کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
6432857 | 1635473 | 2012 | 11 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Early Holocene (8.6Â ka) rock avalanche deposits, Obernberg valley (Eastern Alps): Landform interpretation and kinematics of rapid mass movement Early Holocene (8.6Â ka) rock avalanche deposits, Obernberg valley (Eastern Alps): Landform interpretation and kinematics of rapid mass movement](/preview/png/6432857.png)
In the Obernberg valley, the Eastern Alps, landforms recently interpreted as moraines are re-interpreted as rock avalanche deposits. The catastrophic slope failure involved an initial rock volume of about 45 million m³, with a runout of 7.2 km over a total vertical distance of 1330 m (fahrböschung 10°). 36Cl surface-exposure dating of boulders of the avalanche mass indicates an event age of 8.6 ± 0.6 ka. A 14C age of 7785 ± 190 cal yr BP of a palaeosoil within an alluvial fan downlapping the rock avalanche is consistent with the event age. The distal 2 km of the rock-avalanche deposit is characterized by a highly regular array of transverse ridges that were previously interpreted as terminal moraines of Late-Glacial. 'Jigsaw-puzzle structure' of gravel to boulder-size clasts in the ridges and a matrix of cataclastic gouge indicate a rock avalanche origin. For a wide altitude range the avalanche deposit is preserved, and the event age of mass-wasting precludes both runout over glacial ice and subsequent glacial overprint. The regularly arrayed transverse ridges thus were formed during freezing of the rock avalanche deposits.
⺠Deposits of purported glacial origin have been re-interpreted as rock avalanche. ⺠The age of the rock avalanche is dated to 8.6 ± 0.6 ka. ⺠Regularly-spaced transversal ridges record mechanic waves in the rock avalanche.
Journal: Geomorphology - Volumes 171â172, 15 October 2012, Pages 83-93