The Bada Cu—Au deposit is located in the southern part of the Yulong metallogenic belt and belongs to the Jinshajiang—Ailaoshan—Honghe alkali- rich intrusive belt.It has been widely concerned by geologists because of its great prospecting potential and belongs to the collisional porphyry Cu—Au deposit within the special block,but there is little research on the alkali-rich volcanic—magmatic sequence and its formation age and its relationship with Cu—Au mineralization.On the basis of previous studies,this paper makes a detailed petrographic anatomy,zircon U-Pb chronology,systematic rock geochemistry and Sr—Nd—Hf isotope study of the alkali- rich volcanic complex in Bada Cu—Au mining area,discusses the formation time limit,magmatic source and tectonic background of the volcanic complex,and provides a new idea for ore prospecting prediction in the deep periphery of the mining area.This study not only deepens the understanding of the metallogenic system or metallogenic regularity of the deposit,but also provides a new window for the study of Cenozoic lithospheric tectonic evolution and geodynamic processes in the southeastern margin of the Qinghai—Xizang Plateau.Methods: This paper takes the alkali-rich volcanic—intrusive complex in Bada Cu—Au mining area as the research object.A total of 25 boreholes and fresh outcrop samples were collected,and the whole rock trace analysis were carried out.At the same time,three-type samples of tuff,trachyte and lamproite were analyzed by zircon U-Pb chronology and Sr—Nd—Hf isotope analysis.Results: The 206Pb/238U weighted average ages of zircons from early stage tuff,trachyte and late stage Cloud lamproite are 34.47 ±0.60 Ma,34.88 ±0.59 Ma and 34.18 ±0.53 Ma,respectively.The alkali-rich volcanic complex in Bada Cu—Au mining area is rich in large ion lithophile elements (LILEs) Rb,Sr,Ba and light rare earth elements,but depletes high field strength elements Nb,Ta,Hf and heavy rare earth elements,and shows weak negative Eu anomalies.The ISr value of the rock is between 0.70629 and 0.70851,and the εNd(t) value is-6.41~-1.57,and theεHf(t)value is 0~4.4.The two-stage Nd model age and the two-stage Hf model age are 0.98~1.37 Ga and 0.72~1.09 Ga,respectively.Conclusions: Based on the detailed petrographic anatomy and profile measurement of the alkali-rich volcanic—intrusive complex in Bada Cu—Au mining area,the magmatic events in the same period can be divided into two stages: 1 the early Eocene (34.88~34.47 Ma) alkali-rich volcanic rock—intrusive rock eruption—emplacement event,and 2 the late Eocene (34.18 Ma) lamproite emplacement event.The trace and Sr—Nd—Hf isotopic characteristics of the complex show that it is mainly derived from the partial melting of the enriched mantle metasomatism and contaminated with a small amount of crustal material.The alkali-rich volcanic—intrusive complex in Bada Cu—Au mining area was formed in the post-collision extensional environment of the Qinghai—Tibet Plateau,and the delamination of the lithosphere is the key mechanism for the formation of the complex. Within the deep hornblende syenite porphyry—syenite porphyry,there are NW—SE-trending extensional fracture vein concentration zones or normal faults,which provide transport—precipitation channels for later magmatic ore-forming hydrothermal fluids. Trachyte,tuff and Yunhuang rocks are only the products of volcanic—magmatic events in the same period.