Rubidium-Strontium Chronology and Chemistry of Lunar Material

Abstract

Igneous lunar rocks divide into two chemical types, probably representing two rock units. They form separate close groups on the isochron diagram; no total rock age is valid unless the rocks are cogenetic. Mineral isochrons prove that one type has an age of 3.80 +/-0.11 billion years, equal to the line joining total-rock groups, and the initial ratio of strontium-87 to strontium-86 of both types is close to 0.6994. Soil and breccias chemically resemble a mixture of the two igneous types, with a superimposed variation of mineral components, plus a small transferred component rich in nickel, copper, zinc, and possibly stron-tium-87.

Geochemistry, petrology and ages of the lunar meteorites Kalahari 008 and 009: New constraints on early lunar evolution

“…These ratios are close to the estimated LUNI value of 0.69903 (Papanastassiou et al, 1970), derived from highland rock data. In general, the measured 87 Sr/ 86 Sr values in plagioclase from various lunar rocks do not exceed 0.70000 (Compston et al, 1970;Papanastassiou et al, 1970;Snyder and Taylor, 1994;Nyquist et al, 1996;Norman et al, 1998) and the lowest 87 Sr/ 86 Sr ratio ever measured in any terrestrial mate- Kalahari 009 compared to selected mare basalts. For references see Tables 5 and 7. rial is as high as 0.700510 (early Archean barite from Pilbara, Australia, McCulloch, 1994).…”

Simultaneous analysis of abundance and isotopic composition of nitrogen, carbon, and noble gases in lunar basalts: Insights into interior and surface processes on the Moon

“…The sample which releases the most 40 Ar (totalled across all temperature steps) is 14053, with a crystallisation age of 3.94 Ga (Stettler et al, 1973). By comparison, the 2 samples with the lowest 40 Ar releases (12040 and 15555) have younger crystallisation ages of 3.21 Ga (Compston et al, 1971) and 3.32 Ga (Wasserburg and Papanastassiou, 1971), respectively.…”

Mechanisms for incompatible-element enrichment on the Moon deduced from the lunar basaltic meteorite Northwest Africa 032

“…In this model the Moon follows a path of chondritic evolution until 4.42 Ga and then differentiates forming the source regions of lunar basalts (Nyquist et al, 1995;Nyquist and Shih, 1992). Data are from Borg et al (2004), Carlson and Lugmair (1979), Compston et al (1970Compston et al ( , 1971, Gaffney et al (2007b), Misawa et al (1993), Nyquist et al (1975Nyquist et al ( ,1977Nyquist et al ( , 1981Nyquist et al ( , 2005Nyquist et al ( , 2007, Paces et al (1991), Wasserburg (1970, 1973), , Rankenburg et al (2006), Shih et al (1992Shih et al ( , 2002, Snyder et al (1994Snyder et al ( , 1997, Torigoye-Kita et al (1995), and Unruh et al (1984). of $+0.3.…”