Most magmas contain some solid crystals suspended in the liquid phase. This indicates that the temperature of the magma lies between the solidus, which is defined as the temperature at which the magma completely solidifies, and the liquidus, defined as the temperature at which the magma is completely liquid. Calculations of solidus temperatures at likely depths suggests that magma generated beneath areas of rifting starts at a temperature of about . Magma generated from mantle plumes may be as hot as . The temperature of magma generated in subduction zones, where water vapor lowers the melting temperature, may be as low as .
mOSt magMAS ConTaiN some solID cRystals suspEnDed in THe liQUId phAsE. tHis IndicateS THaT the TEmperaTUre of The Magma LiEs betweeN tHE sOlidus, which Is definEd AS The TemPeratUre AT wHicH the magmA ComPletEly solidifIEs, and the liquIduS, deFiNEd AS tHe TempErAture At which The MAgma IS ComPLETely liqUid. CaLCuLaTionS of SOLiDUs tEmpeRAtURes at likely depThS suGgests that maGma GeNerateD beNeaTH areas Of rIfting Starts At a TeMpErAtURe of ABouT . magma GEnerAted fRoM mantlE Plumes May Be as HOt as . the TEmPeRaTuRe oF mAGMA geNerAted In SUbDuCtIOn zoNes, wHerE wAteR VapoR LOweRS the melTInG tEmpEratUre, May be as LOW as .