In situ Sr/Sr investigation of igneous apatites and carbonates using laser-ablation MC-ICP-MS
Research output: Contribution to journal › Journal article › Research › peer-review
In situ Sr isotopic compositions of coexisting apatite and carbonate for carbonatites from the Sarfartoq alkaline complex, Greenland, have been determined by laser-ablation multicollector inductively coupled plasma mass spectrometry. This study is the first to examine the extent of Sr isotopic homogeneity among coexisting igneous minerals containing high Sr (>3000 ppm) and low Rb ( « 1 ppm) contents within a single ~ 50-µm-thin-section mount. This technique is capable of producing measured Sr/Sr values with analytical precision (~ 0.005%, 2s) approaching those obtained by thermal ionization mass spectrometry but in a much shorter interval of time (100 s vs.>1 h, respectively). The combined total analyses (n = 107) of apatite and carbonate yield Sr/Sr compositions ranging from ~ 0.7025 to ~ 0.7031. This relatively large variation in Sr isotopic compositions (~ 0.0006) is ~ 1 order of magnitude larger than the estimated external reproducibility (~ 0.00005,2s) of the method. The large range in Sr/Sr values suggests that apatite and carbonate precipitated predominantly under nonequilibrium conditions. The isotopic variations observed within individual hand specimens may therefore reflect larger (regional) scale open-system processes, possibly involving mixing of carbonatitic melts derived from distinct mantle sources or from a common isotopically heterogeneous mantle.
Original language | English |
---|---|
Journal | Geochimica et Cosmochimica Acta |
Volume | 67 |
Issue number | 2 |
Pages (from-to) | 289-302 |
Number of pages | 14 |
ISSN | 0016-7037 |
DOIs | |
Publication status | Published - 15 Jan 2003 |
ID: 45193370