Long-lived radioactive isotope systematics, such as Sm-Nd and Lu-Hf, are useful tools as important chronometers and tracers for chemical differentiation processes. Even though Antarctic meteorites include rare meteorites such as ungrouped meteorites, the effects of Antarctic alteration on the Sm-Nd and Lu-Hf systems in chondrites have not yet been evaluated in detail. Moreover, the heterogeneity of Sm-Nd and Lu-Hf data in bulk chondrites prevents the determination of precise average Sm-Nd and Lu-Hf values (e.g., for individual chondrite groups). To examine the effects of Antarctic alteration and sample heterogeneity on the Sm-Nd and Lu-Hf isotope systematics, ten Antarctic H chondrites (HCs) and three HCs from hot deserts were characterized for their modal abundances, elemental abundances, and Sm-Nd and Lu-Hf isotopic compositions. Regardless of the classical weathering index for Antarctic meteorites and the normalized Rb abundance used as a chemical alteration indicator in this study, the modal and elemental abundances in Antarctic HCs appear to be in good agreement with those in non-Antarctic HCs. The Sm-Nd and Lu-Hf isotopic compositions of the characterized H chondrites fall within the range measured for both HC falls and for falls of other chondrite groups, except in the case of the most heavily altered sample. Consequently, the effects of Antarctic alteration processes on the Sm-Nd and Lu-Hf systematics in HCs appear to be limited, except in the case of Asuka 09516. The latter meteorite exhibits severe mineralogical and chemical alteration, with considerable losses of even the rare earth elements (REEs), which are considered relatively immobile. The ¹⁴⁷Sm/¹⁴⁴Nd, ¹⁴³Nd/¹⁴⁴Nd, ¹⁷⁶Lu/¹⁷⁷Hf, and ¹⁷⁶Hf/¹⁷⁷Hf of bulk HCs correlate with their P/Mg and Y/Mg. Furthermore, the Lu-Hf ratios correlate strongly with their P/Ca and Y/Ca as well as their P/Mg and Y/Mg. Thus, the distribution of the elements between constituent minerals in ordinary chondrites (OCs) may control the heterogeneity observed for the bulk Sm-Nd and Lu-Hf data. In this context, the weight ratio of Ca-phosphates to Ca-pyroxene, or at least that of Ca-phosphates to silicates, may be a key factor leading to the observed elemental and isotopic variations. This observation indicates that the nugget effect of Ca-phosphates in OCs as the result of insufficient homogenization or terrestrial alteration leads to the heterogeneities displayed by the Sm-Nd and Lu-Hf data. Moreover, it also indicates that the use of equilibrated OCs for the determination of Sm-Nd and Lu-Hf data is affected more by sample heterogeneity, especially with respect to Ca-phosphates, than is the case for unequilibrated OCs, based on the re-distribution of REEs during thermal metamorphism on their parent bodies. This study demonstrates that Antarctic meteorites commonly preserve their original Sm-Nd and Lu-Hf isotopic compositions as much as chondrite falls, although exceptions are possible in the case of severe alteration. Similar to previous studies, we recommend the use of unequilibrated chondrites, for which the re-distribution of REEs is less extensive, for the determination of well-constrained average Sm-Nd and Lu-Hf isotopic compositions for individual chondrite groups as well as their robust Chondritic Uniform Reservoir values.

长寿命放射性同位素系统，例如Sm-Nd和Lu-Hf，是有用的工具，可作为化学区分过程的重要计时器和示踪剂。尽管南极陨石包括稀有的陨石，例如未分组的陨石，但尚未详细评估南极蚀变对球粒陨石中Sm-Nd和Lu-Hf系统的影响。此外，块状球粒晶体中Sm-Nd和Lu-Hf数据的异质性妨碍了确定精确的平均Sm-Nd和Lu-Hf值（例如，用于各个球粒陨石组）。为了研究南极蚀变和样品异质性对Sm-Nd和Lu-Hf同位素系统的影响，对十个南极H球粒陨石（HC）和来自热沙漠的3个HC进行了模态丰度，元素丰度，Sm-Nd和Sm-Nd表征。 Lu-Hf同位素组成。不管本研究中经典的南极陨石风化指数和归一化的Rb丰度用作化学变化指标，南极HC中的模式和元素丰度似乎都与非南极HC中的模式和元素丰度很好。表征为H球粒陨石的Sm-Nd和Lu-Hf同位素组成均在HC下降和其他球粒陨石群下降的测量范围内，除非样品变化最大。最后，除明日香09516的情况外，南极蚀变过程对HC中Sm-Nd和Lu-Hf系统学的影响似乎是有限的。后者的陨石表现出严重的矿物学和化学蚀变，甚至稀土元素也有相当多的损失。 （REE），它们被认为是相对固定的。这¹⁴⁷ Sm / ¹⁴⁴ Nd，¹⁴³ Nd / ¹⁴⁴ Nd，¹⁷⁶ Lu / ¹⁷⁷ Hf和¹⁷⁶ Hf / ¹⁷⁷大量HC的Hf与它们的P / Mg和Y / Mg相关。此外，Lu-Hf比与其P / Ca和Y / Ca以及它们的P / Mg和Y / Mg密切相关。因此，普通球粒陨石（OCs）中各组成矿物之间元素的分布可能会控制大量Sm-Nd和Lu-Hf数据所观察到的异质性。在这种情况下，Ca-磷酸盐与Ca-吡咯的重量比，或至少Ca-磷酸盐与硅酸盐的重量比，可能是导致观察到的元素和同位素变化的关键因素。该观察结果表明，由于均质性不足或陆地变化不足，钙磷在OC中的金块效应导致Sm-Nd和Lu-Hf数据显示出异质性。而且，它还表明，基于重新分布，与非平衡OC相比，使用平衡OC确定Sm-Nd和Lu-Hf数据受样品异质性的影响更大，尤其是对于钙磷酸盐而言。母体热变质过程中稀土元素的分布。这项研究表明，南极陨石通常保留与原始陨石一样的原始Sm-Nd和Lu-Hf同位素组成，尽管在严重蚀变的情况下可能会出现例外。与以前的研究类似，我们建议使用未平衡的球粒陨石，因为其稀土元素的重新分布较不广泛，可用于确定各个球粒陨石群以及它们各自的球状陨石的受约束的平均Sm-Nd和Lu-Hf同位素组成稳健的软骨均匀储层值。