{"id":25911,"date":"2021-02-03T20:44:41","date_gmt":"2021-02-03T19:44:41","guid":{"rendered":"http:\/\/karmaka.de\/?p=25911"},"modified":"2021-02-03T20:48:01","modified_gmt":"2021-02-03T19:48:01","slug":"australasian-microtektites-across-the-antarctic-continent-evidence-from-the-sor-rondane-mountain-range-east-antarctica","status":"publish","type":"post","link":"https:\/\/karmaka.de\/?p=25911","title":{"rendered":"Australasian microtektites across the Antarctic continent: Evidence from the S\u00f8r Rondane Mountain range (East Antarctica)OPEN ACCESS<\/span> "},"content":{"rendered":"\n

Bastien Soens, Matthias van Ginneken, Steven Goderis<\/p>\n\n\n\n

Geoscience Frontiers
Available online 2 February 2021<\/p>\n\n\n\n

LINK (OPEN ACCESS)<\/strong><\/a>
<\/p>\n\n\n\n

“Highlights<\/p>\n\n\n\n

\u2022 Discovery of microtektites (n\u202f=\u202f33) on the eastern Antarctic continent.
\u2022 Physicochemical properties consistent with the Australasian strewn field.
\u2022 Australasian microtektites distributed on continent-wide scale across Antarctica.
\u2022 Potential to use microtektites as time-stratigraphic tool on Antarctica.
\u2022 Plagioclase- and carbonate-rich target material sampled by most distal ejecta.”<\/p>\n\n\n\n

“The ~790\u202fka Australasian (micro)tektite strewn field is one of the most recent and best-known examples of impact ejecta emplacement as the result of a large-scale cratering event across a considerable part of Earth’s surface (>10% in area). The Australasian strewn field is characterized by a tri-lobe pattern consisting of a large central distribution lobe, and two smaller side lobes extending to the west and east. Here, we report on the discovery of microtektite-like particles in sedimentary traps, containing abundant micrometeorite material, in the S\u00f8r Rondane Mountain (SRM) range of East Antarctica. The thirty-three glassy particles display a characteristic pale yellow color and are predominantly spherical in shape, except for a single dumbbell-shaped particle. The vitreous spherules range in size from 220 to 570\u202f\u03bcm, with an average diameter of ~370\u202f\u03bcm. This compares relatively well with the size distribution (75\u2013778\u202f\u03bcm) of Australasian microtektites previously recovered from the Transantarctic Mountains (TAM) and located ca. 2500\u20133000\u202fkm from the SRM. In addition, the chemical composition of the SRM particles exhibits limited variation and is nearly identical to the \u2018normal-type\u2019 (i.e., <6% MgO) TAM microtektites. The Sr and Nd isotope systematics for a single batch of SRM particles (n\u202f=\u202f26) strongly support their affiliation with TAM microtektites and the Australasian tektite strewn field in general. Furthermore, Sr isotope ratios and Nd model ages suggest that the target material of the SRM particles was composed of a plagioclase- or carbonate-rich lithology derived from a Paleo- or Mesoproterozoic crustal unit. The affiliation to the Australasian strewn field requires long-range transportation, with estimated great circle distances of ca. 11,600\u202fkm from the hypothetical source crater, provided transportation occurred along the central distribution lobe. This is in agreement with the observations made for the Australasian microtektites recovered from Victoria Land (ca. 11,000\u202fkm) and Larkman Nunatak (ca. 12,000\u202fkm), which, on average, decrease in size and alkali concentrations (e.g., Na and K) as their distance from the source crater increases. The values for the SRM particles are intermediate to those of the Victoria Land and Larkman Nunatak microtektites for both parameters, thus supporting this observation. We therefore interpret the SRM particles as \u2018normal-type\u2019 Australasian microtektites, which significantly extend the central distribution lobe of the Australasian strewn field westward. Australasian microtektite distribution thus occurred on a continent-wide scale across Antarctica and allows for the identification of new, potential recovery sites on the Antarctic continent as well as the southeastern part of the Indian Ocean. Similar to volcanic ash layers, the ~790\u202fka distal Australasian impact ejecta are thus a record of an instantaneous event that can be used for time-stratigraphic correlation across Antarctica.”<\/p>\n","protected":false},"excerpt":{"rendered":"

Bastien Soens, Matthias van Ginneken, Steven Goderis Geoscience FrontiersAvailable online 2 February 2021 LINK (OPEN ACCESS) “Highlights \u2022 Discovery of microtektites (n\u202f=\u202f33) on the eastern Antarctic continent.\u2022 Physicochemical properties consistent with the Australasian strewn field.\u2022…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3296],"tags":[4141,3332],"_links":{"self":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25911"}],"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=25911"}],"version-history":[{"count":2,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25911\/revisions"}],"predecessor-version":[{"id":25913,"href":"https:\/\/karmaka.de\/index.php?rest_route=\/wp\/v2\/posts\/25911\/revisions\/25913"}],"wp:attachment":[{"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=25911"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=25911"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/karmaka.de\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=25911"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}