Chronologie et spatialisation de retombées de cendres volcaniques tardiglaciaires dans les massifs des Vosges et du Jura, et le plateau suisse

• Published in: Quaternaire
• Main Authors: Walter‑Simonnet, Anne‑Véronique, Bossuet, Gilles, Develle, Anne‑Lise, Bégeot, Carole, Ruffaldi, Pascale, Magny, Michel, Adatte, Thierry, Rossy, Michel, Simonnet, Jean‑Pierre, de Beaulieu, Jacques‑Louis, Vannière, Boris, Thivet, Matthieu, Millet, Laurent, Regent, Bruno, Wackenheim, Chantal
• Format: Article in Journal/Newspaper
• Language: French
• Published: Association française pour l’étude du quaternaire 2008
• Subjects: Téphrochronologie; Jura; Laacher See Tephra; Chaîne des Puys; Tardiglaciaire; Vosges; Vedde Ash; Suisse; Tephrochronology; Lateglacial; Switzerland; geo; envir; Katla; Le Plateau
• Online Access: https://doi.org/10.4000/quaternaire.2472; http://journals.openedition.org/quaternaire/2472

Establishment of a precise chronicle of the lateglacial and holocene climatic variations requires the use of various dating methods. Among them, tephrochronology allows high-resolution dating and synchronization of these events at a regional scale and sometimes at a continental scale. Study of the record of the climatic variations occuring in western Europe since twenty thousands years leads to the discovery of tephras levels and “cryptotephras” in sediments cored in lakes from the Jura and Vosges mountains, and the Swiss plateau. Some of these levels are invisible to the naked eye. Their detection was obtained using magnetic susceptibility measurement with a 5 mm step along the cores. Our observations allow to complete the western boundary of the southern distribution of the Laacher See Tephra (ca. 12,900 yr, Eifel, Germany). This tephra has been already described in others lacustrine sequences from the Jura and the western and northern Europe. In the sites we have studied, the volcanic glass shards show geochemical compositions comparable to those of the youngest phases of the Laacher See Tephra eruption. Other tephra levels, never described in this region until then, have been detected and characterized. Two very discrete tephra levels, only observed in sites from the Jura and the Swiss plateau, present ages, mineral assemblages and chemical compositions close to those of tephras that were emitted by the Puy de la Nugère (Chaîne des Puys, France) during the Alleröd (about 13,300 yr). Sites from the Vosges mountains are characterized by the occurrence of the rhyolitic Vedde Ash (ca. 12,000 yr, from the icelandic Katla volcano), deposited during the Younger Dryas. Presently, this is the most southwestern occurrence of the Vedde Ash. Our data make up the Eastern France Lateglacial tephrochrology and offer an additional chronological bridge between sedimentary sequences from northern and central Europe and those situated more westerly. They show the importance of the Laacher See Tephra and the Vedde Ash for ...