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16 Nov 2019
The simplest thermal model of oceanic lithosphere is obtained from the heat equation for one (vertical) space dimension. The solution is T(z, t) = T_a erf (z/2 Squareroot kt). a) Given this solution, with k = 10^-6 m^2 s^-1, and an asthenosphere temperature of T_a = 1300 degree C, plot a geotherm for oceanic lithosphere of age 60 Ma. In the plot, let the Vertical axis point down, with a maximum depth of z = 100 km. Label both axes and include units. b) Now define the thickness of the lithosphere by the depth of the 1150 degree C isotherm, and obtain an expression for the lithosphere thickness as a function of time. What is the lithospheric thickness at 20 Ma, 60 Ma and 80 Ma? c) Given a spreading half-rate of 5 cm/year, find the distance (in km) from the ridge axis for the three ages given in part b.
The simplest thermal model of oceanic lithosphere is obtained from the heat equation for one (vertical) space dimension. The solution is T(z, t) = T_a erf (z/2 Squareroot kt). a) Given this solution, with k = 10^-6 m^2 s^-1, and an asthenosphere temperature of T_a = 1300 degree C, plot a geotherm for oceanic lithosphere of age 60 Ma. In the plot, let the Vertical axis point down, with a maximum depth of z = 100 km. Label both axes and include units. b) Now define the thickness of the lithosphere by the depth of the 1150 degree C isotherm, and obtain an expression for the lithosphere thickness as a function of time. What is the lithospheric thickness at 20 Ma, 60 Ma and 80 Ma? c) Given a spreading half-rate of 5 cm/year, find the distance (in km) from the ridge axis for the three ages given in part b.