Abstract The trace element composition of rutile is widely used to constrain the temperature and timing of geological events, the provenance of detrital grains and as a potential indicator of proximal ore mineralisation. Understanding the processes of trace element mobility in rutile is therefore paramount to the successful application of rutile geochemistry to geological research. Using a combination of electron backscattered diffraction and laser-ablation split-stream ICP-MS, we studied the microtextures, trace-element contents and U–Pb isotopes of rutile from the siliciclastic rocks of the Mesoproterozoic Edmund Group, Capricorn Orogen (Western Australia). The Capricorn Orogen experienced multiple tectonothermal events during the Proterozoic under conditions spanning from low- to high-grade metamorphism. Rutile textures, U–Pb ages, trace-element variations and calculated Zr-in-rutile temperatures reveal different generations of rutile, including detrital or metamorphic-hydrothermal grains. U–Pb age data of detrital rutile indicate a wide span of ages (ca. 2.7–1.7 Ga) of the source rocks and Cr-Nb compositions point to metamafic, metapelitic and granitic origins for this rutile. The youngest detrital ages of 1.68 Ga constrain the maximum depositional age of the sedimentary package. The comparison of age spectra across the stratigraphy indicates a change in provenance, with sourcing from circa 1.7 Ga rocks during early stages of deposition, followed by unroofing of older basement during deposition of the youngest units of the Edmund Group. Partial resetting of detrital rutile is observed in the increase of 207Pb/206Pb ratios, accompanied by a decrease of Zr-in-rutile calculated temperatures. Lower-temperature metamorphic-hydrothermal rutile yielded imprecise Mesoproterozoic ages (1.3–1.1 Ga). This rutile has significant variations of Zr/Hf and Nb/Ta extending to values both lower and higher than primitive mantle, which may record crystallisation from, or interaction with hydrothermal fluids. Partial remobilisation of trace elements in metamorphic-hydrothermal rutile is demonstrated by sub-grain domains with sharp geochemical variations and by evidence of element diffusion at grain margins. Orders of magnitude differences in trace element concentrations (including Nb, Cr and Zr) in metamorphic-hydrothermal rutile grains suggest thorough investigation of rutile textures needs to be carried out prior to using the trace element concentrations in rutile for provenance and Zr-in-rutile temperature studies.

中文翻译：

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金红石中的成分修饰和微量元素解耦：来自西澳大利亚摩羯座造山带的见解

摘要 金红石的微量元素组成被广泛用于限制地质事件的温度和时间、碎屑颗粒的来源，并作为近端矿石成矿的潜在指标。因此，了解金红石中微量元素迁移的过程对于金红石地球化学在地质研究中的成功应用至关重要。我们结合使用电子背散射衍射和激光烧蚀分流 ICP-MS，研究了摩羯造山带（西澳大利亚）中元古代埃德蒙群硅质碎屑岩中金红石的微观结构、微量元素含量和 U-Pb 同位素. 摩羯座造山带在元古代期间经历了从低级变质到高级变质的多次构造热事件。金红石结构，U-Pb 年龄，微量元素变化和计算出的金红石中 Zr 温度揭示了金红石的不同世代，包括碎屑或变质热液颗粒。碎屑金红石的 U-Pb 年龄数据表明烃源岩的年龄跨度大（约 2.7-1.7 Ga），而 Cr-Nb 成分表明该金红石的变镁铁质、变泥质和花岗质成因。1.68 Ga 的最年轻碎屑年龄限制了沉积包的最大沉积年龄。整个地层的年龄谱比较表明物源发生了变化，在沉积的早期阶段从大约 1.7 Ga 的岩石中获取，然后在 Edmund Group 最年轻单元的沉积过程中对较旧的基底开顶。在 207Pb/206Pb 比率的增加中观察到碎屑金红石的部分复位，伴随着金红石中锆计算温度的降低。低温变质热液金红石产生了不精确的中元古代（1.3-1.1 Ga）。这种金红石具有显着的 Zr/Hf 和 Nb/Ta 变化，延伸到低于和高于原始地幔的值，这可能记录了从热液流体的结晶或相互作用。变质热液金红石中微量元素的部分再迁移可以通过具有剧烈地球化学变化的亚晶粒域和晶粒边缘元素扩散的证据来证明。微量元素浓度（包括 Nb、