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Cooling and vertical motions of crustal wedges prior to, during and after lateral extrusion in the Eastern Alps: new field kinematic and fission track data from the Mur‐Mürz fault system
Tectonics ( IF 3.3 ) Pub Date : 2020-03-01 , DOI: 10.1029/2019tc005754
I. E. Gelder 1, 2 , E. Willingshofer 1 , P. A. M. Andriessen 3 , R. Schuster 4 , D. Sokoutis 1
Affiliation  

New structural and thermochronological (zircon and apatite fission track) data from the eastern most Alps highlight distinct deformation phases affecting the Austroalpine unit along a major sinistral strike-slip fault system, the Mur-Murz fault (MMF). The data link deformation to vertical motions prior to, during, and after the main phase of lateral extrusion of the orogen. Zircon fission track ages document rapid (ca. 15 °C/Myr) and diachronous (eastward younging) cooling and rock exhumation during the latest Cretaceous to Paleocene. Subsequent regional Eocene to early Miocene cooling below the closure temperature of the apatite fission track system occurred at slow rates (ca. 2 °C/Myr), suggesting that the region was not subject to major surface uplift and erosion during that period. Fault kinematic analysis along the MMF document pre-extrusion NNW-SSE contraction, middle Miocene syn-extrusion NE-SW to NNE-SSW directed shortening, and Late Miocene E-W contraction. All phases are characterized by strike-slip fault regimes. Formation of the complex MMF zone triggered the exhumation of small, fault-bound crustal blocks within the fault zone as documented by middle Miocene apatite fission track ages. Overall, ages are similar on both sides of the fault suggesting that lateral extrusion along the MMF was not associated with significant differential vertical motions. Local Pliocene rock cooling and exhumation was probably related to the buttressing effect of the underthrust Bohemian basement spur. Whereas large-scale, post-extrusion surface uplift of the extruding crustal wedges, such as the “Styrian block,” must have been related to long-wavelength deformation processes affecting the easternmost Alps.

中文翻译:

东阿尔卑斯山横向挤压之前、期间和之后地壳楔的冷却和垂直运动:来自 Mur-Mürz 断层系统的新场运动学和裂变轨迹数据

来自阿尔卑斯山脉最东部的新的结构和热年代学(锆石和磷灰石裂变轨迹)数据突出了影响沿主要左旋走滑断层系统 Mur-Murz 断层 (MMF) 的 Austroalpine 单元的不同变形阶段。在造山带横向挤压的主要阶段之前、期间和之后,数据将变形与垂直运动联系起来。锆石裂变径迹年龄记录了白垩纪至古新世的快速(约 15 °C/Myr)和历时(东向年轻化)冷却和岩石剥落。随后的区域始新世至早中新世冷却低于磷灰石裂变径迹系统的闭合温度以缓慢的速率发生(约 2°C/Myr),表明该地区在此期间没有受到主要的地表隆起和侵蚀。沿 MMF 的断层运动学分析记录了预挤压 NNW-SSE 收缩、中中新世同步挤压 NE-SW 到 NNE-SSW 定向缩短以及晚中新世 EW 收缩。所有阶段都以走滑断层为特征。复杂的 MMF 带的形成触发了断层带内小的、断层束缚的地壳块的剥露,如中中新世磷灰石裂变轨迹年龄所记录的那样。总体而言,断层两侧的年龄相似,表明沿 MMF 的横向挤压与显着的不同垂直运动无关。局部上新世岩石冷却和折返可能与下冲波西米亚基底支刺的支撑作用有关。而挤压地壳楔形体的大规模挤压后表面隆起,如“施蒂里亚块”,
更新日期:2020-03-01
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