In situ X-ray diffraction of aragonite and dolomite at high pressure and high temperature; evidence for dolomite breakdown to aragonite and magnesite

Abstract

Other| June 01, 1996 In situ X-ray diffraction of aragonite and dolomite at high pressure and high temperature; evidence for dolomite breakdown to aragonite and magnesite Isabelle Martinez; Isabelle Martinez State University of New York, Center for High Pressure Research and Department of Earth and Space Sciences, Stony Brook, NY, United States Search for other works by this author on: GSW Google Scholar Jianzhong Zhang; Jianzhong Zhang Search for other works by this author on: GSW Google Scholar Richard J. Reeder Richard J. Reeder Search for other works by this author on: GSW Google Scholar American Mineralogist (1996) 81 (5-6): 611–624. https://doi.org/10.2138/am-1996-5-608 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Isabelle Martinez, Jianzhong Zhang, Richard J. Reeder; In situ X-ray diffraction of aragonite and dolomite at high pressure and high temperature; evidence for dolomite breakdown to aragonite and magnesite. American Mineralogist 1996;; 81 (5-6): 611–624. doi: https://doi.org/10.2138/am-1996-5-608 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Energy-dispersive X-ray powder diffraction spectra have been collected for aragonite (CaC03) and dolomite [CaMg(C03)2] at high pressure and high temperature, using synchrotron radiation and a cubic multi-anvil apparatus. Unit-cell volumes were measured up to 7 GPa and 1073 K along several isothermal paths. This study has confirmed previously determined but still debated values of the bulk incompressibilities at 298 K [65.4(5) GPa for aragonite and 90.7(7) GPa for dolomite] and thermal expansivities at 1 bar [(α)298-1000 K = 6.7(5) 10-5 K-1 for aragonite and (α)298-1000K = 4.1(5) 10-5 K-1 for dolomite]. In addition, new equation-of-state parameters were measured: (∂K/∂T)P [-0.013(2) and −0.025(4) GPa/K for aragonite and dolomite, respectively] and K'0 [2.7(7) and 2.3(5) for aragonite and dolomite, respectively]. We suggest that these equation-of-state parameters could be used in the calculation of high-temperature, high-pressure thermodynamic properties of these carbonates.At pressures exceeding 5 GPa, we observed that dolomite breaks down to aragonite and magnesite. We used the equation-of-state parameters measured in this study to calculate the position of the equilibrium curve: dolomite → aragonite + magnesite. This reaction could be important in the ultra-high-pressure metamorphism of carbonates. This decomposition reaction also provides a useful test of thermodynamic data sets of carbonates at high pressures and temperatures. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.