Chemical compositions of biotites (%) from granite (porphyry) samples in the Dulong Mine、The LA-ICP-MS analytical results of biotites within granite (porphyry) rocks in the Dulong deposit (×10–6)

The SiO2 content of biotite in Dulong granite is 34.8% to 36.0% (with an average of 35.4%), the TiO2 content is 1.92% to 3.47% (with an average of 2.62%), and the Al2O3 content is 19.5% to 20.5% (with an average of 20.0%). The content of FeO(T) ranged from 22.1% to 26.2% (with an average of 23.4%). The content of MnO ranged from 0.585% to 0.754% (with an average of 0.684%). The content of MgO ranged from 3.22% to 4.32% (with an average of 3.90%), the content of Na2O ranged from 0.049% to 0.193% (with an average of 0.093%), and the content of K2O ranged from 9.83% to 10.1% (with an average of 10.0%). In addition, the content of F element ranges from 0.465% to 1.53% (with an average of 0.829%), and the content of Cl element ranges from 0.051% to 0.073% (with an average of 0.062%). 2) The SiO2 content of biotite in Dulong granite porphyre is 34.8% to 36.3% (with an average of 35.2%), the TiO2 content is 1.81% to 2.84% (with an average of 2.17%), and the Al2O3 content is 19.7% to 20.8% (with an average of 20.2%). The FeO(T) content ranged from 22.8% to 24.6% (with an average of 24.0%), the MnO content ranged from 0.947% to 1.23% (with an average of 1.09%), and the MgO content ranged from 2.99% to 3.16% (with an average of 3.04%). The Na2O content ranged from 0.063% to 0.107% (with an average of 0.079%), the K2O content from 9.96% to 10.2% (with an average of 10.1%), the F content from 0.788% to 1.22% (with an average of 0.962%), and the Cl content from 0.024% to 0.060% (with an average of 0.039%).The trace element results of biotite are shown in (Table 2). The biotite In the Dulong granite (DL-1) is enriched with elements such as Li, Co, Zn, Ga, Rb, Nb, Sn, In, and W. Their values are in sequence 1947× 10-6 to 2258× 10-6, 23.4× 10-6 to 29.3× 10-6, and 990× 10-6 1425×10 ⁻ ⁶, 74.2×10 ⁻ ⁶ to 86.6×10 ⁻ ⁶, 945×10 ⁻ ⁶ to 3383×10 ⁻ ⁶, 149×10 ⁻ ⁶ to 620×10 ⁻ ⁶, 117×10 ⁻ ⁶ 147× 10-6, 0.587× 10-6 to 0.820× 10-6, 1.59× 10-6 to 29.4× 10-6. The content of most rare earth elements is extremely low, below the detection limit. Dulong granite porphyry (DL-2) biotite is enriched with elements such as Li, Co, Zn, Ga, Rb, Nb, Sn, In, and W. Their values are 1282× 10-6 to 2003× 10-6, 19.9× 10-6 to 24.3× 10-6, 1321× 10-6 to 1404× 10-6, and 64.8× 10-6 to 84.3× 10-6 in sequence. From 1920× 10-6 to 3477× 10-6, 290× 10-6 to 552× 10-6, 195× 10-6 to 256× 10-6, 0.870× 10-6 to 1.28× 10-6, 8.09× 10-6 to 35.3× 10-6, the content of most rare earth elements is extremely low, below the detection limit. Compared with granite biotite, granitic porphyry biotite is more enriched with elements such as Sn, In and W. The K/Rb value of biotite is usually used to trace the degree of magma differentiation. As the degree of magma differentiation increases, the K/Rb value of biotite gradually decreases. The K/Rb value of biotite in Laojun Mountain granite ranges from 22.5 to 79.9, with an average of 46.0. The K/Rb value of granitic porphyrian biotite ranges from 22.0 to 39.1, with an average of 29.7.