Spatio-temporal changes of upper mantle structure play a significant role in generating and maintaining surface topography. Although geophysical models of upper mantle structure have become increasingly refined, there is a paucity of geologic constraints with respect to its present-day state and temporal evolution. Cenozoic intraplate volcanic rocks that crop out across eastern Australia provide a significant opportunity to quantify mantle conditions at the time of emplacement and to independently validate geophysical estimates. This volcanic activity is divided into two categories: age-progressive provinces that are generated by the sub-plate passage of mantle plumes and age-independent provinces that could be generated by convective upwelling at lithospheric steps. In this study, we acquired and analyzed 78 samples from both types of provinces across Queensland. These samples were incorporated into a comprehensive database of Australian Cenozoic volcanism assembled from legacy analyses. We use geochemical modeling techniques to estimate mantle temperature and lithospheric thickness beneath each province. Our results suggest that melting occurred at depths ≤80 km across eastern Australia. Prior to, or coincident with, onset of volcanism, lithospheric thinning as well as dynamic support from shallow convective processes could have triggered uplift of the Eastern Highlands. Mantle temperatures are inferred to be ∼50–100°C hotter beneath age-progressive provinces that demarcate passage of the Cosgrove mantle plume than beneath age-independent provinces. Even though this plume initiated as one of the hottest recorded during Cenozoic times, it appears to have thermally waned with time. These results are consistent with xenolith thermobarometric and geophysical studies.

中文翻译：

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澳大利亚东部上地幔热结构及其与新生代火山活动和动态地形的关系

上地幔结构的时空变化对地表地形的产生和维持起着重要作用。尽管上地幔结构的地球物理模型已经变得越来越精细，但关于其当前状态和时间演化的地质约束却很少。在澳大利亚东部出土的新生代板内火山岩为量化就位时的地幔条件和独立验证地球物理估计提供了重要机会。这种火山活动分为两类：由地幔柱的亚板块通道产生的年龄渐进区和可能由岩石圈台阶上的对流上升流产生的与年龄无关的区。在这项研究中，我们采集并分析了昆士兰两种类型省份的 78 个样本。这些样本被整合到一个综合的澳大利亚新生代火山活动数据库中，该数据库是根据遗留分析收集的。我们使用地球化学建模技术来估计每个省下方的地幔温度和岩石圈厚度。我们的结果表明融化发生在澳大利亚东部≤80 公里的深度。在火山活动开始之前或同时发生，岩石圈变薄以及浅层对流过程的动态支持可能会引发东部高地的隆升。据推断，在划定 Cosgrove 地幔柱通道的年龄渐进省份下，地幔温度比年龄无关省份下高约 50-100°C。尽管这羽羽流是新生代有记录以来最热的羽流之一，但它似乎随着时间的推移而逐渐减弱。这些结果与捕虏体热气压和地球物理研究一致。