The position of magma chambers?

Question

Where do magma chambers exist? Is it necessary that they exist in the asthenosphere where the circumstances of temperature and pressure are suitable for the rocks to be molten? Or they exist in places of shallow depth?

Answer 1

Magma chambers can exist in the shallow crust, as long as the conditions for the movement of the magma up to shallow conditions is possible. One condition that may be necessary is that there is enough magma to maintain a temperature high enough to still have molten material to get up to the shallow crust. If not, you can imagine a slow moving, small body of magma crystallising before it reaches shallow depths. Indeed, there is quite a bit of evidence for molten material in the crust, with the crust itself melting to produce areas that are rich in melt. The rocks that I study have very high melt conditions, which is a function of the temperature of Moho (crustal/mantle boundary) and the make up of the rocks itself.