L07_18_Sept_Petrology

A series of paraal melang events is necessary to

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: and melAng of igneous rocks Temperature dry molten rock solid rock Pressure A possible scenario for melAng in a subducAon zone P- T phase diagrams and melAng of igneous rocks Temperature A possible scenario for melAng in a subducAon zone molten rock wet solid rock Pressure OK, great. But we sAll have not answered the quesAon of how conAnental- type rocks are derived from their mantle precursors. PrimiAve, Precursor Rocks Evolved, Derived Rocks 1200°C ocean crust 1300°C 1000°C 900°C Bowen’s reacAon series shows the relaAve melAng temperature of the important igneous rock- forming minerals: Here it shows that olivine melts at ~1400°C, pyroxene at ~1300°, quartz at ~800°, and so on. Thus consider a rock heated to 1200°: Olivine, pyroxene, and calcium- rich feldspars would remain as solid minerals, whereas amphiboles, bioAtes, sodium- rich feldspars, etc. would melt. This rock in now parAally melted. conAnental crust 1100°C ParAal MelAng Rock at T1 ParAal MelAng Rock at T1 Rock at T2 T2 > T1 ParAal MelAng Begins ParAal MelAng Residual Rock at T1 Rock at T2 T2 > T1 ParAal MelAng Begins Melt Separate...
View Full Document

This document was uploaded on 03/26/2014 for the course GEC AS.270.103 at Johns Hopkins.

Ask a homework question - tutors are online