A depleted mantle source for Neoproterozoic continental rifting in the Seve Nappe Complex, Kebnekaise region, northern Swedish Caledonides

IF 2 3区地球科学 Q3 GEOSCIENCES, MULTIDISCIPLINARY

Frontiers in Earth Science Pub Date : 2024-08-26 DOI:10.3389/feart.2024.1426525

Riccardo Callegari, Abigail K. Barker, Christopher J. Barnes, Katarzyna Walczak, Grzegorz Ziemniak, Iwona Klonowska, Ellen Kooijman, Sabine Rousku, Karolina Kośmińska, Jarosław Majka

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Abstract

The Central Iapetus Magmatic Province (CIMP) is a large igneous province (LIP) emplaced in the Baltican and Laurentian paleocontinents that marks the onset of the Caledonian Wilson Cycle. Paleozoic magmatism of the CIMP is preserved in both northeastern America and northern Europe. This study investigates rocks belonging to the hyper-extended margin of Baltica currently found in the Seve Nappe Complex of the Scandinavian Caledonides. Specifically, U-Pb zircon geochronology and whole-rock geochemistry are applied to a migmatitic variety of the Vierručohkka amphibolite of the Mårma Terrane, to the Aurek gabbro, and amphibolite of the Aurek Assemblage exposed in the Seve Nappe Complex in the Kebnekaise region, northern Swedish Caledonides. U-Pb zircon geochronology yields crystallization ages of 626 ± 7 Ma for the protolith of the Vierručohkka amphibolite, and 614 ± 2 Ma and 609 ± 1 Ma for the emplacement of the Aurek gabbro and amphibolite protolith, respectively. A younger age of 599 ± 3 Ma is recorded in the Vierručohkka amphibolite and is interpreted as the age of partial melting and migmatization. The geochemical signatures of the rocks demonstrate crustal assimilation during the emplacement of their protoliths and modification due to prograde metamorphic processes during Caledonian subduction. The Vierručohkka amphibolite and the Aurek Assemblage samples display upper and lower crustal assimilation, respectively. Trace elements (Dy, Sm, Lu, and Y) record the growth of metamorphic garnet, while elevated TiO2 contents record the crystallization of metamorphic rutile. Nevertheless, high field strength elements (HSFE) and ∆Nb suggest a depleted mantle source for the magmas of the protoliths of the investigated rocks. Altogether, geochemical data indicate that the igneous activity recorded in the Vierručohkka amphibolite and the Aurek Assemblage between c. 626–609 Ma is related to continental rifting processes associated with the opening of the Iapetus Ocean.

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瑞典喀里多尼亚山脉北部凯布奈凯斯地区塞夫岩层群中新近纪大陆漂移的贫化地幔源

中央伊佩图斯岩浆省（CIMP）是一个大型火成岩省（LIP），位于波罗的海和劳伦廷古陆，标志着喀里多尼亚威尔逊周期的开始。CIMP的古生代岩浆活动保存在美洲东北部和欧洲北部。本研究调查了目前在斯堪的纳维亚喀里多尼亚山脉塞夫斜长岩群中发现的属于波罗的海超延伸边缘的岩石。具体地说，U-Pb 锆石地质年代学和全岩地球化学被应用于 Mårma Terrane 的 Vierručohkka 闪长岩中的一个偏闪长岩品种、Aurek 辉长岩以及出露于瑞典喀里多尼亚山脉北部 Kebnekaise 地区 Seve Nappe 复合体中 Aurek 组合的闪长岩。U-Pb锆石地质年代学得出，Vierručohkka闪长岩原岩的结晶年龄为626±7Ma，Aurek辉长岩和闪长岩原岩的成岩年龄分别为614±2Ma和609±1Ma。Vierručohkka闪长岩的记录年龄较小，为 599 ± 3 Ma，被解释为部分熔融和迁移的年龄。这些岩石的地球化学特征表明，其原岩在形成过程中被地壳同化，并在喀里多尼亚俯冲过程中因原生变质过程而发生变化。Vierručohkka 闪长岩和 Aurek 组合样本分别显示了上地壳同化和下地壳同化。痕量元素（Dy、Sm、Lu 和 Y）记录了变质石榴石的生长过程，而二氧化钛含量的升高则记录了变质金红石的结晶过程。然而，高场强元素（HSFE）和∆Nb表明，调查岩石原岩的岩浆来源于贫乏的地幔。总之，地球化学数据表明，在约 626-609 Ma 之间，Vierručohkka 闪长岩和 Aurek 组合记录的火成岩活动与伊阿佩托斯洋开辟时的大陆漂移过程有关。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Frontiers in Earth Science Earth and Planetary Sciences-General Earth and Planetary Sciences

CiteScore

3.50

自引率

10.30%

发文量

2076

审稿时长

12 weeks

期刊介绍： Frontiers in Earth Science is an open-access journal that aims to bring together and publish on a single platform the best research dedicated to our planet. This platform hosts the rapidly growing and continuously expanding domains in Earth Science, involving the lithosphere (including the geosciences spectrum), the hydrosphere (including marine geosciences and hydrology, complementing the existing Frontiers journal on Marine Science) and the atmosphere (including meteorology and climatology). As such, Frontiers in Earth Science focuses on the countless processes operating within and among the major spheres constituting our planet. In turn, the understanding of these processes provides the theoretical background to better use the available resources and to face the major environmental challenges (including earthquakes, tsunamis, eruptions, floods, landslides, climate changes, extreme meteorological events): this is where interdependent processes meet, requiring a holistic view to better live on and with our planet. The journal welcomes outstanding contributions in any domain of Earth Science. The open-access model developed by Frontiers offers a fast, efficient, timely and dynamic alternative to traditional publication formats. The journal has 20 specialty sections at the first tier, each acting as an independent journal with a full editorial board. The traditional peer-review process is adapted to guarantee fairness and efficiency using a thorough paperless process, with real-time author-reviewer-editor interactions, collaborative reviewer mandates to maximize quality, and reviewer disclosure after article acceptance. While maintaining a rigorous peer-review, this system allows for a process whereby accepted articles are published online on average 90 days after submission. General Commentary articles as well as Book Reviews in Frontiers in Earth Science are only accepted upon invitation.