High-pressure and high-temperature vibrational properties and anharmonicity of carbonate minerals up to 6 GPa and 500 °C by Raman spectroscopy

Abstract

Carbonate minerals play a dominant role in the deep carbon cycle. Determining the high-pressure and high-temperature vibrational properties of carbonates is essential to understand their anharmonicity and their thermodynamic properties under crustal and upper mantle conditions. Building on our previous study on aragonite, calcite (both CaCO 3 polymorphs), dolomite [CaMg(CO 3) 2 ], magnesite (MgCO 3), rhodochrosite (MnCO 3), and siderite (FeCO 3) (Farsang et al. 2018), we have measured pressure-and temperature-induced frequency shifts of Ramanactive vibrational modes up to 6 GPa and 500 ˚C for all naturally occurring aragonite-and calcite-group carbonate minerals, including cerussite (PbCO 3), strontianite (SrCO 3), witherite (BaCO 3), gaspeite (NiCO 3), otavite (CdCO 3), smithsonite (ZnCO 3), and spherocobaltite (CoCO 3). Our Raman and XRD measurements show that cerussite decomposes to a mixture of This is the peer-reviewed, final accepted version for American Mineralogist, published by the Mineralogical Society of America. The published version is subject to change. Cite as Authors (Year) Title. American Mineralogist, in press.

Carbonate assemblages in Cold Bokkeveld CM chondrite reveal complex parent body evolution

“…Instead, the bimineralic grain may document a gradual aragonite-calcite phase transition. This phase transition has been observed experimentally at temperatures ranging from 385 to 468°C (Antao and Hassan 2010; Parker et al 2010;Farsang et al 2018) and the Raman spectra collected upon the transition exhibit similar features to those seen here (Farsang et al 2021). The transition is typically inhibited kinetically by the large associated volume change (from~34 to~37 cm 3 mol −1 as aragonite transforms to calcite), but the presence of aqueous fluids can significantly accelerate the kinetics and lower the effective activation energy for the phase transition, such that it may then occur at much lower temperatures (Bischoff and Fyfe 1968).…”

“…7a-c). The positions of Raman peaks corresponding to external modes (measured at 142 and 259 cm −1 ) in calcite in assemblage 3 are lower than those of any (including exotic) naturally occurring terrestrial rhombohedral carbonate measured using the same instrumental conditions (Farsang et al 2018(Farsang et al , 2021. Raman spectra of most of the meteoritic calcites contain broad G and D bands, indicating the presence of organic carbon in their structure (Table 3).…”

Deep carbon cycle constrained by carbonate solubility

“…Due to the enhanced ionicity of high P-T fluids, carbonates with alkaline earth M 2+ are expected to exhibit higher solubilities. However, these can still be orders of magnitude different, as seen for calcite and magnesite, most probably because of differences in ion size and anharmonicity 48 . The properties of M 2+ also control speciation in liquids, which further affects solubility.…”

Effects of hydrostaticity and Mn-substitution on dolomite stability at high pressure

“…The distorted structural environments provide a potential way to transport carbon into the deep mantle through a plethora of high-pressure polymorphisms of carbonate minerals due to diverse bonding patterns for carbon (Boulard et al, 2020;Lobanov and Goncharov, 2020). Meanwhile, these crystallographic characteristics of carbonates likely play an important role in the storage or transportation of incompatible elements (e.g., K, Ba, Sr) and trace elements (e.g., Zn, Co, Ni, Cd) in the deep mantle, as evidenced by syngenetic diamond inclusions and high temperature and high pressure experiment simulation (Farsang et al, 2021b(Farsang et al, , 2021cFrezzotti et al, 2011;Logvinova et al, 2008Logvinova et al, , 2011.…”