1700 Ma Shachang Complex, Northeast China; Proterozoic rapakivi granite not associated with Paleoproterozoic orogenic crust

Proterozoic rapakivi granites are found on all continents and are characteristically associated with Paleoproterozoic crustal domains that predate the granites by < or =350 m.y. The 1700 Ma Shachang rapakivi granite complex belongs to a rapakivi granite-anorthosite suite that intruded late Archean metamorphic rocks of the North China craton. Our U-Pb zircon and Nd isotopic data show that the protolith of the Shachang granites was differentiated from the mantle at least 800 m.y. before the emplacement of the complex. This renders the Shachang complex a prime example of an anorogenic granite and shows that Paleoproterozoic orogenic crust was not always needed for the generation of Proterozoic rapakivi granites.