The analysis results of major and trace elements in biotite from the Northeast Hunan Mufushan area

EPMA mineral main element testing was conducted on JEOLJXA-8230 electron probe under the following conditions: acceleration voltage of 15.0 kV, probe current of 20 nA, and electron beam spot size of 3 μ m. Sampling time: 10 seconds for characteristic peaks, 5 seconds for background, 30 seconds for characteristic peaks, and 15 seconds for background (<1000 ppm). The calibration standards for each element content are all natural minerals. The test data were corrected using the JEOL ZAF method. LA-ICP-MS instrument for mineral trace element testing: Geolas HD laser ablation system consists of COMPexPro 102 ArF 193 nm excimer laser and MicroLas optical system, with ICP-MS model Agilent 7900. During the laser ablation process, helium gas is used as the carrier gas and argon gas is used as the compensation gas to adjust sensitivity. The two are mixed through a T-shaped joint before entering the ICP. The laser ablation system is equipped with a signal smoothing device. The laser beam spot and frequency analyzed in this study are 44 µ m and 5 Hz, respectively. In the trace element content processing, international glass standard materials NIST 610, BHVO-2G, BCR-2G, and BIR-1G are used for multi external standard without internal standard correction. Each time-resolved analysis data includes approximately 20-30 s blank signal and 50 s sample signal. Offline processing of the analysis data (including selection of samples and blank signals, instrument sensitivity drift correction, and element content calculation) is completed using software ICPMSDataCal.