TY - JOUR

T1 - In situ Sr/Sr investigation of igneous apatites and carbonates using laser-ablation MC-ICP-MS

AU - Bizzarro, Martin

AU - Simonetti, A.

AU - Stevenson, R.K.

AU - Kurszlaukis, S.

PY - 2003/1/15

Y1 - 2003/1/15

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=0037438999&partnerID=8YFLogxK

U2 - 10.1016/S0016-7037(02)01048-7

DO - 10.1016/S0016-7037(02)01048-7

M3 - Journal article

AN - SCOPUS:0037438999

VL - 67

SP - 289

EP - 302

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

SN - 0016-7037

IS - 2

ER -