Exhumation mechanisms of the Tauern Window (Eastern Alps) inferred from apatite and zircon fission track thermochronology
Exhumation mechanisms of the Tauern Window (Eastern Alps) inferred from apatite and zircon fission track thermochronology
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DOI：
10.1002/2016tc004133
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发表时间：
2017-02-01
期刊：
影响因子：
4.2
通讯作者：
Fuegenschuh, Bernhard
中科院分区：
文献类型：
--
作者：
Bertrand, Audrey;Rosenberg, Claudio;Fuegenschuh, Bernhard
平行于造山带的伸展和垂直于造山带的缩短同时发生，并与褶皱作用相适应，从而使陶恩窗被发掘出来。为了研究垂直褶皱和侵蚀以及伸展剥蚀对折返作用的相对贡献，我们提供了以前和新的锆石和磷灰石裂变径迹年龄的地图视图。这些年龄图表明，等年龄等值线与大规模直立褶皱的轴面近似平行。在年龄与距离图上，沿着垂直于圆顶轴的剖面，所有温度计时器都显示出钟形曲线，圆顶铰链区的年龄较年轻，不同计时器之间的年龄差异从四肢到铰链区逐渐减小。所有这些观察结果表明，与侵蚀同步的褶皱是陶恩窗的主要原因。年轻的年龄和更高的褶皱振幅的西部subdome相比，东部的冷却年龄反演的结果，显示较高的折返率在西部证实。这些反映了同一个缩短和折叠事件，同时影响了整个陶恩穹隆，但比西部亚穹隆的速度更高。只有在上新世时期，沿着与窗口接壤的正断层的折返率沿着稍高;因此，伸展去顶可能在上新世占主导地位。向北位移的白云岩压痕是与顺时针旋转，这导致了向西缩短量的增加，因此较高的隆起和折返率在西部亚穹隆。
Orogen-parallel extension and orogen-perpendicular shortening accommodated by folding acted at the same time to exhume the Tauern Window. In order to investigate the relative contribution of upright folding and erosion and of extensional denudation for exhumation, we provide compilations in map view of previous and new zircon and apatite fission track ages. These age maps show that isoage contour lines are subparallel to the axial planes of large-scale, upright folds. On age versus distance diagrams, along a profile perpendicular to the dome axis, all thermochronometers show bell-shaped curves with younger ages in the hinge area of the dome and age differences between different chronometers decreasing from the limbs to the hinge area. All these observations suggest that folding synchronous with erosion was largely responsible for exhumation of the Tauern Window. The younger ages and the higher fold amplitudes of the western subdome compared to the eastern one are corroborated by the results of inversion of cooling ages that show higher exhumation rates in the west. These reflect one and the same shortening and folding event that affected the entire Tauern Dome synchronously, but at higher rates than that in the western subdome. Only during Pliocene time were exhumation rates slightly higher along the normal faults bordering the window; hence, extensional unroofing may have dominated exhumation in the Pliocene. The northward displacement of the Dolomites Indenter was associated to a clockwise rotation, which caused increased amounts of shortening westward, hence higher uplift and exhumation rates in the western subdome.