It is significant for igneous rocks to study the regional geological setting and geodynamic mechanism. The magmatic activities were very intense in south Tibet,as a response to the India plate colliding to the Eurasia continent. However,there is limited report on igneous rocks in the Tethys-Himalaya antimony-gold metallogenic belt,which was near the Main Center Thrust（ MCT）. The Integrated Exploration Area of the Zhaxikang Lead-zinc Deposit is located in the eastern part of this metallogenic belt. Recently,we have found a group of bimodal igneous rocks in the Zhaxikang area. In this study,we carried out zircon U-Pb dating and elemental geochemistry studies for the Segang diabase dikes in this area. The results show that these mafic rocks were emplaced in a large scale extensional setting at the period of Early Cretaceous（ 138134 Ma）,and are characterized by high TiO2,Nb/Y ratio,enrichment of light rare earth elements（ LREEs） and incompatible elements. These diabases also exhibit OIB-like REE and trace element patterns. They were likely generated by the Kerguelen plume and had been contaminated by crustal wall rocks. This study is beneficial to understand the Mesozoic tectonomagmatic process and forming mechanism in south Tibet.
Geological Journal of China Universities