In situ X-ray observation of the reaction dolomite = aragonite + magnesite at 900–1300 K

A primary natrocarbonatitic association in the Deep Earth

“…In another sample (#8/108), a spherical inclusion of wüstite + periclase in dolomite was identified, pointing to its formation under pressure conditions exceeding 86 GPa (Kaminsky et al 2015a). This agrees with the experimental data of Mao et al (2011), who demonstrated, that CaMg(CO 3 ) 2 is stable under lower-mantle conditions at pressures of up to 83 GPa and, possibly, higher, and contrasts earlier data on the decomposing of dolomite into magnesite + aragonite, under lower-mantle P-T conditions (Biellmann et al 1993;Luth 2001;Shirasaka et al 2002). Recent experiments confirm that high-pressure polymorphism in dolomite could stabilize CaMg(CO 3 ) 2 ; this composition transforms at ~17 GPa into 'dolomite-II' (with a monoclinic structure, according to Santillán et al 2003, or an orthorhombic structure, according to Mao et al 2011, or a triclinic structure for Fe-dolomite, according to Merlini et al 2012) and then, at ~35-41 GPa, into 'dolomite-III' (with monoclinic structure, according to Mao et al 2011 or a triclinic structure in the case of Fe-dolomite, according to Merlini et al 2012) .…”

Experimental calibration of clumped isotope reordering in dolomite

“…At 717 °C, dolomite is stable at pCO2 values above ~15 MPa but below ~3 GPa, where it dissociates into aragonite and magnesite (Goldsmith and Heard, 1961;Graf and Goldsmith, 1955;Shirasaka et al, 2002). So, in subsequent runs, we pressurized the cold seal apparatus with 43.5-78.4 MPa of CO2 instead of Ar.…”

Influence of pressure and temperature on the electrical conductivity of dolomite

“…The measurements of the electrical conductivity were performed at pressures ≤6 GPa, because dolomite decomposes into magnesite and aragonite at high pressures (Liu and Lin 1995;Martinez et al 1996;Sato and Katsura 2001;Luth 2001;Shirasaka et al 2002;Buob et al 2006). Figure 2 shows a representative complex impedance curve from a sample of dolomite.…”

“…The extent of the Sato and Katsura 2001;Luth 2001;Shirasaka et al 2002;Antao et al 2004;Buob et al 2006;Hammouda et al 2011;Franzolin et al 2012). Thus, magnesite, dolomite, and aragonite may play an important role in the transportation of carbon in the subducted slab.…”