Spatial distribution and ages of alkaline intrusive rocks in China and related tectonics

On the basis of the geological data from 220 intrusions and isotope ages of 115 rock bodies, the paper discusses the distribution of 18 alkaline intru sive rock belts along deep faults and their relations to the plate tectonic activity. In view of the presence of a large amount of Variscan alkaline r ocks of deep-source character, it is inferred that mantle diapirism was ver y strong in China during the Variscan. Besides anorogenic and postorogenic alkaline granites, there also occur alkaline granites formed in the termina l orogenic stage when the regional tectonic activity was of compressional n ature. Finally, the paper discusses the tectonic environment of the Maoniup ing nordmarkite in Mianning county, Sichuan province, and the authors consi der it to be a compressional environment originating after rift closing.