{"id":31495,"date":"2022-11-06T12:01:13","date_gmt":"2022-11-06T10:01:13","guid":{"rendered":"https:\/\/karmaka.de\/?p=31495"},"modified":"2022-11-06T13:39:58","modified_gmt":"2022-11-06T11:39:58","slug":"keurusselka-impact-structure-finland-overview-new-observations-and-renewed-interpretation-of-the-size","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=31495","title":{"rendered":"Keurusselk\u00e4 impact structure, Finland \u2014 Overview, new observations, and renewed interpretation of the size<span class=\"badge-status\" style=\"background:#787878\">OPEN ACCESS<\/span>&nbsp;"},"content":{"rendered":"\n<p>Satu Hietala, Jarmo Moilanen, J\u00fcri Plado<\/p>\n\n\n\n<p>MAPS<br>Version of Record online: 05 November 2022<\/p>\n\n\n\n<p><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/10.1111\/maps.13920\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>LINK (OPEN ACCESS)<\/strong><\/a><br><a href=\"https:\/\/onlinelibrary.wiley.com\/doi\/epdf\/10.1111\/maps.13920\" target=\"_blank\" rel=\"noreferrer noopener\"><strong>PDF (OPEN ACCESS)<\/strong><\/a><\/p>\n\n\n\n<p class=\"justify-text\">&#8220;The Keurusselk\u00e4 structure is one of Finland&#8217;s 12 meteorite impact structures\u2014one of the world&#8217;s oldest (1150\u2009\u00b1\u200910\u2009Ma) and the largest of its kind in Finland. Findings of numerous well-formed shatter cones in a wide area have helped define and prove Keurusselk\u00e4&#8217;s impact origin. Keurusselk\u00e4 is deeply eroded, making estimating its size challenging. Thus, various size ranges are based on the distribution of shatter cones. This study provides an overview of the earlier published studies in light of the unpublished data resulting from 2003 to 2019 field surveys. Two shatter cone outcrops 15\u2009km from each other were sampled during a field survey in 2019. Thin section samples from these sites were studied with a polarizing microscope, and shock metamorphic features were identified and measured with the universal stage. We also compared topographic and bathymetric Lidar (light detection and ranging) data with the existing geophysical data and shatter cone occurrences. In situ outcrops\u2014Metsom\u00e4ki 9.6\u2009km toward the W and Martinniemi 5.7\u2009km toward SE from the crater&#8217;s center\u2014delimit the maximum radius of shatter cones found so far. Studies resulted in planar fractures parallel to (0001) in Metsom\u00e4ki shatter cones. We determine the size of 37.5\u2009km as the apparent diameter of the Keurusselk\u00e4 impact structure, whereas the 25\u2009km in diameter semicircular feature represents faulted rim structures.&#8221;<\/p>\n","protected":false},"excerpt":{"rendered":"<p>Satu Hietala, Jarmo Moilanen, J\u00fcri Plado MAPSVersion of Record online: 05 November 2022 LINK (OPEN ACCESS)PDF (OPEN ACCESS) &#8220;The Keurusselk\u00e4 structure is one of Finland&#8217;s 12 meteorite impact structures\u2014one of the world&#8217;s oldest (1150\u2009\u00b1\u200910\u2009Ma) and&#8230;<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[90],"tags":[92,3074],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/31495"}],"collection":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=31495"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/31495\/revisions"}],"predecessor-version":[{"id":31497,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/31495\/revisions\/31497"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=31495"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=31495"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=31495"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}