Origin of accretionary lapilli from the Pompeii and Avellino deposits of Vesuvius
Accretionary lapilli from the Pompeii and Avellino Plinian ash deposits of Vesuvius consist of centimeter-sized spheroids composed of glass, crystal, and lithic fragments of submillimeter size. The typical structure of the lapilli consists of a central massive core surrounded by concentric layers of fine ash with concentrations of larger clasts and vesicles and a thin outer layer of dust. Clasts within the lapilli larger than 125 ..mu..m are extremely rare. The median grain-size of the fine ash is about 50 ..mu..m and the size-distribution is well sorted. Most constituent particles of accretionary lapilli display blocky shapes characteristic of grains produced by phreatomagmatic hydroexplosions. We have used the scanning electron microscope (SEM) in conjunction with energy dispersive spectral analysis (EDS) to investigate the textural and chemical variation along traverses from the core to the rim of lapilli from Vesuvius.
- Research Organization:
- Arizona State Univ., Tempe (USA). Dept. of Geology; Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 6037392
- Report Number(s):
- LA-UR-83-1012; CONF-830815-7; ON: DE83011328
- Resource Relation:
- Conference: 18. annual Microbeam Analysis Society conference, Phoenix, AZ, USA, 8 Aug 1983
- Country of Publication:
- United States
- Language:
- English
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