TY - JOUR
T1 - Static compressibility of magnesite to 20 GPa
T2 - Implications for MgCO3 in the lower mantle
AU - Redfern, S. A T
AU - Wood, B. J.
AU - Henderson, C. M B
PY - 1993
Y1 - 1993
N2 - The bulk modulus of MgCO3 magnesite has been measured to 20 GPa at room temperature using X‐ray powder diffraction. Since the response to pressure is primarily compression of the MO6 octahedron, magnesite is substantially less compressible than Ca‐carbonates of similar structure type. Using the Birch equation of state, with KT′ of 4.0, we obtain KT of 142 (±9) GPa at room temperature. The full Birch‐Murnaghan equation of state yields KT of 151 (±7) GPa and KT′ of 2.5. These results, together with other thermodynamic data, have been applied to calculate the stability of magnesite under lower mantle conditions. Assuming lower‐mantle saturation in (Mg,Fe)O, magnesite should be stable to temperatures well in excess of 6000 K at the core‐mantle boundary, i.e. at least up to the solidus of peridotitic or pyroxenitic compositions. This confirms that magnesite is a stable host for carbon in the mantle.
AB - The bulk modulus of MgCO3 magnesite has been measured to 20 GPa at room temperature using X‐ray powder diffraction. Since the response to pressure is primarily compression of the MO6 octahedron, magnesite is substantially less compressible than Ca‐carbonates of similar structure type. Using the Birch equation of state, with KT′ of 4.0, we obtain KT of 142 (±9) GPa at room temperature. The full Birch‐Murnaghan equation of state yields KT of 151 (±7) GPa and KT′ of 2.5. These results, together with other thermodynamic data, have been applied to calculate the stability of magnesite under lower mantle conditions. Assuming lower‐mantle saturation in (Mg,Fe)O, magnesite should be stable to temperatures well in excess of 6000 K at the core‐mantle boundary, i.e. at least up to the solidus of peridotitic or pyroxenitic compositions. This confirms that magnesite is a stable host for carbon in the mantle.
UR - http://www.scopus.com/inward/record.url?scp=0027847955&partnerID=8YFLogxK
U2 - 10.1029/93GL02507
DO - 10.1029/93GL02507
M3 - Article
AN - SCOPUS:0027847955
SN - 0094-8276
VL - 20
SP - 2099
EP - 2102
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 19
ER -