摘要
Ancient MORB-type rocks (AMORB) from the Qinling Orogenic Belt show a high radiogenic Ph isotope and their initial Pb isotopic ratios are close to the growth curve for μ =8.5. The Pb isotopic features of Qinling AMORBs suggest that mantle source was similar to the mantle of Tethyan and of Gondwana domain from the South Hemisphere. This indicates the presence of a Qinling paleo-ocean which has been consumed and has separated North China and Yangtze cratons. The Qinling ocean was possibly part of the ocean including Gondwana domain and Paleo-or Proto Tethys. DUPAL anomaly is a large-scale Pb and Sr isotopic anomaly in oceanic basalts from the South Hemisphere[1]. The paleo-DUPAL anomaly, which has been recognized in Qinling AMORBs, is proven to exist 1.0Ga ago. The results infer that the DUPAL component of the Qinling AMORB is related to the DUPAL anomaly of the South Hemisphere in the geological history.
Ancient MORB-type rocks (AMORB) from the Qinling Orogenic Belt show a high radiogenic Ph isotope and their initial Pb isotopic ratios are close to the growth curve for μ =8.5. The Pb isotopic features of Qinling AMORBs suggest that mantle source was similar to the mantle of Tethyan and of Gondwana domain from the South Hemisphere. This indicates the presence of a Qinling paleo-ocean which has been consumed and has separated North China and Yangtze cratons. The Qinling ocean was possibly part of the ocean including Gondwana domain and Paleo-or Proto Tethys. DUPAL anomaly is a large-scale Pb and Sr isotopic anomaly in oceanic basalts from the South Hemisphere[1]. The paleo-DUPAL anomaly, which has been recognized in Qinling AMORBs, is proven to exist 1.0Ga ago. The results infer that the DUPAL component of the Qinling AMORB is related to the DUPAL anomaly of the South Hemisphere in the geological history.
基金
Project supported by the National Natural Science Foundation of China and the Open Laboratory of Constitution,Interaction and Dynamics of Crust-Mantle System Ministry of Geology and Mineral Resources.
