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Ar-40/ar-39 ages of maskelynite grains from alha 77005
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Nyquist, L. E. Delaney, J. S. Herzog, G. F. Park, J. Lindsay, F. N. Turrin, B. Swisher II, C. |
| Copyright Year | 2013 |
| Description | We present Ar-40/Ar-39 measurements for twelve small (20-60 micro-g) maskelynite samples from the heavily shocked martian meteorite ALHA 77005. The reported modal composition for ALHA 77005 is 50-60% olivine (Fa28), 30-40% pyroxene (Wo5Fs23En72), approx.8% maskelynite (An53), and approx.2% opaques by volume [1]). The meteorite is usually classified as a lherzolite. Previous Studies - Ar-40/Ar-39 results from previous work display disturbed release spectra [2,3]. In study [2], Ar-40/Ar-39 measurements on a 52-mg whole-rock sample produced an extremely disturbed release spec-trum, with all calculated apparent ages > 1 Ga, (Fig. 1). In a subsequent study [3], a light and a dark phase were analyzed. A 2.3-mg sample of the light, relatively low-K phase produced a disturbed release spectrum. For the first 20% of the Ar-39(sub K), most of the apparent ages exceeded >1 Ga; the remaining 80% yielded ages between 0.3-0.5 Ga. The integrated age for this phase is 0.9 Ga. |
| File Size | 90306 |
| Page Count | 2 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_20130011095 |
| Archival Resource Key | ark:/13960/t0vq7xs3c |
| Language | English |
| Publisher Date | 2013-03-18 |
| Access Restriction | Open |
| Subject Keyword | Geophysics Rocks Pyroxenes Spectra Meteorites Achondrites Snc Meteorites Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
