Petrochemical characteristics of leucogranite and a case study of Bengbu leucogranites

Leucogranites have a relatively narrow variation in SiO₂ content (70.5%–75.5%). Giving similar SiO₂ content, leucogranites have relatively higher Al₂O₃ (>13.5%) and lower TFeO + MgO (<2.5%) contents than those of normal granites. These petrochemical characteristics suggest that leucogranites are derived from partial melting at relatively low temperature and are not significantly affected by fractional crystallization. In the present study, we propose that the Al₂O₃ vs SiO₂ and TFeO + MgO vs SiO₂ diagrams can be used to distinguish leucogranites from normal granites. In addition, we report the major element compositions of the Jurassic granitic intrusions from Jingshan-Tushan-Mayishan in the Bengbu area, east-central China. Using the Al₂O₃ vs SiO₂ and TFeO + MgO vs SiO₂ diagrams and the comparison with the High Himalayan leucogranites in mineralogical and petrochemical characteristics, we suggest that the Jingshan-Tushan-Mayishan intrusions belong to a leucogranite belt. Similar to those of the High Himalayan leucogranites, the Bengbu leucogranites have low Mg^# values, indicating that they resulted from low temperature dehydration partial melting of the subducted continental crust of the South China Block at the crustal depth. Supported by National Natural Science Foundation of China (Grant No. 40634023)