The Cretaceous High Arctic Large Igneous Province (HALIP) in Canada, although dominated by tholeiites (135–90 Ma), contains two main groups of alkaline igneous rocks. The older alkaline rocks (∼96 Ma) scatter around major fault and basement structures. They are represented by the newly defined Fulmar Suite alkaline basalt dykes and sills, and include Hassel Formation volcanic rocks. The younger alkaline group is represented by the Wootton Intrusive Complex (92·2–92·7 Ma), and the Audhild Bay Suite (83–73 Ma), both emplaced near the northern coast of Ellesmere Island. Fulmar Suite rocks resemble EM-type ocean island basalts (OIB) and most show limited crustal contamination. The Fulmar Suite shows increases of P2O5 at near-constant Ba–K–Zr–Ti that are nearly orthogonal to predicted fractionation- or melting-related variations, which we interpret as the result of melting composite mantle sources containing a regionally widespread apatite-bearing enriched component (P1). Low-P2O5 Fulmar Suite variants overlap compositionally with enriched HALIP tholeiites, and fall on common garnet lherzolite trace element melting trajectories, suggesting variable degrees of melting of a geochemically similar source. High-P2O5 Hassel Formation basalts are unusual among Fulmar rocks, because they are strongly contaminated with depleted lower crust; and because they involve a high-P2O5–Ba–Eu mantle component (P2), similar to that seen in alkali basalt dykes from Greenland. The P2 component may have contained Ba–Eu-rich hawthorneite and/or carbonate minerals as well as apatite, and may typify parts of the Greenlandic sub-continental lithospheric mantle (SCLM). Mafic alkaline Audhild Bay Suite (ABS) rocks are volcanic and hypabyssal basanites, alkaline basalts and trachy-andesites, and resemble HIMU ocean island basalts in having high Nb, low Zr/Nb and low 87Sr/86Sri. These mafic alkaline rocks are associated with felsic alkaline lavas and syenitic intrusions, but crustally derived rhyodacites and rhyolites also exist. The Wootton Intrusive Complex (WIC) contains geochemically similar plutonic rocks (alkali gabbros, diorites and anatectic granites), and may represent a more deeply eroded, slightly older equivalent of the ABS. Low-P2O5 ABS and WIC alkaline mafic rocks have flat heavy rare earth element (HREE) profiles suggesting shallow mantle melting; whereas High-P2O5 variants have steep HREE profiles indicating deeper separation from garnet-bearing residues. Some High-P2O5 mafic ABS rocks seem to contain the P1 and P2 components identified in Fulmar–Hassel rocks, whereas other samples trend towards possible High-P2O5 + Zr (PZr) and High-P2O5 + K2O (PK) components. We argue that the strongly alkaline northern Ellesmere Island magmas sampled mineralogically heterogeneous veins or metasomes in Greenlandic-type SCLM, which contained trace phases such as apatite, carbonates, hawthorneite, zircon, mica or richterite. The geographically more widespread apatite-bearing component (P1) could have formed part of a heterogeneous plume or upwelling mantle current that also generated HALIP tholeiites when melted more extensively, but may also have resided in the SCLM as relics of older events. Rare HALIP alkaline rocks with high K–Rb–U–Th fall on mixing paths implying strong local contamination from either Sverdrup Basin sedimentary rocks or granitic upper crust. However, the scarcity of potassic alkaline HALIP facies, together with the other trace element and isotopic signatures, provides little support for a ubiquitous fossil sedimentary subduction-zone component in the HALIP mantle source.

中文翻译：

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加拿大高北极大火成岩省碱性岩石：多地幔成分的证据

加拿大白垩纪高北极大火成岩省（HALIP）虽然以拉斑矿为主（135-90 Ma），但包含两大类碱性火成岩。较老的碱性岩石（~96 Ma）散布在主要断层和基底结构周围。它们以新定义的 Fulmar Suite 碱性玄武岩岩墙和窗台为代表，包括 Hassel 组火山岩。较年轻的碱性组以 Wootton 侵入杂岩体 (92·2–92·7 Ma) 和 Audhild Bay Suite (83–73 Ma) 为代表，均位于埃尔斯米尔岛北部海岸附近。Fulmar Suite 岩石类似于 EM 型海洋岛玄武岩 (OIB)，并且大多数显示出有限的地壳污染。Fulmar Suite 显示在接近恒定的 Ba-K-Zr-Ti 下 P2O5 的增加与预测的分馏或熔化相关的变化几乎正交，我们将其解释为含有区域广泛分布的富含磷灰石成分（P1）的复合地幔源熔化的结果。低 P2O5 Fulmar Suite 变体在成分上与富集的 HALIP 拉斑矿重叠，并落在常见的石榴石亮辉石微量元素熔融轨迹上，表明地球化学相似来源的熔融程度不同。高 P2O5 Hassel 组玄武岩在 Fulmar 岩石中不常见，因为它们被贫化的下地壳强烈污染；并且因为它们涉及高 P2O5-Ba-Eu 地幔成分（P2），类似于格陵兰的碱性玄武岩脉中所见的成分。P2 组分可能含有富含 Ba-Eu 的山楂石和/或碳酸盐矿物以及磷灰石，并且可能是格陵兰次大陆岩石圈地幔 (SCLM) 的一部分。镁铁质碱性 Audhild Bay Suite (ABS) 岩石是火山和次浅海玄武岩、碱性玄武岩和粗面安山岩，与 HIMU 海岛玄武岩相似，具有高 Nb、低 Zr/Nb 和低 87Sr/86Sri。这些镁铁质碱性岩石与长英质碱性熔岩和正长岩侵入体有关，但也存在地壳衍生的流纹岩和流纹岩。伍顿侵入杂岩体 (WIC) 包含地球化学相似的深成岩（碱辉长岩、闪长岩和深熔花岗岩），可能代表更深的侵蚀、稍旧的 ABS 等价物。低 P2O5 ABS 和 WIC 碱性镁铁质岩石具有平坦的重稀土元素（HREE）剖面，表明浅地幔熔融；而高 P2O5 变体具有陡峭的 HREE 曲线，表明与含石榴石的残留物分离得更深。一些高 P2O5 基性 ABS 岩石似乎包含在 Fulmar-Hassel 岩石中确定的 P1 和 P2 组分，而其他样品则倾向于可能的高 P2O5 + Zr (PZr) 和高-P2O5 + K2O (PK) 组分。我们认为，强碱性北部埃尔斯米尔岛岩浆采样了格陵兰型 SCLM 中的矿物异质脉或交变体，其中含有微量相，如磷灰石、碳酸盐、山楂石、锆石、云母或里氏石。地理上更广泛的含磷灰石成分（P1）可能形成了异质羽流或上涌地幔流的一部分，当更广泛地熔化时也产生了 HALIP 拉斑矿，但也可能作为更古老事件的遗迹存在于 SCLM 中。具有高 K-Rb-U-Th 的稀有 HALIP 碱性岩石落在混合路径上，这意味着来自 Sverdrup 盆地沉积岩或花岗岩上地壳的强烈局部污染。然而，钾碱性 HALIP 相的稀缺性，以及其他微量元素和同位素特征，几乎没有为 HALIP 地幔源中普遍存在的化石沉积俯冲带成分提供支持。