Oxygen isotope variations in oceanic magmatic rock suites: assimilation-fractional crystallization processes versus mantle source variations

Third party funded individual grant

Project Details

Project leader:
Prof. Dr. Karsten Haase
Prof. Dr. Michael Joachimski
Dr. Stefan Krumm

Contributing FAU Organisations:
Lehrstuhl für Endogene Geodynamik
Lehrstuhl für Geologie (Exogene Dynamik)

Funding source: Deutsche Forschungsgemeinschaft (DFG)
Start date: 01/01/2009
End date: 31/12/2010

Abstract (technical / expert description):

Oxygen isotopes are an important tool to study reactions between ascending mantle-derived magmas and material in the oceanic lithosphere that has been altered by surface processes like for example, sediments or hydrothermally altered rocks. Furthermore, crystal fractionation processes can also affect the O isotope composition especially of evolved magmas because different mineral phases fractionate O isotopes. Both assimilation and crystal fractionation thus impede the study of O isotope compositions of the magma sources in the mantle which could give important insights into recycling processes at subduction zones and in deep mantle plume-derived intraplate magmas. Here we suggest a study of the O isotope variation of five well-characterized lava series from different oceanic magmatic settings (mid-ocean ridge, oceanic intraplate, back-arc, and island arc settings) in order to define the variations between basaltic and silicic lavas and the processes affecting the O isotope ratios. Based on the understanding of lithospheric processes we will be able to distinguish the O isotope composition of the mantle sources of the magmas and draw conclusions on crustal recycling into the deep mantle and into the mantle wedge beneath subduction zones. 

Last updated on 2018-22-11 at 18:20