Flore Van Maldeghem

University of Copenhagen

Large airbursts, the most frequent hazardous impact events, are estimated to occur orders of magnitude more frequently than crater-forming impacts. However, finding traces of these events is impeded by the difficulty of identifying them in the recent geological record. Here, we describe condensation spherules found on top of Walnumfjellet in the Sø...

A newly discovered sedimentary accumulation of micrometeorites in the Sor Rondane Mountains of East Antarctica, close to the Wideroefjellet summit at similar to 2750 m above sea level, is characterized in this work. The focus here lies on 2099 melted cosmic spherules larger than 200 mu m, extracted from 3.2 kg of sampled sediment. Although the Wide...

Rationale Micrometeorites are extraterrestrial particles smaller than ~2 mm in diameter, most of which melted during atmospheric entry and crystallised or quenched to form ‘cosmic spherules’. Their parentage among meteorite groups can be inferred from triple‐oxygen isotope compositions, for example, by secondary ion mass spectrometry (SIMS). This m...

Micrometeorites are estimated to represent the main part of the present flux of extraterrestrial matter found on the Earth’s surface and provide valuable samples to probe the interplanetary medium. Here, we describe large and representative collections of micrometeorites currently available to the scientific community. These include Antarctic colle...

Upon passage through Earth's atmosphere, micrometeorites undergo variable degrees of melting and evaporation. Among the various textural and chemical groups recognized among cosmic spherules, that is, melted micrometeorites, a subset of particles may indicate anomalously high degrees of vaporization based on their chemical and isotopic properties....

Micrometeorites, tiny particles from space (10 – 2000 μm), constantly reach Earth and carry crucial information about the composition and origin of the Solar System. This PhD project mainly focused on micrometeorites found in sedimentary deposits in the Sør Rondane Mountains of Antarctica, applying state-of-the-art petrographic, chemical, and isoto...

Cosmic dust particles originate from a wide variety of solar system and interstellar objects, including sources not identified among meteorite collections. Particles that survive atmospheric entry are retrieved on the Earth's surface as micrometeorites. The recovery of these micrometeorites has recently advanced to rooftop sites. Here, we present t...

Micrometeorites experience varying degrees of evaporation and mixing with atmospheric oxygen during atmospheric entry. Evaporation due to gas drag heating alters the physicochemical properties of fully melted cosmic spherules (CSs), including the size, chemical and isotopic compositions and is thus expressed in its chemical and isotopic signatures....

At the French synchrotron facility SOLEIL, a new X-ray imaging facility PUMA (Photons Utilisés pour les Matériaux Anciens) has been made available to scientific communities studying materials from cultural heritage. This new instrument aims to achieve 2D and 3D imaging with microscopic resolution, applying different analytical techniques including...

Unmelted micrometeorites represent unique extraterrestrial materials that largely preserved the original petrographic, mineralogical and geochemical properties of their precursor parent bodies or phases [e.g., 1]. Five unmelted and scoriaceous micrometeorites, with diameters varying between 142 and 408 µm, that were recovered from sediment traps in...