The Flowers River Igneous Suite of north-central Labrador comprises several discrete peralkaline granite ring intrusions and their coeval volcanic succession. The Flowers River Granite was emplaced into Mesoproterozoic-age anorthosite–mangerite–charnockite–granite (AMCG) -affinity rocks at the southernmost extent of the Nain Plutonic Suite coastal lineament batholith. New U–Pb zircon geochronology is presented to clarify the timing and relationships among the igneous associations exposed in the region. Fayalite-bearing AMCG granitoids in the region record ages of 1290 ± 3 Ma, whereas the Flowers River Granite yields an age of 1281 ± 3 Ma. Volcanism occurred in three discrete events, two of which coincided with emplacement of the AMCG and Flowers River suites, respectively. Shared geochemical affinities suggest that each generation of volcanic rocks was derived from its coeval intrusive suite. The third volcanic event occurred at 1271 ± 3 Ma, and its products bear a broad geochemical resemblance to the second phase of volcanism. The surrounding AMCG-affinity ferrodiorites and fayalite-bearing granitoids display moderately enriched major- and trace-element signatures relative to equivalent lithologies found elsewhere in the Nain Plutonic Suite. Trace-element compositions also support a relationship between the Flowers River Granite and its AMCG-affinity host rocks, most likely via delayed partial melting of residual parental material in the lower crust. Enrichment manifested only in the southernmost part of the Nain Plutonic Suite as a result of its relative proximity to multiple Palaeoproterozoic tectonic boundaries. Repeated exposure to subduction-derived metasomatic fluids created a persistent region of enrichment in the underlying lithospheric mantle that was tapped during later melt generation, producing multiple successive moderately to strongly enriched magmatic episodes.

中文翻译：

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过碱性花河火成岩组岩成因及其对南纳因岩基发育的意义

拉布拉多中北部的弗劳尔斯河火成岩组包括几个离散的过碱性花岗岩环侵入体及其同时代的火山演替。弗劳尔斯河花岗岩位于 Nain Plutonic Suite 海岸线岩基最南端的中元古代钙长石-芒芒石-方钙石-花岗岩 (AMCG) 亲和岩石中。提出了新的 U-Pb 锆石年代学，以阐明该地区出露的火成岩组合之间的时间和关系。该地区含铁橄榄石的 AMCG 花岗岩记录的年龄为 1290 ± 3 Ma，而 Flowers River 花岗岩的年龄为 1281 ± 3 Ma。火山活动发生在三个离散事件中，其中两个分别与 AMCG 和 Flowers River 套房的就位同时发生。共同的地球化学相似性表明，每一代火山岩都来自其同时代的侵入套件。第三次火山事件发生在 1271±3 Ma，其产物与第二阶段火山作用具有广泛的地球化学相似性。与 Nain Plutonic Suite 其他地方发现的等效岩性相比，周围的 AMCG 亲和铁闪长岩和含铁橄榄石的花岗岩显示出适度富集的主要元素和微量元素特征。微量元素成分也支持弗劳尔斯河花岗岩与其 AMCG 亲和主岩之间的关系，这很可能是通过下地壳中残余母质材料的延迟部分熔化。由于其相对靠近多个古元古代构造边界，富集仅在 Nain Plutonic Suite 的最南端表现出来。