supported by the National Natural Science Foundation of China (40372057 and 40772076);the SINOPEC Project (G0800-06-ZS-319);the China Geological Survey (CGS) project (1212010611802)
A SHRIMP U-Pb zircon age of 1437±21 Ma was obtained for a recently discovered K-bentonite bed in the Tieling Formation,situated northeast of Beijing at the boundary between Liaoning and Hebei provinces,on the norther...