Gneiss samples were collected from the Shandong Peninsula, eastern China, in order to carry out Rb-Sr dating using whole rock powder and biotite mineral separates. Middle Proterozoic whole rock age (1808 k 71 Ma) and Middle to Late Proterozoic biotite ages (1312 and 729 Ma) were obtained for country gneisses in the northwestern part of the peninsula. Late Proterozoic whole rock age (707 k 6 1 Ma) and Mesozoic biotite ages (172 and 222 Ma) were obtained for orthogneisses in the southeastern part of the peninsula. These new age data, as well as recent petrological results and published radiometric data, support the subdivision of the Shandong Peninsula into two geological districts: (i) a northwestern area of Proterozoic age represented by a low-and middle-pressure metamorphic sequence belonging to the Sino-Korean craton; and (ii) a southeastern area of Late Proterozoic and Mesozoic age accompanied by ultra-high pressure eclogite.

The chemical Th-U-total Pb isochron method (CHIME) was applied to determine the age of monazite and thorite in five gneisses and zircon in an ultra high-pressure (UHP) phengite schist from the Su-Lu region, easttrn China. The CHIME ages and isotopic ages reported in the literature show that gneisses in the Su-Lu region are divided into middle Proterozoic (1500-1720 Ma) and Mesozoic (100-250 Ma) groups. The Proterozoic group includes paragneiss and orthogneiss of the amphibolite-granulite facies, and their protolith age is late Archean-early Proterozoic. The Mesozoic group is mainly composed of orthogneiss of the greenschist-epidote amphibolite facies, and the protolith age is Middle Paleozoic-Early Proterozoic. The Proterozoic and Mesozoic gneisses occupy northern and southern areas of the Su-Lu region, respectively, which are divided by a major Wulian-Qingdao-Y antai fault. Ultra high-pressure metamorphic rocks occur as blocks in the Mesozoic gneisses, and form a UHP complex.The UHP phengite schist in the Mesozoic orthogneiss contains detrital zircons with late Proterozoic CHIME age (ca 860 Ma). Age of the UHP metamorphism is late Proterozoic or younger, and protolith age of the UHP metamorphic rocks is probably different from that of the surrounding Mesozoic gneisses.