منابع مشابه
Extinct 244Pu in ancient zircons.
We have found evidence, in the form of fissiogenic xenon isotopes, for in situ decay of 244Pu in individual 4.1- to 4.2-billion-year-old zircons from the Jack Hills region of Western Australia. Because of its short half-life, 82 million years, 244Pu was extinct within 600 million years of Earth's formation. Detrital zircons are the only known relics to have survived from this period, and a stud...
متن کاملExamples of twinning and parallel growth in zircons from some Precambrian granites and gneisses
Growth twins, parallel growths, and necked crystals are described from zircon populations from granitic gneisses from the Precambrian of SW. Greenland. From observations of the distribution of internal growth zones it is concluded that whereas twinning takes place early in the growth history of elbow twins it can occur at any time during crystallization of the zircon. Parallel growth is attribu...
متن کاملA Major KREEP-Basalt—Mare Basalt unconformity on the Moon
The lunar regolith records both the geological history and processes of the Moon and also that of particles from the Sun and galaxy. Such a record extends back to the age of the rock unit upon which the regolith is developed, but complex impact gardening and processing makes this record difficult to recover and interpret. Ancient rock units, such as lava flows, begin to have regolith developed ...
متن کاملBasalt weathering across scales
Weathering of silicate minerals impacts many geological and ecological processes. For example, the weathering of basalt contributes significantly to consumption of atmospheric carbon dioxide (CO2) and must be included in global calculations of such consumption over geological timeframes. Here we compare weathering advance rates for basalt (wD β ), where D and β indicate the scale at which the r...
متن کاملJurassic zircons from the Southwest Indian Ridge
The existence of ancient rocks in present mid-ocean ridges have long been observed but received less attention. Here we report the discovery of zircons with both reasonably young ages of about 5 Ma and abnormally old ages of approximate 180 Ma from two evolved gabbroic rocks that were dredged from the Southwest Indian Ridge (SWIR) in the Gallieni fracture zone. U-Pb and Lu-Hf isotope analyses o...
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ژورنال
عنوان ژورنال: The Journal of the Japanese Association of Mineralogists, Petrologists and Economic Geologists
سال: 1960
ISSN: 0021-4825,1883-0765
DOI: 10.2465/ganko1941.44.276