The two major goals of this project are to determine (1) if there are systematic global scale patterns in the magmatic activity of the past 40 m.y., and (2) the nature of sub-lithospheric petrogenetic processes pattern recognition study. The methods of study include compilation and assessment of all the published radiometric dates of igneous rocks (mainly volcanic) in the Circum-Pacific and Mediterranean regions, for the time interval 40 Ma to present, followed by statistical analysis of the data. A two-year NSF supported pilot study has established the validity of the methods and provided a basis for recognizing several statistically-significant patterns in the magmatic activity of the northern Circum-Pacific belt. To evaluate global significance and provide a sounder basis for understanding sub-lithospheric influence, the present study will cover the entire Circum-Pacific and to Mediterranean (i.e. well beyond the influence of a single plate). Thus these previously defined patterns will be tested over a much larger area, and possible correlations of volcanic episodes with plate motions, magnetic polarity reversals, episodes of vertical uplift, and other global scale tectonic events will be evaluated.
