Skip to content. | Skip to navigation

Personal tools

 

 

 

 
     

 

 

 

 

 

 

 

 

 

 

 

 

You are here: Home / PDFs on demand / Bibliographical References of PDFs on demand / Non-Henry's Law behavior of REE partitioning between fluorapatite and CaF2-rich melts: Controls of intrinsic vacancies and implications for natural apatites

Y. Pan, P. Dong and N. Chen (2003)

Non-Henry's Law behavior of REE partitioning between fluorapatite and CaF2-rich melts: Controls of intrinsic vacancies and implications for natural apatites

Geochimica Et Cosmochimica Acta, 67(10):1889-1900.

The partitioning of rare-earth elements (REEs: Gd and multiple REEs), Sr, and Mn between fluorapatite and CaF2-rich melts was investigated over a wide range of REE concentrations (i.e., from 0.8 +/- 0.1 to 25,000 +/- 2600 ppm Gd in fluorapatite) in two different sample assemblies (i.e., tightly covered Pt crucibles and sealed Pt capsules) at 1220 degreesC and atmospheric pressure. Attainment of equilibrium is indicated by selected reversal experiments. The partition coefficient D(Gd) decreases from similar to2 to similar to0.5 with increasing Gd in fluorapatite, hence a marked non-Henry's Law behavior, but becomes independent of composition at and above similar to5000 and similar to1000 ppm Gd for experiments in Pt crucibles and Pt capsules, respectively. Non-Henry's Law behavior is also observed in experiments involving multiple REEs. All REE patterns are convex upward in shape with maxima between Nd and Gd, and D(La)/D(Nd) and D(Nd)/D(Yb) decrease systematically with increasing total REEs in fluorapatite, suggesting that REE fractionations are partly related to non-Henry's Law behavior. These experimental results and local structural data from previous electron paramagnetic resonance spectroscopic studies suggest that the non-Henry's Law behavior of REE partitioning between fluorapatite and melt is controlled by intrinsic Ca2+ vacancies in the c-axis channels. The D(Sr) and D(Mn) values are independent of composition and, therefore, do not deviate from the Henry's Law in their respective compositional ranges investigated in this study. Nonstoichiometry, such as Ca2+ and F- vacancies in the c-axis channels, is well known in natural apatites, particularly in biogenic apatites. Therefore, the observed non-Henry's Law behavior of REE partitioning is expected to have important implications for REE geochemical modeling involving apatites and for the uptake of REES by natural apatites. Particularly, the non-Henry's Law behavior of REE partitioning is at least partly responsible for the commonly observed, bell-shaped REE patterns in fossil biogenic apatites. Copyright (C) 2003 Elsevier Science Ltd.

defect chemistry, biogenic apatites, structural variations, icp-ms, rare-earth elements, site preference, trace-elements, part ii, synthetic fluorapatite, x-ray
WOS:000182881700009
Year

1875 1876 1877 1878 1879
1880 1881 1882 1883 1884
1885 1886 1887 1888 1889
1890 1891 1892 1893 1894
1895 1896 1897 1898 1899

1900 1901 1902 1903 1904
1905 1906 1907 1908 1909
1910 1911 1912 1913 1914
1915 1916 1917 1918 1919
1920 1921 1922 1923 1924

1925 1926 1927 1928 1929
1930 1931 1932 1933 1934
1935 1936 1937 1938 1939
1940 1941 1942 1943 1944
1945 1946 1947 1948 1949

1950 1951 1952 1953 1954
1955 1956 1957 1958 1959
1960 1961 1962 1963 1964
1965 1966 1967 1968 1969
1970 1971 1972 1973 1974

1975 1976 1977 1978 1979
1980 1981 1982 1983 1984
1985 1986 1987 1988 1989
1990 1991 1992 1993 1994
1995 1996 1997 1998 1999

2000 2001 2002 2003 2004
2005 2006 2007 2008 2009
2010 2011 2012 2013 2014
2015 2016 2017 2018 2019
2020 2021 2022 2023 2024

 
e-ressources

 

PDFs on demand
 

 

 

RBINS private PDFs