Granulite xenoliths from Cenozoic basalts in SE China provide geochemical fingerprints to distinguish lower crust terranes from the North and South China tectonic blocks:comment

摘要

A careful examination of the geochemical data set for SE China granulite xenoliths in Cenozoic basalts shows differences between the magmatic and cumulate granulite xenoliths,but no distinction between the Nushan and the other South China magmatic granulite xenoliths.Nushan granulite xenoliths with Archean Nd model ages were most likely derived from the Archean basement of the Yangtze craton itself and overprinted by a Paleoproterozoic to Mesoproterozoic tectonothermal event that occurred in the South China block,including the northern margin of the Yangtze craton.The granulate xenoliths therefore cannot be used to distinguish the North China and South China lower crust.Further,the discovery of the UHP eclogite xenoliths west of the Tanlu fault zone,along with recent paleomagnetic,seismic profiling,and other geochemical studies,favors a deep-seated,Tibetan-type,continental subduction of the Yangtze craton beneath North China along the Tanlu belt.