Vortex magnetic structure in framboidal magnetite reveals existence of water droplets in an ancient asteroid

Abstract

The majority of water has vanished from modern meteorites, yet there remain signatures of water on ancient asteroids. How and when water disappeared from the asteroids is important, because the final fluid-concentrated chemical species played critical roles in the early evolution of organics and in the final minerals in meteorites. Here we show evidence of vestigial traces of water based on a nanometre-scale palaeomagnetic method, applying electron holography to the framboids in the Tagish Lake meteorite. The framboids are colloidal crystals composed of three-dimensionally ordered magnetite nanoparticles and therefore are only able to form against the repulsive force induced by the surface charge of the magnetite as a water droplet parches in microgravity. We demonstrate that the magnetites have a flux closure vortex structure, a unique magnetic configuration in nature that permits the formation of colloidal crystals just before exhaustion of water from a local system within a hydrous asteroid.

Effects of Phosphate on Secondary Mineral Formation During the Bioreduction of Akaganeite (.β-FeOOH): Green Rust Versus Framboidal Magnetite

“…3). Other possibilities include formation by a route analogous to that proposed by Sweeney and Kaplan [71] for framboidal pyrite but with an undefined spherical Fe oxide precursor [65], or by direct precipitation from solution [64]. The formation of framboidal magnetite from a framboidal akaganeite precursor seems unlikely in our system, as we saw no indication of spherical or framboidal akaganeite aggregates in our control system containing pasteurized biomass ( Fig.…”

“…Relative Intensity Framboidal morphology (named for its raspberry-like shape) is not typical for magnetite; however, it has been observed in diverse terrestrial and extraterrestrial materials, including hydrocarbon deposits [60][61], sedimentary carbonate rocks [62][63], and carbonaceous meteorites [64][65]. Several processes leading to the formation of framboidal magnetite have been proposed.…”

The Orgueil meteorite: 150 years of history

“…Magnetite appears in Orgueil in a very wide range of crystal forms, including single crystals, spherical aggregates (spherulites and framboids), and screw‐shaped crystals (Kimura et al. ) called plaquettes (Figs. and ).…”

FORCulator: A micromagnetic tool for simulating first‐order reversal curve diagrams

“…Before inverse methods can be developed, however, it is necessary to have a comprehensive understanding of the forward problem. There have been some significant steps toward this goal for weakly interacting particles [Egli, 2006], but there is a gap in our understanding of FORC diagrams for strongly interacting particles, which are commonplace in natural systems, e.g., in intergrowths [Harrison et al, 2002;Evans et al, 2006;Feinberg et al, 2006], magnetotactic bacteria [Chen et al, 2007;Li et al, 2012Li et al, , 2013, clay-magnetite aggregates [Galindo-Gonzalez et al, 2009], and framboids [Kimura et al, 2013]. The aim of this paper is to develop a tool that solves the forward problem of generating FORC diagrams for strongly interacting single-domain particles with arbitrary spatial arrangement.…”