Microcraters and solar flare tracks in crystals from carbonaceous chondrites and lunar brecciasResults of microcrater and solar-flare track studies of grains from the interiors of five carbonaceous chondrites and one lunar 'soil breccia' are combined to investigate variations in solar flare intensity, variations in micrometeorite particle flux, characteristics of interplanetary submicron particles, and the probable region in space where the precompaction irradiation occurred. The thickness turnover rate, material loss rate, and other parameters of the regolith-like surface where the meteorites must have formed are determined to a certain extent by considering published data on solar-wind and spallogenic species in the meteorites in conjunction with the present data. It is found that: (1) most irradiation features are most plausibly explained in terms of a regolith origin; (2) the shape of the solar-flare energy spectrum has not changed over the last 4.2 billion years; (3) the flux of small micrometeoroids about 4.2 billion years ago cannot have been more than 4 to 20 times higher than the flux today; and (4) parent-body regolith turnover rates were not extremely high.
Document ID
19770051834
Acquisition Source
Legacy CDMS
Document Type
Conference Proceedings
Authors
Goswami, J. N. (Chicago Univ. Chicago, IL, United States)
Hutcheon, I. D. (Chicago, University Chicago, Ill., United States)
Macdougall, J. D. (California, University La Jolla, Calif., United States)