{"id":95,"date":"2014-10-07T14:05:26","date_gmt":"2014-10-07T12:05:26","guid":{"rendered":"http:\/\/karmaka.de\/?p=95"},"modified":"2016-08-24T08:42:46","modified_gmt":"2016-08-24T06:42:46","slug":"new-40ar39ar-dating-of-the-clearwater-lake-impact-structures-quebec-canada-not-the-binary-asteroid-impact-it-seems","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=95","title":{"rendered":"New 40Ar\/39Ar dating of the Clearwater Lake impact structures (Qu\u00e9bec, Canada) \u2013 Not the binary asteroid impact it seems?"},"content":{"rendered":"<p><span style=\"font-size: 14pt;\"><strong>New 40Ar\/39Ar dating of the Clearwater Lake impact structures (Qu\u00e9bec, Canada) \u2013 Not the binary asteroid impact it seems?<\/strong><\/span><\/p>\n<p>Martin Schmieder, Winfried H. Schwarz, Mario Trieloff, Eric Tohver, Elmar Buchner, Jens Hopp, Gordon R. Osinski<\/p>\n<p>Geochimica et Cosmochimica Acta<br \/>\navailable online 7 October 2014<\/p>\n<p><a href=\"http:\/\/www.sciencedirect.com\/science\/article\/pii\/S001670371400595X\" target=\"_blank\"><strong>LINK<\/strong><\/a><\/p>\n<blockquote><p>Whereas the West Clearwater impact affected Ordovician carbonates incorporated into the impact breccia, drill core reports from the 1960s concluded that clasts of Ordovician sedimentary rocks are seemingly absent in the impact breccia lens of the East Clearwater Lake impact structure, which is overlain by &gt;100\u00a0m of post-impact sandstones, shales and carbonates. No resolvable impactor contamination has so far been detected in the West Clearwater impact melt rocks, whereas East Clearwater carries a distinct ordinary (possibly L-) chondritic impactor signature in its melt rocks. East Clearwater Lake might thus represent one among a long list of Ordovician impact structures in North America and northern Europe that were presumably generated in response to the L-chondrite asteroid breakup event \u223c470 Ma ago. Paleogeographic reconstructions show that the Ordovician East Clearwater impact probably occurred in a near-coastal to shallow marine setting, while the Permian West Clearwater impact hit continental Pangaea.\u00a0 Along with the new <sup>40<\/sup>Ar\/<sup>39<\/sup>Ar data, the paleomagnetic, sedimentologic, and paleogeographic findings suggest that the close spatial arrangement of the two Clearwater lakes is probably pure coincidence. The two impact structures seem to represent a \u2018false doublet\u2019 struck by impacts separated by \u223c180 million years in time. The new results for the Clearwater Lake impact structures have major implications for the reliable identification of doublet impact craters and the rate of binary asteroid impacts on Earth and on other planetary bodies in the inner Solar System.<\/p><\/blockquote>\n","protected":false},"excerpt":{"rendered":"<p>New 40Ar\/39Ar dating of the Clearwater Lake impact structures (Qu\u00e9bec, Canada) \u2013 Not the binary asteroid impact it seems? Martin Schmieder, Winfried H. Schwarz, Mario Trieloff, Eric Tohver, Elmar Buchner, Jens Hopp, Gordon R. Osinski&#8230;<\/p>\n","protected":false},"author":1,"featured_media":16,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[90],"tags":[93,91,92,1815,1807],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/95"}],"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=95"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/95\/revisions"}],"predecessor-version":[{"id":9656,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/95\/revisions\/9656"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/media\/16"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=95"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=95"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=95"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}