The basement of the Songliao Basin mainly contains low-grade metamorphic rocks and granites. It has been long disputed whether the basin has Precambrian metamorphic basement. This is a report of zircon SHRIMP U-Pb dating results of a meta-diorite sample, which was taken from the Si-5 drilling hole in the southern portion of the Songliao Basin. The SHRIMP analyses indicate that the meta-diorite with a weighted mean 207Pb/206Pb age of 1839±7 Ma (2σ, n = 8) was emplaced during Paleo-Proterozoic time. Additionally, the meta-diorite has old Nd model ages (TDM1: 2999Ma; TDM2: 2849Ma). These data suggest that the south- ern part of the Songliao Basin do possess Precambrian base- ment.
WANG YingZHANG FuqinZHANG DaweiMIAO LaichengLI TieshengXIE HangqiangMENG QingrenLIU Dunyi
The Xilin Gol Complex,consisting of deformed and metamorphosed rocks,was exposed as a large geological unit wi...
SHI Guanghai~1,LIU Dunyi~2,ZHANG Fuqin~1, JIAN Ping~2,MIAO Laicheng~1,SHI Yuruo~2 & TAO Hua~2 1.Institute of Geology and Geophysics,Chinese Academy of Sciences, Beijing 100029,China
The recently identified Huashan ophiolitic mélange was considered as the eastern part of the Mianlüe suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite and granite intruding basic volcanic rocks indicates crystallization ages of 947±14 Ma and 876±17 Ma respectively. These ages do not support a recently proposed Hercynian Huashan Ocean, but rather favor that a Neoproterozoic suture assemblage （ophiolite） is incorporated into the younger （Phanerozoic） Qinling orogenic belt.
SHI YuruoLIU DunyiZHANG ZongqingMIAO LaichengZHANG FuqinXUE Hongmei
