Mineral compositions of magmatic dikes cutting across Khe Phen granites (Huong Tra, Thua Thien Hue, Central Vietnam)

The Khe Phen granite quarry located in Huong Tra district (Thua Thien Hue province) has been confirmed as a part of the Ba Na granitoid complex (G/K 2 bn ), mostly composed of two-mica granite and porphyritic granite. Field survey data show that the granites here are cut across by five distinct narrow dikes (about 50-70 cm wide) including granite pegmatite, granite aplite, aplite, granodiorite and lamprophyre diorite. Mineral compositions of the granite pegmatite and aplite dikes are similar with those of the host granite, which are mainly comprised of quartz (27-35 %), orthoclase (45-58 %), plagioclase (4-15 %), biotite (1-3 %) and a few opaque minerals. Meanwhile, the granodiorite and lamprophyre diorite dikes are melanocratic and compositionally much more mafic, particularly lamprophyre diorite, evidenced by a presence of hornblende (50-55 %), plagioclase (33-40 %), quartz (3-15 %), calcite (5-17 %)... Origin and emplacement age of the latter dikes have not been reported so far, and thus are needed for further studies based on geochemical and isotopic data.