Abstract

New data have been obtained on composition and age of the Archean supracrustal complexes of the Yalonvara–Pertinjarvi, Korpijarvi, and Pastajarvi structures in the marginal part of the Karelian Craton of the Fennoscandian Shield in the conjunction area with the Svecofennian Orogen. The structures were typically attributed to the single Yalonvara–Ilomantsi greenstone belt. On the basis of geochronological, petrographic, and geochemical data, only the Korpijarvi and Pastajarvi structures with an age of 2.73 Ga can be considered as a continuation of the Hattu greenstone belt in the Ilomantsi province (Finland). More ancient rocks of the Yalonvara–Pertinjarvi structure, estimated at 2.95–2.93 Ga, can be compared with the Mesoarchean basalt–andesite–dacite–rhyolite stratotectonic association of the Hautavaara greenstone structure. The younger Neoarchean rocks metamorphosed under the high-temperature amphibolite facies conditions are composed of gneisses and amphibolites. The ancient greenstone rocks metamorphosed under the greenschist and epidote–amphibolite facies conditions are of tuff nature. The rocks of both complexes are similar in terms of geochemistry to volcanic rocks of the suprasubduction settings, but they are different in proportions of the material of the mantle wedge and subduction plate.

中文翻译：

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与 Svecofennian 地块交界处 Fennoscandian 地盾卡累利阿克拉通不均匀年龄太古宙绿岩结构的上地壳岩石：成分、年龄和起源

摘要

在与斯威科芬造山带结合区的芬诺斯坎德地盾卡累利阿克拉通边缘部分的 Yalonvara-Pertinjarvi、Korpijarvi 和 Pastajarvi 构造的太古宙上地壳复合体的组成和年龄获得了新的数据。这些结构通常归因于单一的 Yalonvara-Ilomantsi 绿岩带。根据年代学、岩石学和地球化学数据，只有年龄为 2.73 Ga 的 Korpijarvi 和 Pastajarvi 构造可以被认为是 Ilomantsi 省（芬兰）Hattu 绿岩带的延续。Yalonvara-Pertinjarvi 结构的更古老岩石，估计在 2.95-2.93 Ga，可以与 Hautavaara 绿岩结构的中太古代玄武岩-安山岩-英安岩-流纹岩层构造组合进行比较。在高温角闪岩相条件下变质的较年轻的新太古代岩石由片麻岩和角闪岩组成。绿片岩和绿帘石-角闪岩相条件下变质的古绿岩具有凝灰岩性质。这两种杂岩的岩石在地球化学方面与超俯冲环境的火山岩相似，但它们在地幔楔和俯冲板块的物质比例上有所不同。