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Laboratory simulation of terrestrial meteorite weathering using the Bensour (LL6) ordinary chondrite

Lee, M. R., Smith, C. L., Gordon, S. H. and Hodson, M. E. (2006) Laboratory simulation of terrestrial meteorite weathering using the Bensour (LL6) ordinary chondrite. Meteoritics & Planetary Science, 41 (8). pp. 1123-1138. ISSN 1086-9379

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Abstract/Summary

Laboratory dissolution experiments using the LL6 ordinary chondrite Bensour demonstrate that meteoritic minerals readily react with distilled water at low temperatures, liberating ions into solution and forming reaction products. Three experiments were performed, all for 68 days and at atmospheric fO(2) but using a range of water/rock ratios and different ternperatures. Experiments I and 2 were batch experiments and undertaken at room temperature, whereas in experiment 3, condensed boiling water was dripped onto meteorite subsamples within a Soxhlet extractor. Solutions from experiment 1 were chemically analyzed at the end of the experiment, whereas aliquots were extracted from experiments 2 and 3 for analysis at regular intervals. In all three experiments, a very significant proportion of the Na, Cl, and K within the Bensour subsamples entered solution, demonstrating that chlorapatite and feldspar were especially susceptible to dissolution. Concentrations of Mg, Al, Si, Ca, and Fe in solution were strongly affected by the precipitation of reaction products and Mg and Ca may also have been removed by sorption. Calculations predict saturation of experimental solutions with respect to Al hydroxides, Fe oxides, and Fe (oxy)hydroxides, which would have frequently been accompanied by hydrous aluminosilicates. Some reaction products were identified and include silica, a Mg-rich silicate, Fe oxides, and Fe (oxy)hydroxides. The implications of these results are that even very short periods of subaerial exposure of ordinary chondrites will lead to dissolution of primary minerals and crystallization of weathering products that are likely to include aluminosilicates and silicates, Mg-Ca carbonates, and sulfates in addition to the ubiquitous Fe oxides and (oxy)hydroxides.

Item Type:Article
Refereed:Yes
Divisions:Faculty of Science > School of Archaeology, Geography and Environmental Science > Department of Geography and Environmental Science
Faculty of Science > School of Archaeology, Geography and Environmental Science > Earth Systems Science
Interdisciplinary centres and themes > Soil Research Centre
ID Code:3743
Uncontrolled Keywords:ANTARCTIC METEORITES AQUEOUS ALTERATION CHEMICAL-ANALYSES DISSOLUTION MECHANISM PRODUCTS STONY PHYLLOSILICATES SPECTROSCOPY METAMORPHISM
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