Abstract Igneous activity from the late Miocene to historic time (most recently 1891 CE) in the Strait of Sicily has created two volcanic islands (Pantelleria and Linosa) and several seamounts. These volcanoes are dominated by transitional (ol + hy-normative) to alkaline (ne-normative) basaltic lavas and scoriae; volcanic felsic rocks (peralkaline trachyte-rhyolite) crop out only on Pantelleria. Although most likely erupted through continental crust, basalts demonstrate no evidence of crustal contamination and are geochemically similar to oceanic island basalts (OIB). Despite their isotopic similarities, there are considerable compositional differences with respect to major and trace element geochemistry both between and within the two islands that are due to short-length scale mantle heterogeneity beneath the region as well as variability in partial melting and magma storage conditions. Published geophysical surveys suggest that lithospheric thickness beneath both islands is ~60 km; this is consistent with the results of our geochemical modelling (59–60 km), which also suggest mantle potential temperatures between 1415 and 1435 °C, similar to those documented in other continental passive rifts. Trace element and isotopic data reveal that the asthenosphere beneath the Strait of Sicily is heterogenous at both inter-island (100s of km) and intra-island (10s of km) scales. Although there is some compositional overlap between the two major synthems at Linosa, in general the older magmas (Arena Bianca, 700 ka) formed as a result of ~5% partial melting of a depleted MORB mantle (DMM) source enriched with a relatively small amount of recycled MORB material, whereas the younger magmas (Monte Bandiera, 530 ka) formed as a result of ~2% partial melting of a similar mantle source. Pantelleria magmas formed from a higher degree (~6%) of partial melting of a DMM source with a relatively greater amount of recycled MORB material and possibly other components. Geochemical modelling also suggests the older magmas on Linosa differentiated at a much shallower level (~8 km) than the younger magmas (~25 km, at or below the base of the crust) prior to eruption. Magmas stored in higher-level reservoirs were effectively homogenized and preserve a narrower compositional range than magmas sourced from depth. Data for the seamounts are scarce and compromised by significant seawater alteration; thus, these volcanic centers cannot be modelled but based on comparative geochemistry with the islands are likely the result of even smaller ( 60 km) lithosphere. Despite the geophysical similarities between the two islands in terms of lithospheric thickness and crustal thinning, melt productivity has been greater at Pantelleria, producing a much larger island and sustaining felsic magmatism, which we hypothesize may ultimately be entirely due to the local occurrence of much more fusible mantle.

中文翻译：

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西西里裂谷带（意大利）海峡玄武岩成因的地球化学约束：对短尺度地幔非均质性重要性的洞察

摘要 西西里海峡从晚中新世到历史时期（最近一次是公元 1891 年）的火成岩活动造成了两个火山岛（潘泰莱里亚岛和利诺萨岛）和几个海山。这些火山以过渡（ol + hy-normative）到碱性（ne-normative）玄武岩熔岩和火山渣为主；火山长英质岩（高碱性粗面纹岩-流纹岩）仅在潘泰莱里亚上出土。虽然玄武岩最有可能通过大陆地壳喷发，但没有证据表明受到地壳污染，并且在地球化学上与大洋岛玄武岩 (OIB) 相似。尽管它们的同位素相似，由于该区域下方短尺度地幔的非均质性以及部分熔融和岩浆储存条件的变化，两个岛屿之间和内部的主要和微量元素地球化学组成存在相当大的差异。已发表的地球物理调查表明，这两个岛屿下方的岩石圈厚度约为 60 公里；这与我们的地球化学模型（59-60 公里）的结果一致，这也表明地幔潜在温度在 1415 至 1435°C 之间，类似于其他大陆被动裂谷中记录的温度。微量元素和同位素数据表明，西西里海峡下方的软流圈在岛间（100 公里）和岛内（10 公里）尺度上都是非均质的。尽管在 Linosa 的两种主要合成物之间存在一些成分重叠，但一般而言，较旧的岩浆（Arena Bianca，700 ka）是由耗尽的 MORB 地幔 (DMM) 源约 5% 部分熔化而形成的，其中富含相对较小的回收的 MORB 材料的数量，而年轻的岩浆（Monte Bandiera，530 ka）是由于类似地幔源约 2% 的部分熔化而形成的。Pantelleria 岩浆由更高程度（~6%）的 DMM 源部分熔化形成，其中含有相对大量的回收 MORB 材料和可能的其他成分。地球化学模型还表明，Linosa 上较老的岩浆在喷发前比年轻的岩浆（约 25 公里，位于地壳底部或下方）在更浅的水平（~8 公里）上分化。储存在较高层储层中的岩浆被有效地均质化，并且比源自深度的岩浆保持更窄的成分范围。海山的数据稀少且受到海水显着改变的影响；因此，这些火山中心无法建模，但根据与岛屿的比较地球化学，很可能是更小（60 公里）岩石圈的结果。尽管这两个岛屿在岩石圈厚度和地壳变薄方面地球物理相似，但潘泰莱里亚的熔体生产力更高，产生一个更大的岛屿并维持长英质岩浆活动，我们假设这最终可能完全是由于当地发生的更多易熔地幔。海山的数据稀少且受到海水显着改变的影响；因此，这些火山中心无法建模，但根据与岛屿的比较地球化学，很可能是更小（60 公里）岩石圈的结果。尽管这两个岛屿在岩石圈厚度和地壳变薄方面地球物理相似，但潘泰莱里亚的熔体生产力更高，产生一个更大的岛屿并维持长英质岩浆活动，我们假设这最终可能完全是由于当地发生的更多易熔地幔。海山的数据稀少且受到海水显着改变的影响；因此，这些火山中心无法建模，但根据与岛屿的比较地球化学，很可能是更小（60 公里）岩石圈的结果。尽管这两个岛屿在岩石圈厚度和地壳变薄方面地球物理相似，但潘泰莱里亚的熔体生产力更高，产生一个更大的岛屿并维持长英质岩浆活动，我们假设这最终可能完全是由于当地发生的更多易熔地幔。