142Nd Evidence for Early (94.53 Ga) Global Differentiation of the Silicate Earth
نویسندگان
چکیده
New high-precision samarium-neodymium isotopic data for chondritic meteorites show that their 142Nd/144Nd ratio is 20 parts per million lower than that of most terrestrial rocks. This difference indicates that most (70 to 95%) of Earth’s mantle is compositionally similar to the incompatible element–depleted source of mid-ocean ridge basalts, possibly as a result of a global differentiation 4.53 billion years ago (Ga), within 30 million years of Earth’s formation. The complementary enriched reservoir has never been sampled and is probably located at the base of the mantle. These data influence models of Earth’s compositional structure and require revision of the timing of global differentiation on Earth’s Moon and Mars.
منابع مشابه
142Nd evidence for early (>4.53 Ga) global differentiation of the silicate Earth.
New high-precision samarium-neodymium isotopic data for chondritic meteorites show that their 142Nd/144Nd ratio is 20 parts per million lower than that of most terrestrial rocks. This difference indicates that most (70 to 95%) of Earth's mantle is compositionally similar to the incompatible element-depleted source of mid-ocean ridge basalts, possibly as a result of a global differentiation 4.53...
متن کاملIsotopic constraints on the age and early differentiation of the Earth.
The Earth's age and early differentiation history are re-evaluated using updated isotopic constraints. From the most primitive terrestrial Pb isotopic compositions found at Isua Greenland, and the Pilbara of Western Australia, combined with precise geochronology of these localities, an age 4.49 +/- 0.02 Ga is obtained. This is interpreted as the mean age of core formation as U/Pb is fractionate...
متن کاملCoupled 182W-142Nd constraint for early Earth differentiation.
Recent high precision (142)Nd isotope measurements showed that global silicate differentiation may have occurred as early as 30-75 Myr after the Solar System formation [Bennett V, et al. (2007) Science 318:1907-1910]. This time scale is almost contemporaneous with Earth's core formation at approximately 30 Myr [Yin Q, et al. (2002) Nature 418:949-952]. The (182)Hf-(182)W system provides a power...
متن کاملA Mercury-like component of early Earth yields U in the core and high mantle 142Nd
Recent 142Nd isotope data indicate that the silicate Earth has an Sm/Nd ratio greater than the supposed chondritic building blocks of the planet. This elevated Sm/Nd has been ascribed either to a “hidden” reservoir in the Earth1,2 or to loss of an early-formed terrestrial crust by impact ablation3. Since removal of crust by ablation would also remove the heat producing elements, K, U and Th, th...
متن کاملEarly differentiation of the Earth and the Moon.
We examine the implications of new 182W and 142Nd data for Mars and the Moon for the early evolution of the Earth. The similarity of 182W in the terrestrial and lunar mantles and their apparently differing Hf/W ratios indicate that the Moon-forming giant impact most probably took place more than 60Ma after the formation of calcium-aluminium-rich inclusions (4.568Gyr). This is not inconsistent w...
متن کامل