Testing an integrated chronology: I‐Xe analysis of enstatite meteorites and a eucrite

Abstract

Iodine-129 ages are mapped to the absolute Pb-Pb time scale using the calibration proposed by Gilmour et al. (2006) who place the closure age of Shallowater at 4563.3 ± 0.4 Ma. Comparison of the combined 129 I-Pb data with associated 53 Mn ages, for objects that have been dated by both systems, indicates that all three chronometers evolved concordantly in the early solar system. The enstatite chondrites are offset from the linear array described by asteroid-belt objects when 53 Mn ages are plotted against combined 129 I-Pb data, supporting the suggestion that 53 Mn was radially heterogeneous in the early solar system.

Non-basaltic asteroidal magmatism during the earliest stages of solar system evolution: A view from Antarctic achondrites Graves Nunatak 06128 and 06129

“…Q-Xenon is typical of primitive chondritic meteorites; its presence here demonstrates retention of a significant signature of extreme volatiles from a presumed primitive parent. Concentrations of trapped xenon components (fissiogenic, iodogenic, trapped) are in a range similar to that observed among milligram samples of lodranites (10 8 -10 10 atoms 132 Xe g À1 (Crowther et al, 2009) and significantly higher than those reported for evolved achondrites, which also tend to exhibit little or no iodogenic 129 Xe (Patzer et al, 2003;Busfield et al, 2008). Assuming iodine was trapped with 129 I/ 127 I $ 10 À4 , 129 Xe concentrations of <10 10 atoms g À1 (Table 5) correspond to iodine concentrations <20 ppb, consistent with the values obtained for evolved achondrites (Busfield et al, 2008).…”

Highly siderophile element and osmium isotope evidence for postcore formation magmatic and impact processes on the aubrite parent body

“…Chronology of aubrites and the aubrite parent body(ies) is not well established, and different isotope systems yield different results. Ages for Shallowater (I-Xe age: 4.563 ± 0.001 Ga; Gilmour et al 2006), Khor Temiki (I-Xe age: 4.566 ± 0.002 Ga; Busfield et al 2008), Bishopville (I-Xe age: 4.54 ± 0.01 Ga ;Podosek 1970), and Pen˜a Blanca Spring (Mn-Cr age: 4.563 ± 0.003 Ga; Shukolyukov and Lugmair 2004) confirm formation in the earliest stages of the solar system. Less precise Rb-Sr and Ar-Ar ages confirm formation of most aubrites around 4.5 Ga (Norton County, Rb-Sr: 4.7 ± 0.1 Ga, Ar-Ar: 4.2-4.5 Ga, Bogard et al 1967Bogard et al , 2010Norton County, Rb-Sr: 4.48 ± 0.04 Ga, Minster and Allegre 1976;Shallowater, Ar-Ar: 4.53 Ga, McCoy et al 1995).…”

“…Ages for Shallowater (I‐Xe age: 4.563 ± 0.001 Ga; Gilmour et al. 2006), Khor Temiki (I‐Xe age: 4.566 ± 0.002 Ga; Busfield et al. 2008), Bishopville (I‐Xe age: 4.54 ± 0.01 Ga; Podosek 1970), and Peña Blanca Spring (Mn‐Cr age: 4.563 ± 0.003 Ga; Shukolyukov and Lugmair 2004) confirm formation in the earliest stages of the solar system.…”

An early I‐Xe age for CB chondrite chondrule formation, and a re‐evaluation of the closure age of Shallowater enstatite

“…Our base data set includes the Gujba I-Xe interval of this work combined with the Pb-Pb age of Krot et al (2005) and the data set of Gilmour et al (2006) where we adopt the 4566.7 ± 1.0 Pb-Pb age of Amelin et al (2007) for the oldest chondrules. Since the Mn-Cr to I-Xe conversion is on a less certain footing (Busfield et al 2008), we exclude data derived indirectly via Mn-Cr that were included in the previous work.…”