The　nature　of　early　Paleozoic　Caledonian　orogeny　(Guangxi　movement),　as　one　of　the　key　geolocial　problems　of　tectonic　evolution　in　South　China,　has　been　controversial　for　a　long　time.　In　this　study　we　report　a　suite　of　early　Paleozoic　basaltic　andesite-andesite　volcanic　rocks　located　at　the　Dashuang　in　the　Cenxi　area　of　southeastern　Guangxi　in　South　China.　Petrogeochemical　data　of　the　basaltic　andesite-andesite　show　the　contents　of　SiO2=47.8%-58.8%,　Al2O3=13.35%-14.25%,　CaO=3.79%-5.61%　and　TiO2=0.46%-0.56%.　It　also　shows　high　contents　of　MgO=4.39%-9.96%,　Ni=141×10-6-210×10-6　and　Cr=427×10-6-750×10-6,　indicating　that　they　belong　to　high　magnesian　(HM)-magnesian　(M)　basaltic　andesite-andesite　from　calc-alkaline　to　transitional　series.　The　volcanic　rocks　exhibit　enriched-LREE,　weak　negative　δEu　abnormally　(0.73-0.92),　(La/Yb)N=3.4-7.9,　(La/Sm)N=3.15-4.95.　Basaltic　andesite-andesite　is　characterized　by　pronounced　enrichment　of　LILEs　(e.　g.　Rb,　Ba,　Th,　U,　K,　Pb),　relative　depletion　of　HFSEs　(e.　g.　Nb,　Ta,　Ti),　and　low　Ti/V=14.7-21.8.　All　these　show　typical　characteristics　of　high　magnesian　(HM)-magnesian　(M)　basaltic　andesite-andesite　(sanukite).　The　LA-ICP-MS　zircon　U-Pb　age　of　the　magnesian　andesite　is　443±4　Ma,　showing　that　the　formation　ages　of　the　volcanic　rock　series　should　be　between　the　Late　Ordovician　and　Early　Silurian　epoch.　In　conclusion,　we　suggest　that　the　Dashuang　volcanic　rocks　are　the　suite　of　high　magnesian　(HM)-magnesian　(M)　basaltic　andesite-andesite　series　formed　in　the　forearc　tectonic　environment　in　Late　Ordovician-Early　Silurian　epoch,　which　provides　key　evidence　for　Early　Paleozoic　oceanic　crust　subduction　between　Yangtze　Craton　and　Cathaysia　block　along　Qinzhou-Hangzhou　tectonic　suture　belt　in　South　China.　©　2016,　Editorial　Department　of　Earth　Science.　All　right　reserved.