation occurs intermittently on the opposite side of the domain. I attempted disabling the shared plugin, incrementally adjusting thermal parameters and lithospheric thickness, and deactivating FastScape, but these did not resolve the issue. Could anyone advise on the potential causes and solutions? Thank you for your expertise!

Best,
Noriel

Nomal one:

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image780×432 9.09 KB

Abnormal one:
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image828×464 37.6 KB

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image1097×642 22.6 KB

It’s one of my input files:

Ar3-2.prm (20.4 KB)

###---------------------------------------------------------------------------Temperature------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
# Temperature boundary conditions
# Top and bottom (fixed) temperatures are consistent with the initial temperature field
# Note that while temperatures are specified for the model sides, these values are not used as the sides are not specified "Fixed temperature boundaries".  Rather, these boundaries are insulating (zero net heat flux).

subsection Boundary temperature model
  set Fixed temperature boundary indicators = bottom, top
  set List of model names = box

  subsection Box
    set Bottom temperature = 1825 
    set Top temperature    =  273
  end
end

subsection Initial temperature model
  set Model name = function

  subsection Function
    set Variable names = x,y
    set Function constants = h=600e3, ts1=273, ts2=723, ts3=993,\
                             A1=1.8e-6, A2=0.45e-6, A3=0.0, \
                             k1=2.5, k2=2.5, k3=2.5, \
                             qs1=0.074, qs2=0.038, qs3=0.020
	set Function expression = if((h-y) <= 20.e3, \
	    ts1 + (qs1/k1)*(h-y) - (A1*(h-y)*(h-y))/(2.0*k1), \
	    if((h-y) > 20.e3 && (h-y) <= 40.e3, \
	        ts2 + (qs2/k2)*(h-y-20.e3) - (A2*(h-y-20.e3)*(h-y-20.e3))/(2.0*k2), \
	        if((h-y) > 40.e3 && (h-y) <= 120.e3, \
	            ts3 + (qs3/k3)*(h-y-40.e3) - (A3*(h-y-40.e3)*(h-y-40.e3))/(2.0*k3), \
	            if((h-y) > 120.e3, \
	                ts3 + (qs3/k3)*(120.e3-40.e3) - (A3*(120.e3-40.e3)*(120.e3-40.e3))/(2.0*k3) + 0.4*((h-y)-120.e3)/1.e3, 273 ))))
  end
end

# Constant internal heat production values (W/m^3) for background material
# and compositional fields.
subsection Heating model
  set List of model names = compositional heating

  subsection Compositional heating
    set Use compositional field for heat production averaging = 1, 0, 0, 1, 1, 1,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0
    set Compositional heating values = 0.0, 0.0, 0.0, 1.8e-6, 0.45e-6, 0.0,0, 0,0, 0,0, 0,0, 0,0, 0,0, 0
  end
end
2

Hi @Noriel,

Thanks for posting the questions to the forum. I unfortunately don’t have any immediate insights into what exactly is happening.

Do you have any subduction models that are behaving in a manner that you expect?

It will be much easier to diagnose the issue if you can show how changing one or two parameters from a “well-behaved” model results in unphysical behavior.

Cheers,
John