Transition from orogen-perpendicular to orogen-parallel exhumation and cooling during crustal indentation — Key constraints from 147Sm/144Nd and 87Rb/87Sr geochronology (Tauern Window, Alps)
Transition from orogen-perpendicular to orogen-parallel exhumation and cooling during crustal indentation — Key constraints from 147Sm/144Nd and 87Rb/87Sr geochronology (Tauern Window, Alps)
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DOI：
10.1016/j.tecto.2015.08.037
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发表时间：
2015-12
期刊：
影响因子：
2.9
通讯作者：
S. Favaro;R. Schuster;M. Handy;A. Scharf;G. Pestal
中科院分区：
文献类型：
--
作者：
S. Favaro;R. Schuster;M. Handy;A. Scharf;G. Pestal
在渐新世晚期至中新世期间，亚得里亚海微板块向北凹陷，东阿尔卑斯山阿尔卑斯造山带（陶恩窗）的核心经历了从造山带正常缩短和推覆后隆起到主要平行造山带伸展和构造去顶的变化。在陶恩窗东部形成穹隆的最低推覆杂岩的含石榴子石组合上获得的新的147 Sm/144 Nd等时线年龄为25.7 ± 0.9 Ma，表明推覆后巴罗型变质作用的高温与穹隆的开始在时间上重叠。新的87 Rb/87 Sr黑云母年龄从这个相同的复杂的结合以前dashed的87 Rb/87 Sr白色云母年龄表明，隆起和折返开始不迟于28 Ma立即在前面的凹进Austroalpine地壳块，然后迁移横向的ESE在快速折返和造山带平行拉伸开始于约23 Ma。快速冷却结束于约17马在下盘的Katschberg正常故障，这界定了东部边缘的陶恩窗口。在陶恩窗的西部也发现了类似的迁移隆起、平行造山带的伸展和冷却模式，那里的快速折返开始于大约20 Ma，比东部晚了2-3 Ma。这种差异的发病迅速折返，以及整体迁移的圆顶从中心到两端的陶恩窗口是由于上述的奥南阿尔卑斯块体的碎片沿着前缘的主要亚得里亚海压痕（南阿尔卑斯山），因为这个压痕先进的北部。
The core of the Alpine orogen in the Eastern Alps (Tauern Window) experienced a change from orogen-normal shortening and post-nappe doming to predominantly orogen-parallel extension and tectonic unroofing during late Oligocene to Miocene northward indentation of the Adriatic Microplate. A new147Sm/144Nd isochron age of 25.7 ± 0.9 Ma on a garnet-bearing assemblage from the lowest nappe complex forming a dome in the eastern part of the Tauern Window indicates that high temperatures related to post-nappe Barrovian-type metamorphism overlapped in time with the onset of doming. New87Rb/87Sr biotite ages from this same complex combined with previously published87Rb/87Sr white mica ages suggest that doming and exhumation began no later than 28 Ma immediately in front of indenting Austroalpine crustal blocks, then migrated laterally to the ESE during rapid exhumation and orogen-parallel stretching beginning at about 23 Ma. Rapid cooling ended at approximately 17 Ma in the footwall of the Katschberg Normal Fault, which delimits the eastern margin of the Tauern Window. A similar pattern of migrating doming, orogen-parallel extension and cooling is recognized in the western part of the Tauern Window, where rapid exhumation began at about 20 Ma, some 2–3 Ma later than in the eastern part. This difference in the onset of rapid exhumation as well as the overall migration of doming from the center to the ends of the Tauern Window are attributed to fragmentation of the aforementioned Austroalpine blocks along the leading edge of the main Adriatic indenter (Southern Alps) as this indenter advanced to the north.