Meteorites Acapulco

Min, K., Farley, K. A., Renne, P. R. and Marti, K. (2003) Single-grain (U-Th)/He ages from phosphates in Acapulco meteorite and implications for thermal history. Earth and Planetary Science Letters, 209, 323-336. 

Nichols, R. H., Hohenberg, . M., Kehm, K., Kim, Y. and Marti, K. (1994) I-Xe studies of the Acapulco meteorite Absolute ages of individual phosphate grains and the Bjurbole standard. Geochimica et Cosmochimica Acta, 58, 2523-2561. 

Palme H., Schultz L., Spettel B., Weber H. W., Wanke H., Christophe Michel-Levy M., and Lorin J. C. (1981) The Acapulco meteorite chemistry, mineralogy and irradiation effects. Geochim. Cosmochim. Acta 45, 727-752. 

Bellas P., FieniC., TrieloffM., and JessbergerE. K. (1997) The coohng history of the Acapulco meteorite as recorded by the Pu and At- At chronometers. Geochim. Cosmochim. Acta 61, 3477-3501. 

Zipfel J., Palme H., Kennedy A. K., and Hutcheon I. D. (1995) Chemical composition and origin of the Acapulco meteorite. Geochim. Cosmochim. Acta 59, 3607—3627. 

This is approximately equivalent to the Mn-Cr closure age for Chervony Kut, the noncumulate eucrite with the highest individual Mn/ Mn initial ratio. Other achondrites, including a palla-site and the unusual basaltic achondrite Acapulco, have Mn-Cr ages 8-10Myr after the HED differentiation event. These timescales are consistent with the notion that a variety of differentiated meteorites sample various depths in asteroids of various sizes during this early epoch following accretion. 

Renne P. R. (2000) Ar-40/Ar-39 age of plagioclase from Acapulco meteorite and the problem of systematic errors in cosmochronology. Earth Planet. Sci. Lett. 175(1-2), 13-26. 

I-Xe experiments. Data in (a) are from Reynolds and Turner (1964). Labels next to points are extraction temperatures (in hundreds of degrees Celsius). Solid points are those defining the correlation line. Dashed line is at a Xe/ Xe ratio typical of chondritic meteorites. Data in (b) are from Brazzle et al. (1999). The extraction temperatures in (b) are actually the temperature of a heating coil containing the sample, rather than the sample itself In this case, even the low temperature extractions fall on the correlation line. A different denom-inator is used because the Xe in the Acapulco phosphates is dominated by fission-produced gas. For the sake of conversion, the trapped °Xe/ Xe ratio is typically about... 

Min K, Mundil R, Reime PR, Ludwig KR (2000) A test for systematic errors in " Ar- Ar geochronology through comparison with U-Pb analysis of a 1.1 Ga rhyolite. Geochim Cosmochim Acta 64 73-98 Min K, Farley KA, Reime P (2001) Single-grain (U-Th)/He Ages from apatites in Acapulco meteorite. 

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