Bland, P. A.; Berry, F. J.; Jull, A. J. T.; Smith, T. B.; Bevan, A. W. R.; Cadogan, J. M.; Sexton, A. S.; Franchi, L. A. and Pillinger, C. T.
|DOI (Digital Object Identifier) Link:||http://dx.doi.org/doi:10.1023/A:1022440217371|
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Ordinary chondrite finds, terrestrial age dated using 14C analyses, from different meteorite accumulation sites, have been examined by Mössbauer spectroscopy to quantitatively determine terrestrial oxidation. We observe differences in weathering rates between sites, and also between different chondrite groups. A comparison of weathering over time, and its effect in 'eroding' meteorites, together with the number and mass distribution of meteorites in each region, enables us to derive estimates of the number of meteorite falls over a given mass per year. Studies of how the oxygen isotopic composition of samples varies with weathering indicate that incipient alteration may occur without a pronounced isotopic effect, possibly due to weathering of silicates to topotactically oriented smectite confined spaces where the water volume is limited. This finding has profound implications for the use of oxygen isotopes as a tool in understanding water-rock interaction. It also may reconcile previously contradictory data regarding the nebular or asteroidal location of pre-terrestrial aqueous alteration. Finally, Mössbauer spectroscopy is also found to be a useful tool in determining mineral abundance in carbonaceous chondrites, where a fine-grained matrix makes traditional approaches inapplicable. Again, the results have implications for the modification of chondritic materials in the early solar system.
|Item Type:||Journal Article|
|Extra Information:||The original publication is available at www.springerlink.com|
|Keywords:||Mössbauer spectroscopy; meteorites; meteorite impact rates; nebula processes; asteroidal processes; chondrite mineralogy|
|Academic Unit/Department:||Science > Life, Health and Chemical Sciences
Other Departments > Other Departments
Science > Physical Sciences
|Interdisciplinary Research Centre:||Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)|
|Depositing User:||Users 6044 not found.|
|Date Deposited:||17 Jul 2006|
|Last Modified:||02 Dec 2010 19:49|
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