{"id":73476,"date":"2025-12-15T12:00:00","date_gmt":"2025-12-15T12:00:00","guid":{"rendered":"https:\/\/www.africa-press.net\/senegal\/politique\/sous-nos-pieds-les-traces-dune-terre-disparue"},"modified":"2025-12-15T22:41:38","modified_gmt":"2025-12-15T22:41:38","slug":"sous-nos-pieds-les-traces-dune-terre-disparue","status":"publish","type":"post","link":"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue","title":{"rendered":"Sous Nos Pieds, les Traces D\u2019Une Terre Disparue"},"content":{"rendered":"

Africa-Press – Senegal. <\/strong><\/span>Une e\u0301quipe internationale a annonce\u0301 la de\u0301couverte de vestiges chimiques de la \u00ab proto-Terre \u00bb, un monde vieux de 4,5 milliards d\u2019anne\u0301es. La Terre primitive s\u2019est d\u2019abord forme\u0301e a\u0300 partir de la fusion de me\u0301te\u0301orites, avant d\u2019e\u0302tre remodele\u0301e, moins de 100 millions d\u2019anne\u0301es plus tard, par l\u2019impact cataclysmique d\u2019un plane\u0301toi\u0308de de la taille de Mars, The\u0301ia. Cette collision, qui a donne\u0301 naissance a\u0300 la Lune, a aussi modifie\u0301 la composition terrestre. Pour les ge\u0301ologues, les mate\u0301riaux originels de la proto-Terre avaient alors irre\u0301me\u0301diablement disparu.<\/p>\n

Pourtant, une e\u0301tude publie\u0301e dans Nature Geoscience indique avoir de\u0301couvert des lambeaux de ce lointain passe\u0301. Pour cela, les chercheurs ont analyse\u0301 des roches provenant d\u2019Isua au Groenland, du bouclier canadien et de Kaapvaal en Afrique du Sud \u2013 des re\u0301gions constitue\u0301es de parties tre\u0300s anciennes et stables de la lithosphe\u0300re continentale \u2013 et des basaltes remontant du manteau profond via les volcans de La Re\u0301union et d\u2019Hawaii.<\/p>\n

L\u2019e\u0301le\u0301ment cle\u0301 de cette e\u0301tude est le potassium, pre\u0301sent partout sur Terre sous trois variantes atomiques (39, 40 et 41). Si les proportions de ces isotopes sont stables dans les roches du manteau, elles sont diffe\u0301rentes dans les me\u0301te\u0301orites, ce qui fait de cet e\u0301le\u0301ment un marqueur inte\u0301ressant pour identifier les mate\u0301riaux primordiaux.<\/p>\n

Un de\u0301ficit anormal en potassium 40<\/b><\/p>\n

Or, les analyses en spectrome\u0301trie de masse ont mesure\u0301 un de\u0301ficit anormal en potassium 40 dans certains e\u0301chantillons. Cela ne peut e\u0302tre explique\u0301 par les processus ge\u0301ologiques actuels, ni par les grands impacts me\u0301te\u0301oritiques connus. Selon les chercheurs, cette signature correspond a\u0300 des mate\u0301riaux forme\u0301s avant la grande collision avec The\u0301ia.<\/p>\n

Pour tester leur hypothe\u0300se, ils ont simule\u0301 4,5 milliards d\u2019anne\u0301es d\u2019e\u0301volution ge\u0301ologique et d\u2019impacts me\u0301te\u0301oritiques. Ils ont ainsi montre\u0301 que l\u2019impact ge\u0301ant a enrichi les roches terrestres en potassium 40. Celles qui en manquent doivent donc provenir d\u2019un manteau ante\u0301rieur a\u0300 cet e\u0301ve\u0301nement \u2013 autrement dit, d\u2019une proto-Terre -, dont des vestiges subsisteraient dans des zones profondes et stables du manteau terrestre.<\/p>\n

