Fig. 4
Thermal models for P–T constrains. (a) The intersection of the fluid inclusion isochores in QSF quartz and the geothermal gradients (yellow area) represents the theoretical entrapment temperature and pressure of fluids under local thermobaric gradient. The realistic P–T range (green area), constrained by the maximum pressure (~ 90 MPa) derived from the burial history at the Junggar Basin margin and the highest temperature obtained from carbonaceous materials, lies outside of the yellow region. (b) The red and blue areas represent the restricted P–T conditions of the early or final stages of silicification, respectively. The blue area is constrained by isochores, the liquid-vapor curve of pure water and the bubble point curve of the CH4–H2O–NaCl fluid mixtures at x bulk (CH4) = 0.001, m NaCl = 3 mol/kg. The bubble point curve was modified after Mao et al. (2013)54.
