U-Th/He Dating

Zeitler, Peter K.

doi:10.1007/978-94-007-6326-5_131-1

Cited by 2 publications

(1 citation statement)

References 64 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Calculating the 4 He gas retention age for GRV 99027 is not straightforward because all measured 4 He/ 3 He ratios are consistent with cosmogenic production, indicating that radiogenic 4 He is low or even absent. To calculate the age, we used the U (9 ppb), Th (31 ppb), and Sm (254 ppb) concentrations measured by Lin et al (2008) and the U-Th-Sm/ 4 He method (Farley 2002;Zeitler 2015). The upper limit on the 4 He retention age, calculated using the total 4 He concentration, is~156 Ma.…”

Section: Gas Retention Ages 4 He and 40 Ar Gas Retention Ages For Grvmentioning

confidence: 99%

The noble gas concentrations of the Martian meteorites GRV 99027 and paired NWA 7906/NWA 7907

Stephenson

Lin

Leya

2017

Meteorit & Planetary Scien

View full text Add to dashboard Cite

Here we present the isotopic concentrations of He, Ne, Ar, Kr, and Xe for the three Martian meteorites, namely Grove Mountains 99027 (GRV 99027), Northwest Africa 7906 (NWA 7906), and Northwest Africa 7907 (NWA 7907). The cosmic ray exposure (CRE) age for GRV 99027 of 5.7 ± 0.4 Ma (1σ) is consistent with CRE ages for other poikilitic basaltic shergottites and suggests that all were ejected in a single event ~5.6 Ma ago. After correcting for an estimated variable sodium concentration, the CRE ages for NWA 7906 and NWA 7907 of 5.4 ± 0.4 and 4.9 ± 0.4 Ma (1σ), respectively, are in good agreement with the CRE age of ~5 Ma favored by Cartwright et al. () for NWA 7034. The data, therefore, support the conclusion that all three basaltic regolith breccias are paired. The 40Ar gas retention age for NWA 7907 of ~1.3 Ga is in accord with Cartwright et al. (). For NWA 7906, we were unable to determine a 40Ar gas retention age. The 4He gas retention ages for NWA 7906 and 7907 are in the range of 200 Ma and are much shorter than the 40Ar gas retention age of NWA 7907, indicating that about 86–88% of the radiogenic 4He has been lost. The Kr and Xe isotopic concentrations in GRV 99027 are composed almost exclusively of Martian interior (MI) gases, while for NWA 7906 and NWA 7907, they indicate gases from the MI, elementally fractionated air, and possibly Martian atmosphere.

show abstract

Section: Gas Retention Ages 4 He and 40 Ar Gas Retention Ages For Grvmentioning

confidence: 99%

The noble gas concentrations of the Martian meteorites GRV 99027 and paired NWA 7906/NWA 7907

Stephenson

Lin

Leya

2017

Meteorit & Planetary Scien

View full text Add to dashboard Cite

show abstract

Helium in diamonds unravels over a billion years of craton metasomatism

et al. 2021

View full text Add to dashboard Cite

Chemical events involving deep carbon- and water-rich fluids impact the continental lithosphere over its history. Diamonds are a by-product of such episodic fluid infiltrations, and entrapment of these fluids as microinclusions in lithospheric diamonds provide unique opportunities to investigate their nature. However, until now, direct constraints on the timing of such events have not been available. Here we report three alteration events in the southwest Kaapvaal lithosphere using U-Th-He geochronology of fluid-bearing diamonds, and constrain the upper limit of He diffusivity (to D ≈ 1.8 × 10−19 cm2 s−1), thus providing a means to directly place both upper and lower age limits on these alteration episodes. The youngest, during the Cretaceous, involved highly saline fluids, indicating a relationship with late-Mesozoic kimberlite eruptions. Remnants of two preceding events, by a Paleozoic silicic fluid and a Proterozoic carbonatitic fluid, are also encapsulated in Kaapvaal diamonds and are likely coeval with major surface tectonic events (e.g. the Damara and Namaqua–Natal orogenies).

show abstract

U-Th/He Dating

Cited by 2 publications

References 64 publications

The noble gas concentrations of the Martian meteorites GRV 99027 and paired NWA 7906/NWA 7907

The noble gas concentrations of the Martian meteorites GRV 99027 and paired NWA 7906/NWA 7907

Helium in diamonds unravels over a billion years of craton metasomatism

Contact Info

Product

Resources

About