The R. James Kirkpatrick Geology Lecture

Recycling of the deep lithosphere beneath the North China Craton

Roberta Rudnick
Univerity of Maryland

The average composition of the continental crust is andesitic, which poses a dilemma since basalt (or picrite) is the main magma type that is produced by mantle melting. There obviously must be processes at work that influence the crust composition in addition to mantle melting. One such process is the loss of dense, mafic to ultramafic material from the base of the continents through density foundering. In this talk I will review evidence for this type of lower crustal recycling in the North China Craton, a region that transformed from a stable Archean craton to a seismically and magmatically active region in the Mesozoic.