Distinguishing Volcanic Contributions to the Overlapping Samoan and Cook-Austral Hotspot Tracks
Distinguishing Volcanic Contributions to the Overlapping Samoan and Cook-Austral Hotspot Tracks
复制标题
区分火山对萨摩亚和库克-澳大利亚热点路径重叠的影响
DOI：
10.1093/petrology/egac032
复制
发表时间：
2022
影响因子：
3.9
通讯作者：
Sinton, John M
中科院分区：
文献类型：
--
作者：
Price, Allison A;Jackson, Matthew G;Blichert-Toft, Janne;Konrad, Kevin;Bizimis, Michael;Koppers, Anthony A;Konter, Jasper G;Finlayson, Valerie A;Sinton, John M
为了对太平洋板块上形成“热点高速公路”的四个重叠热点——萨摩亚、拉罗汤加、阿拉戈-鲁鲁图和麦克唐纳——的贡献进行反卷计算，我们对萨摩亚热点东部地区和萨摩亚热点轨道“下游”地区取样的一套熔岩进行了地球化学表征和/或日期测定（通过40ar /39Ar方法）。研究发现，位于萨摩亚热点径迹轴线以南约60 km的Papatua海山既有HIMU（高μ =238U/204Pb = 20.0）组成（206Pb/204Pb = 20.0）的熔岩，也有丰富的地幔I （EM1）组成，我们认为这是萨摩亚的恢复和起源。我们发现，这些在帕帕图亚EM1恢复活力的熔岩在地球化学上与萨摩亚火山恢复活力的火山活动相似，并表明与附近汤加海沟相关的构造力引起的弯曲隆起，引发了萨摩亚地幔物质的新融化事件，这些物质先前在帕帕图亚下方的太平洋板块底部变平并横向扩散，导致火山活动覆盖了之前的HIMU大厦。我们认为，这一过程在更古老的库克-南岛帕帕图亚火山上产生了萨摩亚复兴的火山作用。我们还研究了位于Samoan热点WNW约820 km的Waterwitch海山，并给出了将其置于Samoan热点趋势的年龄（10.49±0.09 Ma），表明它在遗传上属于Samoan，而不是与Cook-Austral热点有关。因此，除了Papatua海山的HIMU阶段外，目前沿太平洋海底延伸1400公里的Rose海山（~25 Ma）和East Niulakita海山（~45 Ma）之间没有已知的arago - rruutu羽流衍生熔岩流样本。“缺失”的~ 2000万年的arago - rruutu热点轨迹可能已经俯冲到北汤加海沟中，或者可能被重叠的萨摩亚热点随后的火山活动所覆盖，因此无法进行采样。最后，我们探讨了构造再激活作为萨摩亚热点路径西端出现异常年轻火山活动的原因。特克斯{\ vspace * {-1.5 pt}} ?>
To deconvolve contributions from the four overlapping hotspots that form the “hotspot highway” on the Pacific plate—Samoa, Rarotonga, Arago-Rurutu, and Macdonald—we geochemically characterize and/or date (by the40Ar/39Ar method) a suite of lavas sampled from the eastern region of the Samoan hotspot and the region “downstream” of the Samoan hotspot track. We find that Papatua seamount, located ~60 km south of the axis of the Samoan hotspot track, has lavas with both a HIMU (high μ =238U/204Pb) composition (206Pb/204Pb = 20.0), previously linked to one of the Cook-Austral hotspots, and an enriched mantle I (EM1) composition, which we interpret to be rejuvenated and Samoan in origin. We show that these EM1 rejuvenated lavas at Papatua are geochemically similar to rejuvenated volcanism on Samoan volcanoes and suggest that flexural uplift, caused by tectonic forces associated with the nearby Tonga trench, triggered a new episode of melting of Samoan mantle material that had previously flattened and spread laterally along the base of the Pacific plate under Papatua, resulting in volcanism that capped the previous HIMU edifice. We argue that this process generated Samoan rejuvenated volcanism on the older Cook-Austral volcano of Papatua. We also study Waterwitch seamount, located ~820 km WNW of the Samoan hotspot, and provide an age (10.49 ± 0.09 Ma) that places it on the Samoan hotspot trend, showing that it is genetically Samoan and not related to the Cook-Austral hotspots as previously suggested. Consequently, with the possible exception of the HIMU stage of Papatua seamount, there are currently no known Arago-Rurutu plume-derived lava flows sampled along the swath of Pacific seafloor that stretches between Rose seamount (~25 Ma) and East Niulakita seamount (~45 Ma), located 1400 km to the west. The “missing” ~20-million-year segment of the Arago-Rurutu hotspot track may have been subducted into the northern Tonga trench, or perhaps was covered by subsequent volcanism from the overlapping Samoan hotspot, and has thus eluded sampling. Finally, we explore tectonic reactivation as a cause for anomalously young volcanism present within the western end of the Samoan hotspot track.<?TeX {\vspace*{-1.5pt}}?>