A search for ancient detrital zircons in Zimbabwean sediments

Abstract

86 detrital zircon grains from Archaean quartzites from the Mweza and Shurugwi greenstone belts have been dated by the ion probe SHRIMP. Nine of these give ages of 3.75-3.80 Ga, older than any Zimbabwean rocks so far satisfactorily dated, and the Tokwe-Zvishavane gneisses are a possible source for these old grains. However, none are comparable in age with the 4.2Ga zircons discovered in Western Australia. If such old grains exist in the sample it is unlikely ( P > 0.05) that their abundance could exceed 3%. Ages of the younger grains are broadly consistent with the presumed age of the quartzites sampled, though some high Th/U grains in the Shurugwi sample may be anomalously young.

Topographic architecture and drainage reorganization in Southeast China: Zircon U-Pb chronology and Hf isotope evidence from Taiwan

“…The sample surface was cleaned with ethanol to eliminate possible contamination before analysis. In order to reduce the probability of error (Dodson et al, 1988;Zhang et al, 2012), we analyzed at least 120 zircon grains from each sample.…”

Lithofacies control in detrital zircon provenance studies: Insights from the Cretaceous Methow basin, southern Canadian Cordillera

“…The statistical adequacy assessment of Dodson et al (1988) states that 59 grains must be analyzed to achieve 95% confidence of finding every population that exists at the 5% level in a given sample, according to the equation P ϭ (1-ƒ) n , where P is the probability of missing a provenance component, ƒ is the proportion of that component in the total population, and n is the number of grains analyzed. All of the samples presented here consist of 60 individual analyses.…”

A record of continental collision and regional sediment flux for the Cretaceous and Palaeogene core of SE Asia: implications for early Cenozoic palaeogeography

“…These are the Ciemas (Middle Eocene), Bayah (Upper Eocene), Cikalong and Cijengkol (Lower Oligocene) Formations. At least 60 grains per sample were analysed to ensure 95% confidence levels in defining populations present at 5% (Dodson et al 1988;Anderson 2005).…”