Grain coarsening in polymineralic contact metamorphic carbonate rocks: The role of different physical interactions during coarsening

Brodhag, Sabine; Herwegh, Marco; Berger, Alfons

doi:10.1016/j.jsg.2010.12.003

Cited by 11 publications

(12 citation statements)

References 50 publications

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“… Crystal size distribution (CSD) of diopside and phlogopite in selected samples. (a) CSD of diopside included in calcite from sample SB05‐09.2; (b) CSD of diopside along grain boundaries in sample SB05‐09.2; (c) schematic Zener diagram (see Brodhag et al ., in press) and the location of the studied samples; (d) CSD of phlogopite along grain boundaries in sample SB05‐7.4; (e) CSD of phlogopite along grain boundaries in sample SB05‐19.2; (f) CSD of phlogopite along grain boundaries in sample SB05‐34.2. …”

Section: Resultsmentioning

confidence: 99%

“…The differences in driving forces have to be responsible for the similar grain sizes of pyrite and diopside observed in one sample, which has seen the same T–t path, because all other parameters (mainly transport properties; hidden in K in ) are identical in a homogeneous microstructure. As will be discussed in the next section, there are not only variations in the growth kinetics of the different phases, but at the same time the grain size of the matrix phase will also vary as a function of the distribution and volume fraction of the second phases (Brodhag et al. , in press).…”

Section: Discussionmentioning

confidence: 99%

“…The transport of nutrients in such systems occurs along the grain boundary network between the matrix grains and depends strongly on the microstructure of the matrix (Carlson & Gordon, 2004). The matrix grain size increases by coarsening (Brodhag et al. , in press).…”

Section: Discussionmentioning

confidence: 99%

“…Transport and related second‐phase coarsening may therefore depend on the size and geometry of the grain boundary network, their volume fraction and the type of transport (Herwegh et al. , 2005; Brodhag et al. , in press).…”

Section: Discussionmentioning

confidence: 99%

“…For bulk second phase mineralogy, thin section and XRD analysis were used. Thin sections pre‐treated by the two‐step etching method of Herwegh (2000) or polishing and lapping approach (Brodhag et al. , in press) were analysed by backscatter electron imaging, energy dispersive X‐ray spectrometry and electron backscatter diffraction (EBSD) for quantitative microstructural data (for details of sample preparation and analytical methods, see Brodhag et al.…”

Section: Methodsmentioning

confidence: 99%

See 4 more Smart Citations

Reaction‐induced nucleation and growth v. grain coarsening in contact metamorphic, impure carbonates

Berger

Brodhag

Herwegh

2010

Journal Metamorphic Geology

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The understanding of the evolution of microstructures in a metamorphic rock requires insights into the nucleation and growth history of individual grains, as well as the coarsening processes of the entire aggregate. These two processes are compared in impure carbonates from the contact metamorphic aureole of the Adamello pluton (N-Italy). As a function of increasing distance from the pluton contact, the investigated samples have peak metamorphic temperatures ranging from the stability field of diopside ⁄ tremolite down to diagenetic conditions. All samples consist of calcite as the dominant matrix phase, but additionally contain variable amounts of other minerals, the so-called second phases. These second phases are mostly silicate minerals and can be described in a KCMASHC system (K 2 O, CaO, MgO, Al 2 O 3 , SiO 2 , H 2 O, CO 2 ), but with variable K ⁄ Mg ratios. The modelled and observed metamorphic evolution of these samples are combined with the quantification of the microstructures, i.e. mean grain sizes and crystal size distributions. Growth of the matrix phase and second phases strongly depends on each other owing to coupled grain coarsening. The matrix phase is controlled by the interparticle distances between the second phases, while the second phases need the matrix grain boundary network for mass transfer processes during both grain coarsening and mineral reactions. Interestingly, similar final mean grain sizes of primary second phase and second phases newly formed by nucleation are observed, although the latter formed later but at higher temperatures. Moreover, different kinetic processes, attributed to different driving forces for growth of the newly nucleated grains in comparison with coarsening processes of the pre-existing phases, must have been involved. Chemically induced driving forces of grain growth during reactions are orders of magnitudes larger compared to surface energy, allowing new reaction products subjected to fast growth rates to attain similar grain sizes as phases which underwent long-term grain coarsening. In contrast, observed variations in grain size of the same mineral in samples with a similar T-t history indicate that transport properties depend not only on the growth and coarsening kinetics of the second phases but also on the microstructure of the dominant matrix phase during coupled grain coarsening. Resulting microstructural phenomena such as overgrowth and therefore preservation of former stable minerals by the matrix phase may provide new constraints on the temporal variation of microstructures and provide a unique source for the interpretation of the evolution of metamorphic microstructures.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

See 3 more Smart Citations

Reaction‐induced nucleation and growth v. grain coarsening in contact metamorphic, impure carbonates

Berger

Brodhag

Herwegh

2010

Journal Metamorphic Geology

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Patterns of strain localization in heterogeneous, polycrystalline rocks – a numerical perspective

Gardner

Piazolo

Evans

et al. 2017

Earth and Planetary Science Letters

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including the URL of the record and the reason for the withdrawal request. Highlights  Shear zones are difficult to form without a dynamic weakening mechanism  Dynamic weakening can quickly localize strain into an interconnected weak zone  Competing weakening and strengthening processes impact shear zone pattern  Shear zones are dynamic in time and space within a single deformation event  Finite strain patterns do not fully represent the evolution of a shear zone network *Highlights (for review)

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Quantitative analysis of crystal/grain sizes and their distributions in 2D and 3D

Berger

Herwegh

Schwarz

et al. 2011

Journal of Structural Geology

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Grain coarsening in polymineralic contact metamorphic carbonate rocks: The role of different physical interactions during coarsening

Cited by 11 publications

References 50 publications

Reaction‐induced nucleation and growth v. grain coarsening in contact metamorphic, impure carbonates

Reaction‐induced nucleation and growth v. grain coarsening in contact metamorphic, impure carbonates

Patterns of strain localization in heterogeneous, polycrystalline rocks – a numerical perspective

Quantitative analysis of crystal/grain sizes and their distributions in 2D and 3D

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