Establishing of the tectonic affinity and pre- Variscan evolution of the Brunovistulian microcontinent (Czech Republic) by U-Pb and Ar-Ar mineral dating of granitoid basement and cover sediments

通过对花岗岩基底和覆盖沉积物进行 U-Pb 和 Ar-Ar 矿物测年，确定布鲁诺维斯图利亚微大陆（捷克共和国）的构造亲和力和前瓦里斯纪演化

• 批准号: 321248948
• 负责人: Professor Edward Sobel, Ph.D.
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/321248948?language=en
• 关键词: Establishing; tectonic; affinity; pre; Variscan

The Trans-European Suture Zone separates variscan Europe from the East European Craton margin of the palaeo-continent Baltica. It was formed during several major events lasting from the Cambrian to the Silurian. Due to poor exposure and a complex geological structure, many questions about its origin and evolution remain open.Our primary aim is to investigate the affinity and Early Palaeozoic, pre-Variscan evolution of the Brunovistulian microcontinent and its role in the Trans-European Suture Zone. Most of the Brunovistulian microcontinent basement is not exposed but covered by Neoproterozoic and Cambro-Ordovician sediments and few boreholes have reached crystalline basement. For this reason, we will focus on the southwestern part of the BVM around Brno in the Czech Republic, where basement and cover are well exposed, geological relations are clear and Variscan overprinting is limited.Magmatic zircon from several intrusive phases of I-type hornblende-bearing (grano)diorites and tonalites of the Slavkov Terrane basement will be dated to determine crystallization ages and reconstruct the intrusion history of the terrane. In addition, 40Ar/39Ar step-heating dating of magmatic amphibole and biotite from the same samples will be carried out to establish internally consistent cooling age histories. Magmatic zircons from deformed felsic tuff / ignimbrite layers in the Central Basic Belt basement will be dated to establish crystallization ages and elucidate the relation of the belt to the granitoid basement terranes to the west and east.Zircon and detrital white micas from Devonian clastic alluvial fan and alluvial sediments overlying the basement ("basal clastics") will be dated by in situ, single grain methods for as provenance study and establish their source. Conglomerate layers will be targeted as they contain abundant immature detritus derived from metamorphic and igneous rocks. Clasts of locally derived granitoids and exotic, muscovite-bearing granitoid clasts prove the close link between the conglomerates and the geology of the source areas and the erosional products hold an important key to the origin of the Brunovistulian microcontinent.

跨欧洲缝合带将瓦里斯坎欧洲与波罗的海古大陆的东欧克拉通边缘分开。它是在从寒武纪到志留纪的几次重大事件中形成的。由于暴露程度低，地质构造复杂，其起源和演化仍有许多未解之谜。我们的主要目的是研究布鲁诺维斯微大陆的亲缘关系和早古生代、前瓦里斯坎期的演化及其在泛欧缝合带中的作用。大部分布鲁诺维斯微大陆基底未暴露，但被新元古代和寒武-奥陶系沉积物覆盖，很少有钻孔到达结晶基底。因此，我们将重点关注捷克布尔诺附近BVM的西南部，那里的基底和盖层暴露良好，地质关系清晰，Variscan套印有限。对斯拉科夫地体基底含角闪长岩（花岗闪长岩）和闪长岩几个侵入期的岩浆锆石进行定年，确定结晶年龄，重建地体侵入史。此外，还将对同一样品的岩浆角闪洞和黑云母进行40Ar/39Ar阶梯加热定年，以建立内部一致的冷却年龄史。对中央基性带基底变形长英凝灰岩/火成岩中的岩浆锆石进行定年，确定结晶年龄，并阐明其与西部和东部花岗岩基底地体的关系。通过原位、单粒法测定基底上泥盆系碎屑冲积扇和冲积沉积物（“基底碎屑”）中的锆石和碎屑白色云母的年代，进行物源研究并确定其来源。砾岩层中含有大量来自变质岩和火成岩的未成熟碎屑，因此将成为研究的目标。本地花岗岩类碎屑和外来含白云母花岗岩类碎屑证明了砾岩与源区地质之间的密切联系，其侵蚀产物对揭示布鲁诺维斯微大陆的成因具有重要意义。