Steady diffusion model for olivine-plagioclase corona growth

Nishiyama, Tadao

doi:10.1016/0016-7037(83)90141-2

Cited by 55 publications

(49 citation statements)

References 23 publications

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“…The presence of augite, plagioclase and magnetite in a metagabbro corona may be attributed to significantly more calcic garnet (∼ 8 wt % CaO) with a higher X Fe than typical pelitic garnets. Van Lamoen (1979) and Nishiyama (1983) reported coronas after olivine and plagioclase in metamafic rocks and conclusively demonstrated a correlation between the compositions of reactant olivine and product orthopyroxene.…”

Section: Reactant Compositionsmentioning

confidence: 95%

“…The interpretation of corona textures has traditionally been a primary diagnostic tool for inferring metamorphic P -T -t paths and, hence, tectonics (Whitney and McLelland, 1973;Grew, 1980;Joesten, 1986;Droop, 1989;Clarke et al, 1989;Ashworth et al, 1992;White and Clarke, 1997;Norlander et al, 2002;Kelsey et al, 2003;Johnson et al, 2004;Tsunogae and Van Reenen, 2006;Zulbati and Harley, 2007;Hollis et al, 2006). Diffusion-constrained conditions may arise on both the prograde and retrograde paths, but, most commonly, coronas are thought to have formed during retrogression from peak P -T conditions as low-variance equilibria are crossed.…”

Section: Diffusion and Corona Growthmentioning

confidence: 99%

“…This method facilitated an understanding of how layer sequences would evolve as components diffuse down chemical potential gradients. The limitation of Korzhinskii's technique is that many diffusion paths from one reactant to another are possible in the chemical potential diagram, such that more than one possible layer sequence could evolve for a particular P -T condition (Nishiyama, 1983). The advances in thermodynamic formulations of phases required to model these relationships would only be developed by researchers in later decades Holland, 1988, 1990;Holland and Powell, 1998Powell et al, 1998Powell et al, , 2005 and even then only readily applied to coronas using the appropriate activity-composition relationships through pioneering studies by White et al (2008), Štípská et al (2010) and Baldwin et al (2015).…”

Section: Modelling Of Coronasmentioning

confidence: 99%

“…Nishiyama, 1983;Joesten, 1986;Grant, 1988). This early work was hindered by the closed-system constraint in Joesten's model.…”

Section: Quantitative Physical Modelling Of Coronasmentioning

confidence: 99%

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Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Ogilvie

Gibson

2017

Solid Earth

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Abstract. Coronas, including symplectites, provide vital clues to the presence of arrested reaction and preservation of partial equilibrium in metamorphic and igneous rocks. Compositional zonation across such coronas is common, indicating the persistence of chemical potential gradients and incomplete equilibration. Major controls on corona mineralogy include prevailing pressure (P ), temperature (T ) and water activity (aH 2 O) during formation, reaction duration (t) single-stage or sequential corona layer growth; reactant bulk compositions (X) and the extent of metasomatic exchange with the surrounding rock; relative diffusion rates for major components; and/or contemporaneous deformation and strain. High-variance local equilibria in a corona and disequilibrium across the corona as a whole preclude the application of conventional thermobarometry when determining P -T conditions of corona formation, and zonation in phase composition across a corona should not be interpreted as a record of discrete P -T conditions during successive layer growth along the P -T path. Rather, the local equilibria between mineral pairs in corona layers more likely reflect compositional partitioning of the corona domain during steadystate growth at constant P and T .Corona formation in pelitic and mafic rocks requires relatively dry, residual bulk rock compositions. Since most melt is lost along the high-T prograde to peak segment of the P -T path, only a small fraction of melt is generally retained in the residual post-peak assemblage. Reduced melt volumes with cooling limit length scales of diffusion to the extent that diffusion-controlled corona growth occurs. On the prograde path, the low melt (or melt-absent) volumes required for diffusion-controlled corona growth are only commonly realized in mafic igneous rocks, owing to their intrinsic anhydrous bulk composition, and in dry, residual pelitic compositions that have lost melt in an earlier metamorphic event.Experimental work characterizing rate-limiting reaction mechanisms and their petrogenetic signatures in increasingly complex, higher-variance systems has facilitated the refinement of chemical fractionation and partial equilibration diffusion models necessary to more fully understand corona development. Through the application of quantitative physical diffusion models of coronas coupled with phase equilibria modelling utilizing calculated chemical potential gradients, it is possible to model the evolution of a corona through P -T -X-t space by continuous, steady-state and/or sequential, episodic reaction mechanisms. Most coronas in granulites form through a combination of these endmember reaction mechanisms, each characterized by distinct textural and chemical potential signatures with very different petrogenetic implications. An understanding of the inherent petrogenetic limitations of a reaction mechanism model is critical if an appropriate interpretation of P -T evolution is to be inferred from a corona. Since corona modelling employing calculated chemical potential gradie...

