Petrographic and geochemical characterization of the micrometeorite collection from the Sør Rondane Mountains: Nature and origin of the extraterrestrial flux to Earth

• Main Author: Soens, Bastien
• Other Authors: Debaille, Vinciane, Goderis, Steven, Claeys, Philippe, Gao, Yue, Mattielli, Nadine, Folco, Luigi, Schmitz, Birger
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Universite Libre de Bruxelles 2021
• Subjects: Géologie et minéralogie; Géologie; oxygen isotopes; atmospheric effects; isotopes d'oxygènes; effets atmosphériques; Antarctic; The Antarctic; East Antarctica; Dronning Maud Land; Transantarctic Mountains; Sør-Rondane; Sør Rondane Mountains; Antarc*; Antarctica
• Online Access: http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/331729; https://dipot.ulb.ac.be/dspace/bitstream/2013/331729/5/ContratDiSoens.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/331729/3/PhDBastienSoensSeptember2021.pdf; https://dipot.ulb.ac.be/dspace/bitstream/2013/331729/4/TableOfContentsBastienSoens.pdf

The Antarctic continent has traditionally been a successful searching ground for meteoritic material due to its cold and dry climate. Meteorites, and their microscopic analogues micrometeorites, were originally sampled from Antarctic ice and snow. Recently, however, a large collection of micrometeorites was discovered in sedimentary traps and moraine deposits from the Transantarctic Mountains, where extraterrestrial dust particles have accumulated for a prolonged time span (ca. 3–4 Ma). Micrometeorites (or ‘cosmic dust’) show unique chemical and isotopic signatures, which originate from a large and diverse amount of asteroidal and cometary bodies within the Solar System. In addition, they document major events such as the origin and evolution of the Solar System, and provide insight into the source region of their precursor bodies. These sedimentary deposits consequently represent a valuable archive that documents the flux of extraterrestrial material to Earth and ancient meteoritic events over Antarctica.Yet, much of this information is lost during the atmospheric entry stage, where cosmic dust is subjected to frictional heating and is partially or completely molten down. This may significantly alter the original physicochemical and isotopic properties of extraterrestrial dust particles. A thorough understanding of these physicochemical processes is thus required to reconstruct the atmospheric entry of cosmic dust (but also larger objects) and interpret their chemical and isotopic data. During the course of this PhD research, multiple sedimentary deposits from the Sør Rondane Mountains (Dronning Maud Land, East Antarctica) were petrographically examined and chemically-isotopically characterized using state-of-the-art instruments. Furthermore, various experiments and numerical models were constructed to replicate the atmospheric entry stage of both small- and large-sized meteoritic material. This study has demonstrated that the Sør Rondane Mountains sedimentary deposits contain a rich and pristine variety of ...