Abstract:

Granitoids and related mafic rocks are the main components of continental crust and are important in understanding the formation and evolution of continental crust. The origin of granitoids, i.e., the sources of magma and the petrogenetic processes, is the key to studying the geodynamics of continents and to understanding the processes of continental crust growth and lithospheric evolution. In recent years, insitu analysis shows the elemental and isotopic heterogeneity within a single mineral scale. The minerals should have the same isotopic compositions as their host magma. If the chemical and/or isotopic compositions of host magma changed, the compositional zones can record it. It is the heterogeneity of a single grain that makes the insitu mineral geochronology and isotopic analysis be a useful tracer to constrain the age, source and petrogenetic process of granites. With the development of secondary ion mass spectrometry (SIMS) and multiplecollector inductively coupled plasma mass spectrometry (MCICPMS) equipped with laser, the applications of insitu elemental and isotopic analysis advanced the studies of origin of granitoids, especially the source of magma and the petrogenetic process. At present, the widely used methods of insitu analysis are HfO isotopes of zircon, Nd isotope of apatite and titanite, and SrPb isotopes of apatite and plagioclase. On the basis of updated references and our recent work, this paper summarized the applications of insitu isotopic analysis to the study of the origin of granitoids, i.e., tracing the sources of magmas and petrogenetic processes, in order to promote the research on insitu analytical method and the study of granitoids in China.

Key words: in-situ isotopic analysis; granitoid; petrogenesis