Reversed phase equilibrium constraints on the stability of Mg-Fe-Al biotite

Abstract

Biotite is a particularly important mineral in metamorphic rocks because of its occurrence not only in nature over a wide range of bulk compositions and metamorphic grades, but also computationally in numerous equilibria that represent useful thermobarometers and boundaries on petrogenetic grids. In spite of its obvious importance, quantitative calculations involving biotite continue to be relatively uncertain, as evidenced by major differences in computed petrogenetic grids for metapelites (e.g., Spear and Cheney 1989;Powell and Holland 1990;Pattison and Tracy 1991;Xu et al. 1994) and thermobarometric formulations involving biotite (e.g., Ferry and Spear 1978;Perchuk and Lavrent!eva 1983;Aranovich et al. 1988;Holdaway et al. 1997 ABSTRACTThe stability of Mg-Fe-Al biotite has been investigated with reversed phase-equilibrium experiments on four equilibria. Experimental brackets in pure H 2 O and H 2 O-CO 2 mixtures for the equilibrium:phlogopite + 3 quartz = enstatite + sanidine + H 2 O( 1) are in good agreement with previous experiments in mixed-volatile ß uids (Bohlen et al. 1983) and H 2 O-KCl solutions (Aranovich and Newton 1998), while indicating a reduced stability Þ eld for phlogopite compared to previous data in pure H 2 O (Wood 1976;Peterson and Newton 1989). Aluminum solubility in biotite has been determined in the Fe-, Mg-, and Fe-Mg systems from reversed phase-equilibrium data for the equilibria:

A thermodynamic model for titanium and ferric iron solution in biotite

“…Cruciani & Zanazzi, 1994; Brigatti et al. , 2000a; Berman et al. , 2007), here we follow Powell & Holland (1999) in assuming that octahedrally coordinated Al is introduced by a Tschermak‐type exchange and partitions preferentially onto the M1 site, as first proposed by Circone & Navrotsky (1992) and supported by the recent study of Ventruti et al.…”

How continuous and precise is the record of P–T paths? Insights from combined thermobarometry and thermodynamic modelling into subduction dynamics (Schistes Lustrés, W. Alps)

“…(2010) without considering low‐temperature hydrated end‐members. The thermodynamic properties of all other phases involved in tweequ calculations were selected from Berman et al (2007).…”

High T/P evolution and metamorphic ages of the migmatitic basement of northern Sierras Pampeanas, Argentina: Characterization of a mid-crustal segment of the Famatinian belt

“…The garnet solution model of Berman and Aranovich (1996) is used with revised MneMgeFe mixing properties in the version 2.32. For biotite, solubility data between Al, Fe and Mg of Berman et al (2007) are used. For plagioclase, the Al e avoidance model of Fuhrman and Lindsley (1988) is utilized.…”