Earth’s crustal antiquity confirmed
Nature Geoscience
2014년2월24일

The oldest known fragment of continental crust on Earth is 4.4 billion years old, reports a study published online this week in Nature Geoscience. Although past studies infer such an age for Earth’s oldest minerals, the rigour of the isotopic techniques used, and thus the robustness of the age, had been vigorously debated.
John Valley and colleagues map the distribution of lead isotopes within a single grain of the mineral zircon, taken from the Jack Hills region of Western Australia. The age of the oldest Jack Hills zircon has previously been assessed using the uranium-lead radio-isotopic dating technique; according to these measurements, the zircon is 4.4 billion years old. Yet lead isotopes can move around inside the mineral, potentially leading to erroneously old estimates. However, the researchers show that although lead isotopes do move and cluster into small groups, this heterogeneity occurs on such a small scale that the radio-isotopic age measurements will not be affected. By confirming the antiquity of the grain, the results imply that continental crust began forming on Earth about 100 million years after the Earth was struck by a large impact that probably formed the Moon.
In an accompanying News and Views article, Samuel Bowring writes: “The results show that single grains of ancient zircon can yield a rich history, the implications of which date back to the very earliest history of our planet.”
doi: 10.1038/ngeo2075
리서치 하이라이트
-
3월4일
Environment: Reservoirs account for more than half of water storage variabilityNature
-
3월2일
Evolution: Neanderthals may have heard just like usNature Ecology & Evolution
-
3월2일
Geoscience: Earth’s atmosphere may return to low-levels of oxygen in one billion yearsNature Geoscience
-
2월26일
Environment: Shifting from small to medium plastic bottles could reduce PET wasteScientific Reports
-
2월24일
Environment: European forests more vulnerable to multiple threats as climate warmsNature Communications
-
2월11일
Environment: Global CFC-11 emissions in declineNature