Meteorite crater re-interpreted as iceberg pit in west-central Sweden

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.

KEYWORDS:

• Deglaciation
• ice-dammed lake
• iceberg
• impact crater
• Ljusnan Ice Lake
• Torbygget

Acknowledgments

We thank Colby Smith, Geological Survey of Sweden, for providing useful feedback to the manuscript and improving the English language, and Simon Karlsson for the photograph in Fig. 1.

Disclosure statement

No potential conflict of interest was reported by the authors.