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U-Pb dating of middle Eocene-middle Pleistocene multiple tectonic pulses in the Alpine foreland
Solid Earth ( IF 3.2 ) Pub Date : 2021-02-04 , DOI: 10.5194/se-2021-2
Luca Smeraglia , Nathan Looser , Olivier Fabbri , Flavien Choulet , Marcel Guillong , Stefano M. Bernasconi

Abstract. Foreland fold-and-thrust belts record long-lived tectonic-sedimentary activity, from passive margin sedimentation, flexuring, and further involvement into wedge accretion ahead of an advancing orogen. Therefore, dating fault activity is fundamental for plate movement reconstruction, resource exploration, or earthquake hazard assessment. Here, we report U-Pb ages of syntectonic calcite mineralizations from four thrusts and three tear faults sampled, at the regional scale, across the Jura fold-and-thrust belt in the northwestern Alpine foreland (eastern France). Four regional tectonic phases are recognized in the middle Eocene-middle Pleistocene interval: (1) pre-orogenic faulting at 44.7 ± 2.6 and 48.4 ± 1.5 Ma associated to the uplift of the Alpine forebulge, (2) syn-orogenic thrusting at 11.4 ± 1.1, 10.6 ± 0.5, 9.7 ± 1.4, 9.6 ± 0.3, and 7.5 ± 1.1 Ma associated to possible in-sequence thrust propagation, and (3) syn-orogenic tear faulting at 10.5 ± 0.4, 9.1 ± 6.5, 7.3 ± 1.9, 5.7 ± 4.7, 4.8 ± 1.7, and at 0.7 ± 4.2 Ma including the reactivation of a pre-orogenic fault as tear fault at 3.9 ± 2.9 Ma. Previously unknown faulting events at 44.7 ± 2.6 and 48.4 ± 1.5 Ma predate by ~ 10 Ma the accepted late Eocene age for tectonic activity onset in the Alpine foreland. In addition, we dated the previously inferred strike-slip faults re-activation as tear fault. The U-Pb ages demonstrate the long-lived tectonic history at the plate boundary between European and African plates and that the deformation observed in the foreland is directly linked to continental collision.

中文翻译:

高山前陆中新世-中更新世多次构造脉冲的U-Pb测年

摘要。前陆褶皱冲断带记录了长期的构造沉积活动,包括被动边缘沉积,弯曲以及在推进造山带之前进一步参与楔形增生。因此,测年断层活动是板块运动重建,资源勘探或地震灾害评估的基础。在这里,我们报告了在西北高山阿尔卑斯前陆(法国东部)朱拉褶皱-冲断带上从区域规模取样的四个逆冲和三个撕裂断层的方解石方解石成矿的U-Pb年龄。在始新世-中更新世中段识别出四个区域构造阶段:(1)与高山前隆隆隆相关的造山前断层44.7±2.6和48.4±1.5 Ma,(2)同造山逆冲11.4± 1.1、10.6±0.5、9.7±1.4、9.6±0.3和7.5±1。1 Ma与可能的顺序推力传播有关,以及(3)同造山裂缝断裂在10.5±0.4、9.1±6.5、7.3±1.9、5.7±4.7、4.8±1.7和0.7±4.2 Ma包括重新激活造山带断层在3.9±2.9 Ma处为撕裂断层。先前未知的断层事件发生在44.7±2.6和48.4±1.5 Ma之前,早于公认的始新世晚期晚于高寒前陆的构造活动开始。此外,我们将先前推断的走滑断层重新激活称为撕裂断层。U-Pb年龄在欧洲和非洲板块之间的板块边界显示了长期的构造历史,并且在前陆中观察到的变形与大陆碰撞直接相关。7±4.7、4.8±1.7和0.7±4.2 Ma,包括将造山前断层重新激活为3.9±2.9 Ma的撕裂断层。先前未知的断层事件发生在44.7±2.6和48.4±1.5 Ma之前,早于公认的始新世晚期晚于高寒前陆的构造活动开始。此外,我们将先前推断的走滑断层重新激活称为撕裂断层。U-Pb年龄在欧洲和非洲板块之间的板块边界显示了长期的构造历史,并且在前陆中观察到的变形与大陆碰撞直接相关。7±4.7、4.8±1.7和0.7±4.2 Ma,包括将造山前断层重新激活为3.9±2.9 Ma的撕裂断层。先前未知的断层事件发生在44.7±2.6和48.4±1.5 Ma之前,早于公认的始新世晚期晚于高寒前陆的构造活动开始。此外,我们将先前推断的走滑断层重新激活称为撕裂断层。U-Pb年龄在欧洲和非洲板块之间的板块边界显示了长期的构造历史,并且在前陆中观察到的变形与大陆碰撞直接相关。5 Ma早于开始的始新世晚期〜10 Ma在高山前陆开始的构造活动。此外,我们将先前推断的走滑断层重新激活称为撕裂断层。U-Pb年龄在欧洲和非洲板块之间的板块边界显示了长期的构造历史,并且在前陆中观察到的变形与大陆碰撞直接相关。早于新世晚期〜5 Ma,即早于高新时代的构造活动开始于高山前陆。此外,我们将先前推断的走滑断层重新激活称为撕裂断层。U-Pb年龄在欧洲和非洲板块之间的板块边界显示了长期的构造历史,并且在前陆中观察到的变形与大陆碰撞直接相关。
更新日期:2021-02-04
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