The evolution of the European Crust – U-Pb, Pb, Hf, and O isotope systematics of detrital zircon, rutile and K-feldspar from the sediments of major European rivers

欧洲地壳的演化 欧洲主要河流沉积物中碎屑锆石、金红石和钾长石的 U-Pb、Pb、Hf 和 O 同位素系统学

• 批准号: 397638449
• 负责人: Professor Dr. Hans Heinrich Bahlburg
• 金额: --
• 依托单位: Institut für Geologie und Paläontologie
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2023-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/397638449?language=en
• 关键词: evolution; European; Crust; Pb; Hf

Large river system drain wide continental areas spanning different geotectonic domains. The detritus accumulating in the lower reaches of such systems ideally reflects the entirety of the lithological spectra constituting the geotectonic domains. Considering sorting and transport effects, river sediments reflect the composition of the respective continental crust and therefore allow for the analysis of its evolution. This analysis rests mainly on minerals that permit the reconstruction of the isotopic and temporal evolution of the crust. We propose a study of 15 major European river systems to study the geochemical evolution of the European continental crust. We will sample the rivers in the lower reaches to obtain U-Pb age dates from zircon and rutile by LA ICPMS. Both minerals are very resilient under weathering and transport conditions. Zircon is derived originally mainly from felsic to intermediate magmatic and metamorphic rocks whereas rutile may be derived also from mafic metamorphic rocks. Therefore rutile allows for the consideration of the role of more mafic lithologies. We will combine these analyses with the study of O and Hf isotopes in zircon by SHRIMP II and LA ICPMS, respectively. Both isotope systems combined allow for the crucial distinction between juvenile and recycled crustal components. Finally, the Pb isotope analysis of K-feldspar by LA ICPMS will be used to evaluate the recycled component in the detrital zircon data and the climatic influence on the detrital compositions as K-feldspar is a common detrital mineral in first-cycle sands.The primary objective of our study is the analysis of the geochemical evolution of the European continental crust in terms of the temporally changing relative contribution of juvenile additions and recycling of older crust. We will assess the evolution of the European continental crust and its relation to the known supercontinent cycles. We will test the alleged bias of the global U-Pb zircon age and supercontinent record towards collisional granitoids of collisional orogens. We will compare our data with the respective record of the Phanerozoic Andes, a long-standing accretionary orogen. The zircon record of the Andes region reflects the same supercontinent cycles as the collisional orogens commonly favored in the definition of such cycles. We will therefore also test our hypothesis that the alleged bias of the zircon and supercontinent record towards granitoids of interior orogens does not universally apply.

大型河流系统流淌跨越不同大地构造域的广阔大陆区域。在此类系统下游堆积的碎屑理想地反映了构成大地构造域的全部岩性光谱。考虑到分选和运输效应，河流沉积物反映了各自大陆地壳的组成，因此可以分析其演化。这种分析主要依赖于能够重建地壳同位素和时间演化的矿物。我们提议对欧洲 15 个主要河流系统进行研究，以研究欧洲大陆地壳的地球化学演化。我们将对下游河流进行采样，通过 LA ICPMS 获取锆石和金红石的 U-Pb 年龄数据。这两种矿物在风化和运输条件下都具有很强的弹性。锆石最初主要源自长英质至中度岩浆岩和变质岩，而金红石也可能源自镁铁质变质岩。因此，金红石允许考虑更多镁铁质岩性的作用。我们将这些分析与分别通过 SHRIMP II 和 LA ICPMS 对锆石中 O 和 Hf 同位素的研究结合起来。两种同位素系统结合起来可以区分年轻的地壳成分和再生的地壳成分。最后，利用LA ICPMS对钾长石进行Pb同位素分析，评估碎屑锆石数据中的回收成分以及气候对碎屑成分的影响，因为钾长石是第一周期砂中常见的碎屑矿物。我们研究的主要目的是根据新生地壳的时间变化相对贡献和旧地壳的再循环来分析欧洲大陆地壳的地球化学演化。我们将评估欧洲大陆地壳的演化及其与已知超大陆旋回的关系。我们将测试全球 U-Pb 锆石年龄和超大陆记录对碰撞造山带碰撞花岗岩的所谓偏差。我们将把我们的数据与显生宙安第斯山脉（一个长期的增生造山带）的相应记录进行比较。安第斯山脉地区的锆石记录反映了与碰撞造山带相同的超大陆旋回，这种旋回的定义通常受到青睐。因此，我们还将检验我们的假设，即所谓的锆石和超大陆记录对内部造山带花岗岩的偏见并不普遍适用。