|
|
|
|
| Continental Geotherms |
|
| Before to look at what happens to the geotherm during and following lithospheric deformation, let's have a glance at how sensitive is the geotherm to a number of thermal parameters. |
|
| Distribution of Radiogenic Heat Production. |
|
|
| We have assumed so far that A was a constant. However, because the upper crust is enriched in incompatible elements (elements with large radius that have the tendency to move into the melt when partial melting occurs) the radiogenic heat production decreases with depth. A common model assumes that A is divided by e (=2.71) every h metres, h being the length scale of the exponential law: |
|
 |
|
|
 |
|
| The graphs on the right show the geotherm for A decreasing exponentially with various length scale h (10, 25, 50km). Ao is adjusted so that the total radiogenic heat production (R.H.P) is the same in all models. The larger is h (i.e. the deeper are the radiogenic elements) the hotter is the geotherm. |
|
|
|
|
|
|
|
|
|
