Publications

@article{mazzucchelli_fluid-mineral_2024,

title = {Fluid-mineral Equilibrium Under Nonhydrostatic Stress: Insight From Molecular Dynamics},

author = {Mattia L. Mazzucchelli and Evangelos Moulas and Boris J. P. Kaus and Thomas Speck},

url = {https://ajsonline.org/article/92881-fluid-mineral-equilibrium-under-nonhydrostatic-stress-insight-from-molecular-dynamics},

doi = {10.2475/001c.92881},

issn = {1945-452X, 0002-9599},

year  = {2024},

date = {2024-02-01},

urldate = {2024-02-01},

journal = {American Journal of Science},

volume = {324},

abstract = {The interpretation of phase equilibria and reactions in geological materials is based on standard thermodynamics that assumes hydrostatic and homogeneous stress conditions. However, rocks and minerals in the lithosphere can support stress gradients and nonhydrostatic stresses. Currently, there is still not an accepted macroscopic thermodynamic theory to include the effect of nonhydrostatic stress on mineral reactions, and the use of several thermodynamic potentials in stressed geological system remains under debate. In experiments under nonhydrostatic stress, it is often difficult to resolve the direct effect of differential stress on phase equilibria because pressure gradients may be developed. Such gradients can affect the metamorphic equilibria at the local scale. Here, we investigate the direct effect of a homogeneous, nonhydrostatic stress field on the solid-fluid equilibrium using molecular dynamics simulations at non-zero pressure and elevated temperature conditions. Our results show that, for simple single-component systems at constant temperature, the equilibrium fluid pressure of a stressed system is always larger than the value of fluid pressure at hydrostatic stress conditions. The displacement of the equilibrium value of the fluid pressure is about an order of magnitude smaller compared to the level of differential stress in the solid crystal. Thus, phase equilibria can be accurately predicted by taking the fluid pressure as a proxy of the equilibration pressure. On the contrary, the mean stress of the solid can deviate substantially from the pressure of the fluid in stressed systems at thermodynamic equilibrium. This has implications on the use of thermodynamic pressure in geodynamic models since the fluid pressure is a more accurate proxy for predicting the location of metamorphic reactions, while the equilibrium density of the solid has to be determined from its mean stress.},

keywords = {mineral-fluid interaction, molecular dynamics, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{angel_garnet_2022,

title = {Garnet EoS: a critical review and synthesis},

author = {Ross J. Angel and Mattia Gilio and Mattia Mazzucchelli and Matteo Alvaro},

url = {https://doi.org/10.1007/s00410-022-01918-5},

doi = {10.1007/s00410-022-01918-5},

issn = {1432-0967},

year  = {2022},

date = {2022-05-01},

urldate = {2022-05-01},

journal = {Contributions to Mineralogy and Petrology},

volume = {177},

number = {5},

pages = {54},

abstract = {All available volume and elasticity data for the garnet end-members grossular, pyrope, almandine and spessartine have been re-evaluated for both internal consistency and for consistency with experimentally measured heat capacities. The consistent data were then used to determine the parameters of third-order Birch–Murnaghan EoS to describe the isothermal compression at 298 K and a Mie–Grüneisen–Debye thermal-pressure EoS to describe the PVT behaviour. In a full Mie–Grüneisen–Debye EoS, the variation of the thermal Grüneisen parameter with volume is defined as $$textbackslashgamma = textbackslashgamma _0textbackslashleft(textbackslashfracVV_0textbackslashright)textasciicircumq$$. For grossular and pyrope garnets, there is sufficient data to refine q which has a value of q = 0.8(2) for both garnets. For other garnets, the data do not constrain the value of q and we therefore refined a q-compromise version of the Mie–Grüneisen–Debye EoS in which both γ/V and the Debye temperature θ D are held constant at all P and T, leading to $$textbackslashleft( textbackslashraise0.7extextbackslashhbox$textbackslashpartial C_textbackslashtextV $ textbackslash!textbackslashmathordtextbackslashleft/ textbackslashvphantom textbackslashpartial C_textbackslashtextV  textbackslashpartial Ptextbackslashright.textbackslashkern-textbackslashnulldelimiterspace textbackslash!textbackslashlower0.7extextbackslashhbox$textbackslashpartial P$ textbackslashright)_textbackslashtextT = 0$$, parallel isochors and constant isothermal bulk modulus along an isochor. Final refined parameters for the q-compromise Mie–Grüneisen–Debye EoS are: PyropeAlmandineSpessartineGrossularV0 (cm3/mol)a113.13115.25117.92125.35K0T (GPa)169.3 (3)174.6 (4)177.57 (6)167.0 (2)$$Ktextasciicircumtextbackslashprime_0textbackslashtextT$$4.55 (5)5.41 (13)4.6 (3)5.07 (8)θ D0771 (28)862 (22)860 (35)750 (13)γ01.185 (12)1.16 (fixed)1.18 (3)1.156 (6)for pyrope and grossular, the two versions of the Mie–Grüneisen–Debye EoS predict indistinguishable properties over the metamorphic pressure and temperature range, and the same properties as the EoS based on experimental heat capacities. The biggest change from previously published EoS is for almandine for which the new EoS predicts geologically reasonable entrapment conditions for zircon inclusions in almandine-rich garnets.},

