|
|||||
|
|
Pyroxene-melt equilibria: an updated model |
|
| Authors: | Roger L Nielsen Paula M Davidson Timothy L Grove |
| Institution: | 1. College of Oceanography, Oregon State University, 97331, Corvallis, OR, USA 2. National Bureau of Standards, 20899, Gaithersburg, MD, USA 3. Department of Earth, Atmospheric and Planetary Science, Massachusetts Institute of Technology, 02139, Cambridge, MA, USA |
| Abstract: | An updated model for pyroxene-melt equilibria at 1 atm has been developed and calibrated using new and existing experimental data in order to refine calculations of liquid lines of descent, which simulate the effect of igneous differentiation processes. We combine the Davidson and Lindsley (1985) model for activities of components in clinopyroxene and orthopyroxene solid solutions, a i p , where i represents a quadrilateral endmember, with the Nielsen and Drake (1979) expressions for component activities in the melt, a i L (two-lattice melt model). The chemical potential differences for pyroxene-melt equilibria are expressed in the form: $$\Delta \mu _{\iota } = 0 = In \left( {{{a_i^p } \mathord{\left/{\vphantom {{a_i^p } {a_i^L }}} \right.\kern-\nulldelimiterspace} {a_i^L }}} \right) + A_i + {{B_i } \mathord{\left/{\vphantom {{B_i } T}} \right.\kern-\nulldelimiterspace} T}$$ Pyroxene compositions were projected to quadrilateral compositions with the method of Lindsley and Anderson (1983). The regression constants A i and B i were calculated from experimental data that consists of 282 pyroxene-melt pairs, including 83 orthopyroxene-melt pairs. These experiments were all performed at 1 atm and represent compositions ranging from basalts (alkali to lunar) to dacites (42–66 wt% SiO2). The model is calibrated for 1000 |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ | |