Recent work on the Panzhihua intrusion has produced two separate models for the crystallisation of the intrusion:(1) low-Ti,high CaO and low H_2O(0.5 wt.%) parent magma(equivalent to Emeishan low-Ti basalt) at FMQ;and(2) high-Ti,low CaO and higher H_2O(>1.5 wt.%) parent magma(equivalent to Emeishan high-Ti basalt) at FMQ + 1.5.Modelling of these parent magma compositions produces significantly different results. We present here detailed f(O_2) and H_2O modelling for average compositions of both Emeishan high-Ti and low-Ti ferrobasalts in order to constrain the effects on crystallisation sequences for Emeishan ultra-mafic -mafic layered intrusions.Modelling is consistent with numerous experimental studies on ferro-basaltic magmas from other localities(e.g.Skaergaard intrusion).Modelling is compared with the geology of the Panzhihua intrusion in order to constrain the crystallisation of the gabbroic rocks and the Fe-Ti oxides ore layers.We suggest that the gabbroic rocks at the Panzhihua intrusion can be best explained by crystallisation from a parent magma similar to that of the high-Ti Emeishan basalt at moderate H_2O contents(0.5-1 wt.%) but at the lower end of TiO_2 content for typical high-Ti basalts(2.5 wt.%TiO_2). Distinct silicate disequilibrium textures in the Fe-Ti oxide ore layers suggest that an influx of H_2O may be responsible for changing the crystallisation path.An increase in H_2O during crystallisation of gabbroic rocks will result in the depression of silicate liquidus temperatures and resultant disequilibrium with the liquid.Continued cooling of the magma with high H_2O then results in precipitation of Mt-Uv alone. The H_2O content of parent magmas for mafic layered intrusions associated with the ELIP is an important variable.H_2O alters the crystallisation sequence of the basaltic magmas so that at high H_2O and f(O_2) Mt -Uv crystallises earlier than plagioclase and clinopyroxene.Furthermore,the addition of H_2O to an anhydrous magma can explain silicate disequilibrium texture observed in the Fe-Ti oxide ore layers. Recent work on the Panzhihua intrusion has produced two separate models for the crystallisation of the intrusion: (1) low-Ti, high CaO and low H_2O (0.5 wt.%) Parent magma (equivalent to Emeishan low-Ti basalt) at FMQ; parent magma (equivalent to Emeishan high-Ti basalt) at FMQ + 1.5. Modeling of these parent magma compositions produces significantly different results. We present here (2) high-Ti, low CaO and higher H_2O detailed f (O_2) and H_2O modeling for both compositions of both Emeishan high-Ti and low-Ti ferrobasalts in order to constrain the effects on crystallisation sequences for Emeishan ultra-mafic -mafic layered intrusions. Modeling is consistent with numerous experimental studies on ferro -basaltic magmas from other localities (egSkaergaard intrusion). Modeling is compared with the geology of the Panzhihua intrusion in order to constrain the crystallisation of the gabbroic rocks and the Fe-Ti oxides ore layers. We suggest that the gabbroic rocks at the Panzhihua intrusion can be best explained by a crystallization from a parent magma similar to that of the high-Ti Emeishan basalt at moderate H 2 O contents (0.5-1 wt.%) but at the lower end of TiO 2 content for typical high-Ti basalts .% TiO_2). Distinct silicate disequilibrium textures in the Fe-Ti oxide ore layers suggest that an influx of H_2O may be responsible for changing the crystallisation path. Increase in H_2O during crystallisation of gabbroic rocks will result in the depression of silicate liquidus temperatures and resultant disequilibrium with the liquid. Canceled cooling of the magma with high H_2O then results in precipitation of Mt-Uv alone. The H_2O content of parent magmas for mafic layered intrusions associated with the ELIP is an important variable. H_2O als the crystallisation sequence of the basaltic magmas so that at high H_2O and f (O_2) Mt -Uv crystallises earlier than plagioclase and clinopyroxene. Futurerther, the addition of H_2O to an anhydrous magma can explainsilicate disequilibrium texture observed in the Fe-Ti oxide ore layers.