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2 results

  • 13 - Formation of Main Belt Asteroids

  • from Part III - Implications for the Formation and Evolution of the Solar System
  • Edited by Simone Marchi, Southwest Research Institute, Boulder, Colorado, Carol A. Raymond, California Institute of Technology, Christopher T. Russell, University of California, Los Angeles
  • Book:
    Vesta and Ceres
    Published online:
    01 April 2022
    Print publication:
    31 March 2022, pp 199-211

  • Summary

    From the viewpoint of planet formation in the Solar System, Main Belt asteroids are the remnants of the so-called planetesimal population, the building bricks of planets that formed ubiquitously all over the Solar Nebula. Over the last years evidence has grown that planetesimals formed big from the gravitational collapse of a local accumulation of mm–cm sized so-called pebbles, rather than small, as models of collisional coagulation would suggest. The precise size distribution of original planetesimals remains a central question in planetology. An asteroid (and other small bodies) could be a fragment of a larger parent body or it could be an original planetesimal. Here, we outline observational and theoretical constraints on the formation of MBAs. We discuss the current state of research on the size–frequency distribution, the ages of asteroids, and the implications on the formation of asteroids. We review planetesimal formation theory, specifically focusing on the initial sizes of primordial planetesimals.

  • Boron metasomatism in the Brabant Massif (Belgium): Geochemical and petrographical evidence of Devonian tourmalinite pebbles

  • C. Corteel, P. De Paepe
  • Journal:
    Netherlands Journal of Geosciences / Volume 82 / Issue 2 / July 2003
    Published online by Cambridge University Press:
    01 April 2016, pp. 197-208
    • Article
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  • New petrographical and geochemical evidence of tourmalinite pebbles from two Lower and three Middle Devonian formations from Belgium is presented. Petrography, REE, transition metal and microprobe data of the studied rocks suggest it are (meta)sediment-derived tourmalinites formed by boron metasomatism (and hydrothermal brecciation) in an intrusive setting. Tourmaline mineralizations within eastern Avalonia are known in south-east Ireland, the English Lake District and East Anglia. Based on previously suggested relations between Early Palaeozoic igneous activity in last two mentioned regions and the Brabant Massif, it is presumed that the Brabant Massif also underwent granite-related tourmalinization and that this was the source of the studied pebbles. Petrologie differences between pebbles found in Middle Devonian formations and pebbles from Lower Devonian formations, suggest that fluid circulation occurred on a regional scale, possibly extending into the Stavelot massif.