E\u0301tonnamment, la signature observe\u0301e dans ces e\u0301chantillons ne correspond a\u0300 aucune me\u0301te\u0301orite connue. Ce qui signifie que les mate\u0301riaux me\u0301te\u0301oritiques ayant forme\u0301 la proto-Terre restent a\u0300 de\u0301couvrir.<\/p>\n

Pour plus d’informations et d’analyses sur la Senegal<\/span>, suivez Africa-Press<\/span><\/strong><\/p>\n","protected":false},"excerpt":{"rendered":"

Africa-Press – Senegal. Une e\u0301quipe internationale a annonce\u0301 la de\u0301couverte de vestiges chimiques de la \u00ab proto-Terre \u00bb, un monde vieux de 4,5 milliards d\u2019anne\u0301es. La Terre primitive s\u2019est d\u2019abord forme\u0301e a\u0300 partir de la fusion de me\u0301te\u0301orites, avant d\u2019e\u0302tre remodele\u0301e, moins de 100 millions d\u2019anne\u0301es plus tard, par l\u2019impact cataclysmique d\u2019un plane\u0301toi\u0308de de la […]<\/p>\n","protected":false},"author":82,"featured_media":73475,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[22,10],"tags":[44],"class_list":["post-73476","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-divers","category-toutes-les-actualites","tag-senegal-2"],"yoast_head":"\nSous Nos Pieds, les Traces D\u2019Une Terre Disparue - Senegal<\/title>\n<meta name=\"description\" content=\"Une e\u0301quipe internationale a annonce\u0301 la de\u0301couverte de vestiges chimiques de la \u00ab proto-Terre \u00bb, un monde vieux de 4,5 ...\" \/>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\" \/>\n<meta property=\"og:locale\" content=\"fr_FR\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"Sous Nos Pieds, les Traces D\u2019Une Terre Disparue\" \/>\n<meta property=\"og:description\" content=\"Une e\u0301quipe internationale a annonce\u0301 la de\u0301couverte de vestiges chimiques de la \u00ab proto-Terre \u00bb, un monde vieux de 4,5 ...\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\" \/>\n<meta property=\"og:site_name\" content=\"Senegal\" \/>\n<meta property=\"article:published_time\" content=\"2025-12-15T12:00:00+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2025-12-15T22:41:38+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/static.africa-press.net\/senegal\/sites\/13\/2025\/12\/sm_1765867131.445389.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1200\" \/>\n\t<meta property=\"og:image:height\" content=\"900\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"cfeditorfr\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"\u00c9crit par\" \/>\n\t<meta name=\"twitter:data1\" content=\"cfeditorfr\" \/>\n\t<meta name=\"twitter:label2\" content=\"Dur\u00e9e de lecture estim\u00e9e\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\"},\"author\":{\"name\":\"cfeditorfr\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/#\/schema\/person\/2b1cf3cd81a31e3cd26889ca66d677f1\"},\"headline\":\"Sous Nos Pieds, les Traces D\u2019Une Terre Disparue\",\"datePublished\":\"2025-12-15T12:00:00+00:00\",\"dateModified\":\"2025-12-15T22:41:38+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\"},\"wordCount\":442,\"commentCount\":0,\"image\":{\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue#primaryimage\"},\"thumbnailUrl\":\"https:\/\/static.africa-press.net\/senegal\/sites\/13\/2025\/12\/sm_1765867131.445389.jpg\",\"keywords\":[\"Senegal\"],\"articleSection\":[\"Divers\",\"Toutes les actualit\u00e9s\"],\"inLanguage\":\"fr-FR\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue#respond\"]}]},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\",\"url\":\"https:\/\/www.africa-press.net\/senegal\/toutes-les-actualites\/sous-nos-pieds-les-traces-dune-terre-disparue\",\"name\":\"Sous Nos Pieds, les Traces D\u2019Une Terre Disparue - 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