The chemical Th‐U‐total Pb isochron ages of Jiaodong and Jiaonan metamorphic rocks in the Shandong Peninsula, eastern China

Publisher Website
Google Scholar
Abstract
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, eastern 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‐Yantai 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.

This publication has 17 references indexed in Scilit: