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The Petrogenetic Model, an Extension of Bowen's Petrogenetic Grid

Wyllie, Peter J. (1962) The Petrogenetic Model, an Extension of Bowen's Petrogenetic Grid. Geological Magazine, 99 (6). pp. 558-569. ISSN 0016-7568. doi:10.1017/S0016756800059859.

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Bowen's petrogenetic grid is a PT projection containing univariant curves for decarbonation, dehydration, and solid-solid reactions, with vapour pressure (P_f) equal to total pressure (P_s). Analysis of experimental data in the system MgO–CO_2–H_2O leads to an expansion of this grid. Three of the important variables in metamorphism when P_f = P_s are P, T, and variation of the pore fluid composition between H_2O and CO_2. These can be illustrated in a three-dimensional petrogenetic model; one face is a PT plane for reactions occurring with pure H_2O, and the opposite face is a similar plane for reactions with pure CO_2; these are separated by an axis for pore fluid composition varying between H_2O and CO_2. Superposition of the PT faces of the model provides the petrogenetic grid. The reactions within the model are represented by divariant surfaces, which may meet along univariant lines. For dissociation reactions, the surfaces curve towards lower temperatures as the proportion of non-reacting volatile increases, and solid-solid reaction surfaces are parallel to the vapour composition axis and perpendicular to the PT axes. The relative temperatures of reactions and the lines of intersections of the surfaces can be illustrated in isobaric sections. Isobaric sections are used to illustrate reactions proceeding at constant pressure with (1) pore fluid composition remaining constant during the reaction, with temperature increasing (2) pore fluid composition changing during the reaction, with temperature increasing, and (3) pore fluid changing composition at constant temperature. The petrogenetic model provides a convenient framework for a wide range of experimental data.

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Additional Information:© 1962 Cambridge University Press. Contribution No. 62-5 from The College of Mineral Industries. I wish to thank H.L. Barnes, G.A. Chinner, T.N. Clifford, H.J. Greenwood, O.F. Tuttle, and L.S. Walter for their useful comments and helpful criticisms at various stages in the preparation of this manuscript, and J. Hass for his skill with the drafting pen. The ideas expressed above developed as a result of experimental studies in the systems CaO-MgO-CO2-H2O and CaO-SiO2-CO2-H2O, which were supported by the Department of Scientific and Industrial Research (at Leeds University, England) and The National Science Foundation.
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Department of Scientific and Industrial Research (UK)UNSPECIFIED
Issue or Number:6
Record Number:CaltechAUTHORS:20160120-084249856
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Official Citation:Peter J. Wyllie (1962). The Petrogenetic Model, an Extension of Bowen's Petrogenetic Grid. Geological Magazine, 99, pp 558-569. doi:10.1017/S0016756800059859
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63791
Deposited By: Tony Diaz
Deposited On:20 Jan 2016 20:28
Last Modified:10 Nov 2021 23:21

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