!--------1---------2---------3---------4---------5---------6---------7---------8
subroutine melt_check(i) 
!--------1---------2---------3---------4---------5---------6---------7---------8
  use global_constants, only : rkind, density, dt, time,year,Myr &
    & , volume_ratio_rock, Rocky_Core, mass_ratio_rock_H2O_solar
  use global_parameters, only : radius, temp, surface_area, dr, halfdr
  use heat_parameters, only : specific_heat, latent_heat_init &
    & , thermal_conductivity
  use ice_parameters, only : temperature_melting_I
  use material_parameters, only : ice_water_rock, iw, mn, material_select &
    & , iw_old, ir_old, drock, radius_water, ii, mass_ratio_rock &
    & , mass_ratio_ice, mass_ratio_water, mass_ratio_anhydrous_rock, mass_ratio_hydrous_rock
  use energy, only : lat_energy
  use heat_radiogenic, only : iAl, ftime
  implicit none
  integer,intent(in) :: i
  real(rkind) :: dm,  m, latent_heat, coef_dm, time_Myr&
    & , Tspecific_heat, Tdensity
  if(mn(i) == 11 .OR. mn(i) == 13 .OR. mn(i) == 12 .OR. mn(i) == 9) return
  m = mass_ratio_ice(i)
  if(m == 0._rkind) then
    return
  elseif(m > 0._rkind) then
    if(mn(i) == 7 .OR. mn(i) == 6) then
      mn(i) = 7
    elseif(mn(i) == 8) then
      mn(i) = 8
    elseif(mn(i) == 3) then
      mn(i) = 3
    else
      call log_error(i,'melt_check mn(i)')
      return
    endif
    latent_heat = latent_heat_init
    coef_dm = Tspecific_heat(i)/(latent_heat)
    dm = (temp(i)-temperature_melting_I)*coef_dm
    lat_energy(i) = lat_energy(i) + latent_heat*dm*Tdensity(i)*surface_area(i)*dr/dt
    temp(i) = temperature_melting_I
    m = m - dm
    mass_ratio_water(i) = mass_ratio_water(i) + dm
  time_Myr = (time/year+ftime(iAl))/Myr
    if(m <= 1e-7_rkind) then
      m = 0._rkind
      if(i>=2) drock = drock + (radius(i)+halfdr-radius_water) &
        & *(mass_ratio_anhydrous_rock(i)/density(4)+mass_ratio_hydrous_rock(i)/density(4))&
        & *Tdensity(i)*radius_water*radius_water
      radius_water = radius(i)+halfdr
      if(i /= 0) then
        if(Rocky_Core) mn(i) = 1
        if(.NOT.Rocky_Core) mn(i) = 15
      elseif(i == 0) then
        m = 0._rkind
        if(.NOT.Rocky_Core) mn(i) = 15
      endif
    endif
  elseif(m < 0._rkind) then
    m = 0._rkind
    if(i>=2) drock = drock + (radius(i)+halfdr-radius_water) &
      & *(mass_ratio_anhydrous_rock(i)/density(4)+mass_ratio_hydrous_rock(i)/density(4))&
      & *Tdensity(i)*radius_water*radius_water
      radius_water = radius(i)+halfdr
    if(i /= 0) then
      if(Rocky_Core) mn(i) = 1
      if(.NOT.Rocky_Core) mn(i) = 15
    elseif(i == 0) then
      m = 0._rkind
      if(.NOT.Rocky_Core) mn(i) = 15
    endif
    return
  else
    write(999,*) 'error occurs at melt_check!'
    write(999,*)  i, temp(i), m
    call log_error(i,'melt_check')
    return
  endif
  mass_ratio_ice(i) = m
  return
end subroutine melt_check