ABSTRACT

This study shows the occurrence of numerous iceberg imprints on the bottom of former ice-dammed lakes in Härjedalen, west-central Sweden. Discussion of the genesis of the so-called “impact crater” known as the Tor structure at Torbygget, which is located in this area, motivated an examination of the area using high-resolution digital elevation models. Previous investigations have suggested that this crater was created by a meteorite impact about 2000 years ago, forming a semi-round depression. The results of our investigation clearly indicate that the feature was formed by a grounding iceberg, scouring the bed of an ice-dammed lake during deglaciation about 11 000-10 000 cal. BP. Geomorphic evidence of an ice-dammed lake (multiple and abundant well-developed shorelines) are consistent with earlier mapping efforts in the area. Furthermore, an abundance of geomorphological traces of iceberg activity is found within the paleo-ice-dammed lake basins. Based on this we suggest that the depression at Torbygget is not an impact crater but formed by a grounded iceberg.

摘要

这项研究表明，在瑞典中西部的Härjedalen，前冰封的湖底出现了许多冰山烙印。对位于该地区Torbygget的所谓“撞击坑”（Tor structure）的所谓“撞击坑”的成因的讨论，激发了使用高分辨率数字高程模型对该区域进行检查的动机。先前的研究表明，这个陨石坑是由大约2000年前的陨石撞击形成的，形成了半圆形的凹陷。我们的调查结果清楚地表明，该特征是由一个接地的冰山形成的，在冰消过程中大约11000-10 000 cal冲刷了一个被冰封的湖泊的河床。BP。冰封的湖泊（多且丰富的发达海岸线）的地貌证据与该地区较早的制图工作是一致的。此外，在古冰堰塞的湖盆中发现了大量的冰山活动地貌痕迹。基于此，我们认为Torbygget的凹陷不是撞击坑，而是由接地的冰山形成的。