ABSTRACT Studies of impact structures in Sweden date back almost 60 years. They have so far resulted in the confirmation and understanding of eight impact structures and one impact-derived breccia layer, including the largest confirmed impact structure in the western part of Europe, the Siljan impact structure. Several additional structures have been proposed as impact derived, but they have to date not been confirmed. In this contribution, I summarize the current state of knowledge about the impact cratering record of Sweden. This is an up-to-date, comprehensive review of the features of known impact structures (and impact-related deposits) in Sweden. The described impact structures formed over a time period spanning from the Cambrian to the Cretaceous, and the preservation of several small (~1–2 km in diameter) Paleozoic impact structures indicates that the conditions securing their protection were close to optimal, with formation in a shallow epicontinental sea and rapid cover by protective sediments followed by a regional geologic evolution permitting their preservation. The generally well-preserved state of some of these crater structures contradicts the general assumption that such small impact structures can only be preserved for approximately a couple of thousand to a few million years. The Lockne-Målingen, Tvären, Granby, and Hummeln impact structures all have ages that place their formation in a period of proposed increased cratering rate on Earth following the breakup event of the L-chondrite parent body in the asteroid belt. However, to date, evidence other than a temporal correlation is missing for all of these structures except for Lockne (and Målingen), which has been shown to have formed by the impact of an L-chondritic body.

ABSTRACT There are currently 31 confirmed structures of impact origin in Australia. More than 49 additional structures have been proposed to have formed due to asteroid impact but await confirmation. Many discoveries have been made in Australia in the time since the last comprehensive review of the Australian impact cratering record was published in a peer-reviewed journal in 2005. These include further expanding the record of confirmed craters, and providing new insights into a variety of impact-related processes, such as shock deformation, phase transitions in accessory minerals, new impact age determinations, studies of oblique impacts, and more. This update is a review that focuses principally on summarizing discoveries made since 2005. Highlights since then include confirmation of five new Australian impact structures, identification of Earth’s oldest recognized impact structure, recognition of shock deformation in accessory minerals, discovery of the high-pressure phase reidite in Australia, determination of the links between impact craters and some ore deposits, and publication of the first generation of numerical hydrocode models for some Australian craters.