SUN Zai-bo, LV Xiao-ping, YU Sai-ying, LIU Jun-ping, TIAN Su-mei, LI Xu-gui
(Yunnan Institute of Geological Survey, Kunming 650216, China)
Abstract: Manxiu diorite pluton, paralleling distributing with the famous Nanlinshan rock body, is located in southeast Jinghong City and consists of biotite amphibole diorite, biotite amphibole quartz diorite and quartz diorite mass pieces broken porphyry. Four diorite samples were collected for LA-ICP-MS zircon U-Pb dating. The analyzed results show that these samples yield 321±14 Ma, 305.7±9.3 Ma, 291.3±7.6 Ma and 307.4±7.3 Ma, respectively, indicating that Manxiu diorite had formed during the Late Carboniferous-Early Permian. The trace elements’ features of whole-rock suggest that these samples are rich in Th and Zr with depleted Nb and Hf. All the samples are enriched with light rare earth elements with weakly Eu negative anomaly (δEu=0.73 to 0.98, average 0.85) and non-significant Ce anomaly (δCe=0.89 to 1.06, average 0.95). The trace elements and rare earth elements imply that Manxiu diorite is similar to the volcanic arc granite and is in the process of transiting to syn-collision granite. Therefore, the diagenesis ages and petro-geochemistry characteristics of Manxiu diorite pluton suggest that the south Lancangjiang Tectonic Belt has been still oceanic island arc subduction zone during the Late Carboniferous-Early Permian.
Keywords: diorite; LA-ICP-MS; zircon; U-Pb age; petro-geochemistry; geological implication; Manxiu rock body; south Lancangjiang Tectonic Belt
ACTA MINERALOGICA SINICA Vol. 35, No. 4, 2015, Page 473-480
