Publications

@article{murri_role_2022,

title = {The role of symmetry-breaking strains on quartz inclusions in anisotropic hosts: Implications for Raman elastic geobarometry},

author = {M. Murri and J. P. Gonzalez and M. L. Mazzucchelli and M. Prencipe and B. Mihailova and R. J. Angel and M. Alvaro},

url = {https://www.sciencedirect.com/science/article/pii/S0024493722001256},

doi = {10.1016/j.lithos.2022.106716},

issn = {0024-4937},

year  = {2022},

date = {2022-08-01},

urldate = {2022-08-01},

journal = {Lithos},

volume = {422-423},

pages = {106716},

abstract = {Raman elastic geobarometry for mineral host-inclusion systems is used to determine the strains acting on an inclusion still entrapped in its host by measuring its Raman wavenumber shifts which are interpreted through the phonon-mode Grüneisen tensors of the inclusion phase. The calculated inclusion strains can then be used in an elastic model to calculate the pressure and temperature conditions of entrapment. This method is applied frequently to host inclusion systems where the host is almost elastically isotropic (e.g. garnet) and the inclusion is elastically anisotropic (e.g. quartz and zircon). In this case, when the entrapment occurs under hydrostatic conditions the host will impose isotropic strains on the inclusion which in turn will develop non-hydrostatic stress. In this scenario the symmetry of the inclusion mineral is preserved and the strains in the inclusion can be measured via Raman spectroscopy using the phonon-mode Grüneisen tensor approach. However, a more complex situation arises when the host-inclusion system is fully anisotropic, such as when a quartz inclusion is entrapped within a zircon host, because the symmetry of the inclusion can be broken due to the external anisotropic strain field imposed on the inclusion by the host, which in turn will modify the phonon modes. We therefore calculated the strain states of quartz inclusions entrapped in zircon hosts in multiple orientations and at various geologically relevant pressure and temperature conditions. We then performed ab initio Hartree-Fock/Density Functional Theory (HF/DFT) simulations on α-quartz in these strain states. These HF/DFT simulations show that the changes in the positions of the Raman modes produced by strains that are expected for symmetry broken quartz inclusions in zircon are generally similar to those that would be seen if the quartz inclusions remained truly trigonal in symmetry. Therefore, the use of the trigonal phonon-mode Grüneisen tensor to determine the inclusion strains does not lead to geologically significant errors in calculated quartz inclusion entrapment pressures in zircon.},

keywords = {ab-initio, Crystallography, Density Functional Theory, DFT, Elastic anisotropy, Elastic thermobarometry, Raman spectroscopy, Raman thermobarometry},

pubstate = {published},

tppubtype = {article}

}

@article{campomenosi_using_2021,

title = {Using the elastic properties of zircon-garnet host-inclusion pairs for thermobarometry of the ultrahigh-pressure Dora-Maira whiteschists: problems and perspectives},

author = {Nicola Campomenosi and Marco Scambelluri and Ross J. Angel and Joerg Hermann and Mattia L. Mazzucchelli and Boriana Mihailova and Francesca Piccoli and Matteo Alvaro},

url = {https://doi.org/10.1007/s00410-021-01793-6},

doi = {10.1007/s00410-021-01793-6},

issn = {1432-0967},

year  = {2021},

date = {2021-04-01},

urldate = {2021-04-01},

journal = {Contributions to Mineralogy and Petrology},

volume = {176},

number = {5},

pages = {36},

abstract = {The ultrahigh-pressure (UHP) whiteschists of the Brossasco-Isasca unit (Dora-Maira Massif, Western Alps) provide a natural laboratory in which to compare results from classical pressure (P)–temperature (T) determinations through thermodynamic modelling with the emerging field of elastic thermobarometry. Phase equilibria and chemical composition of three garnet megablasts coupled with Zr-in-rutile thermometry of inclusions constrain garnet growth within a narrow P–T range at 3–3.5 GPa and 675–720 °C. On the other hand, the zircon-in-garnet host-inclusion system combined with Zr-in-rutile thermometry would suggest inclusion entrapment conditions below 1.5 GPa and 650 °C that are inconsistent with the thermodynamic modelling and the occurrence of coesite as inclusion in the garnet rims. The observed distribution of inclusion pressures cannot be explained by either zircon metamictization, or by the presence of fluids in the inclusions. Comparison of the measured inclusion strains with numerical simulations shows that post-entrapment plastic relaxation of garnet from metamorphic peak conditions down to 0.5 GPa and 600–650 °C, on the retrograde path, best explains the measured inclusion pressures and their disagreement with the results of phase equilibria modelling. This study suggests that the zircon-garnet couple is more reliable at relatively low temperatures (textless 600 °C), where entrapment conditions are well preserved but chemical equilibration might be sluggish. On the other hand, thermodynamic modelling appears to be better suited for higher temperatures where rock-scale equilibrium can be achieved more easily but the local plasticity of the host-inclusion system might prevent the preservation of the signal of peak metamorphic conditions in the stress state of inclusions. Currently, we cannot define a precise threshold temperature for resetting of inclusion pressures. However, the application of both chemical and elastic thermobarometry allows a more detailed interpretation of metamorphic P–T paths.},

