TY - JOUR
T1 - Staurolite stability and related parageneses
T2 - Theory, experiments, and applications
AU - Ganguly, Jibamitra
N1 - Funding Information:
The experimental work was carried out at Yale University, U.S.A., 1967 through 1969, supported by National Science Foundation grants (U.S.A.) GP-1545and GA-1354. Thanks are due to Dr. Sydney P. Clark, Jr., for his sponsorship and providing the facilities. Most of the theoretical work and the final task of writing the paper were accomplished at the Jadavpur University, Calcutta, 1969 through 1970, during the tenure of an appointment in the Scientists' Pool of the Government of India. The paper has been revised to its present form at the Birla Institute of Technology and Science, Pilani (Raj), India. Part of the publication expenses were borne by a grant from the University Grants Commission, Government of India, administered through the last-named organization. Appreciation is expressed to Drs. David Wones and Stephen W. Richardson for many critical comments and suggestions which resulted in considerable improvement of the manuscript.
PY - 1972/6
Y1 - 1972/6
N2 - The results of recent investigations on the stability limits of staurolite have been combined together with those of the present study to develop a semi-quantitative model of the P-T-fo2-X relations of staurolite±quartz±magnetite. The problem with respect to the hydroxyl content of staurolite has been analysed; it is concluded that no evidence has yet been mustered to discount the idealised stoichiometry proposed by Naray-Szabó & Sasvari (1958), at least as a limiting composition. The stability limits of staurolite±magnetite have been calculated from the experimental data for the equilibria involving quartz. Also the conditions over which the assemblage cordierite+magnetite+quartz could be stable, as well as a quantitative model for the fo2-P stability of almandine ± quartz have been deduced theoretically.An analysis is presented of the paragenetic relations of staurolite in common pelitic schists. It is suggested that the formation of staurolite at the expense of either chloritoid or chlorite, rather than the unqualified first appearance of staurolite as proposed by Winkler (1970), should define a 'staurolite-in' isograd in the range of 500-575 °C. In regional metamorphism, chloritoid, staurolite, and aluminum silicates should, under equilibrium conditions, be unstable relative to almandine in graphitic pelitic schists involving magnetite (chloritoid/staurolite/Al2SiO6+magnetite+quartz↑almandine+O2+H2O). The limits of P-T conditions over which staurolite and cordierite may coexist in natural assemblages have been deduced; it is restricted, almost entirely within the field of andalusite, between 500-700 °C, and 2-6 kbars, thus defining the range of P-T conditions for the 'low-pressure intermediate'- or 'Buchan'-type amphibolite facies discussed by Miyashiro (1961). In assemblages involving staurolite and andalusite, cordierite rather than almandine should usually be stable; the reverse holds for assemblages involving staurolite and sillimanite.
AB - The results of recent investigations on the stability limits of staurolite have been combined together with those of the present study to develop a semi-quantitative model of the P-T-fo2-X relations of staurolite±quartz±magnetite. The problem with respect to the hydroxyl content of staurolite has been analysed; it is concluded that no evidence has yet been mustered to discount the idealised stoichiometry proposed by Naray-Szabó & Sasvari (1958), at least as a limiting composition. The stability limits of staurolite±magnetite have been calculated from the experimental data for the equilibria involving quartz. Also the conditions over which the assemblage cordierite+magnetite+quartz could be stable, as well as a quantitative model for the fo2-P stability of almandine ± quartz have been deduced theoretically.An analysis is presented of the paragenetic relations of staurolite in common pelitic schists. It is suggested that the formation of staurolite at the expense of either chloritoid or chlorite, rather than the unqualified first appearance of staurolite as proposed by Winkler (1970), should define a 'staurolite-in' isograd in the range of 500-575 °C. In regional metamorphism, chloritoid, staurolite, and aluminum silicates should, under equilibrium conditions, be unstable relative to almandine in graphitic pelitic schists involving magnetite (chloritoid/staurolite/Al2SiO6+magnetite+quartz↑almandine+O2+H2O). The limits of P-T conditions over which staurolite and cordierite may coexist in natural assemblages have been deduced; it is restricted, almost entirely within the field of andalusite, between 500-700 °C, and 2-6 kbars, thus defining the range of P-T conditions for the 'low-pressure intermediate'- or 'Buchan'-type amphibolite facies discussed by Miyashiro (1961). In assemblages involving staurolite and andalusite, cordierite rather than almandine should usually be stable; the reverse holds for assemblages involving staurolite and sillimanite.
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U2 - 10.1093/petrology/13.2.335
DO - 10.1093/petrology/13.2.335
M3 - Article
AN - SCOPUS:0141487195
SN - 0022-3530
VL - 13
SP - 335
EP - 365
JO - Journal of Petrology
JF - Journal of Petrology
IS - 2
ER -