Implement continental geotherm from Chapman (1986)

[alanjyu]

To address Issue #778, I implemented the continental geotherm profile for the Continental Plate model, using the 1-D steady state heat equation from Chapman (1986):

$$ T(z) = T_{t} + \frac{q_{t}}{k} \Delta z - \frac{A}{2k} {\Delta z}^2 $$

where $T$ is temperature in K, $z$ is depth, $T_t$ is the top surface temperature of the feature in K (denoted 'top temperature' in the input file), $q_t$ is the top surface heat flux in W $\text{m}^{-1}$ $\text{K}^{-1}$ ('top heat flux'), $k$ is the thermal conductivity in W $\text{m}^{-1}$ $\text{K}^{-1}$ ('thermal conductivity'), $A$ is the heat production per unit volume in W $\text{m}^{-3}$ ('heat generation per unit volume'), and $\Delta z$ is change in depth between the current depth and the minimum depth in m.

The test and documentation will be implemented later.

[alanjyu]

I added the test files for the Chapman continental geotherm.

[github-actions]

Benchmark	Main	Feature	Difference (99.9% CI)
Slab interpolation simple none	1.117 ± 0.013 (s=389)	1.132 ± 0.010 (s=414)	+1.1% .. +1.6%
Slab interpolation curved simple none	1.133 ± 0.012 (s=392)	1.146 ± 0.013 (s=400)	+0.9% .. +1.4%
Spherical slab interpolation simple none	1.101 ± 0.009 (s=426)	1.110 ± 0.009 (s=391)	+0.6% .. +1.0%
Slab interpolation simple curved CMS	1.166 ± 0.011 (s=386)	1.178 ± 0.010 (s=385)	+0.8% .. +1.2%
Spherical slab interpolation simple CMS	1.446 ± 0.013 (s=310)	1.453 ± 0.013 (s=313)	+0.2% .. +0.7%
Spherical fault interpolation simple none	1.103 ± 0.012 (s=380)	1.113 ± 0.010 (s=434)	+0.7% .. +1.2%
Cartesian min max surface	2.555 ± 0.018 (s=182)	2.586 ± 0.028 (s=171)	+0.9% .. +1.5%
Spherical min max surface	7.184 ± 0.065 (s=72)	7.246 ± 0.066 (s=55)	+0.3% .. +1.4%

[MFraters]

Looks good to me, thanks for implementing this!