Trace‐element signatures of apatites in granitoids from the Mt Isa Inlier, northwestern Queensland
Trace‐element signatures of apatites in granitoids from the Mt Isa Inlier, northwestern Queensland
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DOI：
10.1046/j.1440-0952.2001.00879.x
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发表时间：
2001-08
影响因子：
1.2
通讯作者：
E. Belousova;S. Walters;W. Griffin;S. O’Reilly
中科院分区：
文献类型：
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作者：
E. Belousova;S. Walters;W. Griffin;S. O’Reilly
利用激光烧蚀电感耦合等离子体质谱（ICP-MS）微探针研究了伊萨山因利尔花岗岩类岩石中磷灰石的微量元素含量。结果表明，磷灰石中微量元素（特别是稀土元素（REE）、Sr、Y、Mn和Th）的分布强烈地反映了母岩的化学特征。磷灰石中微量元素浓度的变化与SiO2含量、铁的氧化态、总碱和铝饱和指数（ASI）等参数相关。磷灰石中Y、HREE和Mn的相对富集和Sr的相对亏损反映了寄主花岗岩的分异程度。磷灰石从强氧化的岩体往往有更高的浓度轻稀土元素相对于MREE。锰浓度较高的磷灰石从还原花岗岩，因为Mn 2+直接取代Ca 2+。磷灰石的La/Ce比值与全岩K2 O和Na 2 O含量以及氧化态和ASI密切相关。由于磷灰石微量元素组成反映了整个岩石的化学性质，因此它可以作为识别矿化花岗岩系列的有用指示矿物，其中特定的矿化类型与具有特定地球化学指纹的花岗岩类有关。
The concentrations of trace elements in apatite from granitoid rocks of the Mt Isa Inlier have been investigated using the laser‐ablation inductively coupled plasma‐mass spectrometry (ICP‐MS) microprobe. The results indicate that the distribution of trace elements (especially rare‐earth elements (REE), Sr, Y, Mn and Th) in apatite strongly reflects the chemical characteristics of the parental rock. The variations in the trace‐element concentrations of apatite are correlated with parameters such as the SiO2 content, oxidation state of iron, total alkalis and the aluminium saturation index (ASI). The relative enrichment of Y, HREE and Mn and the relative depletion of Sr in the apatites studied reflect the degree of fractionation of the host granite. Apatites from strongly oxidised plutons tend to have higher concentrations of LREE relative to MREE. Manganese concentrations are higher in apatite from reduced granitoids because Mn2+substitutes directly for Ca2+. The La/Ce ratio of apatite is well‐correlated with the whole‐rock K2O and Na2O contents, as well as with the oxidation state and ASI. Because apatite trace‐element composition reflects the chemistry of the whole rock, it can be a useful indicator mineral for the recognition of mineralised granite suites, where particular mineralisation styles are associated with granitoids that have specific geochemical fingerprints.