{"id":60,"date":"2020-10-30T10:19:51","date_gmt":"2020-10-30T10:19:51","guid":{"rendered":"http:\/\/www.oceanblogs.org\/msm96\/?p=60"},"modified":"2020-10-30T10:19:54","modified_gmt":"2020-10-30T10:19:54","slug":"pebbles-in-deep-sea-sediments","status":"publish","type":"post","link":"https:\/\/www.oceanblogs.org\/msm96\/2020\/10\/30\/pebbles-in-deep-sea-sediments\/","title":{"rendered":"Pebbles in deep-sea sediments"},"content":{"rendered":"\n<p>&#8212; Deutscher Text folgt unten &#8212;<\/p>\n\n\n\n<p>As described by my colleague Palash, we are collecting sediment with the Multicorer (MUC). Typical deep sea sediment is greyish-brownish, sticky mud. Like the stuff used for making pottery. Deep-sea sediment generally consists of very fine particles:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>carried from land into the ocean, either by rivers or by wind-blown dust,<\/li><li>derived from single-cell organisms like foraminifera and diatoms living in the water column or on the sea bed,<\/li><li>formed locally on the seafloor.<\/li><\/ul>\n\n\n\n<p>Unexpectedly, however, in some of the MUC cores we find pebbles up to 2 cm in size. What are they and where do they come from?<\/p>\n\n\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"542\" height=\"366\" src=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/grafik-3.png\" alt=\"\" class=\"wp-image-61\" srcset=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/grafik-3.png 542w, https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/grafik-3-300x203.png 300w\" sizes=\"auto, (max-width: 542px) 100vw, 542px\" \/><figcaption>(by Doris Maicher)<\/figcaption><\/figure>\n\n\n\n<p>Components larger than a few micrometers can not be transported over long distances by wind nor by water. Our work area Porcupine Abyssal Plains (PAP) is situated some 500 km offshore. To cut a long story short, it is icebergs which carry the coarse debris, as so-called ice-rafted debris (IRD).<\/p>\n\n\n\n<p>When a glacier on land moves over the bedrock, it scrapes off chunks of rock in all sizes and incorporates them into the ice. Icebergs calving from these glaciers then drift over the ocean, driven by wind and ocean currents. During their drift the icebergs melt and the rocks drop and sink to the ocean floor \u2013 from where we recovered some of them in our MUC cores.<\/p>\n\n\n\n<figure class=\"wp-block-gallery columns-3 is-cropped wp-block-gallery-1 is-layout-flex wp-block-gallery-is-layout-flex\"><ul class=\"blocks-gallery-grid\"><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"439\" height=\"393\" src=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-1-1.png\" alt=\"\" data-id=\"62\" data-full-url=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-1-1.png\" data-link=\"https:\/\/www.oceanblogs.org\/msm96\/?attachment_id=62#main\" class=\"wp-image-62\" srcset=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-1-1.png 439w, https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-1-1-300x269.png 300w\" sizes=\"auto, (max-width: 439px) 100vw, 439px\" \/><figcaption class=\"blocks-gallery-item__caption\">Mafic rock<\/figcaption><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"437\" height=\"370\" src=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-2-1.png\" alt=\"\" data-id=\"63\" data-full-url=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-2-1.png\" data-link=\"https:\/\/www.oceanblogs.org\/msm96\/?attachment_id=63#main\" class=\"wp-image-63\" srcset=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-2-1.png 437w, https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-2-1-300x254.png 300w\" sizes=\"auto, (max-width: 437px) 100vw, 437px\" \/><figcaption class=\"blocks-gallery-item__caption\">Carbonate<\/figcaption><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"441\" height=\"329\" src=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-3-1.png\" alt=\"\" data-id=\"64\" data-full-url=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-3-1.png\" data-link=\"https:\/\/www.oceanblogs.org\/msm96\/?attachment_id=64#main\" class=\"wp-image-64\" srcset=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-3-1.png 441w, https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-3-1-300x224.png 300w\" sizes=\"auto, (max-width: 441px) 100vw, 441px\" \/><figcaption class=\"blocks-gallery-item__caption\">Plutonic rock<\/figcaption><\/figure><\/li><li class=\"blocks-gallery-item\"><figure><img loading=\"lazy\" decoding=\"async\" width=\"445\" height=\"304\" src=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-4.png\" alt=\"\" data-id=\"65\" data-full-url=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-4.png\" data-link=\"https:\/\/www.oceanblogs.org\/msm96\/?attachment_id=65#main\" class=\"wp-image-65\" srcset=\"https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-4.png 