Using palaeomagnetic and isotopic data to investigate late to post-Caledonian tectonothermal processes within the Western Terrane of Svalbard
Using palaeomagnetic and isotopic data to investigate late to post-Caledonian tectonothermal processes within the Western Terrane of Svalbard
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利用古地磁和同位素数据研究斯瓦尔巴群岛西部地体晚至后加里东期的构造热过程
DOI：
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发表时间：
2017
影响因子：
2.7
通讯作者：
M. Burzyński
中科院分区：
文献类型：
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作者：
K. Michalski;G. Manby;K. Nejbert;J. Domańska;M. Burzyński
本文介绍了西斯匹次卑尔根岛奥斯卡II地10个古地磁点共205个变基性岩样品的分析结果。岩相学、构造和古地磁资料均表明，加里东期前变质基性岩的铁磁组构发生了广泛的重定向和强烈的铁磁化。新的原位激光烧蚀电感耦合等离子体质谱40 Ar/39 Ar年龄测定结果表明，容矿岩石经历了3次重定事件，分别为426 - 380 Ma（广义加里东期）、377 - 326 Ma和377 - 326 Ma。 300 Ma间隔。 后两个重置事件在时间上与巴伦支海陆棚范围内的裂谷控制沉降事件相吻合。推导出的古地磁数据不落在预期的表观极漂移路径的Laurussia同后加里东时间。因此，人们研究了四种模型来解释这种缺乏对应性，这些模型援引了古地理大圆和小圆旋转、涉及逆冲推覆和正铲式断层的区域构造作用。古地磁数据并不支持斯瓦尔巴群岛西部与Pearya之间的重建，而是指出了与北大西洋开放有关的铲状断层的重要性，该断层改变了西斯匹次卑尔根褶皱和冲断带的几何形状。补充材料：（1）变基性岩现场特征，（2）应用岩石磁性和古地磁程序的详细描述，（3）调查的地质年代学样品的显微图像，（4）现场LA-ICP-MS 40 Ar/39 Ar同位素年龄测定结果，（5）调查的变基性岩的显微、SEM和BSE图像，以及（6）磁化率的各向异性，可在www.example.com上获得https://doi.org/10.6084/m9.figshare.c.3673924。
The analytical results of a total of 205 metabasic specimens from 10 palaeomagnetic sites collected from Oscar II Land in Western Spitsbergen are presented. Petrographic, structural and palaeomagnetic data all demonstrate that the pre-Caledonian ferromagnetic fabric of the metabasic rocks has been extensively reoriented and intensively remineralized. New in situ laser ablation inductively coupled plasma mass spectrometry 40Ar/39Ar age determinations suggest that the host rocks have been subject to three resetting events during the 426 – 380 Ma (Caledonian sensu lato), 377 – 326 Ma and c. 300 Ma intervals. The latter two resetting events coincide in time with the Barents Shelf-wide rift-controlled subsidence events. The derived palaeomagnetic data do not fall on the expected apparent polar wander path of Laurussia for syn- to post-Caledonian time. Consequently, four models invoking palaeogeographical great and small circle rotations, regional tectonism involving thrusting and normal listric faulting have been investigated to account for this lack of correspondence. The palaeomagnetic data do not lend support to reconstructions linking Western Svalbard with Pearya but point instead to the importance of listric faulting related to the opening of the North Atlantic Ocean that modified the geometry of the West Spitsbergen Fold and Thrust Belt. Supplementary material: (1) Field characteristics of metabasic sites, (2) detailed description of applied rock magnetic and palaeomagnetic procedures, (3) microscopic images of investigated geochronological samples, (4) in situ LA-ICP-MS 40Ar/39Ar isotopic age determination results, (5) microscopic, SEM and BSE images of investigated metabasites, and (6) anisotropy of magnetic susceptibility are available at https://doi.org/10.6084/m9.figshare.c.3673924.