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Section: Reactant Compositionsmentioning

confidence: 95%

Section: Diffusion and Corona Growthmentioning

confidence: 99%

Section: Modelling Of Coronasmentioning

confidence: 99%

“…Nishiyama, 1983;Joesten, 1986;Grant, 1988). This early work was hindered by the closed-system constraint in Joesten's model.…”

Section: Quantitative Physical Modelling Of Coronasmentioning

confidence: 99%

See 2 more Smart Citations

Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Ogilvie

Gibson

2017

Solid Earth

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“…However, it was used to analyse observed sequences of metasomatic zoning and rims around reacting mineral grains to constrain the relative values of the transport coefficients (cf. Joesten, 1977;Foster, 1981;Nishiyama, 1983). Recently, Abart et al (2012) used a similar approach to constrain not only the sequence of layers but also the microstructure of such reaction rims.…”

Section: The Reaction Path Approach To Reactive Transportmentioning

confidence: 99%

Sculpting of Rocks by Reactive Fluids

Jamtveit¹,

Hammer²

2012

Geochem Persp

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Geometry of a large‐scale, low‐angle, midcrustal thrust (Woodroffe Thrust, central Australia)

et al. 2017

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The Musgrave Block in central Australia exposes numerous large‐scale mylonitic shear zones developed during the intracontinental Petermann Orogeny around 560–520 Ma. The most prominent structure is the crustal‐scale, over 600 km long, E‐W trending Woodroffe Thrust, which is broadly undulate but generally dips shallowly to moderately to the south and shows an approximately top‐to‐north sense of movement. The estimated metamorphic conditions of mylonitization indicate a regional variation from predominantly midcrustal (circa 520–620°C and 0.8–1.1 GPa) to lower crustal (~650°C and 1.0–1.3 GPa) levels in the direction of thrusting, which is also reflected in the distribution of preserved deformation microstructures. This variation in metamorphic conditions is consistent with a south dipping thrust plane but is only small, implying that a ≥60 km long N‐S segment of the Woodroffe Thrust was originally shallowly dipping at an average estimated angle of ≤6°. The reconstructed geometry suggests that basement‐cored, thick‐skinned, midcrustal thrusts can be very shallowly dipping on a scale of many tens of kilometers in the direction of movement. Such a geometry would require the rocks along the thrust to be weak, but field observations (e.g., large volumes of syntectonic pseudotachylyte) argue for a strong behavior, at least transiently. Localization on a low‐angle, near‐planar structure that crosscuts lithological layers requires a weak precursor, such as a seismic rupture in the middle to lower crust. If this was a single event, the intracontinental earthquake must have been large, with the rupture extending laterally over hundreds of kilometers.

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Steady diffusion model for olivine-plagioclase corona growth

Cited by 55 publications

References 23 publications

Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Arrested development – a comparative analysis of multilayer corona textures in high-grade metamorphic rocks

Sculpting of Rocks by Reactive Fluids

Geometry of a large‐scale, low‐angle, midcrustal thrust (Woodroffe Thrust, central Australia)

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