keywords = {Crystallography, Elastic thermobarometry, Elasticity, Garnet, Single-crystal X-ray diffraction, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{angel_self-consistent_2021,

title = {A self-consistent approach to describe unit-cell-parameter and volume variations with pressure and temperature},

author = {R. Angel and M. Mazzucchelli and J. Gonzalez-Platas and M. Alvaro},

doi = {10.1107/S1600576721009092},

issn = {1600-5767},

year  = {2021},

date = {2021-12-01},

urldate = {2021-12-01},

journal = {Journal of Applied Crystallography},

volume = {54},

number = {6},

pages = {1621--1630},

abstract = {A method is presented for the self-consistent description of the variations of unit-cell parameters of crystals with pressure and temperature.},

keywords = {Crystallography, Elastic anisotropy, Elastic thermobarometry, Elasticity, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{Milani2017,

title = {Thermo-elastic behavior of grossular garnet at high pressures and temperatures},

author = {S. Milani and Ross John Angel and L. Scandolo and M. L. Mazzucchelli and T. B. Ballaran and S. Klemme and M. C. Domeneghetti and R. Miletich and K. S. Scheidl and M. Derzsi and K. Tokár and M. Prencipe and M. Alvaro and F. Nestola},

url = {https://doi.org/10.2138/am-2017-5855},

doi = {10.2138/am-2017-5855},

issn = {19453027},

year  = {2017},

date = {2017-01-01},

urldate = {2017-01-01},

journal = {American Mineralogist},

volume = {102},

number = {4},

pages = {851--859},

abstract = {© 2017 by Walter de Gruyter Berlin/Boston 2017. The thermo-elastic behavior of synthetic single crystals of grossular garnet (Ca 3 Al 2 Si 3 O 12 ) has been studied in situ as a function of pressure and temperature separately. The same data collection protocol has been adopted to collect both the pressure-volume (P-V) and temperature-volume (T-V) data sets to make the measurements consistent with one another. The consistency between the two data sets allows simultaneous fitting to a single pressure-volume-temperature Equation of State (EoS), which was performed with a new fitting utility implemented in the latest version of the program EoSFit7c. The new utility performs fully weighted simultaneous fits of the P-V-T and P-K-T data using a thermal pressure EoS combined with any P-V EoS. Simultaneous refinement of our P-V-T data combined with that of K T as a function of T allowed us to produce a single P-V-T-K T equation of state with the following coefficients: V 0 =1664.46(5)Å 3 K TO =166.57(17)GPa and K′=4.96(7)α (300K,1bar) =2.09(2)×10 -5 K -1 with a refined Einstein temperature (θ E ) of 512 K for a Holland-Powell-type thermal pressure model and a Tait third-order EoS. Additionally, thermodynamic properties of grossular have been calculated for the first time from crystal Helmholtz and Gibbs energies, including the contribution from phonons, using density functional theory within the framework of the quasi-harmonic approximation.},

keywords = {ab-initio, Density Functional Theory, DFT, Elastic thermobarometry, equations of state, high-pressure, high-temperature, thermal expansion, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{Scandolo2015ab,

title = {Thermal expansion behaviour of orthopyroxenes: the role of the Fe-Mn substitution},

author = {L. Scandolo and Mattia Luca Mazzucchelli and M. Alvaro and Fabrizio Nestola and F. Pandolfo and M. C. C Domeneghetti},

url = {https://doi.org/10.1180/minmag.2015.079.1.07},

doi = {10.1180/minmag.2015.079.1.07},

issn = {14718022},

year  = {2015},

date = {2015-01-01},

urldate = {2015-01-01},

journal = {Mineralogical Magazine},

volume = {79},

number = {1},

pages = {71--87},

keywords = {Crystallography, Elasticity, equations of state, Single-crystal X-ray diffraction, thermal expansion, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{Milani2015,

title = {Diamond–garnet geobarometry: The role of garnet compressibility and expansivity},

author = {Sula Milani and Fabrizio Nestola and Matteo Alvaro and Daria Pasqual and Mattia Luca Mazzucchelli and M C Domeneghetti and C A Geiger},

url = {http://www.sciencedirect.com/science/article/pii/S0024493715001097},

doi = {10.1016/j.lithos.2015.03.017},

year  = {2015},

date = {2015-01-01},

urldate = {2015-01-01},

journal = {Lithos},

volume = {227},

number = {0},

pages = {140--147},

keywords = {Crystallography, Diamond, Elastic thermobarometry, equations of state, Experiments, Garnet, petrology, Raman thermobarometry, Single-crystal X-ray diffraction, thermal expansion, thermodynamics},

pubstate = {published},

tppubtype = {article}

}

@article{Angel2015diamond,

title = {Diamond thermoelastic properties and implications for determining the pressure of formation of diamond–inclusion systems},

author = {Ross John Angel and Matteo Alvaro and Fabrizio Nestola and Mattia Luca Mazzucchelli},

doi = {10.1016/j.rgg.2015.01.014},

year  = {2015},

date = {2015-01-01},

urldate = {2015-01-01},

journal = {Russian Geology and Geophysics},

volume = {56},

number = {1-2},

pages = {211--220},

keywords = {Diamond, Elastic thermobarometry, Elasticity, equations of state, petrology, thermodynamics},

pubstate = {published},

tppubtype = {article}

}