445w, https:\/\/www.oceanblogs.org\/msm96\/wp-content\/uploads\/sites\/73\/2020\/10\/Picture-4-300x205.png 300w\" sizes=\"auto, (max-width: 445px) 100vw, 445px\" \/><figcaption class=\"blocks-gallery-item__caption\">fine (left) and coarse (right) grained sandstone<\/figcaption><\/figure><\/li><\/ul><figcaption class=\"blocks-gallery-caption\">(Images by Doris Maicher)<\/figcaption><\/figure>\n\n\n\n<p>Looking at our pebbles in detail reveal that the IRDs are composed of different kinds of rocks, e.g. plutonic rocks, carbonates, sandstones and volcanic rocks (see pictures further down). With further studies like geochemical analysis, we hope to trace them back to their source area, probably the Canadian Shield, Greenland and perhaps the Icelandic-Scandinavian area. &#8211; <em>With kind greetings from board, Doris<\/em><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><strong>Steinchen in Tiefsee-Sedimenten<\/strong><\/h2>\n\n\n\n<p>Wie es schon mein Kollege Palash beschrieben hat, sammeln wir Sedimente vom Meeresboden mit einem Multicorer (MUC). Typisches Tiefsee-Sediment ist grau-brauner Ton; ganz \u00e4hnlich wie das Material, das zum T\u00f6pfern verwendet wird. Das Sediment besteht aus sehr, sehr feinen Partikeln, die<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>vom Land in den Ozean eingebracht wurden, entweder vom Wind oder durch Fl\u00fcsse<\/li><li>von einzelligen Organismen wie Foraminiferen und Diatomeen stammen, die in der Wassers\u00e4ule oder am Meeresboden leben<\/li><li>direkt am Meeresboden gebildet werden.<\/li><\/ul>\n\n\n\n<p>Ganz unerwartet haben wir in einigen MUC-Kernen aber auch kleine Steinchen von bis zu 2 cm Gr\u00f6\u00dfe gefunden. Was ist das, und wo kommen sie her?<\/p>\n\n\n\n<p>Partikel, die gr\u00f6\u00dfer sind als einige Mikrometer, k\u00f6nnen weder von Wind noch von Wasser \u00fcber lange Distanzen transportiert werden. Unser Arbeitsgebiet, Porcupine Abyssal Plains (PAP) liegt ca. 500 km vom Land entfernt. Um es kurz zu machen: es sind Eisberge, die das grobe Material herantransportiert haben. Es wird im Fachjargon <em>ice-rafted debris<\/em> (IRD) genannt.<\/p>\n\n\n\n<p>Wenn sich ein Gletscher \u00fcber die Landoberfl\u00e4che bewegt, hobelt er von der Landoberfl\u00e4che Material ab. Das Gr\u00f6\u00dfenspektrum reicht von Sand bis zu tonnenschweren Findlingen, und alles wird im Eis eingeschlossen. Von den Gletschern kalben Eisberge, die dann \u00fcber das Meer treiben, angetrieben von Wind und vor allem Meeresstr\u00f6mungen. W\u00e4hrend der Drift schmelzen die Eisberge und ihre Fracht an Steinen wird freigesetzt, die Steine sinken zum Meeresboden \u2013 von wo wir einen Teil wieder mit unseren MUCs eingesammelt haben.<\/p>\n\n\n\n<p>Die Steinchen, im Detail betrachtet, sind petrologisch eine bunte Mischung. Es treten plutonische Kristallingesteine auf, Karbonate, Sansteine und vulkanische Gesteine (siehe Bilder weiter unten). Mit weiterf\u00fchrenden Studien, wie zum Beispiel geochemischen Analysen, hoffen wir, die Steine zu ihrem jeweiligen Ursprungsort zur\u00fcckverfolgen zu k\u00f6nnen. Vermutlich kamen sie vom Kanadischen Schild, Gr\u00f6nland und vielleicht aus Isl\u00e4ndisch-Skandinavischen Gebieten. &#8211; <em>Mit herzlichen Gr\u00fc\u00dfen von Bord, Doris<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>&#8212; Deutscher Text folgt unten &#8212; As described by my colleague Palash, we are collecting sediment with the Multicorer (MUC). Typical deep sea sediment is greyish-brownish, sticky mud. Like the stuff used for making pottery. Deep-sea sediment generally consists of very fine particles: carried from land into the ocean, either by rivers or by wind-blown [&hellip;]<\/p>\n","protected":false},"author":214,"featured_media":61,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[],"class_list":["post-60","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-at-sea"],"_links":{"self":[{"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/posts\/60","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/users\/214"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/comments?post=60"}],"version-history":[{"count":2,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/posts\/60\/revisions"}],"predecessor-version":[{"id":67,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/posts\/60\/revisions\/67"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/media\/61"}],"wp:attachment":[{"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/media?parent=60"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/categories?post=60"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/msm96\/wp-json\/wp\/v2\/tags?post=60"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}