keywords = {Elastic thermobarometry, Garnet, metamorphic rocks, petrology, Raman spectroscopy, Raman thermobarometry, Zircon},

pubstate = {published},

tppubtype = {article}

}

@article{Campomenosi2020,

title = {Using polarized Raman spectroscopy to study the stress gradient in mineral systems with anomalous birefringence},

author = {N. Campomenosi and Mattia Luca Mazzucchelli and B. D. Mihailova and Ross John Angel and Matteo Alvaro},

url = {https://doi.org/10.1007/s00410-019-1651-x},

doi = {10.1007/s00410-019-1651-x},

issn = {14320967},

year  = {2020},

date = {2020-02-01},

urldate = {2020-02-01},

journal = {Contributions to Mineralogy and Petrology},

volume = {175},

number = {2},

pages = {1--16},

abstract = {Polarized Raman spectroscopy was applied to garnet hosts which exhibit anomalous birefringence around inclusions of zircon and quartz to elucidate the spatial distribution of the anisotropic strain fields in the vicinity of the host-inclusion boundary. We show that there is a direct relationship between the stress-induced birefringence and the Raman scattering generated by the fully symmetric phonon modes (the A1g modes in cubic crystals). Our experimental results coupled with selected finite element models show that the ratio between the measured Raman peak intensity collected in cross and parallel polarized scattering geometries of totally symmetric modes represents a useful tool to constrain the radial stress profile in the host around the inclusions. Further, we demonstrate how group-theoretical considerations and tensor analysis of the morphic effect (external-field-induced change of the symmetry) on the phonons and the optical properties of the host can help to derive useful information on the symmetry of the stress field. Finally, we show experimentally that, under the same amount of applied stress, this approach is more sensitive than the commonly used approach of measuring differences in phonon frequencies and provides better opportunities to map the spatial variations of strain. This approach is an alternative technique to study structural phenomena associated with anomalous birefringence in host crystals surrounding stressed inclusions and could be applied to other systems in which similar optical effects are observed.},

keywords = {Crystallography, Elastic anisotropy, Elasticity, Raman spectroscopy, Stress},

pubstate = {published},

tppubtype = {article}

}

@article{Campomenosi2018,

title = {How geometry and anisotropy affect residual strain in host-inclusion systems: Coupling experimental and numerical approaches},

author = {Nicola Campomenosi and Mattia Luca Mazzucchelli and Boriana Mihailova and Marco Scambelluri and Ross John Angel and Fabrizio Nestola and Alessandro Reali and Matteo Alvaro},

url = {https://pubs.geoscienceworld.org/msa/ammin/article/103/12/2032/567206/How-geometry-and-anisotropy-affect-residual-strain},

doi = {10.2138/am-2018-6700CCBY},

issn = {0003-004X},

year  = {2018},

date = {2018-12-01},

urldate = {2018-12-01},

journal = {American Mineralogist},

volume = {103},

number = {12},

pages = {2032--2035},

keywords = {Elastic anisotropy, Elastic thermobarometry, Elasticity, Experiments, Raman spectroscopy},

pubstate = {published},

tppubtype = {article}

}

@article{murri_raman_2018,

title = {Raman elastic geobarometry for anisotropic mineral inclusions},

author = {Mara Murri and Mattia Luca Mazzucchelli and Nicola Campomenosi and Andrey V. Korsakov and Mauro Prencipe and Boriana D. Mihailova and Marco Scambelluri and Ross John Angel and Matteo Alvaro},

url = {https://doi.org/10.2138/am-2018-6625CCBY},

doi = {10.2138/am-2018-6625CCBY},

issn = {0003004X},

year  = {2018},

date = {2018-11-01},

urldate = {2018-11-01},

journal = {American Mineralogist},

volume = {103},

number = {11},

pages = {1869--1872},

keywords = {ab-initio, Density Functional Theory, Deviatoric stress, DFT, Elastic anisotropy, Elastic thermobarometry, metamorphic rocks, Raman spectroscopy, Raman thermobarometry},

pubstate = {published},

tppubtype = {article}

}