Thicknesses of some lunar mare basalt flows and ejecta blankets based on chemical kinetic data |
| |
| Authors: | Robin Brett |
| |
| Institution: | NASA Johnson Space Center, Houston, Texas 77058, U.S.A. |
| |
| Abstract: | Data on the kinetics of some chemical reactions occurring in lunar samples are used to estimate cooling rates over limited temperature ranges. These results, together with data on thermal conductivity and specific heats of lunar samples, have been applied to estimate the thicknesses of the cooling units.Estimates for mare basalts indicate that they were derived from cooling units no thicker than 10 m. Breccias are derived from cooling units up to a few meters in thickness. This suggests that most lunar breccias are the product of a series of relatively local events rather than large basin-forming events. If this conclusion is correct, the significance of the radiometric ages of lunar breccias needs to be re-evaluated, as does the assignment of breccias to individual basin-forming events on the basis of their trace element contents. If the breccias are a product of the major basin-forming events, it is unlikely that so many would show an age of about 4.0 b.y. It is likely that a large proportion of materials sampled would have escaped resetting by these major events, and a wider spread of ages would be observed. Attempts to link a given breccia to a specific basin-forming event on the basis of its crystallization age therefore appear to be unfounded. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
