Abstract New methods to determine the titanium (Ti) mass-dependent isotope fractionation of solar system materials to high precision were developed by combining internally normalised Ti isotope data with double-spike analyses utilising a 47Ti 49Ti double spike. The procedure includes a three-stage ion-exchange separation procedure to isolate Ti from the sample matrix that provides high-purity Ti fractions that are necessary for high-precision Ti isotope analyses. Analyses of sample aliquots that were spiked before and after the ion-exchange separation procedure demonstrate that Ti isotope fractionation can be induced by the separation procedure. This outcome requires the addition of the double spike before the ion exchange separation procedure in order to accurately determine the natural mass-dependent Ti isotope fractionation of samples. Multiple double spike analyses of an Alfa Aesar Ti standard performed over eight months yielded a reproducibility (2σ standard deviation) of 0.033‰ for δ49/47Ti (differences in 49Ti/47Ti relative to the OL-Ti standard). Terrestrial sample analyses display a 2σ reproducibility of 0.018 to 0.031‰ for δ49/47Ti. Titanium isotope results for three terrestrial USGS magmatic reference samples (AGV-2, BHVO-2 and BCR-2) agree well with literature data and therefore demonstrate the accuracy and precision of the presented methodologies. Achondritic meteorites display an overall range of 0.75‰ for δ49/47Ti. The ungrouped achondrite NWA 7325 has a more positive composition by 0.64‰ for δ49/47Ti compared to all other investigated samples likely reflecting Ti isotope fractionation induced by magmatic differentiation associated with highly reducing conditions and potentially associated with oxide and plagioclase formation. In contrast, eucrites with δ49/47Ti of −0.020 ± 0.070 and − 0.003 ± 0.033and the first mass-dependent Ti isotope data for an acapulcoite (Dhofar 125; δ49/47Ti = 0.094 ± 0.033) show only limited magmatic Ti isotope fractionation. Chondrites also display a relatively restricted range of 0.085‰ for δ49/47Ti, including one calcium‑aluminum rich inclusion (CAI) from Allende and the first mass-dependent Ti isotope data for two Rumuruti chondrites (NWA 753 and NWA 755). Furthermore, the mass-dependent Ti isotope composition of chondrites overlaps with that of eucrites and the acapulcoite Dhofar 125 indicating that nebular processes induce only limited Ti isotope fractionation. Additionally, the Ti isotope data indicate that thermal metamorphism also produced marginal Ti isotope fractionation at the bulk sample scale for chondrites. Small mass-dependent Ti isotope variations between different bulk meteorite samples are also evident, which might reflect sample heterogeneity. Importantly, the mass-dependent Ti isotope composition of the Earth and Moon overlap with the composition of the investigated chondrites, eucrites and acapulcoites within the 2 standard deviation uncertainties.

中文翻译：

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太阳系材料中的钛同位素分馏

摘要 通过将内部归一化的 Ti 同位素数据与使用 47Ti 49Ti 双尖峰的双尖峰分析相结合，开发了高精度确定太阳系材料中钛 (Ti) 质量相关同位素分馏的新方法。该程序包括一个三阶段离子交换分离程序，用于从样品基质中分离 Ti，从而提供高精度 Ti 同位素分析所需的高纯度 Ti 馏分。在离子交换分离过程之前和之后加标的样品等分试样的分析表明，分离过程可以诱导 Ti 同位素分馏。这一结果需要在离子交换分离程序之前添加双尖峰，以便准确确定样品的自然质量相关 Ti 同位素分馏。Alfa Aesar Ti 标准品在八个月内进行的多次双加标分析得出 δ49/47Ti 的重现性（2σ 标准偏差）为 0.033‰（49Ti/47Ti 相对于 OL-Ti 标准品的差异）。陆地样品分析显示 δ49/47Ti 的 2σ 重现性为 0.018 至 0.031‰。三个陆地 USGS 岩浆参考样品（AGV-2、BHVO-2 和 BCR-2）的钛同位素结果与文献数据非常吻合，因此证明了所提出方法的准确性和精密度。无球粒陨石显示 δ49/47Ti 的整体范围为 0.75‰。未分组的无球粒陨石 NWA 7325 具有更正的成分 0。与所有其他研究样品相比，δ49/47Ti 为 64‰，这可能反映了由与高度还原条件相关的岩浆分化诱导的 Ti 同位素分馏，并可能与氧化物和斜长石形成相关。相比之下，具有 -0.020 ± 0.070 和 - 0.003 ± 0.033 的 δ49/47Ti 的 eurites 和 acapulcoite (Dhofar 125; δ49/47Ti = 0.094 ± 0.033) 的第一个质量相关的 Ti 同位素数据仅显示了有限的岩浆化分数。球粒陨石的 δ49/47Ti 含量也相对受限，为 0.085‰，包括来自阿连德的一个富含钙铝的包裹体 (CAI) 和两个 Rumuruti 球粒陨石（NWA 753 和 NWA 755）的第一个质量相关的 Ti 同位素数据。此外，球粒陨石的质量相关 Ti 同位素组成与 eucrites 和 acapulcoite Dhofar 125 重叠，表明星云过程仅引起有限的 Ti 同位素分馏。此外，Ti 同位素数据表明，热变质作用还在球粒陨石的大块样品规模上产生了边缘 Ti 同位素分馏。不同大块陨石样品之间与质量相关的小Ti同位素变化也很明显，这可能反映了样品的异质性。重要的是，在 2 个标准偏差不确定度内，地球和月球的质量相关 Ti 同位素组成与所研究的球粒陨石、磷晶石和 acapulcoites 的组成重叠。Ti 同位素数据表明，热变质作用还在球粒陨石的大块样品尺度上产生了边缘 Ti 同位素分馏。不同大块陨石样品之间与质量相关的小Ti同位素变化也很明显，这可能反映了样品的异质性。重要的是，在 2 个标准偏差不确定度内，地球和月球的质量相关 Ti 同位素组成与所研究的球粒陨石、磷晶石和 acapulcoites 的组成重叠。Ti 同位素数据表明，热变质作用还在球粒陨石的大块样品尺度上产生了边缘 Ti 同位素分馏。不同大块陨石样品之间与质量相关的小Ti同位素变化也很明显，这可能反映了样品的异质性。重要的是，在 2 个标准偏差不确定度内，地球和月球的质量相关 Ti 同位素组成与所研究的球粒陨石、磷晶石和 acapulcoites 的组成重叠。