Slow crystal settling controls the diversity of high-silica granites of the Late Cretaceous Shengsi Pluton at northeastern tip of southeast China

•The 97 Ma I-A transitional Shengsi granites comprise two phases by crystal-melt separation.•Medium-grained phase (MGP) represents the cumulate with less melts extracted.•Fine-grained phase (FGP) shows variable and depleted middle rare earth elements.•FGP is formed by fractional crystallization of titanite + plagioclase + zircon.•FGP represents the melt extracted from a crystal mush, leaving the residue forming MGP.